Stormwater Master Plan-2001

STORMWATER
MASTER PLAN
DARE COUNTY
NORTH CAROLINA
JL1NE 45 2001
Prepared By:
URS CORPORATION
Raleigh, North Carolina

I STORMWATER MASTER PLAN
DARE COUNTY
North Carolina
1
June 4, 2001
The preparation of this report was financed in part through a grant provided by the North
ICarolina Coastal Management Act of 1972, as amended, which is administered by the office of
Ocean and Coastal Resource Management, National Oceanic and Atmospheric Administration.
Prepared by:
'
URS Corporation
3109 Poplarwood Court, Suite 301
Raleigh, North Carolina 27604
[phone]
Fax: [phone]

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DARE COUNTY
' TABLE OF .CONTENTS STORMWATER MASTER PLAN
Section Page
' Executive Summary ........................................................................................................ E-1
Chapter 1 - Purpose and Goals
1.1 Purpose of the Master Plan......................................................................................1-1
1.2 Goals of the Plan.....................................................................................................1-1
' 1.3 Structure of the Plan................................................................................................1-2
1.4 Methodology............................................................................................................1-3
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Chapter 2 - Regulation/Ordinance Review
2.1
Federal Regulations.................................................................................................
2-1
2.2
State Regulations.....................................................................................................
2-5
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2.2.1 Division of Coastal Management..................................................................
2-5
2.2.2 Division of Land Resources..........................................................................
2-6
2.2.3 Division of Water Quality..............................................................................
2-7
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2.2.4 'North Carolina Division of Highways.............................................................
2-11
2.2.5 NCDOT Subdivision Roads..........................................................................
2-16
2.2.6 NCDOT Policy on Street and Driveway Access to Highways ........................2-17
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2.3
Local Ordinances.....................................................................................................
2-18
Chapter
3 - Policy
'
3.1
Responsibilities........................................................................................................
3-1
3.2
Stormwater Management.........................................................................................
3-1
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3.2.1 Public Education/Involvement........................................................................
3.2.2 Pollution Prevention.......................................................................................
3-1
3-1
3.2.3 Illicit Discharge Detection and Elimination......................................................
3-2
3.2.4 Increased Runoff Due to Development...........................................................
3-3
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3.3
Drainage System Design, Operation, and Maintenance ...........................................
3-3
3.4
Best Management Practices....................................................................................
3-3
3.5
Floodplain Development...........................................................................................
3-4
Overview
Chapter
4 - County
4.1
4.2
Setting......................................................................................................................4-1
Hydrography............................................................................................................
4-1
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4.3
Hydrologic and Hydraulic Characteristics4-1
4.3.1 Waterbodies.................................................................................................
4-1
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4.3.2 Soils.............................................................................................................
4-2
4.4
Water Quality Characteristics...................................................................................
4-4
4.5
Land Use.................................................................................................................
4-5
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4.6
Effects on Water Quality...........................................................................................
4-5
4.7
Effects on Water Quantity........................................................................................
4-6
4.8
Future Development.................................................................................................
4-7
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DARE COUNTY
TABLE OF CONTENTS STORMWATER MASTER PLAN
Section
Page
Chapter 5 — Drainage Problem Area Recommendations
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5.1 Selection Criteria..................................:...................................................................
5.2 Evaluation and Recommendations...........................................................................
5-1 .
5-2
5.2.1 Mainland.......................................................................................................5-2
5.2.2 Roanoke Island............................................................................................
5-2
5.2.3 Northern Beaches.........................................................................................
5-6
5.2.4 Southern Beaches/Hatteras Island...............................................................
5-9
5.2.5 Countywide Drainage Issues........................................................................
5-16
5.3 Water Quality Evaluation..........................................................................................
5-16
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5.4 Operation and Maintenance . .
5-17
Chapter 6 - Stormwater. Management Program
6.1 Recommendation Summary .....................................................................................
6-1
6.2 Project Selection Criteria..........................................................................................
6-1
6.3 Capital Improvement Program.................................................................................
6-3
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6.4 Operation and Maintenance Program.......................................................................
6-3
6.5 Funding....................................................................................................................6-4
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6.6 Public Involvement...................................................................................................
Chapter 7 - References
6-6
LIST OF APPENDICES
Appendix A North Carolina Stormwater Management Regulations
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Appendix B North Carolina Stormwater Management Permit
Appendix C Public Information Flyers
Appendix D North Carolina Sewage Treatment and Disposal Systems Regulations
Appendix E Dare County Soil Characteristics
Appendix F Charlotte -Mecklenburg Stormwater Services Credit Application Instruction
Manual
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LIST OF TABLES
Table 4-1
Stormwater Pollutants
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Table 4-2
Table 4-3
Population Data Dare County
Population Data Dare County Municipalities
Table 5-1
Recommendations
Table 6-1
Project Selection Criteria and Rankings
Table 6-2
Capital Improvement Program
LIST OF FIGURES
Figure 4-1
Location Map
Figure 4-2
Hydrologic Units
Figure 5-1
Mainland Drainage Problem Areas
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Figure 5-2
Roanoke Island Drainage Problem Areas
Figure 5-3
Northern Beaches Drainage Problem Areas
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Figure 5-4
Southern Beaches/Hatteras Island Drainage Problem Areas
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DARE COUNTY
EXECUTIVE SUMMARY STORMWATER MASTER PLAN
The Dare County Stormwater Master Plan provides an outline of the stormwater management
policies and actions for the unincorporated portions of Dare County. This document provides
direction for stormwater management for the County. The starting point for this Plan begins with
the purpose, goals, and objectives described in this chapter.
The purpose of the Dare County Stormwater Master Plan is to provide a comprehensive and
unified framework for stormwater management which follows the Master Plan, complies with
all regulations, and includes a Capital Improvement Program that will benet'it the entire
County.
The following goals provide the direction in meeting the purpose of improving hydrological functions
and of protecting and improving water quality:
1) Evaluate the ponding/drainage and water quality problems in the County and recommend
actions to mitigate these problems.
2) Provide a capital improvement program and outline maintenance actions that incorporate
recommendations from the plan.
3) Outline an implementation plan for recommended action items.
An overview of federal, state, and County regulations and ordinances pertaining to stormwater
management are provided in Chapter Two. Policy regarding responsibilities, ordinances, system
operation and maintenance, easement acquisition, and public involvement is described in Chapter
Three. An overview of the County with regard to hydrography, hydrology, hydraulics, and land use
is presented in Chapter Four. The water ponding and drainage problems in the county are
described and action items for these problems are provided in Chapter Five. The policy,
maintenance, and capital improvement action items described in Chapter Six should be considered
the first steps in working to achieve a sound stormwater management program. Further information
such as detailed tasks for each action item should be addressed in future tasks.
The recommendations for each area of concern were evaluated based upon the safety, water
quantity, and water quality benefits provided by the recommended solution. Severe ponding occurs
in several areas, and water often covers the roadways causing potential safety hazards. The areas
of concern and recommended solutions are described in Chapter Five. The evaluation criteria are
presented in Chapter Six.
Preliminary, order -of -magnitude cost estimates are provided in Chapter Six. Future adjustments to
these program costs will have to be made as more information (survey, modeling, etc.) is completed.
Additional public input is also important as the stormwater management program proceeds. Public
education and public involvement is critical to a successful stormwater management program.
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' CHAPTER ONE DARE COUNTY
PURPOSE AND GOALS STORMWATER MASTER PLAN
' The Dare County Stormwater Master Plan (Plan) is a document that outlines an approach to
stormwater management for the unincorporated portions of Dare County. This document provides
direction for stormwater management for the Dare County (County). The starting point for this Plan
' begins with the purpose, goals, and objectives described in this chapter.
Stormwater master plans that have the most success are the ones with clear purpose, goals and
' action items. In order to develop a clear purpose and goals, it is necessary to identify the problems
or potential problems in the watershed. Drainage/ponding and water quality within the County have
been identified as problems and the purpose and goals described below provide direction for the
' future stormwater management effort to improve these problems.
1.1 PURPOSE
' The purpose of the Dare County Stormwater Master Plan is to provide a comprehensive and
unified framework for stormwater management which follows the Master Plan, complies with
all regulations, and includes a Capital Improvement Program that will benefit the entire
' County.
The purpose of the Stormwater Master Plan is to provide a framework for a Stormwater
Management Program that will restore hydrological functions and protect water quality within the
County. The framework for the Stormwater Management Program will incorporate the policies and
procedures already established by the County, provide new program components, and recommend
' changes to existing ordinances and policies. The implementation of these recommended policies
and projects is an important step to having an effective and substantial program.
The Plan will identify the components of the Stormwater Management Program and outline the
' action items for implementation. The recommended action items will help to meet the goals for the
program, which are described in the next section.
' 1.2 GOALS OF THE PLAN
The goals of the plan are to provide the direction needed to meet the purpose of improving
' hydrological functions and protecting and improving water quality. The specific goals are to:
1. Evaluate the water quantity and water quality problems in the County and recommend
' actions to mitigate these problems.
2. Provide a capital improvement program and outline maintenance actions that incorporate
' recommendations from the plan.
3. Outline an implementation plan for recommended action items.
' Action items are necessary to carry out the work in achieving these goals. The action items
recommended for each area of the Stormwater Management Program are summarized in Chapter
6. The following bolded items are the action items for the Dare County Stormwater Management
Program.
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PURPOSE AND GOALS STORMWATER MASTER PLAN
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9. Evaluate the water drainage problems in the County and recommend actions to mitigate
these problems.
This master plan will evaluate the water quality and quantity problems on the island and discuss
recommended solutions. The solutions may need to be policy decisions that require revisions to
the existing ordinances or actions such as a maintenance project to restore the capacity of an
existing ditch.
2. Provide a capital improvement program and outline maintenance actions that incorporate
recommendations from the plan.
The recommended capital improvements and maintenance actions will be prioritized in order to
create a program that outlines budget requirements. Funding needs will be discussed and future
actions with regards to the stormwater management program will be provided.
3. Outline an implementation plan for recommended action items.
An implementation plan for the action items is necessary in order make sure that the vision and
goals are achieved. A plan can only succeed if it is implemented and not collecting dust on a shelf.
1.3 STRUCTURE OF THE PLAN
Chapter One - Purpose and Goals
The purpose and goals have been described and the contents of the plan are listed in this section.
The methodology is provided to describe the basis for the recommendations.
Chapter Two - Regulation/Ordinance Review
In this chapter all federal, state and local regulations and ordinances relating to stormwater will be
reviewed.
Chapter Three - Policy
In this chapter, the existing policy with regards to stormwater management is described. Changes
to existing policy and new areas requiring a policy decision action are provided.
Chapter Four — County Overview
This chapter provides a description of the physical setting and the interaction of land use, soil types,
water features, and hydrology and their effect on water quantity and quality.
Chapter Five — Watershed Characteristics
The characteristics of the County, along with the quantity and quality problems, are described and
action items recommended.
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' CHAPTER ONE DARE COUNTY
PURPOSE AND GOALS STORMWATER MASTER PLAN
' Chapter Six - Stormwater Management Program
The action items from the preceding chapters are summarized. The estimated costs for the
' recommended action items are provided in this chapter. Funding sources are identified.
1.4 METHODOLOGY
' The methodology for this Plan is to use existing data to evaluate and recommend the action items
necessary to achieve the stated goals. Problem area locations and descriptions for each of the
hydrologic units have been obtained from Dare County personnel, NRCS personnel, citizens, and
' water quality monitoring data. Public input to the stormwater management plan was obtained
during public workshops held in Manteo and Buxton.
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CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
Decisions the County currently makes regarding stormwater issues have an effect on future water
quality, storm drain system performance, and system condition. This chapter outlines the existing
federal, state and County regulations and ordinances regarding stormwater management and
evaluates policy changes necessary for effective management in the future.
2.1 FEDERAL REGULATIONS
This section provides a summary of federal regulations that presently define or in the future may
affect stormwater management requirements for the County. The goal of this review is to identify
and summarize the regulatory and technical issues that must be incorporated into the County's
stormwater management and development policies. The summarized requirements presented in
this section will subsequently be compared to existing County stormwater management policies with
recommended modifications provided as necessary.
The Clean WaterAct
In 1972, Congress amended the Federal Water Pollution Control Act, referred to as the Clean Water
Act (CWA), to prohibit the discharge of any pollutants to waters of the United States from a point
source, unless the discharge is authorized by an National Pollutant Discharge Elimination System
(NPDES) permit. As pollution control measures for industrial process wastewater and municipal
sewage were implemented and refined, it became evident that more diffuse sources of water
pollution were adversely impacting water quality. In particular, stormwater runoff from large surface
areas, such as agricultural and urban land, was found to significantly impair water quality.
At the Federal level, Sections 401, 402 and 404 of the Clean Water Act require permits for those
activities that might affect water quality either through direct discharge of dredged materials or from
runoff. The most recent Federal Regulations that will significantly impact existing storm water
management practices are 40 CFR Parts 9, 122, 123, and 124 - National Pollutant Discharge.
Elimination System (NPDES) — Regulations for Revision of the Water Pollution Control Program
Addressing Storm Water Discharges; Final Rule (commonly referred to as Phase II Storm Water
Regulations).
Phase I NPDES Stormwater Regulations
In 1987, Congress amended the CWA to require implementation of a comprehensive national
program for addressing storm water discharges. This implementation has occurred in two phases.
The first phase, referred to as "Phase I," was promulgated in November 1990. Phase I requires
NPDES permits for storm water discharge from a large number of priority sources including:
• Municipal separate storm sewer systems generally serving populations of 100,000 or more.
• Several categories of industrial activity, including construction sites that disturb five or more
acres of land.
Applicability to Dare County
As of the year 2001, the County is not required to obtain an NPDES stormwater discharge
permit under the Phase I regulations because of its small population and lack of
industrial activity.
Phase 11 Stormwater Regulations
The second phase, referred to as "Phase II," was promulgated in August 1995. These regulations
were adopted in December 1999. Phase II expands the existing stormwater program to include:
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REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
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• Discharges of stormwater from smaller municipalities in urbanized areas.
• Construction sites that disturb between one and five acres of land.
Certain sources are excluded from Phase II based on a demonstrable lack of impact on water
quality. This regulation also allows other sources not automatically regulated on a national basis
to be designated for inclusion based on their increased likelihood for local impairment of water
quality. Phase II conditionally excludes stormwater discharges from industrial facilities that have "no
exposure" of industrial activities or materials to storm water. States with NPDES permitting authority
(North Carolina Division of Water Quality has permitting authority) can extend NPDES requirements
to smaller Counties if there is reason to anticipate that stormwater runoff from those areas has been
or may impact high quality waters. Phase II requires that industrial facilities owned by Small
Municipal Separate Storm Sewers Systems (MS4s) obtain coverage under an NPDES permit by
March 10, 2003.
The EPA believes that the implementation of six measures identified for small MS4s should cost
effectively reduce pollutant discharges. In addition, they believe that the implementation of Best
Management Practice (BMP) controls at small construction sites will also reduce pollutants in urban
storm water. Expected benefits include reduced scouring and streambed erosion improved aesthetic
water quality, reduced eutrophication of aquatic systems, improved wildlife, improved tourism, and
the reduced costs for siting reservoirs. These six measures and BMPs provide the framework for
the program requirements. The stormwater management program requirements, as required by
Phase II, are as outlined below:
• Public Education and Outreach on Stormwater Impacts
• Public Involvement/Participation
• Illicit Discharge Detection and Elimination
• Construction Site Stormwater Runoff Control
• Post -Construction Stormwater Management in New Development and Redevelopment
• Pollution Prevention/Good Housekeeping for Municipal Operations
Public Education and Outreach on Stormwater Impacts
Under Phase II, operators of small MS4s must implement a public education program or conduct
outreach activities to distribute educational materials to the community. The education programs
and/or outreach activities should inform individuals and households about the impacts stormwater
discharges have on water bodies and identify the steps that must be taken to reduce storm water
pollution. It is anticipated that public understanding will foster endorsement of the program. MS4s
are encouraged to collaborate with their States to fulfill the public education requirement. In
particular, MS4s are encouraged to work with any existing State implemented educational programs.
Public Involvement/Participation
As part of the Phase II Public Involvement/Participation requirement, municipal stormwater
management programs are required to comply with applicable State and local public notice
requirements. The final rule recommends implementing a public participation process to reach out
and engage all economic and ethnic groups. The EPA believes that early and frequent public
involvement can expedite schedules, improve public support, and provide a more successful
program.
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' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' Illicit Discharge Detection and Elimination
Under the Phase II requirements, any NPDES permit issued to an operator of a regulated small MS4
must, at a minimum, require the operator to develop, implement and enforce an illicit discharge
' detection and elimination program. Under this final rule, the NPDES permit will require the operator
of a regulated small MS4 to:
• Develop a storm sewer system map showing the location of all outfalls, and names and
location of all waters of the United States that receive discharges from those outfalls.
• Effectively prohibit though ordinance, or other regulatory mechanism, illicit discharges into
the separate storm sewer system and implement appropriate enforcement procedures and
' actions as needed, and to the extent allowable under State, Tribal, or local law.
• Develop and implement a plan to detect and address illicit discharges, including illegal
dumping, to the system;
• Inform public employees, businesses, and the general public of hazards associated with
illegal discharges and improper disposal of waste.
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The illicit discharge and elimination program must only address non-stormwater discharges if it falls
under the categories listed below and if the operator of the small MS4 identifies them as significant
contributors of pollutants to its small MS4. These categories include: water line flushing, landscape
irrigation, diverted stream flows, rising ground waters, uncontaminated ground water infiltration,
uncontaminated pumped ground water, discharges from potable water sources, foundation drains,
air conditioning condensation, irrigation water, springs, water from crawl space pumps, footing
drains, lawn watering, individual residential car washing, flows from riparian habitats and wetlands,
dechlorinated swimming pool discharges, and street wash water.
Construction Site Stormwater Runoff Control
The Phase II final rule requires operators of regulated small MS4s to develop, implement and
enforce a pollutant control program to reduce pollutants in any stormwater runoff from construction
activities that result in land disturbance of one or more acres. Construction activity on sites
disturbing less than one acre must be included in the program if the construction activity is part of
a larger common plan of development or sale that would disturb one or more acres. The
construction runoff control program must include an ordinance or other regulatory mechanism to
require erosion and sediment controls to the extent practicable and allowable under State, Tribal
or local law. The program must also include sanctions to ensure compliance. The program must
also include, at a minimum:
• Requirements for construction site operators to implement appropriate erosion and sediment
control.
• Procedures for site plan review by the small MS4, which incorporate consideration of
potential water quality impacts.
• Requirements to control other waste such as discarded building materials, chemical and
sanitary waste at the site that may adversely affect water quality.
• Procedures for receipt and consideration of information submitted by the public to the MS4.
Post -Construction Stormwater Management in New Development and Redevelopment
Studies and investigations indicate that prior planning and designing for the minimization of
pollutants in stormwater discharges is the most cost-effective approach to stormwater quality
management. Under the Phase II requirements, any NPDES permits issued to an operator of a
regulated small MS4 must require the operator to develop, implement, and enforce a program to
address stormwater runoff from new development and redevelopment projects that result in land
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' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
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disturbance of greater than or equal to one acre. This also includes projects less than one acre,
which are part of a larger common plan of development or sale, that discharge into the MS4. The
NPDES permit will require the operator of a regulated small MS4 to:
• Develop and implement strategies that include a combination of structural and/or non-
structural BMPs.
• Use an ordinance or other regulatory mechanism to address post -construction runoff from
new development and redevelopment projects to the extent allowable under State, Tribal or
local law.
• Ensure adequate long-term operation and maintenance of BMPs.
• Ensure that controls are in place that would minimize adverse water quality impacts.
Pollution Prevention/Good Housekeeping for Municipal Operations
Phase II specifies that operators of MS4s must develop and implement an operation and
maintenance program that includes a training component and focuses on preventing or reducing
stormwater from municipal operations. The program must include government employee training
that addresses prevention measures pertaining to municipal operations such as: parks, golf courses
and open space maintenance; fleet maintenance; new construction or land disturbance; building
oversight; planning; and stormwater system maintenance. The program may use existing
stormwater pollution prevention training materials offered by the State, Tribe, EPA, or environmental,
public interest, or trade organizations. The EPA encourages operators of MS4s to include the
following in their programs:
• Implement maintenance activities, maintenance schedules, and long-term inspection
procedures for structural and non-structural stormwater controls to reduce floatables and
other pollutants discharged from the separate storm sewers.
• Implement controls for reducing or eliminating the discharge of pollutants from street, roads,
highways, municipal parking lots, maintenance and storage yards, waste transfer stations,
fleet or maintenance shops with outdoor storage areas, .and salt/sand storage locations and
snow disposal areas operated by the MS4.
• Adopt procedures for the proper disposal of waste removed from the waste removed from
the separate storm sewer systems and areas listed above, including dredge spoil,
accumulated sediments, floatables, and other debris.
• Adopt procedures to ensure that new flood management projects are assessed for impacts
on water quality and existing projects are assessed for incorporation of additional water
quality protection devices or practices.
Applicability to Dare County
The final Phase II regulations, dated December 9,1999, list areas in the United States that require
or may require permitting under the Phase II program. These areas include:
• Urbanized areas of the United States
• Governmental entities located fully or partially within an urbanized area
• Governmental entities (located outside of an urbanized area) that must be
examined by the NPDES permitting authority for potential designation.
As of May 2001, Dare County was not included on any of these lists, and has not been
designated to obtain a permit. Although a Phase 11 permit is not required at this time,
URS recommends that the County implement applicable Phase 11 management measures
as part of its long-term stormwater management policies. These management measures
are good standard practice for water quality protection, and their implementation would
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' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
ensure that Phase 11 requirements would be in place if a permit becomes necessary in the
future.
' 2.2 STATE REGULATIONS
Stormwater management requirements in North Carolina fall under the jurisdiction of the North
' Carolina Administrative Code (NCAC), the North Carolina Coastal Area Management Act (CAMA),
and the North Carolina Sedimentation Pollution Control Act. The associated agencies responsible
for the implementation of stormwater management requirements are the Department of Environment
' Natural Resource (DENR); the Sedimentation Control Commission; and the Coastal Resources
Commission (CRC), respectively. Summarized stormwater management requirements for the three
agencies are provided as follows and will serve as the technical basis for recommended
modifications to County ordinances. The DENR, Division of Coastal Management (DCM), Division
' of Land Resources, and the Division of Water Quality (DWQ) regulate development and land use
activities to protect water quality. Additionally, the North Carolina Division of Highways has
published guidelines for drainage studies and hydraulic design, and the North Carolina Department
' of Transportation has drainage standards for subdivision highways.
2.2.1 DIVISION OF COASTAL MANAGEMENT
' The Division of Coastal Management (DCM) regulates development activities and stormwater
controls that occur in the 20 coastal counties of North Carolina through the Coastal Area
Management Act (CAMA) (15A NCAC 7H, 7J, & G.S. 133A, Article 7). Any land disturbing activity
which occurs in an area of environmental concern (AEC) must receive a CAMA permit. The DCM
reviews proposed development plans and refers to the local CAMA Land Use Plans and determines
' if a Major, Minor or General Permit is required.
A Major permit is required for land disturbing activities which:
• occur in an AEC
alter more than 20 acres of land
• propose a structural footprint exceeding 60,000 square feet on a single parcel
• require other State or Federal permits
• excavates or drills for natural resources in an AEC or under water
A Minor permit is required when a Major permit is not required. The following activities are exem t
' from a Minor permit:
• maintenance and repair (excluding replacement) of existing structure which does not violate
CAMA standards
• accessory uses or structures related to the main use of the site that require no electricity,
plumbing, or other service connections and do not exceed an area of 200 square feet
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For an exemption from a minor development permit, the project must meet all of the following
exemptions:
• development activities do not disturb more than 200 square feet on land with a slope greater
than 10%
• threatened or endangered plants and animals must not be removed, damaged or destroyed
• development activities do not alter surface drainage channels
• the form or vegetation of a frontal dune must not be altered
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REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' • development activities must be not be within 20 feet of permanent surface waters
• the project must be in compliance with CAMA standards and local land use plans and
ordinances
Development activities requiring a CAMA Major Permit may also require one of the following permits
that are issued by the State:
• permit to excavate and/or fill
• easement in lands covered by water
• water quality certification
' 2.2.2 DIVISION OF LAND RESOURCES
The Division of Land Resources requires a Sedimentation and Erosion Control Plan for land
disturbing activities greater than one acre (15A NCAC 4B & G.S. 113A, Article 4). The purpose of
the Sedimentation and Erosion Control Plan is to show practices that will be implemented, during
and after construction, that will control erosion and prevent sediments from leaving the site. Erosion
' and sedimentation control is required regardless of the size of the land surface disturbance.
Primary requirements for a Sedimentation and Erosion Control Plan are as follows:
' • A sufficient buffer zone must be retained or established along any natural water course or
lake to contain all visible sediment to the first 25 percent of the buffer strip nearest the
disturbed area. An undisturbed 25-foot buffer must be maintained along trout waters.
• The angle of cut -and -fill slopes must be no greater than that sufficient for proper
stabilization. Graded slopes must be vegetated or otherwise stabilized within 30 working
days of completion of a phase of grading.
' • Off -site sedimentation must be prevented, and a ground cover sufficient to prevent erosion
must be provided within 30 working days or 120 calendar days, whichever is shorter.
Additionally,
• Erosion and sedimentation control measures must be designed to provide protection from
a rainfall event equivalent in magnitude to the 10-year peak runoff. In areas where High
Quality Waters (HQWs) are a concern the design requirement is the 25-year storm.
• Runoff velocities must be controlled so that the peak runoff from the 10-year frequency
storm occurring during or after construction will not damage the receiving stream channel
at the discharge point. The velocity must not exceed the greater of:
' 1. The maximum nonerosive velocity of the existing channel, based on soil texture.
2. Peak velocity in the channel prior to disturbance.
3. If neither condition can be met, then protective measures must be applied to the
receiving channel.
The law created the Sedimentation Control Commission to develop and administer North Carolina's
sedimentation and erosion control program. This program is implemented by the DENR, Land
Quality Section under the Commission's direction. Authorized local governments or agencies may
adopt their own ordinances; however, local programs must be approved by the Commission and
must meet or exceed the minimum standards set by the state. If their programs are approved, local
governments administer and enforce them. Because these programs vary widely in content and
scope, the administering agency should be consulted to avoid violations of local ordinances.
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REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' The state assists and encourages local governments and other state agencies to develop their own
erosion and sedimentation control programs. The DENR reviews local programs as needed to
assure uniform enforcement of the Act.
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As part of the educational requirements of the Sedimentation Pollution Control Act, the
Sedimentation Control Commission sponsored the development of a design manual for erosion and
sediment control planning. The ESC design manual is a basic reference for the preparation of a
comprehensive erosion and sedimentation control plan and for the design, construction and
maintenance of individual practices.
The ESC design manual contains information useful in the selection and design of Best
Management Practices (BMPs) used in sedimentation and erosion control. The ESC design manual
is intended to serve as a guide to help local governments and developers comply with the
Sedimentation Pollution Control Act.
2.2.3 DIVISION OF WATER QUALITY
The Classifications and Water Quality Standards Applicable to Surface Water of North Carolina
(15A NCAC 213 & G.S. 143-214.1, 215.1, 215.3 Article 3) defines surface water classifications and
provides development restrictions and buffer requirements. Surface waters in Dare County area
include the ocean, the Intracoastal Waterway, Croatan Sound, Currituck Sound, Pamlico Sound,
Roanoke Sound, Alligator River, and various other small lakes, rivers, and canals.
The following letter system is used to define the "best usage classifications" for waters in Dare
County area:
SA Tidal systems designated for shell fishing for market purposes, primary recreation,
aquatic life propagation and survival, fishing, wildlife, and secondary recreation.
SB Indicates a designation of a tidal system for primary recreation, aquatic life
propagation/protection and secondary recreation.
SC Tidal systems designated for aquatic life propagation and maintenance of biological
integrity, wildlife, secondary recreation, agriculture and any other usage except
primary recreation or shellfishing.
C Fresh water systems designated for aquatic life propagation and maintenance of
biological integrity, wildlife, secondary recreation, agriculture and any other usage
except primary recreation or drinking water supplies.
HQW (High Quality Waters) Indicates a supplemental classification for waters protected
by an Antidegradation Policy enforced through the DENR. These include waters
with excellent ratings based on biological & physical/chemical characteristics, such
as NC Marine Fisheries Commission designated primary nursery areas (PNA) and
Wildlife Resource Commission designated trout waters.
ORW (Outstanding Resource Waters) Those waters that have exceptional state or national
recreational or ecological significance and which have exceptional water quality.
SW Swamp waters, or waters which have low velocities and other natural characteristics
which are different from adjacent streams.
The SA primary classification denotes surface waters, such as the Pamlico Sound, which are
suitable for commercial shellfishing and all other tidal saltwater uses. Supplemental classifications
such as HQW provide added protection for waterbodies.
06/01/01 2-7
1

IJ
' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' The Division of Water Quality enforces the Stormwater Management regulation and general statute
(15A NCAC 2H and G.S.143-215.1) and the Water Supply Watershed Protection Act (15A NCAC
2B & G.S. 143-214.5) for the protection of surface waters. These rules were developed to control
' pollutants in stormwater runoff, limit impervious surfaces or built upon area, and ensure that
adequate stormwater management practices are implemented.
North Carolina Administrative Code Section 15A NCAC2H.1000
The North Carolina stormwater management regulations are located in Administrative Code Section
15A NCAC2H.1000, which is included as Appendix A of this report. To ensure the protection of
surface waters of the State, a stormwater management permit is required for any development
activities which require a CAMA major development permit (see Section 2.2.1 of this report) or a
Sedimentation/Erosion Control Plan (see Section 2.2.2 of this report) and which meet any of the
following criteria:
' 1. Are located in the 20 coastal counties.
' 2. Drain to Outstanding Resource Waters (ORW)"
3. Drain to High Quality Waters (HQW)
' Dare County is included in the 20 coastal counties and is subject to permitting requirements as
specified in 15A NCAC 2H.1005. Permitting requirements as specified in 15A NCAC 2H.1005 are
described in the following paragraph. A North Carolina stormwater management permit application
form is provided in Appendix B.
Stormwater Permitting Requirements: Coastal Counties
' Stormwater management permits for development activities within the 20 coastal counties fall into
one of the three following categories:
' 1. Development activities that drain to Outstanding Resource Waters (ORW).
2. Development activities within one-half mile of and draining to SA (saltwater shell fishing
' and primary recreation) waters or unnamed tributaries to SA Waters.
3. Development activities in areas except those defined in items 1 and 2.
Dare County has a significant number of SA waters; therefore permitting requirements are primarily
as specified by category 2.
' Dare County Permitting Requirements (SA Waters)
Permitting requirements for the County's SA waters are classified according to low density and high
density options. Permitting requirements for the two options are summarized as follows:
Low Density Option
1. Built -upon area of 25 percent or less; or proposed development of single family
residences on lots with one-third of an acre (14,520 square feet) or greater with a built
upon area of 25 percent or less.
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' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' 2. Stormwater runoff transported primarily by vegetated conveyances; conveyance
system shall not include a discrete stormwater collection system as defined in 15A
NCAC 2H.1002.
' 3. Curb and gutter systems are allowed as specified in 15A NCAC 2H.1008(g). If curb
and gutter systems are provided, a flow spreader mechanism must be located at the
swale entrance and a signed Operation and Maintenance Plan must be provided.
4. A vegetative buffer of at least 30-feet wide between impervious areas and surface
waters.
' High Density Option
1. No direct outlet channels or pipes to SA waters unless permitted in accordance with 15A
' NCAC 21-1.0126.
2. Stormwater control systems must be infiltration systems designed in accordance with
' 15A NCAC 2H.1008.
4. Stormwater control systems must be designed to control runoff from all surfaces
generated by one and one-half (1.5) inches of rainfall.
' 5. Runoff in excess of the design volume must flow overland through a vegetative filter with
a minimum length of 50 feet.
' Dare County Permitting Requirements (SC Waters)
Permitting requirements for the County's SC waters are classified according to low density and high
' density options. Permitting requirements for the two options are summarized as follows:
Low Density Option
1. Built -upon area of 30 percent or less; or proposes development of single family residences on
lots with one-third of an acre (14,520 square feet) or greater with a built upon area of 30 percent
or less.
' 2. Stormwater runoff transported primarily by vegetated conveyances; conveyance system shall
not include a discrete stormwater collection system as defined in 15A NCAC 2H.1002.
' 3. Curb and gutter systems are allowed as specified in 15A NCAC 2H.1008(g). If curb and
gutter systems are provided, a flow spreader mechanism must be located at the swale
entrance and a signed Operation and Maintenance Plan must be provided.
' 4. A vegetative buffer of at least 30-feet wide between impervious areas and surface waters.
' High Density Option
1. Stormwater control systems must be infiltration systems, wet detention ponds, or alternative
stormwater management systems designed in accordance with 15A NCAC 2H.1008.
2. Stormwater control systems must be designed to control runoff from all surfaces generated by
one (1) inch of rainfall.
06/01/01 2-9

' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' Dare County Permitting Requirements (SC HQW Waters)
SC HQW permitting requirements are summarized as follows for future reference:
Low Density Option
1. Built -upon area of 12 percent or less; or proposes development of single family residences on
lots with one acre (43,560 square feet) or greater with a built upon area of 30 percent or less.
2. Stormwater runoff transported primarily by vegetated conveyances; conveyance system shall
not include a discrete stormwater collection system as defined in 15A NCAC 2H.1002.
' 3. Curb and gutter systems are allowed as specified in 15A NCAC 2H.1008(g). If curb and gutter
systems are provided, a flow spreader mechanism must be located at the swale entrance and
a signed Operation and Maintenance Plan must be provided.
4. A vegetative buffer of at least 30-feet wide between impervious areas and surface waters.
' High Density Option
1. Control systems must be wet detention ponds or alternative storm water management systems
designed in accordance with 15A NCAC 21-1.1008.
' 2. Control systems must be designed to control runoff from all surfaces generated by one (1) inch
of rainfall.
' Dare County Permittinq Requirements (ORW Waters)
Water quality conditions shall clearly maintain and protect the outstanding resource values of waters
classified as Outstanding Resource Waters (ORW). Stormwater management strategies to protect
' resource values of waters classified as ORW shall be developed on a site -specific basis during the
proceedings to classify these waters as ORW. The requirements of this Rule serve as the minimum
conditions that must be met by development activities. More stringent stormwater management
' measures may be required on a case -by -case basis where it is determined that additional measures
are required to protect water quality and maintain existing and anticipated uses of these waters.
' Freshwater ORWs - Low Density Option
1. Built -upon area of 12 percent or less or proposes single family residential development on lots
of one acre or greater;
' 2. Stormwater runoff transported primarily by vegetated conveyances; conveyance system shall
not include a discrete stormwater collection system; and
i
3. A 30 foot wide vegetative buffer.
Freshwater ORWs - High Density Option
1. Control systems must be wet detention ponds or alternative stormwater management; and
2. Control systems must be designed to control runoff from all surfaces generated by one inch of
rainfall.
06/01/01 2-10

' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' Saltwater ORWs
1. Within 575 feet of the mean high water line of designated ORW areas, development activities
shall comply with the low -density option as specified above for Freshwater ORWs.
11
F�
2. Projects draining to saltwaters classified as ORW that impact the Areas of Environmental
Concern (AEC), determined pursuant to G.S. 113A-113, shall delineate the ORW AEC on the
project plans and conform to low density requirements as specified above in Freshwater ORWs.
Best Management Practice (BMP) Design Criteria
North Carolina's approach to stormwater quality management in the 20 coastal counties is based -
first on minimizing impervious surfaces and, secondly, on treating stormwater runoff from these
surfaces. The State uses a pollutant removal BMP design standard of 85% removal for total
suspended solids (TSS).
A stormwater BMP design manual, included as Appendix C, was published by DENR in November
1995. The manual includes design criteria and TSS removal efficiencies for stormwater BMP types
recommended by the State.
As described above, the State requires specific types of stormwater BMPs for low density and high -
density development in the 20 coastal counties. Design criteria for BMPs are outlined in 15A NCAC
2H .1008.
2.2.4 NORTH CAROLINA DIVISION OF HIGHWAYS
Guidance in methods, policies, procedures, and criteria that must be followed during highway
drainage studies and hydraulic designs is provided in the North Carolina Division of Highways,
Guidelines for Drainage Studies and Hydraulic Design document. Information from this document
is pertinent to the development of recommended County stormwater management policies there are
various state roads in unincorporated Dare County.
General Drainage Policies and Practices
North Carolina long adhered to the Civil Law Rule in regard to surface water drainage. This rule
obligates owners of lower land to receive the natural flow of surface water from higher lands. It
subjects a landowner to liability whenever he interferes with the natural flow of surface waters to the
detriment of another in the use and enjoyment of his land. Since almost any use of land involves
some change in the drainage and water flow, a strict application of the civil law principles was
impracticable in a developing society. Thus, a more moderate application of this rule evolved to
allow a landowner reasonable use of his property.
The North Carolina Supreme Court formally adopted the Rule of Reasonable Use with respect to
surface water drainage and abandoned the Civil Law Rule (Pendergrast V. Aiken) in August 1977.
The adopted Reasonable Use Rule allows each landowner to make reasonable use of his land even
' though by doing so, he alters in some way the flow of surface water thereby harming other
landowners. Liability is incurred only when this harmful interference is found to be unreasonable
and causes substantial damage.
' There are still some unanswered questions in the application of the adopted Reasonable Use Rule
to specific areas of State agency activities. However, the rule is in line with the realities of modem
06/01/01 2-11

CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
life and will provide just, fair and consistent treatment. Therefore, the policies and practices of the
Division of Highways in regard to surface drainage matters follow this rule.
Engineer's Responsibility
The Reasonable Use Rule places responsibility on the "landowner" to make reasonable use of his
land. While "reasonable use" is open for interpretation on a case -by -case basis, it would certainly
infer from an engineering standpoint that provisions for, and treatment of, surface waters on the
property are made in accordance with sound, reasonable and acceptable engineering practices.
Therefore, the policies and practices of the Division of Highways in regard to surface drainage
matters follow this rule.
The rule also states that liability incurs only when harmful interference with the surface water is
found to be unreasonable and causes substantial damage. Therefore, it is incumbent on the
Engineer to evaluate the potential effects of surface water activities on both up and downstream
properties and to include provision in the design to hold these effects to reasonable levels.
Augmentation. Acceleration
Development of property can cause an increase in the quantity and peak rate of flow by increasing
impervious areas and providing more hydraulically efficient channels and overland flow. It is the
' policy of the Division of Highways to develop and make reasonable use of its lands and rights -of -
way through sound, reasonable and acceptable engineering practices and to deny responsibility for
augmented accelerated flow caused by its improvements unless determined to cause unreasonable
and substantial damage. It is likewise the policy of the Division of Highways to expect this same
' practice and acceptance of responsibility by other property owners and those engaged in the
development of these properties.
171
Diversions
Diversions are defined as the act of altering the path of surface waters from one drainage outlet to
another. It is the policy of the Division of Highways to design and maintain its road systems, so that
no diversions are created thereby, insofar as is practicable from good engineering practice.
Any person(s) desiring to create a diversion into any highway rights -of -way shall do so only after
receiving written permission. This permission will be granted only after it has been determined that
the additional flow can be properly handled without damage to the highway, that the cost for any
required adjustments to the highway system will be bome by the requester, and that appropriate
consideration and measures have been taken to indemnify and save harmless the Division of
Highways from potential downstream damage claims. It is Division of Highways policy not to become
a party to diversions unless refusal would create a considerable and real hardship to the requesting
party.
Improvements and Maintenance of Drainage Within the Right-Of-WaY
Drainage structures and ditches shall be kept open and maintained at a functioning level such that
they do not present an unreasonable level of damage potential for the highway or adjacent
properties.
' Where the elevation of the flow -line of an existing culvert under a highway is not low enough to
adequately provide for natural drainage, the Division of Highways will assume full responsibility for
lowering the culvert or otherwise provide needed improvement.
06/01/01
2-12

n
C�
H
CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
Where a requested culvert invert adjustment is a result of a property owner lowering the flow -line
of the inlet and outlet ditch in order to improve drainage of his property, the following considerations
shall be given to the action taken:
• The lowered drain must have a reasonable expectancy of being functional and maintainable.
• Division of Highways participation (up to full cost) must be based on benefit gained by the
roadway drainage system as a result of the lowering.
• Where the new installation is of doubtful benefit, or of no benefit to highway drainage, the
requesting party must bear the entire cost of installation.
Where the size of an existing highway culvert is determined to be of unacceptable adequacy in
regard to the roadway system functioning as a result of a general overall development of the
watershed, it is the Division of Highways' responsibility to replace the structure or otherwise take
appropriate action. Where this same culvert inadequacy is the result of a single action or
development, it is felt to fall within the realm of "unreasonable and substantially damaging" under
the State adopted drainage ruling. Therefore, the party responsible for the action or development
should bear the cost of replacement.
Where a new culvert crossing is requested, if the culvert is required for proper highway drainage or
sufficient benefits to the highway drainage system would occur, the full cost will be bome by the
Division of Highways providing there is no diversion of flow involved. Where the new installation is
of doubtful or no benefit to highway drainage, the property owner will bear the entire cost. When
both parties receive benefit, a joint effort may be negotiated.
Established culvert crossings will be maintained and requests to eliminate any culvert should have
approval of the State Hydraulics Engineer.
When new private drives are constructed entering the highway, the property owner can fumish,
delivered to the site, the amount, type and size pipe designated by the Division of Highways, to be
installed by maintenance forces.
No alteration, attachment, extension, nor addition of appurtenance to any culvert shall be allowed
on highway rights -of -way without written permission.
Improvements and Maintenance of Drainage Outside the Right -Of -Way
While it is the responsibility of the Division of Highways to provide for adequate drainage for
constructing and maintaining the State Highway System, it is not its policy nor responsibility to
provide improved drainage for the general area traversed by such roads, unless incidental to the
drainage of the road or highway itself. Drainage involvement outside the highway rights -of -way is
limited to two general areas of justification:
• Sufficient benefit would be gained by such action to warrant the cost. These benefits would
be in such areas as reduction in roadway flood frequency or extent, facilitation of
maintenance, or a reduction in potential damages.
• Work is required to correct a problem or condition created by some action of the Division of
Highways.
It is not the responsibility of the Division of Highways to eliminate flooding on private property that
is not attributable to acts of the agency or its representative.
06/01i01 2-13

' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' In general, outlet ditches will be maintained for a sufficient distance below the road to provide
adequate drainage therefore. On large outlets serving considerable areas outside the right-of-way,
the maintenance should be done on a cooperative basis, with the benefited properties bearing their
' proportionate share. Shares will, in general, be based on proportioning of runoff from the areas
served by the outlet.
' It is not the policy of the Division of Highways to pipe inlet or outlet drains, natural or artificial, outside
the right-of-way, which existed as open drains prior to existence of the highway. Where the property
owner wishes to enclose an inlet or outlet, the Division of Highways may install the pipe adjacent
to the right-of-way if justified by reason of reduced maintenance, safety or aesthetics if the pipe is
' furnished at the site by the property owner. This does not apply to the development of commercial
property.
Obstructions
It is the policy of the Division of Highways that when a drain is blocked below the highway, which
is detrimental to highway drainage, if from natural causes, the Division of Highways will take
' necessary measures to remove the block or obstruction. Where the block is caused by wrongful
acts of others, it is the policy of the Division of Highways to take whatever recourse deemed
advisable and necessary to cause the party responsible to remove the block. Where a block occurs
' downstream of a highway, whether natural or artificial, and is of no consequence to the Division of
Highways, it is the policy to remain neutral in causing its removal.
Drainage Easements
' Where runoff is discharged from the right of way at a point where there is no natural drain or existing
ditch, a permanent drainage easement is required to allow construction of a ditch or channel to
convey the discharge to an acceptable natural outlet. When the discharge is into a natural drain or
' existing ditch and the increase in flow would exceed the capacity or otherwise create a problem, a
temporary drainage easement can be obtained to allow enlarging or otherwise improving the drain
to a point where the increase in discharge will not cause damage. It is generally preferable that any
' structural feature such as a drop inlet, catch basin, or pipe -end be contained within a permanent
easement.
E
Subdivision Streets
When road and streets built by others are accepted onto the system for maintenance, responsibility
for the drainage system, discharge pattern and outlet locations is as it existed at the time of
acceptance and is limited to the rights -of -way.
Hvdrologv
The hydrological analysis phase involves the determination of discharge rates and/or volumes of
runoff that the drainage facilities will be required to convey or control. Many hydrological methods
are available and most can be appropriately and effectively used under proper control and
application. When the site involves a FEMA flood study area, discharge methods and values
provided in the report will take precedent over these methods for determining compliance with the
regulation. The results from any hydrologic procedure should be compared to historical site
information and adjustments made in the values estimated or procedure used when deemed
appropriate. The designer must also consider potential future land use changes within a watershed
over the life of a roadway structure and include this effect when estimating design discharges.
06/01/01 2-14

CHAPTER TWO DARE COUNTY
' REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
d
Method for Calculatin_g Peak Discharge
If a watershed less than 10 acres is primarily composed of pavement, grassed shoulders and
slopes, and/or other mixed surface type runoff, the rational formula should be used for discharge
determination.
Highway Design Discharge Criteria
One specific criterion on which the design is evaluated and generally referred to as the "design
discharge" is the flood level and frequency which results in inundation of the travelway. The
minimum desirable levels of protection from travelway inundation by roadway classification are listed
as follows:
Roadway Classification Frequency
Interstate (1) 50 year
Primary (US & NC) 50 year
Secondary (Major, City thoroughfare) 50 year
Secondary 25 year
Culvert Design Criteria
There are four discharge levels that must be evaluated for each culvert design. These are:
1. The "design discharge".
2. The Q100 base flood.
3. Q-overtopping. This discharge is computed after a trial size is selected.
4. Q10 for outlet protection and erosion control measures.
Other discharges may be required on a site -specific basis. Examples are:
1. Q-average. For permit determination.
2. Q-bank full. For fish passage, channel stability or floodplain analysis.
Storm Drainage System Design Criteria
The purpose of a storm drainage system is to collect and transport stormwater runoff from the
highway to an outlet. The complete system consists of the curb and gutter, inlet structures, lateral
and trunk line pipes, and junctions and manholes. The design process for storm drainage systems
usually follows the basic steps of planning/data collection, hydrologic/hydraulic design, and outfall
analysis.
Design Frequency
' Roadway inlet location, capacities and gutter spread is to be analyzed using a standard rainfall
intensity of 4.0 inches/hour. The storm drain pipe system is to be designed using a Q10 discharge
with a minimum time of concentration of 10 minutes assuming 100% pick-up at each inlet.
' In sag areas where relief by curb overflow is not provided, the system standard design level (Q25
— Q50) is to be used for analysis to ensure traffic flow is not interrupted.
06/01/01 2-15

' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' Pipe System
Storm drain pipes shall be concrete unless a site limitation such as grade or corrosive conditions
dictate the use of an alternate material. The minimum pipe size to serve a single inlet is 12 inches.
' For more than one inlet, or a length of more than 100 feet, a 15-inch pipe is the minimum size.
When differing size pipes enter and exit a junction, the desired practice is to match the crowns of
the pipes.
' Roadside Ditches
A roadside ditch is a man-made channel generally paralleling the roadway surface and distinguished
by a regular geometric shape. Roadway ditches are to be designed to contain as a minimum the
Q5 (5-year) flow. The typical roadway ditch section is established with sufficient depth to drain the
pavement subbase and flat side slopes for safe vehicle traversability. This generally provides very
generous capacity for the design flow requirements. Therefore, actual capacity determination can
be done on a selective basis at sites on common project grades to verify adequacy and establish
limitations on the length of the ditch run.
' The size requirements of the project special side ditches along the toes -of -fill will be established
based on an analysis of the design flood. This ditch capacity analysis will be performed using
Mannings' equation. The roadway section including shoulders and slopes shall be considered an
urban watershed.
2.2.5 NCDOT SUBDIVISION ROADS
' A subdivision road is one that serves a parcel or tract of land that is subdivided into two or more lots,
building sites or other divisions for sale or building development for residential purposes where such
subdivisions include a new road or change in an existing road.
Subdivision roads may be designated public or private. Public designations will be built to minimum
construction standards of the North Carolina Department of Transportation (NCDOT) as required
under North Carolina General Statute 136-102.6. Private roads need not meet minimum
construction requirements, but must meet minimum construction requirements before ever
becoming a part of the State -maintained system.
' NCDOT Subdivision Roads Drainage Design and Construction Requirements
Design criteria for NCDOT subdivision roads are provided in Subdivision Roads — Minimum Design
Standards, which is included as Appendix H of this report. Drainage design and construction
requirements for state -maintained subdivision roads are summarized for review purposes in the
following paragraphs.
' Requirements forAddition of Subdivision Roads to the State System
• Erosion and Sedimentation — All subdivision roads shall have an acceptable permanent
vegetative cover established and other acceptable permanent erosion control measures
' installed in accordance with Division of Highways' specifications, prior to addition to the
State -maintained system.
All pipe culverts, storm sewers and appurtenances shall be free of all debris and silt build-up
and shall be structurally and hydraulically sound, and functioning in a normal manner. All
drainage ditches shall be of such a width and depth and with such a slope as to carry the
anticipated discharges. Paved ditches or riprap shall be required where necessary.
' 06/01/01
2-16

CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
Minimum Drainage Requirements for Subdivision Roads
The Division of Highways shall review all drainage prior to acceptance of any facility to the State
System. All storm drainage shall be adequate so that the road may be maintained without excessive
cost, and not cause flooding on private property from storm runoff of the design frequency.
Permanent drainage easements may be required. The minimum design frequency shall be as
follows but may be increased at the recommendation of the State Hydrographic Unit Head.
1. Storm sewer collector— 10 years
2. Cross drainage — 25 years
In areas where ditch grades or quantities of flow deem it impracticable to establish and maintain
vegetation, an erosive resistant lining such as paving or rock riprap may be required. Subsurface
drainage shall be adequate to maintain a stable subgrade.
When road crossings are within areas designated as flood hazard areas under the Federal Flood
' Insurance Program, the design must be approved by the responsible local governing agency for its
consistency with local flood zoning ordinances.
Minimum Criteria for Curb and Gutter Design
Minimum design criteria for curb and gutter include the following:
• All curb and gutter sections must meet Division of Highways standards
• The standard 2' x 6" concrete curb and gutter is the preferred type to be used. Types of
' other curb may be used provided the 6" height is maintained.
• The concrete Valley Gutter is an allowable type.
• Any other types of gutter will be subject to the approval of the Division Engineer after review
on an individual basis. Approval will be subject to the terrain factors in the area under study
as they relate to potential maintenance problems.
' 2.2.6 NCDOT POLICY ON STREET AND DRIVEWAY ACCESS TO HIGHWAYS
The North Carolina Department of Transportation has deemed it necessary to regulate the location,
' design, construction, and maintenance of street and driveway connections to the State Highway
System for the purpose of protection for such highways, economy of maintenance, preservation of
proper drainage, safe and efficient movement of traffic thereon, and full utilization of the taxpayer's
' investment. The objective of this Policy is to establish uniform criteria governing such location,
design, construction, and maintenance. A copy of the NCDOT policy document, dated January
1987, is provided in Appendix I. Drainage requirements for street and driveway access to highways
' are summarized for review purposes in the following section.
Drainage Requirements for Street and Driveway Access to Highways
Driveways must be constructed so that they do not adversely affect the highway drainage or
drainage of the adjacent properties. The drainage and the stability of the highway subgrade must
not be impaired by driveway construction or roadside development. In no case may the construction
of a driveway cause water to flow across the highway pavement, or to pond on the shoulders or in
the ditch, or result in erosion within the right-of-way.
I
0&01/01 2-17
1

' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' 1. Drainage collected by ditches, gutters, or pipes on private property shall not be discharged
into the highway drainage system unless expressly approved by the Division of Highways.
The applicant may be required to submit a drainage study to the Division of Highways
justifying the drainage system proposed and the pipe or sewer sizes to be used. Natural
drainage laws and practices must be observed.
' 2. Where the construction of a driveway necessitates crossing a highway ditch, a culvert pipe
shall be installed in the ditch. The low point of the driveway profile shall be at or close to the
ditch line. Under no circumstances will existing ditches or gutters be filled without adequate
alternate provisions for drainage being made.
3. Culvert pipe shall be of a size adequate to cant' the anticipated flow in the ditch as
determined by the Division of Highways and shall not be smaller than 15 inches, inside
diameter.
4. The structural material and gauge of the driveway culvert pipe shall be adequate to
withstand the loads from the anticipated vehicular traffic across the driveway. The culvert
shall meet or exceed the requirements of the North Carolina Standard Specifications for
Roads and Structures. The length of the culvert may be determined as the sum of the width
' of the driveway (surfaced width and shoulder) at the ditch line and the length needed to
accommodate a sideslope of at least 1 vertical to 3 horizontal from the driveway grade to the
ditch. A minimum 20 feet of pipe shall be used on all commercial and residential subdivision
' driveways. Plastic pipe is not acceptable for drainage purposes.
5. Where headwalls orwingwalls are constructed with drainage facilities, a minimum roadway
clearance of 30 feet, measured from the edge of pavement, should be observed unless
' protected by guardrail. The use of flared -end sections should be encouraged.
6. All drainage structures deemed necessary by the Division of Highways, including incidentals,
' shall be furnished by the applicant. The Division of Highways will install the drainage pipe
for the applicant at the current rate of installation. If, however, the applicant makes the
installation, the Division of Highways is required to inspect the installation, and the applicant
n
will be appropriately charged for the inspection. One inspection fee will be charged for each
application, regardless of the number of installations involved, provided all installations are
available for inspection.
2.3 LOCAL ORDINANCES
The local ordinances are critical in regulating development through zoning and planning. The local
ordinances should control the density of development and establish building codes consistent with
sound environmental practice. The unincorporated areas of Dare County that are currently unzoned
include Wanchese and the mainland villages of Mann's Harbor, Stumpy Point, and East Lake. The
following provides a summary of some of the subdivision and zoning ordinances for Dare County.
Dare County has the following subdivision and zoning ordinances in place to control development:
• minimum lot size, per the subdivision ordinance, is 20,000 square feet for lots with a private
well (this includes unzoned areas within the County).
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' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' • minimum lot size, per the subdivision ordinance, is 15,000 square feet for lots served by
central water (this includes unzoned areas within the County).
• minimum lot size of 20,000 square feet for single family homes with a private well and on -site
' septic system in zones N-H, CP-R, RS-1, MP-1, RS-6, RS-8, RS-10, R-1, R-1A, R-2, R-2A,
R-26, R-3, R-4, C-1, S-1, V-C and VC-2.
• minimum lot size of 15,000 square feet for single family homes served by a central water
supply and on -site septic system in zones N-H, CP-R, RS-1, MP-1, RS-6, RS-8, RS-10, R-1,
R-1A, R-2, R-2A, R-213, R-3, R-4, C-1, S-1, V-C and VC-2.
• minimum lot size of 15,000 square feet for single family homes served by a central water
supply and a central wastewater disposal system in zones N-H, CP-R, RS-1, MP-1, RS-6,
RS-8, RS-10, R-1, R-1 A, R-2, R-2A, R-213, C-1, S-1, V-C and VC-2.
• minimum lot size of 40,000 square feet for single family homes in zone SED-1.
' • minimum lot size requirement is 30,000 square feet for duplexes with a private well and on -
site septic system, 25,000 square feet for duplexes served by a central water supply and on -
site septic system, or 20,000 square feet for duplexes served by a central water supply and
a central wastewater disposal system in zone S-1.
• minimum lot size requirement is 25,000 square feet for duplexes in zones RS-6, RS-8, RS-
10, R-2, R-2A, R-213, and R-3 unless served by an approved public or community sewage
disposal system, in which case the lot size may be reduced to 12,500 square feet (15,000
' square feet in zone R-2, 20,000 square feet in zone R2-A and R2-13).
• minimum lot size of 80,000 square feet for duplexes in zone SED-1.
• minimum lot size of 7,500 square feet for first dwelling unit and 7,212 square feet for each
additional dwelling unit in multi -family dwellings in zone RS-6.
• minimum lot size of 7,500 square feet for first dwelling unit and 5,000 square feet for each
additional dwelling unit in multi -family dwellings in zone RS-8.
' minimum lot size of 7,500 square feet for first dwelling unit and 4,000 square feet for each
additional dwelling unit in multi -family dwellings in zones RS-10, and R-3.
• minimum lot size of 160,000 square feet, developed at a density of one unit per 40,000
' square feet for cluster lots in zone SED-1.
• minimum lot size of 30,000 square feet for residential businesses in zones R-2A and R-213.
• minimum lot size of 40,000 square feet for commercial services in zone CS.
• minimum lot size of 20,000 square feet for commercial businesses in zone V-C.
' For commercial districts all minimum lot sizes must be sufficient to meet requirements of
County Health Department.
• 35-foot building height restrictions for zones N-H, CP-R, RS-1, MP-1, RS-6, RS-8, RS-10,
' R-1, R-1A, R-2, R-213, R-3, R-4, C-1, C-2, C-3, CS, V-C, and SED-1.
• a 52-foot building height restriction for zones R-2A and S-1.
' • The maximum allowable lot coverage by principal use and all accessory structures is 20%
for zones N-H and SED-1 (lots used as cluster sites).
• The maximum allowable lot coverage by principal use and all accessory structures is 25%
for zone SED-1 (lots 80,000 or more square feet).
' • The maximum allowable lot coverage by principal use and all accessory structures is 30%
for zones CP-R, RS-1, MP-1, RS-6, RS-8, RS-10, R-1, R-1A, R-2, R-2A, R-213(for homes,
bed and breakfasts, and resident businesses), R-3, R-4, V-C (single family homes), SED-1
(lots 60,000-79,999 square feet).
• The maximum allowable lot coverage by principal use and all accessory structures is 35%
for zones 1-1 and SED-1 (lots 40,000-59,000 square feet).
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' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' • The maximum allowable lot coverage by principal use and all accessory structures is 50%
for zones R-213 (for all structures not listed above) and C-1.
• The maximum allowable lot coverage by principal use and all accessory structures is 60%
for zones C-2, C-3, CS, S-1, and V-C (other than single family homes).
See the Dare County Zoning Ordinances for specific requirements. There are several zoning
' districts in which vegetation removal is restricted. Dare County has requirements for stormwater
drainage included in their subdivision ordinances. These requirements dictate that surface water
drainage in all subdivisions must comply with NC DOT standards.
' CAMA Land Use Plan
Dare County is currently in the process of updating its CAMA Land Use Plan. Statements of local
policy on land use issues which affect stormwater management in Dare County which are discussed
' in the following paragraphs are taken from the 1994 Land Use Plan.
Floodplain Management
' Dare County supports the administration of all applicable floodplain management regulations and
the National Flood Insurance program.
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7
F
Areas of Environmental Concern (AECs) Estuarine Waters, Public Trust Waters, Ocean Hazard
Areas
According to the policy statement regarding AECs, Dare County shall seek to ensure that these
areas are protected and only those uses which are compatible with the appropriate management
of the Estuarine System will be allowed. Such development must be compatible so as to minimize
the likelihood of significant loss of private property and public resources. Enforcement of the
County's Zoning Ordinance, Subdivision Regulations, CAMA use standards, and the National Flood
Insurance Program's base flood elevation standards will continue to protect these resources.
Stormwater Runoff
The County recognizes the value of water quality maintenance in regards to protecting commercial
and recreational fishing resources and providing clean water for other recreational purposes. The
stormwater management program will provide another tool for the County to reduce stormwater
pollution to the waterways and enhance the water quality in the area.
In a survey that was distributed in 2000 for the update to the Land Use Plan, citizens were asked
two main stormwater related questions. The first was whether public funds should be spent to
address stormwater ponding and drainage issues on private property. The second question was
whether Dare County should establish a full-time stormwater management and ditch maintenance
program. In response to the first question, a slight majority, 57.6% disagreed or strongly disagreed
with the expenditure of public funds to address stormwater drainage problems on private property.
36.7% were supportive of the use of public funds in this manner. On the issue of a full-time County
stormwater management and ditch maintenance program, 84.7% were supportive. Only 10.7%
were not in agreement.
Surface Water Quality
The County is continuing to seek methods to protect and enhance the water quality of the estuarine
system, and to develop new management measures and practices to improve water quality. The
stormwater management program will provide another tool for the County to reduce stormwater
pollution to the waterways and enhance the water quality in the area.
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' CHAPTER TWO DARE COUNTY
REGULATION/ORDINANCE REVIEW STORMWATER MASTER PLAN
' Protection of Trees and Vegetation
The County's policy is to provide the public with information on best management practices for tree
removal and land clearing, but not to prevent vegetation removal on private property due to a conflict
' with property rights generally associated with private ownership.
Types of Urban Growth Patterns Desired
The implementation of the stormwater management program will not affect the desired growth
patterns on the island. The program will help to improve visual aspects on the island (reducing or
eliminating standing water during storms), which will help to encourage the desired growth patterns.
' Redevelopment of Developed Areas, Including the Relocation of Threatened Structures
It is County policy that density allowances for redevelopment areas conform to existing County
building and zoning regulations, even if they are more restrictive than when the structure was
' originally built.
Continuing Public Participation
' County policy is to assure that all residents have a full and adequate opportunity to be informed of
and participate in the County's planning decision -making process. The stormwater management
program also includes public education and public participation.
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.' CHAPTER THREE DARE COUNTY
POLICY STORMWATER MASTER PLAN
This chapter outlines the existing County policies regarding stormwater management and evaluates
what policies need changes for effective management in the future. Current responsibilities of the
County are explained in this chapter.
' 3.1 RESPONSIBILITIES
' Stormwater management in the Dare County is currently the responsibility of the State of North
Carolina. Dare County will be responsible for stormwater management when the County implements
a stormwater management program and adopts a stormwater management ordinance.
Currently the County has the following responsibilities regarding stormwater management:
• Approval of site plans with respect to amount of built upon area, setbacks from the mean
high water mark.
• Inspection of new subdivisions for compliance with subdivision ordinances, including
stormwater drainage systems.
3.2 STORMWATER MANAGEMENT
The County does not currently have a Stormwater Management Ordinance. A stormwater ordinance
is needed to help prevent illicit discharges and dumping into the storm drain. An ordinance can
make it illegal to put gasoline, oil, antifreeze, and other pollutants into the storm drain system. It
would also be illegal for any person to put anything in the ditch, storm drain, or other drainage way
' that impedes or interferes with the free flow of stormwater. Additionally, the stormwater ordinance
would also assist in limiting the amount of impervious surface on lots, thus reducing the quantity of
stormwater entering the storm drain system, and help to reduce the risk of flooding during storms.
' 3.2.1 PUBLIC EDUCATION/INVOLVEMENT
' This Stormwater Master Plan provides a way for the County to improve stormwater management
in the future and to reduce deficiencies of the storm drain system. An important part of the plan is
educating citizens about stormwater runoff, the importance of protecting the environment by not
polluting the stormwater runoff, and ways that they can reduce stormwater runoff to help decrease
' flooding. Two handouts containing information about stormwater and ways the citizens can help
reduce stormwater runoff were made available to the public at the informational workshops, and
through the County Planning Department. Copies of these handouts are included in Appendix C.
' Additional information could be supplied to the public as inserts included in County tax bills or
handouts provided at real estate offices.
' The County has also provided for public involvement as part of the development of the stormwater
management program. Two public workshops, one in Manteo and one in Buxton were held to inform
the public about the program and to solicit input regarding areas of concern and potential solutions.
' The public provided input on additional areas of concern and other topics.
3.2.2 POLLUTION PREVENTION
' Pollution prevention can play a large part in the amount of pollution that enters the waterways
through stormwater runoff. Educating business owners and citizens about pollution prevention
techniques is the best approach to reduce or prevent pollution. The County can implement
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' CHAPTER THREE DARE COUNTY
POLICY STORMWATER MASTER PLAN
' programs at very little (or no) cost that are effective at reducing pollution. The following programs
are recommended for stormwater pollution prevention:
• Identify local facilities which will accept waste oil/household chemicals and if none are
' located in the area, the County may coordinate with the State to sponsor pollution disposal
drives on a designated quarterly schedule.
• Develop specific lawn maintenance recommended practices for the area and make a
' pamphlet to be mailed in the beginning of every spring.
• Develop a recommended list of vegetation that are effective in filtering pollutants, promote
voluntary planting of a vegetative buffer.
' • Coordinate with commercial business owners to establish parking lot cleaning operations
including recommended procedures and schedules.
' 3.2.3 ILLICIT DISCHARGE DETECTION AND ELIMINATION
Illicit discharge detection and elimination is a way for the County to ensure that only stormwater is
entering the stormwater system. The infiltration of septic tank effluent into drainage channels and
wetlands have been identified by the County as an ongoing concern. Currently, the County Health
Department sites, permits, and inspects septic tank systems on a case -by -case basis. In the future,
it is possible that the impact of septic tank discharges on the quality of County stormwater runoff will
' be scrutinized more closely by regulatory agencies.
Under the final NPDES Phase II rule, permit requirements for system operators, regarding illicit
' discharges, will include the following:
1. Develop a storm sewer system map showing the location of all outfalls, and names and location
of all waters of the United States that receive discharges from those outfalls.
2. Effectively prohibit though ordinance, or other regulatory mechanism, illicit discharges into the
separate storm sewer system and implement appropriate enforcement procedures and actions
as needed, and to the extent allowable under State, Tribal, or local law.
R
3. Develop and implement a plan to detect and address illicit discharges, including illegal dumping,
' to the system;
4. Inform public employees, businesses, and the general public of hazards associated with illegal
discharges and improper disposal of waste.
Currently, Item 2 is addressed by County septic tank siting and permit requirements. Item 4 has
' been incorporated into the County's Stormwater Master Plan by URS. Items 1 and 3 are interrelated
in nature, with Item 1 (the development of storm sewer system mapping) being necessary to
implement Item 3.
' At this point in time, there is no County drainage system mapping. Of the four items shown above
related to the management of illicit discharges, the preparation of drainage system mapping with
drainage boundary delineation and outfall identification would provide the greatest long-term benefit
to the County, especially if the County plans to implement a long-term maintenance program. In
addition to the illicit discharge issues, the mapping would be very beneficial in the general
administration of the County's stormwater management program. URS recommends that the
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' CHAPTER THREE DARE COUNTY
POLICY STORMWATER MASTER PLAN
County should incorporate the preparation of drainage system mapping into its long-term stormwater
management goals.
' 3.2.4 INCREASED RUNOFF DUE TO DEVELOPMENT
As land is developed, the area of perviousness usually decreases. This decrease accelerates the
' runoff of rainfall and increases the peak rates of flow. If measures are not taken during design, this
increased rate of flow can cause flooding and erosion and sedimentation problems. The use of
structural BMPs can provide a solution, as can the implementation of a stormwater ordinance.
' 3.3 DRAINAGE SYSTEM DESIGN, OPERATION AND MAINTENANCE
0
A stormwater drainage system consists of manmade conduits and channels and natural ponds,
streams, creeks, rivers, and floodplains. Flooding is the most noticeable problem that occurs with
poorly designed or maintained drainage systems. North Carolina Department of Transportation
design criteria has been reviewed for applicability in the service area and these criteria were
summarized in Section 2.2.5 - 2.2.6. These design criteria, along with NCDENR stormwater design
criteria are excellent references and should be followed by the County during design and
construction of additional stormwater management measures. The County may also want to
develop their own Stormwater Drainage Design Manual.
It is important that the County has an easement for its storm drain systems so maintenance and
repairs can be performed when necessary. For County -owned storm drain systems carrying runoff
from public right-of-way, the County may want to obtain an easement for any drainage channel.
Storm drain systems which only carry runoff from private property are considered private systems
and the County is not responsible for their maintenance.
If the County so decides, the operation and maintenance of the drainage system in the County will
be the responsibility of the County. In order for the County to effectively maintain the stormwater
drainage system, the County should create an inventory of the major components. This inventory
should include type, location, size, material, slope, length, condition, and current ownership. Some
of this has been collected from previous field investigations of the drainage system. All areas of the
system should be put on a schedule that identifies what type of maintenance needs are to be
performed and how often it should be done. A contingency plan should be developed that outlines
what maintenance activities are needed after a major storm or hurricane.
A step-by-step procedure for responding to minor maintenance and repair requests should also be
developed. The amount of major and minor maintenance work performed will need to be tracked
as a way to evaluate stormwater management program success.
3.4 BEST MANAGEMENT PRACTICES (BMPs)
BMPs are methods or practices that can effectively reduce stormwater pollution. Some BMPs
prevent pollutants from reaching stormwater such as street sweeping and other BMPs reduce the
amount of pollutants already in the runoff such as an infiltration trench. Structural control BMPs
described in the North Carolina Department of Environment and Natural Resources Stormwater
Management Guidance Manual include:
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' CHAPTER THREE DARE COUNTY
POLICY STORMWATER MASTER PLAN
' • infiltration trenches/basins
• dry detention basins
• wet retention basins
' • grassed swales
filter strips
• constructed wetlands
' 3.5 FLOODPLAIN MANAGEMENT
' Dare County participates in the Federal Flood Insurance Program. As part of this program, if a
building is located in a flood prone area, the ground floor elevation must be certified before a
building permit can be issued.
No changes are recommended to the existing floodplain practices and policies regulated by the
County. Any drainage system improvements proposed in the floodplain will have to comply with the
existing requirements.
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' CHAPTER FOUR DARE COUNTY
COUNTY OVERVIEW STORMWATER MASTER PLAN
' This overview describes the physical features of the unincorporated portions of Dare County and
the effects these features have on stormwater quality and quantity. The incorporated areas of Dare
County not addressed in this plan include the municipalities of Kill Devil Hills, Kitty Hawk, Manteo,
' Nags Head, and Southern Shores. Additionally, federal lands such as National Parks Service
Property, National Seashore property, National Wildlife Refuges, and military Reservations are not
addressed in this Plan.
4.1 SETTING
L'
Dare County is located along the eastern seaboard of North Carolina and borders 85 miles of the
Atlantic Ocean. The county is part of the lower Coastal Plain physiographic region of North Carolina
and has a mean elevation of 12 feet. Figure 4-1 shows the location of Dare County. Mainland Dare
County is predominantly residential development with some commercial businesses. The barrier
islands of Dare County, known as the Outer Banks, have a steady year-round population with a
significant increase during the summer months due to seasonal tourism. Figure 4-1 illustrates the
Dare County limits.
4.2 HYDROGRAPHY
Approximately 89% of Dare County is located within the Pasquotank River Basin, which begins in
the southeast comer of Virginia, and flows southeast into North Carolina continuing to the Atlantic
Ocean. A portion of this river basin has been classified by the United State Geological Survey
(USGS) as the Albemarle watershed and has been given a corresponding 8-digit hydrological unit
code (HUC) (03010205). The Albemarle watershed contains most of the Dare County mainland,
Roanoke Island, and barrier islands north of Oregon Inlet. Primary water features include Currituck
Sound, Albemarle Sound, Roanoke Sound, Croatan Sound, and the Atlantic Ocean.
The remaining portion of Dare County is included in the USGS Pamlico Sound watershed
(03020105). This watershed encompasses portions of both the Pasquotank River Basin and the
Tar -Pamlico River Basin. Within the Pamlico watershed, the Pasquotank River Basin includes the
barrier islands from Oregon Inlet to Hatteras Inlet. The Tar -Pamlico River Basin contains the
peninsula formed at the southeast comer of the Dare County mainland, located between the Long
Shoal River and Sandy Point. Primary water features of this watershed include the Pamlico Sound
and the Atlantic Ocean.
Within this watershed, the United States Department of Agriculture Natural Resources Conservation
Service (NRCS) has delineated 19 subwatershed areas with 14-digit HUCs for the purpose of
natural resource planning. The beginning of the 14-digit code uses the 8-digit designation of the
USGS HUC.
Figure 4-2 shows the boundaries of these river basins and 8-digit USGS hydrological units.
4.3 HYDROLOGIC AND HYDRAULIC CHARACTERISTICS
4.3.1 WATERBODIES
' The Albemarle Sound is a large estuarine waterbody containing fresh to brackish water. Salinity is
low due to dilution from freshwater inflow from several rivers including the Chowan, Roanoke,
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' CHAPTER FOUR DARE COUNTY
COUNTY OVERVIEW STORMWATER MASTER PLAN
' Pasquotank, and Alligator rivers. The Alligator River is a large blackwater river that flows into the
Albemarle Sound from the southeast. A major portion of this river (south of US 64) has been
designated as outstanding resource waters (ORW) as determined by the NC Division of Water
Quality (DWQ) Water Quality Standards Program. ORWs are considered to have exceptional state
or national recreational or ecological significance. These waters are of excellent quality and require
special protection to maintain existing uses. The Alligator River borders the Alligator River National
' Wildlife Refuge on the eastern shore and serves as a spawning area for anadromous fish.
Currituck Sound is in the northeast portion of the basin and is characterized as a shallow waterbody
' containing fresh to brackish water. Wind movement largely influences water circulation in the
sound. The Northwest River, which receives drainage from the Great Dismal Swamp, is a major
tributary to Currituck Sound.
' The Croatan, Roanoke, and Pamlico Sounds border the eastern side of the barrier islands south
of Currituck Sound. A majority of this estuarine area is classified as shellfish harvesting areas (SA).
SA waters are tidal systems that have been designated for shellfish harvesting, primary recreation,
' fishing, aquatic life propagation, and wildlife use. Some of these waters are classified as SB
waters, which are waters that are used for primary recreation, including frequent or organized
swimming. Currituck Sound and Kitty Hawk Bay are classified SC waters. The Best Usage
classification of these waters is considered aquatic life propagation and maintenance of biological
integrity, wildlife, secondary recreation, and other uses besides primary recreation and shellfishing.
' Salt marshes occur between the open water of the sounds and the upland areas of the barrier
islands. These marshes are comprised of several various marsh grasses which filter shoreline
runoff and river deposits.
' The majority of the Dare County is located within the 100-year flood plain. There is an area along
with the northeastern side of Roanoke Island, and a small area north of Wanchese that is located
outside the 100- and 500-year floodplains. The majority of the Outer Banks in Dare County are
' within the 100-year floodplain, with the exception of some small areas around Buxton, some areas
near Nags Head, Kill Devil Hills and Kitty Hawk, and some small areas in the villages of Duck and
Colington.
' 4.3.2 SOILS
' Dare County is comprised of several general soil groups also called soil units. The 1977 Dare
County Soil Survey categorizes these units based on similar soil types, patterns, relief, and
drainage. Typically, these areas consist of one or more major soils and several minor soils. These
general categories are used to compare the suitability of large areas for general land uses, but
' should not be used for individual site selection. For the purposes of this document, however, they
offer a concise description of the general soil characteristics of the county. A detailed table of all
Dare County soils in contained in Appendix E.
' Mainland
The Dare County mainland consists of very poorly drained organic and mineral soils. The water
table is at or near the surface for a large portion of the year. Wetness and flooding are the area's
main limitations. Additionally, low strength, subsidence, and the risk of fire limit the organic soils
during dry periods. The soils found on the mainland make up 71 percent of the soils found in the
' entire county.
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' CHAPTER FOUR DARE COUNTY
COUNTY OVERVIEW STORMWATER MASTER PLAN
' The Pungo-Belhaven soil unit is found on broad flats and consists of near) level very poorly
9 Y � rY P Y
drained soils. These soils have a mucky surface layer with an underlay of loamy material. This unit
comprises approximately 51 percent of the county. These soils are used almost exclusively as
woodland and wildlife habitat due to several limitations that affect urban and agricultural uses.
These limitations include wetness, low strength, flooding, and a high percentage of logs, roots, and
' stumps in the organic layer.
11 percent of Dare County is comprised of the Hyde -Cape Fear soil unit. These soils are nearly
level, very poorly drained soils, with a loamy surface layer and a loamy or clayey subsoil. Hyde -
Cape Fear soils are found on broad flats predominantly in the northern central portion of the
mainland. Management concerns include wetness, flooding, and low strength.
' Ponzer-Roper soils comprise 9 percent of the county and are found on broad flats throughout the
central mainland. They are nearly level, very poorly drained soils and have a mucky surface layer
with a loamy underlay. These soils are susceptible to wetness and flooding, and are also limited
' by excessive humus and low strength.
The Dare County mainland marsh areas are lined with a thin strip of soils generalized as the
t Hobonny-Careret-Currituck soil unit. This soil unit is also found on Roanoke Island and the Outer
Banks, cumulatively comprising 10 percent of the county. These soils are nearly level, very poorly
drained and are primarily utilized as wildlife habitat due to frequent flooding by tides, extreme
' wetness, and exposure to salt spray. The soils consist of a mucky or sandy surface layer with a
similar substratum.
A small portion of the mainland, the Manns Harbor area, is located on the Baymeade-Icaria-Johns
' soil unit. These soils are more prevalent on Roanoke Island and are discussed in the following
section.
' Roanoke Island
A large portion of the soil on Roanoke Island is categorized as the Hobonny-Carteret-Currituck soil
unit. These nearly level, very poorly drained soils have a sandy or mucky surface and subsurface
' layers and are found in marsh areas. These areas are utilized almost exclusively as woodland and
wildlife habitat due to frequent flooding and extreme wetness.
' The developed areas of Roanoke Island are mainly located on the Baymeade-Icada-Johns soil unit.
These soils are nearly level to sloping, with drainage ranging from well drained to very poorly
drained. They are found on flats, gently sloping ridges, and depressions with a sandy surface and
a loamy subsoil. Collectively, these soils comprise 2 percent of the county's soils. Development
' and agricultural uses of these soils are limited due to the slope, seepage, the sandy texture, and the
flooding of low areas during high -wind tides.
' Northem Beaches and Hatteras Island, Including Colington
The Newhan-Duckston-Corolla soils are found along the seaboard side of the Northern Beaches
and Hatteras Island and make up 11 percent of the county's soils. Soils within this unit are nearly
' level to steep, and range from excessively drained to poorly drained. They are sandy throughout,
making them unsuitable for cropland or woodland uses. These areas are mainly used for urban,
recreational and beach activities.
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' CHAPTER FOUR DARE COUNTY
COUNTY OVERVIEW STORMWATER MASTER PLAN
' Fripp-Ousley-Osier soils are found on gently sloping or sloping ridges, on flats, and in depressions
on the sound side of the Northern Beaches and Hatteras Island. These sandy soils make up 6
percent of the county's soils and range from excessively drained to poorly drained. Management
' concerns include slope, wetness, seepage, flooding.
The sound side of the Northern Beaches and Hatteras Island is also sporadically lined with a thin
strip of marshland soils generalized as the Hobonny-Careret-Currituck soil unit. This soil unit is also
found on Roanoke Island and the Dare County mainland. Cumulatively, it comprises 10 percent of
the county. These soils are nearly level, very poorly drained and are primarily utilized as wildlife
' habitat due to frequent flooding by tides, extreme wetness, and exposure to salt spray. The soils
consist of a mucky or sandy surface layer with a similar substratum.
n
C
4.4 WATER QUALITY CHARACTERISTICS
Several Dare County shellfish harvesting areas (SA) have been closed for many years due to poor
water quality, specifically high fecal coliform bacteria levels, as determined by the NC Department
of Health, Shellfish Sanitation Section. These prohibited territories include:
• All waters in Shallowbag Bay and its tributaries,
• Waters on the south side of the mouth of Broad Creek, including Mill Creek and its
tributaries,
• Waters on the northern end of Broad Creek, including all of Johns Creek,
• Waters around the Villas Condominium STP Outfall,
• Some waters near Whalebone,
• Some waters south of the Oregon Inlet Fishing Center,
• Waters near Ballast Point, including Pirates Cove and other tributaries in the area,
• Waters near Sand Point,
• Waters near north Shore of Baum Creek on Roanoke Island,
• Waters near North Shore of Spencer Creek,
• Waters near mouth of Manns Harbor,
• Waters near South End of Roanoke Island,
• Waters near Lake Worth drainage canal, on west side of Stumpy Point Bay,
• Waters on east side of Stumpy Point Bay near Drain Point,
• Waters near Hatteras Ferry Landing,
• Waters in creek near entrance to Sandy Bay on Hatteras Island,
• Waters in Sandy Bay upstream into creeks and canals,
• All creeks, canals and tributaries along Hatteras Island between Durant Point and
Brooks Point, to include Joe Sour Creek,
• All waters along the shoreline from north of Buxton, through Bald Point, to just east of
Brooks Point,
• All of Rodanthe Harbor,
• All of Salve Harbor,
• All of Avon Harbor,
• All waters in Askins Creek, and all waters to the east of a line from Shellbank Point, to
the western edge of Colington Island, to Mann Point.
For a complete description of the closed shellfishing areas, please contact the Shellfish Sanitation
Section of the N.C. Department of Environmental Health. The main contributors to the impairment
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' CHAPTER FOUR DARE COUNTY
COUNTY OVERVIEW STORMWATER MASTER PLAN
' of these waters have been identified as urban runoff, failing septic tank systems, and marinas
(DWQ, 1997).
Unincorporated Dare County, like many of the coastal areas and barrier islands in North Carolina
have septic tank systems, not a municipal sewer system. Some of the incorporated areas do have
municipal sewer systems. Many of the coastal areas which still have septic tanks in use have very
high fecal colifom counts in the surrounding estuarine waters.
Dare County initiated a Water Testing and Management Program in 1995 to develop a
' comprehensive program to evaluate the surface waters in and around Dare County. Currently there
are 28 sites around the County being sampled. Additionally, the Albemarle -Pamlico Citizen's Water
Quality Monitoring Program, which began in 1987, has several sites in northern Dare County where
' surface water samples are collected. DWQ has also performed sampling at several sites in Dare
County.
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Benthic Macroinvertebrates have been collected at thirteen locations within the County during the
early 1990's. Somewhat degraded water quality was noted at Spencer Creek at the DOT ferry rehab
facility, Shallowbag Bay near the Manteo WWTP outfall, and in Wanchese Harbor. The mouth of
Currituck Sound, at the northern end of the County, was found to support the most diverse and
intolerant community in the state within its salinity range (DWQ, 1997).
4.5 LAND USE
The unincorporated areas of Dare County primarily consist of federal conservation areas. Among
these are the Alligator River National Wildlife Refuge, the Pea Island National Wildlife Refuge, and
the Cape Hatteras National Seashore Recreation Park.
The unincorporated portions of Dare County that support predominantly residential and commercial
properties are the villages of Sanderling, Duck, Colington, Rodanthe, Waves, Salvo, Avon, Buxton,
Frisco, Hatteras, along with Roanoke island, and the mainland. These residential and commercial
properties mainly consist of impervious surfaces as a result of paved areas (e.g., roads, streets,
parking lots, driveways, etc.) and structures (e.g., shopping centers, commercial buildings, houses,
etc.). Vegetation, if present, varies and includes maintained lawns, maintained scrub areas along
utility easements, or landscaped areas.
4.6 EFFECTS ON WATER QUALITY
Stormwater runoff is rainfall or snowmelt that runs off the ground or impervious surfaces (buildings,
roads, parking lots, etc.) and ultimately drains to surface waters including streams, ponds, lakes,
estuaries, sounds, or the ocean. Most of the Dare County drainage system consists of swales along
roads which collect stormwater runoff. There are also several catch basins with piped outfalls to the
Sound.
The collection systems, although not adequate, mainly address the water quantity problem by
helping to reduce flooding but do not address the water quality problem of pollutant removal.
Wetlands and vegetated areas perform the natural function of reducing the flow rate of stormwater
runoff and allowing the pollutants to settle and filter through soils. This natural pollutant removal
system by the environment helps to reduce the impact of man-made pollution on surface waters.
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' CHAPTER FOUR DARE COUNTY
COUNTY OVERVIEW STORMWATER MASTER PLAN
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Land use dictates the type of pollutants that enter stormwater runoff and ultimately impact surface
waters. First flush is the first portion of runoff from a storm and it usually contains the highest
concentrations of pollutants. The land use within the service area affects water quality because of
the associated pollutants. Table 4-1 shows the land use activities associated with pollutants.
Table 4-1
Stormwater Pollutants
Pollutant
- Land Use Activity.
Suspended solids and turbidity
Plowing agricultural fields/gardens
• Land clearing for development without proper
sedimentation/erosion controls
Nutrients (chlorophyll a, phosphorus, nitrogen)
• Fertilizer application to lawns, golf courses,
and nitrogen) crops
Fecal coliform
vi
• Overuse or failure of septic tanks
• Package plant malfunctions
• Leaks in sewer lines
• Waste from pets, domestic and wild animals
Oil and grease
• Leaky automobiles, industrial areas, illegal
dumping
Toxic chemicals
• Automobiles, industrial areas, illegal dumping,
pesticide application
Stormwater management includes control practices and preventive measures which will improve
water quality. Chapter 5 discusses the water quality problems on the island and provides
recommended mitigation measures.
4.7 EFFECTS ON WATER QUANTITY
Stormwater runoff quantity problems occur in various locations throughout Dare County. These
problems include:
• Flooding/ localized drainage problems,
• soil erosion,
• freshwater flow increase to estuaries/shellfish harvest areas, and
• clogged pipes, culverts, and ditches caused by debris from flooded areas.
Development typically causes an increase in the volume and velocity of stormwater runoff that can
result in environmental problems. Increased impervious surfaces reduce the opportunity for
stormwater runoff to be naturally retained and filtered by vegetation, wetlands, and estuaries. Pipe
culverts located under roads allow a ditch, or channel to flow under the road. Culverts located under
driveways allow ditches to flow under the driveway.
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CHAPTER FOUR DARE COUNTY
COUNTY OVERVIEW STORMWATER MASTER PLAN
' Major drainage problems observed on the island, discussed in Chapter 5, are a direct result of the
inadequate size, number, and/or location of inlets and lack of vegetated ditches to accommodate
the increased stormwater runoff from development impervious surfaces. Stormwater management
' will allow the County to effectively design, implement, construct, and manage stormwater controls
to prevent environmental problems associated with the increasing amount of stormwater quantity.
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4.8 FUTURE DEVELOPMENT
As outlined in the 1994 CAMA Dare County Land Use Plan, future development will focus on
residential development in existing subdivisions and a limited amount of commercial development.
The unincorporated areas of Dare County do not have access to a centralized wastewater treatment
system; therefore future development is limited to areas with soils suitable for septic tank systems.
Table 4-2 illustrates the Dare County population data and the projections of the N.C. Office of State
Planning. It is significant to note that this data includes all portions of the county, including
municipalities. Population growth in these areas, seen in Table 4-3, is considerably higher than the
growth of the county as a whole. Further, this indicates a lower countywide growth rate for the
remaining unincorporated portions.
In 1990, the U.S. Census determined the year-round population of Dare County to be 22,746. The
2000 U.S. Census determined the year-round population of Dare County to be 29,967. With that
data, the N.C. Office of State Planning (OSPL) has projected the 2010 population to be 36,674, an
increase of 24% over 10 years. The OSPL has also projected a population increase of 19.4%
during the period from 2010 through 2020. Table 4-2 illustrates this growth pattern.
Table 4-2
Population Data
Dare County
1990
2000
% Growth
2010
% Growth
2020
%'Growth
(Census)
(Census)
(1990-
(Projected)
(2000-
(Projected)
(2010-
2000)
2010)
2020)
22,746
29,967--r
26.8
36,674
24.0
43,765
19.4
Table 4-3
Population Data
Dare County Municipalities
Municipality
1990
(Census)
2000
(Census)
%Growth
(1990-2000)
Kill Devil Hills
4,238
5,897
39.1
Kitty Hawk
1,937
2,991
54.4
Manteo
991
1,052
6.2
Nags Head
1,838
2,700
46.9
Southern Shores
1,447
2,201
52.1
Overall, this growth and development will cause an increase in overall imperviousness in developed
areas of Dare County.
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11
CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
5.1 SELECTION CRITERIA
During the development of recommendations for each area of concern, several criteria were
evaluated to determine the most appropriate BMP for each area. The criteria which were evaluated
were:
• Cost to implement and maintain
• Regulatory requirements
• Effectiveness at solving the problem
• Acceptability to the County and the public
• Reliability
• Implementability
• Environmental impact
• Commitment to longevity
Cost to implement and maintain
The cost to implement and maintain each BMP was evaluated and compared. Specific costs for
each BMP were not determined, but relative costs of each BMP type were compared to determine
the most cost effective solutions.
Regulatory Requirements
Each BMP was evaluated to determine if any special regulatory requirements would have to be met
for implementation.
Effectiveness at solvinq the problem
Each BMP was evaluated to determine the effectiveness at solving the flooding and/or water quality
problem(s). The recommended BMP may only alleviate the problem, not completely solve it, but the
other criteria indicated that this BMP was the most appropriate.
Acceptability to the County and the public
Each BMP was evaluated as to whether it would be an acceptable solution to the County and to the
public. Education is an important aspect to acceptability of a BMP.
Reliabili
The reliability over time of each BMP was evaluated. Some BMPs retain their effectiveness longer
than others with a limited amount of maintenance.
' Implementability
Some structural BMPs can not be constructed in certain areas to regulatory and/or physical
constraints.
Environmental Impacf
Each BMP was evaluated to determine if any positive or negative environmental impacts would
occur due to implementation of the BMP.
Commitment to Longevity
For this criterion, the amount of maintenance required was evaluated to assess whether a
commitment will and/or can be made in regards to long-term maintenance and upkeep of the BMP.
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CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
5.2 EVALUATIONS AND RECOMMENDATIONS
Flooding is the primary stormwater problem on the island of Dare County. The following sections
provide an explanation of the flooding areas of concern, and recommendations for improvements.
Deficiencies and recommendations are summarized in Table 5-2.
5.2.1 MAINLAND
There are some ponding issues in the Manns Harbor, East Lake and Stumpy Point area, mainly due
to lack of drainage swales along the roadway. Additionally, the County needs to take an active
approach to evaluating the condition of the "mosquito ditches' which are located on the mainland
and throughout the County. Often times, these ditches are located on private property, where the
County has no jurisdiction for maintenance and upkeep. In certain areas the county may want to
evaluate the need for obtaining drainage easements in order to properly maintain the ditches. This
should be evaluated on a case -by -case basis.
5.2.2 ROANOKE ISLAND
There are several areas on Roanoke Island that have reoccurring drainage and ponding problems.
These areas are described below.
' Raleigh Woods
The Raleigh Woods subdivision is located on the north end of Roanoke Island, off US 64/264, east
of the airport. A visual inspection of the subdivision performed by URS Corporation indicated that
' there was little or no drainage system present. A few grassed swales were located along the
roadside near the rear of the subdivision, though overall, a drainage system was lacking.
' Existing drainage problems identified in the Raleigh Woods area included standing water in and
along the road, which often extended significantly into front and back yards. The ponding and
drainage appears to be the worst near the back of the subdivision, and at some of the cross streets.
This is primarily due to the soil types present in this area. Though most of the soil is fairly well
drained, with several feet to the water table, Icaria soils are present in localized areas. The
seasonal high water table in these areas is at or near the surface, which could contribute to ponding
problems if the runoff is not directed away from these areas.
Ponding is several inches deep and extends across the entire road on many occasions. These
' ponding conditions cause a safety hazard for pedestrians and motorists, along with the potential for
property damage to cars from hidden obstructions under the water.
' In order to solve the flooding problem in this area it is recommended that roadside drainage swales
and driveway culverts be installed throughout the subdivision. New culverts should be constructed
of corrugated HDPE and have minimum diameter of 15 inches. Metal culverts should not be used
' due to the corrosion and other durability issues in this climate.
These swales and culverts should be able to be installed within the road right-of-way so that the
County has access for maintenance. If not, the County may have to evaluate obtaining drainage
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DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
easements so maintenance can be performed on the swales. Another very important aspect is
homeowner education. The homeowners must be informed about the importance of these swales
' and that they should not be altered or filled. A comprehensive educational program can go a long
way to limiting maintenance hassles from homeowners altering or filling swales.
' Grassed swales will help reduce the ponding problem by eliminating standing water in the roadway
and providing additional surface area for infiltration. The vegetation (grasses) in the swales also
removes pollutants (filtration and nutrient uptake) from the stormwater runoff.
Since all lots in this subdivision have not been built out at this time, the additional building that could
take place in this subdivision will only increase the ponding problems along the roadway unless the
' homeowners are required to retain all additional runoff from the increased impervious surfaces on
their lots. This is not a very popular idea to most property owners, thus an ordinance requiring such
activities would be very difficult to implement. URS recommends that the County investigate the
purchase of some land in the subdivision, or possibly adjacent to the subdivision for a small dry
detention basin. The drainage swales could then be graded to this detention basin as a holding
area and an increased infiltration area during storms.
The size of drainage swales and driveway culverts, along with the amount of grading necessary will
have to be determined through simple hydraulic and hydrologic (H & H) studies of the area. A
detailed survey is also necessary prior to completion of the H&H survey and design efforts.
The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
' maps will have to be obtained prior to design.
To reduce the amount of stormwater runoff which reaches the street, and the County's storm drain
system, URS recommends that the County encourage its residents to reduce the amount of
impervious surface on their lots, and to direct stormwater runoff (from rooftops and other impervious
surfaces) to vegetated areas, instead of directly off their property and into the street (or onto a
neighbors property). A recommended stormwater ordinance that will assist in accomplishing this
' is included in Appendix C. Depending on the method of funding of the County's stormwater
management program (Section 6.5), the County may want to offer fee/tax credits for residents
constructing french drains or infiltration areas for runoff from impervious surfaces on their lots. (This
would be applicable with a stormwater utility or stormwater fee/tax).
Through evaluation of various BMPs, grassed swales, with a stormwater ordinance, was determined
to be the most cost effective, applicable, and effective at solving the flooding problems in the area.
As long as the swale system is maintained, it is a reliable stormwater BMP. There are no negative
environmental impacts associated with an infiltration system in this area. Public education will be
necessary to inform the residents of the need for the system, how the system will solve the flooding
problem, and what they need to do to comply with the stormwater ordinance (if adopted by the
County).
Garden Drive and Mother Vineyard Road
There have been several reports of drainage problems associated with the drainage channel that
runs from the end of Garden Road, under Mother Vineyard Road past Webb Court and eventually
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' CHAPTER FIVE
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RECOMMENDATIONS STORMWATER MASTER PLAN
' flows out to the Sound. A visual inspection of the drainage channel performed by URS revealed a
P 9
lack of maintenance on the channel and apparent lack of capacity for storm flows. Additionally, the
' culvert beneath Mother Vineyard Road will most likely require replacement with a larger culvert.
The soils in the area of this channel are Johns loamy sands, which have a moderate to rapid
' permeability. Drainage channels are an excellent way for draining this type of soil.
During rainstorms this ditch fills rapidly and overflows onto surrounding properties. These flooding
' conditions cause a safety hazards, along with the potential for property damage on adjacent
properties.
' An additional potential hazard is the continuous standing water in the drainage channel. It is
possible that regrading of this channel could increase flow, thereby reducing or eliminating the
standing water. A detailed survey of the channel and surrounding areas would determine if
' regrading were possible.
URS recommends enlargement of the channel after completion of a hydraulic and hydrologic
evaluation to determine the appropriate size of this channel. Additionally, an evaluation of the
' drainage area to determine the appropriate culvert size under Mother Vineyard Road will be
necessary for culvert replacement.
' URS also recommends the County obtain a drainage easement along this channel so maintenance
can be performed. Another very important aspect is homeowner education. The homeowners must
be informed about the importance of these channels and that they should not be altered or filled.
' A comprehensive educational program can go a long way to limiting maintenance hassles from
homeowners altering or filling drainage channels.
As stated above, the size of the channel, along with grading requirements and the size of the culvert
' will have to be determined through hydraulic and hydrologic (H & H) modeling of the area. A
detailed survey is also necessary prior to completion of the modeling efforts.
' Through evaluation of various BMPs, increasing the size of the drainage channel, with a stormwater
ordinance, was determined to most cost effective, applicable, and effective at solving the flooding
problems in the be the area. As long as the drainage system is maintained, it is a reliable stormwater
' BMP. There are no negative environmental impacts associated with an infiltration system in this
area. Public education will be necessary to inform the residents of the need for the system, how the
system will solve the flooding problem, and what they need to do to comply with the stormwater
' ordinance (if adopted by the County).
Wanchese
Wanchese is located on the southern end of Roanoke Island. A visual inspection of the village
' performed by URS indicated that there was little or no drainage system present. A few grassed
swales were located along a few roads, though overall a drainage system was lacking. Existing
drainage problems identified in the Wanchese area included standing water in and along the
' Oberlin, Daniels, and Tillett Roads, along with various sections of NC 345.
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DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
The soils in this area are Johns loamy sands, which have a moderate to rapid permeability.
Drainage channels are an excellent way for draining this type of soil, provided they have the
appropriate capacity and are graded correctly.
Ponding is several inches deep and extends across the entire road on many occasions. These
' ponding conditions cause a safety hazard for pedestrians and motorists, along with the potential for
property damage to cars from hidden obstructions under the water.
In order to solve the flooding problem in this area it is recommended that roadside drainage swales
and driveway culverts be installed in the areas experiencing the ponding problems. New culverts
should be constructed of corrugated HDPE and have minimum diameter of 15 inches. Metal
' culverts should not be used due to the corrosion and other durability issues in this climate.
Since NC 345 is a NCDOT roadway, there must be coordination with NCDOT. All plans and
' designs must be approved by NCDOT prior to implementation. '%It may be possible to obtain
assistance from NCDOT on the construction of the system. URS recommends that the County have
a meeting with NCDOT to discuss the issues along NC 345 and how the NCDOT and the County
can work together to alleviate the drainage problems.
These swales and culverts should be able to be installed within the road right-of-way so that the
County has access for maintenance. If not, the County may have to evaluate obtaining drainage
easements so maintenance can be performed on the swales. Another very important aspect is
homeowner education. The homeowners must be informed about the importance of these swales
and that they should not be altered or filled. A comprehensive educational program can go a long
' way to limiting maintenance hassles from homeowners altering or filling swales.
Grassed swales will help reduce the ponding problem by eliminating standing water in the roadway
and providing additional surface area for infiltration. The vegetation (grasses) in the swales also
removes pollutants (filtration and nutrient uptake) from the stormwater runoff.
The size of drainage swales and driveway culverts, along with the amount of grading necessary will
have to be determined through simple hydraulic and hydrologic (H & H) studies of the area. A
detailed survey is also necessary prior to completion of the H&H survey and design efforts.
' The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
maps will have to be obtained prior to design.
j
Through evaluation of various BMPs, grassed swales, with a stormwater ordinance, was determined
to be the most cost effective, applicable, and effective at solving the flooding problems in the area.
As long as the swale system is maintained, it is a reliable stormwater BMP. There are no negative
environmental impacts associated with an infiltration system in this area. Public education will be
necessary to inform the residents of the need for the system, how the system will solve the flooding
problem, and what they need to do to comply with the stormwater ordinance (if adopted by the
County).
06/01/01 5-5

CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
5.2.3 NORTHERN BEACHES
NC12 in Duck
Significant ponding occurs along NC 12 in Duck. Ponding is several inches deep and extends into
the travel lanes on many occasions. These ponding conditions cause a safety hazard for
pedestrians and motorists, along with the potential for property damage to cars from hidden
obstructions under the water.
There are few storm drain inlets along NC 12. Therefore, due to the grading of the lots in the area,
and the lack of any stormwater management facility, there is no place for the stormwater to flow.
' In order to solve the ponding problems in this area it is recommended that grassed infiltration swales
are constructed. Since NC 12 is a NCDOT roadway, there must be coordination with NCDOT. All
plans and designs must be approved by NCDOT prior to implementation. It may be possible to
obtain assistance from NCDOT on the construction of the system. URS recommends that the
' County have a meeting with NCDOT to discuss the issues along NC 12 and how the NCDOT and
the County can work together to alleviate the ponding problems.
The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
maps will have to be obtained prior to design.
' The location and number of storm drain inlets, along with the size of infiltration facilities will have to
be determined through hydraulic and hydrologic (H & H) modeling of the area. A detailed survey
I
is also necessary to prior to completion of the modeling efforts.
Through evaluation of various BMPs, grassed infiltration swales, with a stormwater ordinance, was
determined to be the most cost effective, applicable, and effective at solving the flooding problems
in the area. With cooperation from the NCDOT, this is an implementable BMP. As long as the
grassed infiltration swales are maintained, it is a reliable stormwater BMP. There are no negative
environmental impacts associated with a swale system in this area. Public education will be
necessary to inform the residents of the need for the system, how the system will solve the flooding
problem, and what they need to do to comply with the stormwater ordinance (if adopted by the
County).
Baum Bay Harbor
Baum Bay Harbor is located on the northern beach area of Dare County, just east of the Wright
' Brothers National Memorial. There have been several reports of drainage problems associated with
the roadside drainage swales that run through Baum Bay Harbor and eventually flow out to the
Sound. A visual inspection of the drainage swales performed by URS revealed a lack of
' maintenance on the channel, filling of the swales by property owners, apparent lack of capacity for
storm flows, and inadequate culvert capacity.
' The soils in this area are Ousley fine sands, which have a rapid permeability. Though wetness is
often a problem in these soils, drainage swales and canals are an excellent way for draining this
type of soil.
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' CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
' RECOMMENDATIONS STORMWATER MASTER PLAN
During rainstorms, these swales back up into the roadway and into yards due to blockages and
' inadequate, damaged, or removed culverts. These flooding conditions cause a safety hazards to
pedestrians and vehicles, along with the potential for property damage on adjacent properties.
In order to solve the flooding problem in this area it is recommended that roadside drainage swales
' and driveway culverts be regraded and/or reinstalled throughout the subdivision. Several of the
swales are improperly graded (i.e. no slope), and many of the culverts are inadequately sized to
handle the capacity. New culverts should be constructed of corrugated HDPE and have minimum
diameter of 15 inches. Metal culverts should not be used due to the corrosion and other durability
issues in this climate.
' Additionally, the roads themselves need to be evaluated. Low spots and lack of crowning on the
roadways is often a main contributor to standing water in and along the roadways. Where this
occurs, repair and/or regrading of the roads may be necessary to alleviate the problems. Where
' these roads are NCDOT roadways, there must be coordination with NCDOT. All plans and designs
must be approved by NCDOT prior to implementation. It may be possible to obtain assistance from
NCDOT on the construction of the system. URS recommends that the County have a meeting with
NCDOT to discuss the issues along these roads and how the NCDOT and the County can work
together to alleviate the ponding problems.
These swales and culverts should be able to be installed within the road right-of-way so that the
' County has access for maintenance. If not, the County may have to evaluate obtaining drainage
easements so maintenance can be performed on the swales. Another very important aspect is
homeowner education. The homeowners must be informed about the importance of these swales
' and that they should not be altered or filled. A comprehensive educational program can go a long
way to limiting maintenance hassles from homeowners altering or filling swales.
' Grassed swales will help reduce the ponding problem by eliminating standing water in the roadway
and providing additional surface area for infiltration. The vegetation (grasses) in the swales also
removes pollutants (filtration and nutrient uptake) from the stormwater runoff.
' The size of drainage swales and driveway culverts, along with the amount of grading necessary will
have to be determined through simple hydraulic and hydrologic (H & H) studies of the area. A
detailed survey is also necessary to prior to completion of the H&H survey and design efforts.
The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
' maps will have to be obtained prior to design.
Through evaluation of various BMPs, improving the drainage swales and replacing
' damaged/missing culverts, with a stormwater ordinance, was determined to most cost effective,
applicable, and effective at solving the flooding problems in the be the area. As long as the drainage
system is maintained, it is a reliable stormwater BMP. There are no negative environmental impacts
associated with the swale system in this area. Public education will be necessary to inform the
residents of the need for the system, how the system will solve the flooding problem, and what they
need to do to comply with the stormwater ordinance (if adopted by the County).
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' CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
Colington Road
Significant ponding occurs along Colington Road, west of Baum Bay Harbor. Ponding is several
' inches deep and extends into the travel lanes on many occasions. These ponding conditions cause
a safety hazard for pedestrians and motorists, along with the potential for property damage to cars
from hidden obstructions under the water.
There is no storm drain system along Colington Road. Therefore, due to the grading of the lots in
the area, and the lack of any stormwater management facility, there is no place for the stormwater
' to flow. Additional problems along Colington Road include the low roadway elevation in several
areas. Visual inspection of areas of the roadway indicate that in areas where the roadway is
adjacent to Blounts Bay and nearby creeks, the roadway is located at nearly the same elevation as
these waterbodies. Thus, during strong wind tides or heavy rains, the water will extend into the
roadway.
' The soils in this area are Ousley fine sands, which have a rapid permeability, and Currituck mucky
peat. Though wetness is often a problem in the Ousley soils, drainage swales and canals are an
excellent way for draining this type of soil. Currituck soils are very poorly drained with a seasonal
high water table of 1 foot above to 1 foot below the ground surface.
In order to solve the ponding problems in this area it is recommended that grassed infiltration swales
are constructed in the areas of ponding along Colington Road. Raising and regrading the roadway
' in the low elevation areas, which typically correspond to the areas of Currituck soils, is also
recommended. Drainage swales will not be effective in the Currituck soils due to the high water
table present in these areas.
' Since Colington Road is a NCDOT roadway, there must be coordination with NCDOT. All plans and
designs must be approved by NCDOT prior to implementation. It may be possible to obtain
' assistance from NCDOT on the construction of the system. URS recommends that the County have
a meeting with NCDOT to discuss the issues along Colington Road and how the NCDOT and the
County can work together to alleviate the ponding problems.
' The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
maps will have to be obtained prior to design.
' The size of grassed swales, along with the grading will have to be determined through hydraulic and
hydrologic (H & H) modeling of the area. A detailed survey is also necessary to prior to completion
' of the modeling efforts.
Through evaluation of various BMPs, grassed infiltration swales, with a stormwater ordinance, and
' raising/regrading the roadway in various areas was determined to be the most cost effective,
applicable, and effective at solving the flooding problems in the area. With cooperation from the
NCDOT, this is an implementable BMP. As long as the grassed infiltration swales are maintained,
it is a reliable stormwater BMP. There are no negative environmental impacts associated with a
swale system in this area. Public education will be necessary to inform the residents of the need
for the system, how the system will solve the flooding problem, and what they need to do to comply
with the stormwater ordinance (if adopted by the County).
' 06/01/01 5_8

CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
' The Dare County Planning Department received a letter from the Martin's Point Homeowners
Association notifying the County of stormwater problems within their subdivision. The County will
work with Martins Point on these issues. It should be noted, though, that the roads in this
neighborhood are private roads, therefore County funds cannot be used to solve the drainage
' problems. The County cannot use public funds to solve drainage problems on private roads. The
County will work with Martins Point to help them find solutions to their flooding problems.
' 5.2.4 SOUTHERN BEACHES/HATTERAS ISLAND
Rodanthe/Waves/Salvo
Rodanthe, Waves, and Salvo are located south of Oregon Inlet on Hatteras Island. A visual
inspection of the villages' drainage performed by URS indicated that there was little or no drainage
system present. Existing drainage problems identified in the area included standing water in and
along the many of the side streets. There is also a drainage problem, associated with the drainage
channel, which is located in Rodanthe, and flows out to the Sound near the Amusement Park. This
channel starts east of NC 12 around the center of Buxton and flows south. The current problems
occur due to the channel being filled in south of Beulah Oneal Drive. The channel starts again at
S. Holiday Blvd. and continues south across Trade Winds Drive and Atlantic Drive, and flows out
to the Sound south of the Amusement park and North of South Shore Drive.
' Ponding is several inches deep and extends into the roadways in several locations. These ponding
conditions cause a safety hazard for pedestrians and motorists, along with the potential for property
damage to cars from hidden obstructions under the water.
' In order to solve the ponding problem in this area it is recommended that roadside drainage swales
and driveway culverts be installed in the areas experiencing the ponding problems. New culverts
should be constructed of corrugated HDPE and have minimum diameter of 15 inches. Metal culverts
should not be used due to the corrosion and other durability issues in this climate.
These swales and culverts should be able to be installed within the road right-of-way so that the
County has access for maintenance. If not, the County may have to evaluate obtaining drainage
easements so maintenance can be performed on the swales. Another very important aspect is
homeowner education. The homeowners must be informed about the importance of these swales
and that they should not be altered or filled. A comprehensive educational program can go a long
way to limiting maintenance hassles from homeowners altering or filling swales.
' Grassed swales will help reduce the ponding problem by eliminating standing water in the roadway
and providing additional surface area for infiltration. The vegetation (grasses) in the swales also
removes pollutants ffiiltration and nutrient uptake) from the stormwater runoff.
' The size of drainage swales and driveway culverts, along with the amount of grading necessary will
have to be determined through simple hydraulic and hydrologic (H & H) studies of the area. A
detailed survey is also necessary to prior to completion of the H&H survey and design efforts.
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DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
maps will have to be obtained prior to design.
The drainage channel in Rodanthe requires a separate solution. URS understands that a portion
' of this channel has been filled in property owners, thus eliminating its connection with the Sound.
The ideal solution would be to reopen the ditch, though permitting problems exist with this solution.
Due to the poor soils in the area, infiltration basins will be ineffective. Therefore, URS recommends
the construction of a wet retention basin adjacent, but offline from the northern (disconnected)
section of the channel. This will increase storage capacity during storm events and significantly
reduce or eliminate the problem with the ditch no longer being connected with the Sound.
' The County will need to investigate the purchase of property in this area for a retention basin. The
size of basin will have to be determined through hydraulic and hydrologic (H & H) studies of the
area. A detailed survey is also necessary to prior to completion of the H&H survey and design
efforts.
Through evaluation of various BMPs, grassed swales, with a stormwater ordinance, was determined
to be the most cost effective, applicable, and effective at solving the roadway ponding problems in
the area, and a wet retention basin was determined to be the most cost effective, applicable, and
effective at solving the drainage problems associated with the Rodanthe drainage ditch. As long
' as the swale system and retention basin are maintained, they are reliable stormwater BMPs. There
are no negative environmental impacts associated with an the swales and retention basin in this
area. Public education will be necessary to inform the residents of the need for the systems, how
' the system will solve the flooding problem, and what they need to do to comply with the stormwater
ordinance (if adopted by the County).
In areas where these ponding/drainage problems occur on private roads, County funds cannot be
used to solve the drainage problem. The County cannot use public funds to solve drainage
problems on private roads.
' Avon
Avon is located south of Salvo on Hatteras Island. A visual inspection of the village's drainage
performed by URS indicated that there was little or no drainage system present. Existing drainage
' problems identified in the area included standing water in and along the many of the side streets.
Ponding is several inches deep and extends into the roadways in several locations. These ponding
' conditions cause a safety hazard for pedestrians and motorists, along with the potential for property
damage to cars from hidden obstructions under the water.
' In order to solve the ponding problem in this area it is recommended that roadside drainage swales
and driveway culverts be installed in the areas experiencing the ponding problems. New culverts
should be constructed of corrugated HDPE and have minimum diameter of 15 inches. Metal culverts
should not be used due to the corrosion and other durability issues in this climate.
These swales and culverts should be able to be installed within the road right-of-way so that the
County has access for maintenance. If not, the County may have to evaluate obtaining drainage
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RECOMMENDATIONS STORMWATER MASTER PLAN
easements so maintenance can be performed on the swales. Another very important aspect is
homeowner education. The homeowners must be informed about the importance of these swales
and that they should not be altered or filled. A comprehensive educational program can go a long
way to limiting maintenance hassles from homeowners altering or filling swales.
Grassed swales will help reduce the ponding problem by eliminating standing water in the roadway
and providing additional surface area for infiltration. The vegetation (grasses) in the swales also
removes pollutants (filtration and nutrient uptake) from the stormwater runoff.
The size of drainage swales and driveway culverts, along with the amount of grading necessary will
have to be determined through simple hydraulic and hydrologic (H & H) studies of the area. A
detailed survey is also necessary to prior to completion of the H&H survey and design efforts.
The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
maps will have to be obtained prior to design.
Through evaluation of various BMPs, grassed swales, with a stormwater ordinance, was determined
' to be the most cost effective, applicable, and effective at solving the flooding problems in the area.
As long as the swale system is maintained, it is a reliable stormwater BMP. There are no negative
environmental impacts associated with an infiltration system in this area. Public education will be
' necessary to inform the residents of the need for the system, how the system will solve the flooding
problem, and what they need to do to comply with the stormwater ordinance (if adopted by the
County).
' Peter's Ditch
Peter's Ditch is located on Hatters Island in the Buxton area. The eastern end of the ditch is located
' near the Fesseden Center and continues westward through Buxton. There have been several
reports of drainage problems associated with this drainage channel. Investigations and a visual
inspection of the drainage channel performed by URS revealed a lack of maintenance on the
channel and apparent lack of capacity for storm flows. Additionally, several culverts along the
' channel are undersized.
During rainstorms this channel fills rapidly and backs up into surrounding properties in several
locations. These flooding conditions cause a safety hazards, along with the potential for property
damage on adjacent properties.
' URS recommends maintenance of the channel, to include debris and excessive vegetation removal.
Additionally, an evaluation of the drainage area to determine the appropriate culvert sizes will be
necessary for culvert replacement.
URS also recommends the County obtain a drainage easement along this channel so maintenance
can be performed. Another very important aspect is homeowner education. The homeowners must
be informed about the importance of these channels and that they should not be altered or filled.
A comprehensive educational program can go a long way to limiting maintenance hassles from
homeowners altering or filling drainage channels.
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The appropriate size of the channel, along with grading requirements and the size of the culverts
will have to be determined through hydraulic and hydrologic (H & H) modeling of the area. A
detailed survey is also necessary to prior to completion of the modeling efforts.
Through evaluation of various BMPs, maintenance of the drainage channel, hydraulic analysis, and
culvert replacement, were determined to most cost effective, applicable, and effective BMPs for
solving the drainage problems in the area. As long as the drainage system is maintained, it is a
reliable stormwater BMP. There are no negative environmental impacts associated with an
maintenance and upgrade of this system. Public education will be necessary to inform the residents
of the need for the system, how the system will solve the flooding problem, and what they need to
do to reduce stormwater runoff.
Jesse's Ditch
Jesse's Ditch is also located on Hatters Island in the Buxton area. The sections of this drainage
channel that have the most problem are located near the cement plant in Buxton, and near the
Crossroads, across NC12 from the Pilot House Restaurant. There have been several reports of
drainage problems associated with this drainage channel. Investigations and a visual inspection
of the drainage channel performed by URS revealed a lack of maintenance on the channel and
apparent lack of capacity for storm flows. Additionally, several culverts along the channel are
undersized.
' During rainstorms this channel fills rapidly and backs up into surrounding properties in several
locations. These flooding conditions cause a safety hazards, along with the potential for property
damage on adjacent properties.
URS recommends maintenance of the channel, to include debris and excessive vegetation removal.
Additionally, an evaluation of the drainage area to determine the appropriate culvert sizes will be
necessary for culvert replacement.
URS also recommends the County obtain a drainage easement along this channel so maintenance
can be performed. Another very important aspect is homeowner education. The homeowners must
be informed about the importance of these channels and that they should not be altered or filled.
A comprehensive educational program can go a long way to limiting maintenance hassles from
homeowners altering or filling drainage channels.
The appropriate size of the channel, along with grading requirements and the size of the culverts
will have to be determined through hydraulic and hydrologic (H & H) modeling of the area. A
detailed survey is also necessary prior to completion of the modeling efforts.
Through evaluation of various BMPs, maintenance of the drainage channel, hydraulic analysis, and
culvert replacement, were determined to most cost effective, applicable, and effective BMPs for
solving the drainage problems in the area. As long as the drainage system is maintained, it is a
reliable stormwater BMP. There are no negative environmental impacts associated with an
maintenance and upgrade of this system. Public education will be necessary to inform the residents
of the need for the system, how the system will solve the flooding problem, and what they need to
do.
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CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
Rocky Rollinson Lane
Rocky Rollinson Lane is located in Buxton on Hatteras Island. A visual inspection of the town
performed by URS indicated that there was little or no drainage system present.
The soils in this area are Fripp fine sands, which have a rapid permeability. Drainage channels are
' an excellent way for draining this type of soil, provided they have the appropriate capacity and are
graded correctly.
' Ponding is several inches deep and extends across the entire road on many occasions. These
ponding conditions cause a safety hazard for pedestrians and motorists, along with the potential for
property damage to cars from hidden obstructions under the water.
' In order to solve the flooding problem in this area it is recommended that roadside drainage swales
and driveway culverts be installed in the areas experiencing the ponding problems. New culverts
should be constructed of corrugated HDPE and have minimum diameter of 15 inches. Metal
' culverts should not be used due to the corrosion and other durability issues in this climate.
These swales and culverts should be able to be installed within the road right-of-way so that the
' County has access for maintenance. If not, the County may have to evaluate obtaining drainage
easements so maintenance can be performed on the swales. Another very important aspect is
homeowner education. The homeowners must be informed about the importance of these swales
and that they should not be altered or filled. A comprehensive educational program can go a long
way to limiting maintenance hassles from homeowners altering or filling swales.
' Grassed swales will help reduce the ponding problem by eliminating standing water in the roadway
and providing additional surface area for infiltration. The vegetation (grasses) in the swales also
removes pollutants (filtration and nutrient uptake) from the stormwater runoff.
n
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I
The size of drainage swales and driveway culverts, along with the amount of grading necessary will
have to be determined through simple hydraulic and hydrologic (H & H) studies of the area. A
detailed survey is also necessary prior to completion of the H&H survey and design efforts.
The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
maps will have to be obtained prior to design.
Through evaluation of various BMPs, grassed swales, with a stormwater ordinance, was determined
to be the most cost effective, applicable, and effective at solving the flooding problems in the area.
As long as the swale system is maintained, it is a reliable stormwater BMP. There are no negative
environmental impacts associated with an infiltration system in this area. Public education will be
necessary to inform the residents of the need for the system, how the system will solve the flooding
problem, and what they need to do to comply with the stormwater ordinance (if adopted by the
County).
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DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
' Off Old Li hthouse Road
Old Lighthouse Road is located on the eastern end of Buxton, on Hatteras Island. A visual
' inspection of the area performed by URS indicated that there was little or no drainage system
present. Poor street maintenance was adding to the drainage problems.
' Ponding is several inches deep and extends across the entire road in several areas. These ponding
conditions cause a safety hazard for pedestrians and motorists, along with the potential for property
damage to cars from hidden obstructions under the water.
In order to solve the flooding problem in this area it is recommended that roadside drainage swales
and driveway culverts be installed in the areas experiencing the ponding problems, in addition to
regrading and repaving of the roadways. New culverts should be constructed of corrugated HDPE
and have minimum diameter of 15 inches. Metal culverts should not be used due to the corrosion
and other durability issues in this climate.
' These swales and culverts should be able to be installed within the road right-of-way so that the
County has access for maintenance. If not, the County may have to evaluate obtaining drainage
easements so maintenance can be performed on the swales. Another very important aspect is
' homeowner education. The homeowners must be informed about the importance of these swales
and that they should not be altered or filled. A comprehensive educational program can go a long
way to limiting maintenance hassles from homeowners altering or filling swales.
Grassed swales will help reduce the ponding problem by eliminating standing water in the roadway
and providing additional surface area for infiltration. The vegetation (grasses) in the swales also
removes pollutants (filtration and nutrient uptake) from the stormwater runoff.
The size of drainage swales and driveway culverts, along with the amount of grading necessary will
have to be determined through simple hydraulic and hydrologic (H & H) studies of the area. A
detailed survey is also necessary prior to completion of the H&H survey and design efforts.
The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
maps will have to be obtained prior to design.
' Through evaluation of various BMPs, grassed swales, with a stormwater ordinance, was determined
to be the most cost effective, applicable, and effective at solving the flooding problems in the area.
As long as the swale system is maintained, it is a reliable stormwater BMP. There are no negative
environmental impacts associated with an infiltration system in this area. Public education will be
necessary to inform the residents of the need for the system, how the system will solve the flooding
problem, and what they need to do to comply with the stormwater ordinance (if adopted by the
' County).
Kohler Drive and Altoona Drive, Hatteras
Kohler Drive and Altoona Drive are located in Hatteras. A visual inspection of the roads performed
' by URS indicated that there was little or no drainage system present.
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CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
Ponding is several inches deep and extends across the entire road on many occasions. These
ponding conditions cause a safety hazard for pedestrians and motorists, along with the potential for
property damage to cars from hidden obstructions under the water.
In order to solve the flooding problem in this area it is recommended that roadside drainage swales
and driveway culverts be installed in the areas experiencing the ponding problems. New culverts
should be constructed of corrugated HDPE and have minimum diameter of 15 inches. Metal
culverts should not be used due to the corrosion and other durability issues in this climate.
These swales and culverts should be able to be installed within the road right-of-way so that the
County has access for maintenance. If not, the County may have to evaluate obtaining drainage
easements so maintenance can be performed on the swales. Another very important aspect is
homeowner education. The homeowners must be informed about the importance of these swales
and that they should not be altered or filled. A comprehensive educational program can go a long
way to limiting maintenance hassles from homeowners altering or filling swales.
Grassed swales will help reduce the ponding problem by eliminating standing water in the roadway
and providing additional surface area for infiltration. The vegetation (grasses) in the swales also
removes pollutants (filtration and nutrient uptake) from the stormwater runoff.
The size of drainage swales and driveway culverts, along with the amount of grading necessary will
' have to be determined through simple hydraulic and hydrologic (H & H) studies of the area. A
detailed survey is also necessary prior to completion of the H&H survey and design efforts.
The presence of utility easements will have to be taken into account during design. For roadside
swales, there should be sufficient space both vertically and laterally to construct the BMP. Utility
maps will have to be obtained prior to design.
0
0
d
Through evaluation of various BMPs, grassed swales, with a stormwater ordinance, was determined
to be the most cost effective, applicable, and effective at solving the flooding problems in the area.
As long as the swale system is maintained, it is a reliable stormwater BMP. There are no negative
environmental impacts associated with an infiltration system in this area. Public education will be
necessary to inform the residents of the need for the system, how the system will solve the flooding
problem, and what they need to do to comply with the stormwater ordinance (if adopted by the
County).
NC 12 in Hatteras
Significant ponding occurs along NC 12 in Hatteras. Ponding is several inches deep and extends
into the travel lanes on many occasions. These ponding conditions cause a safety hazard for
pedestrians and motorists, along with the potential for property damage to cars from hidden
obstructions under the water.
There are few storm drain inlets along NC 12. Therefore, due to the grading of the lots in the area,
and the lack of any stormwater management facility, there is no place for the stormwater to flow.
The soils in this area of NC 12 include Duckston and Corolla. Duckston soils have a very rapid
permeability, but a very high water table (at or near the surface). Corolla soils have a rapid
06/01/01 5-15

CHAPTER FIVE
DRAINAGE PROBLEM AREA DARE COUNTY
RECOMMENDATIONS STORMWATER MASTER PLAN
permeability, and a deeper water table, though a drainage system through the area is often difficult
' due to the low elevations.
In order to solve the ponding problems in this area, due to the soil types and low elevations, it is
recommended that the stormwater be piped to wet retention basins or constructed wetlands. Since
' NC 12 is a NCDOT roadway, there must be coordination with NCDOT for any drainage
improvements within the right-of-way. All plans and designs must be approved by NCDOT prior to
implementation. It may be possible to obtain assistance from NCDOT on the construction of the
system. URS recommends that the County have a meeting with NCDOT to discuss the issues
along NC 12 and how the NCDOT and the County can work together to alleviate the ponding
problems.
' The County will have to investigate the possible purchase of land for the retention facility(s). The
location and size of the retention facilities will have to be determined through hydraulic and
hydrologic (H & H) modeling of the area. A detailed survey is also necessary prior to completion of
the modeling efforts.
Through evaluation of various BMPs, wet retention basins or constructed wetlands were determined
to be the most cost effective, applicable, and effective BMP for solving the flooding problems in the
area. With cooperation from the NCDOT, this is an implementable BMP. As long as the retention
basin or wetlands area are maintained, it is a reliable stormwater BMP. There are no negative
' environmental impacts associated with a retention basin or wetland in this area. Public education
will be necessary to inform the residents of the need for the system, how the system will solve the
flooding problem, and what they can do to reduce drainage problems.
' 5.2.5 COUNTYWIDE DRAINAGE ISSUES
' To reduce the amount of stormwater runoff which reaches the street, and the County's storm drain
system, URS recommends that the County encourage its residents to reduce the amount of
impervious surface on their lots, and to direct stormwater runoff (from rooftops and other impervious
surfaces) to vegetated areas, instead of directly off their property and into the street (or onto a
' neighbors property). A recommended stormwater ordinance that will assist in accomplishing this,
is included in Appendix C. Depending on the method of funding of the County's stormwater
management program (Section 6.5), the County may want to offer fee/tax credits for residents
constructing french drains or infiltration areas for runoff from impervious surfaces on their lots. (This
would be applicable with a stormwater utility or stormwater fee/tax).
' 5.3 WATER QUALITY
Although water quality in the Dare County area is better than some of the surrounding areas, it is
' of critical importance that the quality of the stormwater runoff be improved in order to not only
prevent the degradation of the water quality in the area, but to improve the water quality.
Improvement in the quality of the stormwater runoff may make it possible to see openings in
' previously closed shellfishing waters. The above described BMP facilities (along with the
stormwater ordinance and a public education program) will also help reduce the amount of pollution
in the stormwater runoff, thus improving water quality in the estuaries.
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RECOMMENDATIONS STORMWATER MASTER PLAN
5.4 OPERATION AND MAINTENANCE
During the field inspection of the system several inlets were covered with dirt and debris and many
of the roadside swales were blocked and/or filled in. In particular, on several of the canal streets,
wood has been placed around several of the swales (for landscaping or similar reason), which block
water from the roadway and other impervious surfaces from flowing into the swale. Most of the
inlets and pipe systems are in need of maintenance and pumping to remove sand buildup.
' Additionally, all storm drain inlets should be inspected and cleaned at least once a year, and/or after
each major storm. Prior to implementation of any of the above actions an inspection of the existing
system, to include determining the length of all pipes, should be completed. This will determine if
' any of the existing system can be used in conjunction with new systems
Major ditches should be identified and put into an inventory system for future maintenance tracking.
' Regular monitoring and maintenance of all components of the storm -drain system is recommended
to prevent problems. It is also recommended that the County investigate purchasing or leasing a
vacuum system for cleaning out storm drain pipes and the infiltration systems.
' Roadside swales should be periodically cleaned of debris and mowed. Vegetation is critical for
infiltration and pollutant removal, but excessive vegetation will block flow.
' Table 5-1
Recommendations
Dare County
H
1]
Location
Problem Description
Recommended Action
Raleigh Woods
Ponding
Swales
Garden Road and Mother
Vineyard Road
Inadequate drainage channel
Improve channel and culverts
Wanchese
Ponding
Swales
NC 12 in Duck
Ponding
Swales
Baum Bay Harbor
Poor drainage channel
Improve channel and culverts
Colington Road
Ponding
Swales and road
improvements
Rodanthe, Waves, Salvo
Ponding/Altered drainage
channel
Swales and retention basin
Avon
Ponding
Swales
Peter's Ditch
Drainage Channel
Maintenance
Channel maintenance and
improve culverts
Jesse's Ditch
Drainage Channel
Maintenance
Channel maintenance and
improve culverts
Rocky Rollinson Lane
Ponding
Swales
Off Old Lighthouse Road
Ponding
Swales and road
improvements
Kohler Lane and Altoona Lane
Ponding
Swales
NC 12 in Hatteras
Ponding
Wet retention basins or
constructed wetlands
06/01/01 5-17

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CHAPTER SIX
STORMWATER DARE COUNTY
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
The recommendations presented in Chapter 5 are summarized in this Chapter. Some of the
recommendations should be implemented as Capital Improvement Program (CIP) projects which are
prioritized using the criteria described in Section 6.2. Recommendations for minor repair and
maintenance should be made part of the County's operating budget. Recommended policy changes
may or may not have budget implications.
6.1 RECOMMENDATION SUMMARY
The project rankings are shown in Table 6-1. Costs for the recommendations were estimated (order
of magnitude) and are shown in Table 6-2. It should be noted that these are only estimates.
Surveying and Hydraulic & Hydrologic modeling are necessary to determine more precise estimates
on sizes of facilities, length of pipe, etc. The costs of obtaining drainage easements and whether the
County can obtain land needed for several of the projects is also a factor. Therefore, these costs
should only be looked at a s order of magnitude given the recommendations presented in Chapter
5.
6.2 PROJECT SELECTION CRITERIA
The project selection criteria were used to evaluate which recommended projects are the most
crucial and should be implemented first in the Capital Improvement Program. The following criteria
used were:
• Safety
• Quantity Benefits
• Quality Benefits
Safety
This criterion is for projects that maintain safe travelways during rain storms and protecting against
property damage from drainage problems and ponding. The safety benefits are apparent from the
nature of the project.
' Quantity Benefits
Problems that are caused by increased runoff volumes and peak discharges include sedimentation
of estuaries and storm drain system components, increased maintenance, erosion and flooding
problems. Quantity problems may be due to existing development or potential problems due to
' planned development may be averted with recommended projects.
Quality Benefits
' The amount of water quality benefits are not easily determined for each project. Problems caused
by poor water quality include increased sediment loading, algae blooms caused by excess pollutants
in the runoff, loss of plant life due to pollutants, and loss of fishing, shellfishing, and other recreation
due to pollutants. Projects which improve the quality of stormwater runoff will ,help protect and
improve the quality of water in the canals and the estuaries.
' Table 6-1 lists the project selection criteria along with the rankings of each proposed project.
06/01/01 6-1

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CHAPTER SIX
STORMWATER DARE COUNTY
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
Table 6-1
Project Selection Criteria and Ranking
Dare County
Evaluation Criteria
Overall
Problem
Project :
Recommended
Safety/
Quantity
Quality
Location
Description
Health
Benefits
Benefits
Ranking
Action
Raleigh
Ponding
3
7
5
4
Swales
Woods
Garden Road
Inadequate
11
5
12
10
Improve channel
and Mother
drainage
and culverts
Vineyard Road
channel
Wanchese
Ponding
14
11
9
13
Swales
NC 12 in Duck
Ponding
6
9
8
8
Swales
Baum Bay
Poor
7
4
11
7
Improve channel
Harbor
drainage
and culverts
channel
Colington
Ponding
5
10
6
6
Swales and road
Road
improvements
Rodanthe,
Ponding/Alter
12
1
1
3
Swales and
Waves, Salvo
ed drainage
retention basin
channel
Avon
Ponding
13
14
14
14
Swales
Peter's Ditch
Drainage
2
3
4
2
Channel
Channel
maintenance and
Maintenance
im rove culverts
Jesse's Ditch
Drainage
1
2
3
1
Channel
Channel
maintenance and
Maintenance
improve culverts
Rocky
Ponding
9
13
10
12
Swales
Rollinson Lane
Off Old
Ponding
15
15
15
15
Swales and road
Lighthouse
improvements
Road
Kohler Lane
Ponding
4
12
7
8
Swales
and Altoona
Lane
NC 12 in
Ponding
8
8
2
5
Wet retention
Hatteras
basins or
constructed
wetlands
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' CHAPTER SIX
STORMWATER DARE COUNTY
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
6.3 CAPITAL IMPROVEMENT PROGRAM
' Inadequate system capacity is the biggest water quality and quantity problem requiring capital
improvements. Table 6-1 describes the capital improvement actions that have been recommended,
and the recommended order of project implementation. The implementation priority was determined
' based upon the ranking of the project with regard to the project evaluation criteria described in
Section 6.2.
' Surveying and modeling of the area is considered a top priority in order to determine the size and
amount of improvements that need to be done to fix problem drainage and ponding areas.
Stormwater modeling is briefly described below.
1
r
Water Quantity Modeling
Stormwater quantity is modeled to predict flooding problems and analyze drainage system capacity
and hydraulic performance. A detailed hydrologic and hydraulic computer model is suited the
analysis of a large drainage area that links runoff hydrographs from smaller subdrainage areas.
Simpler models are available to use for specific design calculations such as for culverts, drop inlets,
site drainage systems, etc.
Water Quality Modeling
Specific modeling objectives need to be defined in order to guide the work effort. Not every water
quality problem needs to be modeled in order to characterize the problem or find a solution.
Measured data is usually preferred in characterizing the problem. Water quality modeling can be
used for reasons such as:
• to determine the total maximum daily load (TMDL) to a waterbody
• to help determine location and type of BMP strategies which are most effective
• to analyze specific problems such as eutrophication of a lake or sediment loadings to a
stream
One of the watershed planning issues that could be analyzed with a model is the reduction of
existing nonpoint source pollutant loadings and prevention of future additional nonpoint source
pollutant loadings. This issue will use modeling as a tool to make policy decisions regarding land use
controls and to provide information regarding a regional BMP program and regional riparian buffer
program. The type of water quality modeling software chosen will depend on the particular objective
to be achieved and the characteristics of the waterbody to be modeled.
The estimated costs for the action items are preliminary, order of magnitude costs. The costs for
various items are highly dependent upon factors that cannot be determined at this time, such as the
exact length of swales, number of culverts, etc. None of these costs include easement acquisition.
The scheduling of these action items is dependent upon the County's financing needs and methods.
Funding options are described in Section 6.5.
6.4 OPERATION AND MAINTENANCE PROGRAM
In order to have a successful stormwater management program, an operation and maintenance
program must be developed. The County must have a commitment to maintaining stormwater
06/0 vo1 6-3

CHAPTER SIX
STORMWATER DARE COUNTY
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
structures over the long term. No structural BMPs will be effective over the long term without routine
maintenance. A planned program of storm drain inspections, and minor cleaning, a planned program
of ditch cleaning, and a planned program of infiltration system inspection should be implemented.
A work order process and form should be developed to track work progress and to record
maintenance work for overall program success.
Maintenance costs will be dependent on the length of pipe, length of roadside swales, number of
drop inlets, and size of infiltration facilities. A few estimates for maintenance costs are approximately
$1.00 per linear foot for cleaning ditches and pipes (assuming County personnel and equipment),
approximately $40-$75 per inlet for cleaning (depending on size), and approximately $1,000 per year
to clean each infiltration facility (each facility will vary with size and type). It is recommended that the
County purchase a vacuum truck for cleaning pipes and infiltration facilities. The County should also
investigate the use of the spoil areas used by the Corps of Engineers for dredge spoils as a place
to dispose of sediment from the pipes and inlets. In other areas, this sediment has also been placed
on the beach for renourishment. Both these actions would require permitting.
6.5 FUNDING
' The amount necessary to fund these projects can come from several sources. The costs estimated
for the action items are preliminary, order -of -magnitude amounts.
' Taxes
The County could raise property taxes to fund part or all of the program. The public usually does not
respond well to this option. A dedicated millage would require a referendum, which may be difficult
to sell to the public. A dedicated millage would mean that the County could depend on a certain
amount year to year being committed to a planned program of O & M and replacement and
improvements.
0
Stormwater Utility
An independent tax authority, or the creation of a stormwater utility could be established to collect
stormwater fees. A service rate study would need to be performed to critically evaluate the charges
and fees, and to distribute the costs of the stormwater management program proportionately among
the users. The costs of the stormwater management program include: administration including
overhead, customer billing, customer complaint response, ditch and pipe cleaning, illicit discharge
investigation, site plan review, public education, and capital improvement program.
Many localities divide the total costs by the amount of impervious area in their service area to
calculate a unit cost. An equivalent residential unit (ERU), which is the average amount of
impervious area for a single family residence, is used as the billing unit. Non-residential property
owners are billed according to the number of ERUs equivalent to the total impervious area on their
property.
Utility Credits
A utility credit is a reduction in the stormwater utility fee for a property. It is given because of a
drainage system improvement located on the property which causes a reduction in pollutants and/or
a reduction in the peak flows and volumes leaving the property. It can be used as an incentive for
06/01/01 6-4

H
CHAPTER SIX
STORMWATER DARE COUNTY
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
voluntary construction of BMPs. The reasons and benefits of a utility credit program need to be
established before it is implemented. Is the credit program perceived as necessary for public
acceptance of the utility charges? Will it be perceived as enough of an incentive for voluntary
implementation of BMPs and riparian buffers? An example of a stormwater utility credit application
instruction manual from the Charlotte -Mecklenburg is provided in Appendix F.
The implementation of a BMP or buffer used to receive credit will reduce some of the cost to the
County for construction of a similar facility for a water quantity/quality benefit. However, some portion
of the utility charge should be retained for those properties with credits in order to receive revenue
for on -going program needs such as administration, system operation and maintenance, and
inspection of on -site facilities. The loss of long-term revenue due to the credit program should not
unfairly cause a burden to other customers without credits by making them pay more than their share
of costs.
Grants and Loans
There are several sources that the County can apply to for grants and low interest loans. Due to the
location of the County, and its sensitive environment, the County should have a good chance at
receiving a variety of grants. Some of these programs include:
• Clean Water Management Trust Fund
• Clean Water Act Section 319 Grants
• Small Watershed Program Grants
• State Construction Grants and Loans
These possible sources of additional funding will need to be evaluated by the County to establish
policy on additional funding methods.
0&01/01 6-5

H
CHAPTER SIX
STORMWATER DARE COUNTY
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
Table 6-2
Capital Improvement Program
Dare County
Location
Action Description
Estimated Cost
Raleigh Woods
Ponding
$20,000-50,000
Garden Road and Mother
Vineyard Road
Inadequate drainage channel
$10,000-$15,000
Wanchese
Ponding
$20,000-50,000
NC 12 in Duck
Ponding
$40,000
Baum Bay Harbor
Poor drainage channel
$15,000430,000
Colington Road
Ponding
$20,000-$200,000+
Rodanthe, Waves, Salvo
Ponding/Altered drainage channel
$50,000
Avon
Ponding
$20,000450,000
Peter's Ditch
Drainage Channel Maintenance
$5,000-$10,000
Jesse's Ditch
Drainage Channel Maintenance
$5,000410,000
Rocky Rollinson Lane
Ponding
$20,000-50,000
Off Old Lighthouse Road
Ponding
$60,000 - $100,000
Kohler Lane and Altoona
Lane
Ponding
$50,000 - $100,000
NC 12 in Hatteras
Ponding
$50,000
Note: Many of these costs will be able to be reduced depending upon the amount of use of
County equipment, personnel, etc.
1 - This high -end cost is assuming possible elevation and regrading of road. Cost may even be
higher with this option.
6.6 PUBLIC INVOLVEMENT
It is recommended that the County implement a comprehensive public education/public involvement
program. There already exists some public involvement with the Water Quality Sampling program
that has been in place since 1995. The education programs and/or outreach activities should inform
individuals and households about the impacts stormwater discharges have on water bodies and
identify the steps that must be taken to reduce stormwater pollution. It is anticipated that public
understanding will foster endorsement of the stormwater management program.
Activities that could be implemented include storm drain stenciling, quarterly stormwater newsletters
which update citizens on activities being undertaken through the County stormwater management
program and gives tips for residents to reduce stormwater runoff on their property, and
drawing/coloring contests for school children with information about the do's and don'ts of stormwater
management. The County may want to hold periodic stormwater seminars possibly in conjunction
06/01/01
W.

CHAPTER SIX
STORMWATER DARE COUNTY
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
with other, well -attended County activities. The County is encouraged to contact the Division of
Water Quality for information regarding state educational programs in which the County may be able
to become involved.
6-7

CHAPTER SEVEN DARE COUNTY
REFERENCES STORMWATER MASTER PLAN
Arnold, J.A., ed., D.E. Line, S.W. Coffey, and J. Spooner. 1993. Stormwater
' Management Guidance Manual. North Carolina Cooperative Extension Service
and North Carolina Division of Environmental Management. Raleigh, NC.
Center for Watershed Protection and Land Ethics, Inc. Blueprint to Protect Coastal
'
Water Quality. A Guide to Successful Growth Management in the Coastal
Region of North Carolina, Prepared for the Neuse River Council of Governments
'
and the North Carolina Division of Environmental Management.
Environmental Protection Agency.
1995. Watershed Protection: A Project Focus. Washington, DC: Office of
Wetlands, Oceans, and Watersheds.
'
1997a. Designing an Information Management System for Watersheds.
Washington, DC: Office of Wetlands, Oceans, and Watersheds, Office of
Wastewater Management and Office of Water. �
1997b. Top 10 Watershed Lessons Learned. EPA 840-F-97-001. Washington,
DC: Office of Water and Office of Wetlands, Oceans, and Watersheds.
'
North Carolina Department of Environment and Natural Resources.
1997. Basinwide Assessment Report— Pasquotank River Basin. Environmental
'
Sciences Branch.
1997. Pasquotank River Basinwide Water Quality Plan. Division of Water Quality.
1999. Tar -Pamlico River Basinwide Water Quality Plan. Division of Water
Quality.
'
A Guide to Protecting Coastal Resources Through the CAMA Permit Program.
Raleigh, NC: Division of Coastal Management.
County Land Use Plan Update.
Dare County. 1994. Dare
Ogden Environmental and Engineering Services, Inc. 1994. Charlotte -Mecklenburg
'
Storm Water Services Credit Application Instruction Manual. Charlotte, NC: City
of Charlotte Storm Water Services.
'
US Department of Agriculture. 1986. Soil Survey of Dare County, North Carolina. Soil
Conservation Service.
1
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� APPENDIX A
North Carolina
' Stormwater Management Regulations

11
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STATE OF
NORTH CAROLINA
DEPARTMENT OF D E & N R
ENVIRONMENT &
NATURAL RESOURCES
DIVISION OF
WATER QUALITY
Administrative Code Section:
15A NCAC 2H .1000
Stormwater Management
Amended Effective: December 1, 1995
Environmental
Management Commission
Raleigh, North Carolina
11

I '
II SECTION .1000 - STOR 4VNrATER MANAGEMENT
.1001 STORMWATER MANAGEMENT POLICY
The rules in this Section set forth the requirements for application and issuance of permits for stormwater
management systems in accordance with G.S. 143-215.1(d) and 15A NCAC 2H .0200. These requirements
to control pollutants associated with stormwater runoff apply to development of land for residential,
I' commercial, industrial, or institutional use but do not apply to land management activities associated with
agriculture or silviculture unless specifically addressed in special supplemental classifications and management
strategies adopted by the Commission.
History Note: Statutory Authority G.S. 143-214.1; 143-214.7; 143-215.3(a)(1);
Eff. January 1, 1988;
Amended Eff. September 1, 1995.
I' .1002 DEFINITIONS
The definition of any word or phrase in this Section shall be the same as given in Article 21, Chapter 143
1' of the General Statutes of North Carolina, as amended. Other words and phrases used in this Section are
ffdefined as follows:
(1) "Built -upon Area" means that portion of a development project that is covered by impervious or
(' partially impervious cover including buildings, pavement, gravel roads and parking areas, recreation
facilities (e.g., tennis courts), etc. (Note: Wooden slatted decks and the water area of a swimming
pool are considered pervious).
(2) "CAMA Major Development Permits" mean those permits or revised permits required by the Coastal
I' Resources Commission according to 15A NCAC 71 Sections .0100 and .0200.
(3) "Certificate of Stormwater Compliance" means the approval for activities that meet the requirements
for coveraEe under a stormwater general permit for development activities that are regulated by this
Section.
(4) "Coastal Counties" include Beaufort, Bertie, Brunswick, Camden, Carteret. Chowan, Craven.
Currituck, Dare, Gates, Hertford, Hyde, New Hanover, Onslow, Pamlico, Pasquotank, Pender.
Perquimans, Tyrrell, and Washington.
f (5) "Curb Outlet System" means curb and gutter installed in a development which meets low density
criteria [Rule .1003(d)(1) of this Section] with breaks in the curb or other outlets used to convey
stormwater runoff to grassed swales or vegetated or natural areas and designed in accordance with
Rule .1008(g) of this Section.
(6) "Development" means any land disturbing activity which increases the amount of built -upon area or
which otherwise decreases the infiltration of precipitation into the soil.
' (7) "Drainage Area or Watershed" means the entire area contributing surface runoff to a single point.
(8) "Forebay" means a flevice located at the head of a wet detention pond to capture incoming sediment
I,
before it reaches the main portion of the pond. The t-orebay is typically an excavated settling basin or a section separated by a low weir.
(9) "General Permit" means a "permit" issued under G.S. 143-215.1(b)(3) and (4) authorizing a category
of similar activities or discharges.
t' (10) "Infiltration Systems" mean stormwater control (( systems designed to allow runoff to pass or move (infiltrate/exfiltrate) into the soil.
(I1) "Notice of Intent" means a written notification to the Division that an activity or discharge is
I' intended to be covered by a general permit and takes the place of "application" used with individual
permits.
(12) "Off -site Stormwater Systems" mean stormwater management systems that are located outside the
boundaries of the specific project in question, but ' designed to control stormwater drainage from that project and other potential development sites. These systems shall designate responsible parties for
operation and maintenance and may be owned and operated as a duly licensed utility or by a local
government.
I, (13) "On -site Stormwater Systems" mean the systems necessary to control stormwater within an individual
.FORTH CAROLINA ADAUX1,7TRAMPE CODE 12r1519S Page I

` --- - L!"v 11,11"UIVAILIVIAL MANAGEMENT TISA: 02H .1000
development project and located within the project boundaries.
(14) "Redevelopment" means any rebuilding activity which has no net increase in built -upon area or
which provides equal or greater stormwater control than the previous development (stormwater
' . controls shall not be allowed where otherwise prohibited).
(15) "Seasonal High Water Table" means the highest level that groundwater, at atmospheric pressure,
I, reaches in the soil in most years. The seasonal high water table is usually detected by the mottling
of the soil that results from mineral leaching.
(16) I "Sedimentation/Erosion Control Plan" means any plan, amended plan or revision to an approved plan submitted to the Division of Land Resources or delegated authority in accordance with G.S.
113A-57.
(17) "Stormwater" is defined in G.S. 143, Article 21.
(18) "Stormwater Collection System" means any conduit, pipe, channel, curb or gutter for the primary
purpose of transporting (not treating) runoff: A stormwater collection system does not include
vegetated swales, swales stabilized with armoring or alternative methods where natural topography
or other physical constraints prevents the use of vegetated swales (subject to case -by -case review),
curb outlet systems, or pipes used to carry drainage underneath built -upon surfaces that are
associated with development controlled by the provisions of Rule .1003(d)(1) in this Section.
(19) "10 Year Storm" means the surface runoff resulting from a rainfall of an intensity expected to be
equaled or exceeded, on the average, once in 10 years, and of a duration which will produce the
maximum peak rate of runoff, for the watershed of interest under average antecedent wetness
conditions.
(20) "Water Dependent Structures" means a structure for which the use requires access or proximity to
' or siting within surface waters to fulfill its basic purpose, such as boat ramps, boat houses, docks,
and bulkheads. Ancillary' facilities such as restaurants, outlets for boat supplies, parking lots and
boat storage areas are not water dependent uses.
' (21) "Wet Detention Pond" means a structure that provides for the storage and control of runoff and
includes a designed and maintained permanent pool volume.
(22) "Vegetative Buffer" means an area of natural or established vegetation directly adjacent to surface
waters through which stormwater runoff flows in a diffuse manner to protect surface waters from
degradation due to development activities. The width of the buffer is measured horizontally from
the normal pool elevation of impounded structures, from the bank of each side of streams or rivers.
and from the mean high water line of tidal waters, perpendicular to the shoreline.
(23) "Vegetative Filter" means an area of natural or planted vegetation through which stormwater runoff
flows in a diffuse manner so that runoff does not become channelized and which provides for control
of stormwater runoff through infiltration of runoff and filtering of pollutants. The defined length of
the filter shall, be provided for in the direction of stormwater flow.
Hisror,.- XQte: Statutory Authority G.S. 143-213; 143-214.1: 143-214.7; 143-21:.3(a)(1);
Eff. January 1, 1988:
Amended Ef . December 1, 1995; September 1, 1995.
.1003 STORMWATER A'IANAGEAMN'T: COVERAGE: APPLICATION: FEES
(a) The intent of the Commission is to achieve the water quality protection which low density development
near sensitive waters provides. To that end, the Director, by applying the standards in this Section shall cause
development to comply with the antidegradation requirements specified in 15A 1\CAC 2B .0=01 by protecting
surface waters and highly productive aquatic resources from the adverse impacts of uncontrolled high density
development or the potential failure of stormwater control measures. y
(b) To ensure the protection of surface waters of the State in accordance with G.S. 143-214.7, a permit is
required in accordance with the provisions of this Section for any development activities which require a
CANNA major development permit or a Sedimentation/Erosion. Control Plan and which meet any of the
followin_ criteria:
(1) development activities located in the 20 coastal counties as defined in Rule .1002(4) of this Section:
(2) development activities draining
2B .0225; or to Outstanding Resource Waters (ORW) as defined in 15A NCAC
(3) development activities within one mile of and draining to High Quality Waters (HQW) as defined
:FORTH CAROLINA ADdIIuVISTRATIVE CODE 121151'95 page 2

in 15A NCAC 2B .0101(e)(5).
Projects under a common plan of development shall be considered as a single project and shall require
stormwater management in accordance with this Section. Local governments with delegated
I' Sedimentation/Erosion Control Programs often implement more stringent standards in the form of lower
thresholds for land area disturbed. In these situations, the requirements of this Rule apply only to those
projects that exceed the state's minimum area of disturbance as outlined in G.S. 113A-57. Specific I' permitting options, including general permits for some activities, are outlined in Paragraph (d) of this Rule.
(c) Development activity with a CAMA major development permit or a Sedimentation/Erosion Control Plan
approved prior to January 1, 1988 are not required to meet the provisions of these Rules unless changes are
made to the project which require modifications to these approvals after January 1, 1988.
(d) Projects subject to the permitting requirements of this Section may be permitted under the following
stormwater management options:
I (1). Low Density Projects: Projects permitted as low density projects must be designed to meet and
maintain the applicable low density requirements specified in Rules .1605 through .1007 of this
Section. The Division shall review project plans and assure that density levels meet the applicable
Ilow density requirements. The permit shall require recorded deed restrictions and protective
' covenants to ensure development activities maintain the development consistent with the plans and
specifications approved by the Division.
(2) High Density Projects: Projects permitted as high density projects must be designed to meet the applicable high density requirements specified in Rules .1005 through .1007 of this Section with
I, stormwater control measures designed, operated and maintained in accordance with the provisions
of this Section. The permit shall require recorded deed restrictions and protective covenants to
ensure development activities maintain the development consistent with the plans and specifications
approved by the Division. Stormwater control measures and operation and maintenance plans
developed in accordance with Rule .1008 of this Section must be approved by the Division. In
addition, NPDES permits for stormwater point sources may be required according to the provisions
I{ of 15A NCAC 2H .0126.
(3) Other Projects: Development may also be permitted on a case -by -case basis if the project:
(A) controls runoff through an off -site stormwater system meeting provisions of this Section;
' (B) is redevelopment which meets the requirements of this Section to the maximum extent practicable;
(C) otherwise meets the provisions of this Section and has water dependent structures, public roads
and public bridges which minimize built -upon surfaces, divert stormwater away from surface
I' waters as much as possible and employ other best management practices to minimize water .
`` quality impacts.
(4) Director's Certification: Projects may be approved on a case -by -case basis if the project is certified
by the Director that the site is situated such that water quality standards and uses are not threatened
and the developer demonstrates that:
(A) the development plans and specifications indicate stormwater control measures which shall be
installed in lieu of the requirements of this Rule: or
(B) the development is located such a distance from surface waters that impacts from pollutants
present in stormwater from the site shall be effectively mitigated.
(5) General Permits: Projects may apply for permit coverage under general permits for specific types
of activities. The Division shall develop general permits for these activities in accordance with
Rule .1013 of this Section. General Permit coverage shall be available to activities including, but
not limited to:
I, (A) construction of bulkheads and boat ramps;
(B) installation of sewer lines with no proposed built -upon areas;
(C) construction of an individual single family residence; and
(D) other activities that, in the opinion of the Director. meet the criteria in Rule -_1013 of this Section.
Development designed to meet the requirements in Subparagraphs (d)(1) and (d)(3) of this Paragraph must
demonstrate that no areas within the project site are of such high density that stormwater runoff threatens
' 1vater quality.
W Applications: Any person with development activity meeting the criteria of Paragraph (b) of this Rule
shall apply for permit coverage through the Division. Previously issued Stormwater Certifications (issued in
taccordance with stormwater management rules effective prior to September 1, 1995) revoked due to
NORM CAROLINA ADMINISTRATIVE CODE 12,15195 Page 3

A "JVLE - ,t N VIA4110jVNIENTAL MANAGEMENT
I' Tl SA: 02H .1000
certification violations must apply for permit coverage. Stormwater management permit applications, project
plans, supporting information and processing fees shall be submitted to the appropriate Division of
I' Environmental Management regional office. A processing fee, as described in Paragraph (f) of this Rule, must
`` be submitted with each application. Processing fees submitted in the form of a check or money order shall
be made payable to N.C. Department of Environment, Health, and Natural Resources. Applications which
I!' are incomplete or not accompanied by the processing fee may be returned. Permit applications shall be signed
as follows:
(1) in the case of corporations, by a principal executive officer of at least the level of vice-president,
r or his authorized representative;
(2) in the case of a partnership, by a general partner and in the case of a limited partnership, by a
general partner;
I(3) in the case of a sole proprietorship, by the proprietor;
' (4) in the case of a municipal, state or other public entity by either a principal executive officer,
ranking official or other duly authorized employee.
The signature of the consulting engineer or other agent shall be accepted on the application only if
accompanied by a letter of authorization.
(f) Permit Fees:
(1) For every application for a new or revised permit under this Section, a nonrefundable application
processing fee in the amount stated in Subparagraph (f)(2) of this Paragraph shall be submitted at
the time of application.
(A) Each permit application is incomplete until the application processing fee is received;
(B) No processing fee shall be charged for modifications of permits when initiated by the Director;
(C) A processing fee of forty dollars ($40.00) shall be charged for name changes;
(D) No processing fee shall be required for name changes associated with the initial transfer of
property from the developer to property owner or responsible party. Any subsequent changes
[, in ownership shall be subject to the name change processing fee in Part (C) of this Para;ra h.
(2) Schedule of Fees P
I' Permit Application
Processing Fee
New Timely
Applications/ Reneiva'ls
Nloditications/ Without
Rate Renewal Modifications
Low Density $'''S \,
High Density 385
` Other 72J
Director's Certification 350'
\; A
General Permits 50
(D Supporting Documents and Information. This Paragraph outlines those supporting documents and
information that must be submitted with stormwater applications. Additional information may also be
` applicable or required. The applicant shall attempt to submit all necessary information to describe the site.
development and stormwater management practices proposed. The following documents and information shall
I, be submitted with stormwater applications:
II(1) two sets of detailed plans and specifications for the project;
(2) plans and specifications must be dated and sealed as outlined in Rule .10086) of this Section and
show the revision number and date;
(3) general location map showing orientation of the project with relation to at least two references
I' .FORTH C.4ROLI1VA A.D111JVJSTRATI ,T CODE 12,1IS/95
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I, (numbered roads, named streams/rivers, etc.) and showing the receiving water (a USGS map
preferable);
(4) topographic map(s) of the project area showing original and proposed contours and drainage
I' patterns;
(5) delineation of relevant boundaries including drainage areas, seasonal high water table, wetlands,
I property/project boundaries and drainage easements;
(6) existing and proposed built -upon area including roads, parking areas, buildings, etc.;
(7) technical information showing all final numbers, calculations, assumptions, drawing and procedures
associated with the stormwater management measures including but not limited to: built -upon area,
I' runoff coefficients, runoff volume, runoff depth, flow routing, inlet and outlet configuration (where
applicable), other applicable information as specified;
(8) _ operation and maintenance plan signed by responsible party;
(9) recorded deed restriction and protective covenants. As an alternative proposed deed restriction and
protective covenants and a signed agreement to provide final recorded articles shall be accepted
when final documents are not available at the time of submittal.
I' (h) Permit Issuance and Compliance: Stormwater management permits shall be issued in a manner
consistent with the following:
(1) Stormwater management permits issued for low density projects shall not require permit renewal.
t (2) Stormwater management permits issued for projects that require the construction of engineered
stormwater control measures shall be issued for a period of time not to exceed 10 years.
Applications for permit renewals shall be submitted 180 days prior to the expiration of a permit
I and must be accompanied by the processing fee described in Para ra h g p (f) of this Rule.
(3) Stormwater management permits shall be issued to the developer or owner and shall cover the
entire master plan of the project ("stormwater master plan permit"). The master plan permit shall
include specifications for Stormwater management measures associated with each individual lot or
property within the project.
(4) Any individual or entity found to be in noncompliance with the provisions of a stormwater
management permit or the requirements of this Section is subject to enforcement procedures as set
I, forth in G.S. 143, Article 21.
History Note: Statutory Autlrorhy G.S. 143-214.1; 143-214.7; 143-215.1(d): 143-215.3(a)f1);
Eff. January 1, 1988;
Amended Eff. December 1, 1995; September 1, 1995.
` .1004 STATEWIDE STOPUNIWATER GL71DELLNES
History Note: Statutory Authority G.S. 143-214.1; 143-214.7; 143-215.3(a)(1): 143-215.8A:
Eff: January 1, 1988;
' Repealed Eff. September 1. 1995.
.1005 STOPUNIWATER REQUIRENEEN TS: COASTAL COLYTIES
I, All development activities within the coastal counties which require a stormwater management permit in
accordance with Rule .1003 of this Section shall manage stormwater runoff as follows:
(1) development activities within the coastal counties draining to Outstanding Resource Waters (ORW)
I, shall meet requirements contained in Rule .1007 of this Section;
(2) development activities within one-half mile of and draining to SA waters or unnamed tributaries to
SA waters:
I(a) Low Density Option: Development shall be permitted pursuant to Rule .1003(d)(1) of this Section
' if the development has:
(i) built -upon area of 25 percent or less: or proposes development of single family residences on lots
Iwith one-third of an acre or greater with a built -upon area of 25 percent or less;
' (ii) stormwater runoff transported primarily by vegetated conveyances; conveyance system shall not
include a discrete stormwater collection system as defined to Rule .1002 of this Section;
(iii) a 30 foot wide vegetative buffer.
!' (b) High Density Option: Higher density developments shall be permitted pursuant to Rule .1003(d)(2)
I
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I' of this Section if stormwater control systems meet the following criteria:
(i) no direct outlet channels or, pipes to SA waters unless permitted in accordance with 15A NCAC
I' 2H .0126;
GO control systems must be infiltration systems designed in accordance with Rule .1008 of this
Section to control the runoff from all surfaces generated by one and one-half inches of rainfall.
Alternatives as described in Rule .1008(h) of this Section may also be approved if they do not
I' discharge to surface waters in response to the design storm;
(iii) runoff in excess of the design volume must flow overland through a vegetative filter designed in
accordance with Rule .1008 of this Section with a minimum length of 50 feet measured from
I, mean high water of SA waters;
(3) development activities within the coastal counties except those areas defined in Items (1) and (2) of
this Paragraph:
I, (a) Low Density Option: Development shall be permitted pursuant to Rule .1003(d)(1) of this Section
if the development has:
(i) built -upon area of 30 percent or less; or proposes development of single family residences on lots
(, with one-third of an acre or greater with a built -upon area of 30 percent or less;
(ii) stormwater runoff transported primarily by vegetated conveyances; conveyance system shall not
include a discrete stormwater collection system as defined in Rule .1002 of this Section;
I(iii) a 30 foot wide vegetative buffer.
' (b) High Density Option: Higher density developments shall be permitted pursuant to Rule .1003(d)(2)
of this Section if stormwater control systems meet the following criteria:
(i) control systems must be infiltration systems, wet detention ponds or alternative stormwater
(, management systems designed in accordance with Rule .1008 of this Section.
(ii) control systems must be designed to control runoff from all surfaces generated by one inch of
rainfall.
i, History Note: Statutory Authority G.S. 143-214.1; 143-214'.7. 143-
Eff. September 1. 1995. 215.1; 143-215.3(a�;
I' .1006 STOPM-WATER REQUIREMENTS: HIGH QUALITY WATERS
All development activities which require a stormwater management permit under Rule .1003 of this Section
Iand are within one mile of and draining to waters classified as High Quality Waters (HQW) shall manage
' stormwater runoff in accordance with the provisions outlined in this Rule. Vlore stringent stormwater
-bv-case basis inhere it is determined that additional measures
management measures may be required on a case
are required to protect water quality and maintain existing and anticipated uses of these waters.
I' (1) All waters classified as WS-1 or WS-I1 (15A NCAC 2B .0212 and .0214) and all waters located in
the coastal counties (Rule .1005 of this Section) are -xcluded from the requirements of this Rule
since they already have requirements for stormwater management.
I, (2) Low Density Option: Development shall be permitted pursuant to Rule .1003(c)(1) of this Section
if the development has:
(a) built -upon area of 12 percent or less or proposes single family residential development on lots of
I' one acre or greater;
(b) stormwater runoff transported primarily by vegetated conveyances; conveyance system shall not
include a discrete stormwater collection system as defined in Rule .1002 of this Section:
(c) a 30 foot wide vegetative buffer.
(' (3) High Density Option: Higher density developments shall be permitted pursuant to Rule .1003(c)(2')
Of this Section if stormwater control systems meet the following criteria:
I(a) control systems must be wet detention ponds or alternative stormwater management systems
' designed in accordance with Rule .1008 of this Section;
(b) control systems must be designed to control runoff from all surfaces generated by one inch of
rainfall.
I' History Note: Staturon• Awhorin• G. S. 143-214.1; 143-214. ; _
. 143-215.1; 143 215.3(a);
Eff. September 1, 1995;
I' Amended Eff. December 1. 1995.
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.1007 STORNINVATER REQUIREMEi US: OUTSTAN ;G RESOURCE WATERS
All development activities which require a stormwater management permit under Rule .1003 of this Section
and which drain to waters classified as Outstanding Resource Waters (ORW) shall manage stormwater runoff
in accordance with the provisions of this Rule. Water quality conditions shall clearly maintain and protect
the outstanding resource values of waters classified as Outstanding Resource Waters (ORW). Stormwater
I' management strategies to protect resource values of waters classified as ORW shall be developed on a site
specific basis during the proceedings to classify these waters as ORW. The requirements of this Rule serve
as the minimum conditions that must be met by development activities. More stringent stormwater
I' management measures may be required on a case -by -case basis where it is determined that additional measures
are required to protect water quality and maintain existing and anticipated uses of these waters.
(1) Freshwater ORWs: Development activities which require a stormwater management permit under
I' Rule .1003 of this Section and which drain to freshwaters classified as ORW shall manage
stormwater runoff as follows:
(a) Low Density Option: Development shall be permitted pursuant to Rule .1003(d)(1) of this Section
if the development has:
I (i) built -upon area of 12 percent or less or proposes single family residential development on lots
of one acre or greater;
(ii) stormwater runoff transported primarily by vegetated conveyances; conveyance system shall not
include a discrete stormwater collection system as defined in Rule .1002 of this Section; and
(iii) a 30 foot wide vegetative buffer.
(b) High Density Option: Higher density developments shall be permitted pursuant to Rule .1003(d)(2)
I, of this Section if stormwater control systems meet the following criteria: `
(i) control systems must be wet detention ponds or alternative stormwater management systems
designed in accordance with Rule .1008 of this Section: and
(ii) control systems must be designed to control runoff from all surfaces generated by one inch of
rainfall.
(2) Saltwater ORWs: Development activities which require a stormwater management permit under Rule
I.1003 of this Section and which drain to saltwaters classified as ORW shall manage stormwater
' runoff as follows:
(a) Within 575 feet of the mean high water line of designated ORW areas, development activities shall
comply with the low density option as specified in Rule .1005(2)(a) of this Section.
I' (b) Projects draining to saltwaters classified as ORW that impact the Areas of Environmental Concern
(AEC), determined pursuant to G.S. 113A-113, shall delineate the ORW AEC on the project plans
and conform to low density requirements as specified in Rule .1005(2)(a) of this Section within the
(' ORW AEC.
(c) After the Commission has received a request to classify Class SA waters as ORW and given
permission to the Director to schedule a public hearing to consider reclassification and until such
I' time as specific stormwater design criteria become effective, only development which meets the
requirements of Rule .1003(d)(3)(A), (B) and (C) and Rule .1005(2)(a) of this Section shall be
approved within 575 feet of the mean high water line of these waters.
I'-Histon• Note: Statutory Authoritv G.S. 143-214.1; 143-214.7,- 143-215.1. 143-215.3(a):
Eff. September 1, 1995.
I' .1003 DESIGN OF STORNMATER AL41NAGEN NT NfEASURES
(a) Structural Stormwater Control Options. Stormwater control measures which may be approved pursuant
to this Rule and which shall not be considered innovative include:
(' (I) Stormwater infiltration systems including infiltration basins/ponds, swales, and vegetative filters:
(2) Wet detention ponds; and
(3) Devices approved in accordance with Paragraph (b) of this Rule.
I' All stormwater management structures are subject to the requirements of Paragraph (c) of this Rule.
(b) Innovative Systems. Innovative measures for controlling stormwater which are not well established
through actual experience may be approved on a demonstration basis under the following conditions:
(1) There is a reasonable expectation that the control measures will be successful;
I' (2) The projects are not located near High Quality Waters (HQW).
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I, (3) Monitoring requirements are included to verify the performance of the control
measures;
(4) Alternatives are available if the control measures fail and shall be required when the Director
(� determines that the system has failed.
(c) General Engineering Design Criteria For All Projects.
(1) The size of the system must take into account the runoff at the ultimate built -out potential from all
Isurfaces draining to the system, ' including any off -site drainage. The storage volume of the system shall be calculated to provide for the most conservative protection using runoff calculation methods
described on pages A.1 and A.2 in "Controlling Urban Runoff: A Practical Manual For Planning
And Designing Urban BMPs" which is hereby incorporated by reference not including
I amendments. This document is available through the Metropolitan Washington (D.C.) Council of
Governments at a cost of forty dollars ($40.00). This method is also described in the Division's
document "An Overview of Wet Detention Basin Design." Other engineering methods may be
(' approved if these methods are shown to provide for equivalent protection;
(2) All side slopes being stabilized with vegetative cover shall be no steeper than 3:1 (horizontal to
vertical);
I' (3) All stormwater management structures shall be located in recorded drainage easements for the
purposes of operation and maintenance and shall have recorded access easements to the nearest
public right-of-way. These easements shall be granted in favor of the party responsible for
(' operating and maintaining the stormwater management structures;
(4) Vegetative filters designed in accordance with Paragraph (f) of this Rule are required from the
overflow of all infiltration systems and discharge of all stormwater wet detention ponds. These
Ifilters shall be at least 30 feet in length, except where a minimum length of 50 feet is required in
' accordance with Rule .1005(2)(b)(iii) of this Section;
(5) Stormwater controls shall be designed in accordance with the provisions of this Section. Other
designs may be acceptable if these designs are shown by the applicant, to the satisfaction of the
I' Director, to provide equivalent protection;
(6) In accordance with the Antidegradation Policy as defined in 15A NCAC 2B .0201, additional
control measures may be required on a case -by -case basis to maintain and protect. for existing and
I, anticipated uses, waters with quality higher than the standards; and
(7) Stormwater control measures used for sedimentation and erosion control during the construction
phase I' must be cleaned out and returned to their designed state. (d) Infiltration System Requirements. Infiltration systems may be designed to provide infiltration of the
entire design rainfall volume required for a site or a series of successive systems may be utilized. Infiltration
may also be used to pretreat runoff prior to disposal in a wet detention ponds. The following are general
requirements:
' (1) Infiltration systems shall be a minimum of 30 feet from surface waters and 50 feet from Class SA
waters;
(2) Infiltration systems shall be a minimum distance of 100 feet from water supply wells;
(3) The bottom of infiltration systems shall be a minimum of two feet above the seasonal high water
table;
(4) Infiltration systems must be designed such that runoff in excess of the design volume by-passes the
system and does not flush pollutants through the system:
(5) Infiltration systems must be designed to complete!• draw down the design storage volume to the
seasonal high water table under seasonal high water conditions within five days and a
hydrogeologic evaluation may be required to determine whether the system can draw dawn in five
days:
(6) Soils must have a minimum hydraulic conductivin• of 0.52 inches per hour to be suitable for
' infiltration;
(7) Infiltration systems must not be sited on or in till material. unless approved on a case -by -case basis
under Paragraph (h) of this Rule,
(8) Infiltration systems may be required on a case -by -case basis to have an observation well to provide
' ready inspection of the system;
(9) If runoff is directed to infiltration systems during construction of the project, the system must be
restored to design specifications after the project is complete and the entire drainage area is
' stabilized.
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' (e) Wet Detention Pond Requirements. These practices may be used as a primary treatment device or as
Y P rY
a secondary device following an infiltration system. Wet detention ponds shall be designed for a specific
pollutant removal. Specific requirements for these systems are as follows:
(1) The design storage volume shall be above the permanent pool;
(2) The discharge rate from these systems following the one inch rainfall design storm shall be such
that the draw down to the permanent pool level occurs within five days, but not in less than two
days;
(3) The design permanent pool level mean depth shall be a minimum of three feet and shall be
' designed with a surface area sufficient to remove 85 percent of total suspended solids. The design
for 85 percent total suspended solids removal shall be based on "Methodology for Analysis of
Detention Basins for Control of Urban Runoff Quality" which is hereby incorporated by reference
l not including subsequent amendments. This document is available from the U.S. Environmental
' Protection Agency (Document number EPA440/5-87-001) at no cost;
(4) The inlet structure must be designed to minimize turbulence using baffles or other appropriate
design features and shall be located in a manner that avoids short circuiting in the pond;
' (5) Pretreatment of the runoff by the use of vegetative filters may be used to minimize sedimentation
and eutrophication of the detention pond;
(6) Wet detention ponds shall be designed with a forebay to enhance sedimentation at the inlet to the
I' pond;
(7) The basin side slopes for the storage volume above the permanent pool shall be stabilized with
vegetation down to the permanent pool level and shall be designed in accordance with
I Subparagraph (c)(2) of this Rule;
(8) The pond shall be designed with side slopes no steeper than 3:1 (horizontal to vertical);
(9) The pond shall be designed to provide for a vegetative shelf around the perimeter of the basin.
(' This shelf shall be gently sloped (6:1 or flatter) and shall consist of native vegetation;
(10) The pond shall be designed to account for sufficient sediment storage to allow for the proper
operation of the facility between scheduled cleanout periods.
I(f) Vegetative Filter Requirements. Vegetative filters shall be used as a non-structural method for providing
' additional infiltration, filtering of pollutants and minimizing stormwater impacts. Requirements for these
filters are as follows:
(1) A distribution device such as a swale shall be used to provide even distribttion of runoff across
I, the width of the vegetative filter; .
(2) The slope and length of the vegetative filter shall be designed, constructed and maintained so as
to provide a non -erosive velocity of flow through the filter for the 10 year storm and shall have
(, a slope of five percent or less, where practicable. and
(3) Vegetation in the filter may be natural vegetation, grasses or artificially planted wetland vegetation
appropriate for the site characteristics.
I � W Curb Outlet Systems. Projects that meet the low density provisions of Rules .1005 through .1007 of .
this Section may use curb and gutter with outlets to convey the stormwater to grassed swales or vegetated
areas prior to the runoff discharging to vegetative filters or wetlands. Requirements for these curb outlet
systems are as follows:
I, (1) The curb outlets shall be located such that the swale or vegetated area can carry the Deal: flow from
the 10 year storm and the velocity of the flow shall be non -erosive;
(=) The longitudinal slope of the swale or vegetated area shall not exceed five percent, where
(' practicable;
(3) The side slopes of the swale or vegetated area shall be no steeper than 5:1 (horizontal to vertical).
Where this is not practical due to physical constraints, devices to slow the rate of runoff and
I' encourage infiltration to reduce pollutant delivery shall be provided;
(4) The minimum length of the swale or vegetated area shall be 100 feet; and
(5) In sensitive areas, practices such as check dams, rock or wooden, may be required to increase
(, detention time within the Swale or vegetated area.
(h) Alternative Design Criteria. In addition to the control measures outlined in Paragraphs (b), (d), (e),
it) and (g) of this Rule, stormwater management systems consisting of other control options or series of
I� control options may be approved by the Director on a case -by -case basis. This approval shall only be given
in cases where the applicant can demonstrate that the Alternative Design Criteria shall provide equal or better
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• A TISA: 02H .1000
stormwater control, equal or better protection of waters of the state, and result in no increased potential for
nuisance conditions. The criteria for approval shall be that the stormwater management system shall provide
for 85 percent average annual removal of Total Suspended Solids and that the discharge rate from the
meets one of the following: system
(1) the discharge rate following the one -inch design
runo
down to the pre -storm design stage within five days, but not le sstorm shall becth natwoedays or olume draws
(2) the post development discharge rate shall be no larger than predevelopment discharge
one year 24 hour storm, ge rate for the
(i) Operation and maintenance plans. Prior to approval of the development by the Division an operation
and maintenance plan or manual shall be provided by the developer for stormwater systems, indicating the
Operation and maintenance actions that shall be taken, specific quantitative criteria used for determining when
those actions shall be taken, and who is responsible
that shall be taken and who shall be respoible forfor
reshose toringcat storms. wateplan
stemust clearly indicate the steps
a failure occurs and must include an acknowled meresponssystem to design specifications if
maintained consistent with the requirements in these plans and thehorigi al plans and any modifications to these
ble party. Development must be
'plans must be approved by the Division.
' 0) System Design. Stormwater systems must be designed by an individual who meets any North
occupational licensing requirements for the type of system proposed. Upon completion of construction, the
designer for the type of stormwater system installed must certify that the system was inspected during
construction, was constructed in substantial conformity with plans and specifications approve
and complies with the requirements of this Section prior to issuance of the certificate Of ocaup by the
y Division
' History Note: Statutory Authority G. S. 143-214 1; 143-214. 7; 143-215.1; 143-215.3(a);
Eff. September 1. 1995.
.1009 STAFF REVIEW AND PERMIT PREPARATIO\
(a) The staff of the permitting agency shall conduct a review of plans, specifications and other project data
accompanying
the application and shall determine if the application and required information are complete.
The staff shall acknowledge receipt of a complete application.
(b) If the application is not complete with all required information, the application may be returned to the
applicant. The staff shall advise the applicant by mail:
(1) how the application or accompanying supporting information may be modified to make them
acceptable or complete; and
(2) that the 90 day processing period required in G.S. 143-2
complete application with required supporting informations 1 begins upon receipt of corrected or
(c) If an application is accepted and later found to be incomplete, the applicant shall be advised how the
application or accompanying supporting information may be modified to make them acceptable or complete.
and that if all required information is not submitted within 30 days that the project shall be returned as
incomplete.
Histor} Note: Statutory dtutlrorin G. S. 143-215.1; 143-21:.3(a);
Eff. September 1, 1995.
.1010 Fr' AL ACTION ON PEXVJ1T APPLICATIONS TO SION
(a) The Director shall take final action on all applications not ITaterBE ha�90 days following .
complete application and with required information. All e Y receipt of a
Permits or renewals shall be in writing. permits or renewals of permits and decisions denying
(b) The Director is authorized to:
(1) issue a permit containing such conditions as are necessary to effectuate the purposes of G.S. 143,
Article 21;
(2) issue permit containing time schedules for achie:•inz compliance with applicable water quality
standards and other legally applicable requirements;
(3) deny a permit application where necessary to effectuate:
(A) the purposes of G.S. 143, Article 21;
(B) the purposes of G.S. 143-215.67(a);
TH C.IROLINA .4D,11I,V1STRATIVE CODE
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I(C) rules on coastal waste treatment, disposal, found in Section .0400 of this Subchapter;
(D) rules on "subsurface disposal systems," found in 15A NCAC 18A .1900. Copies of these Rules
are available from the Division of Environmental Health, P.O. Box 29535, Raleigh, North
Carolina 27626-0535; and ,
(E) rules on groundwater quality standards found in Subchapter 2L of this Chapter.
(4) hold public meetings when necessary to obtain additional information needed to complete the
review of the application. The application will be considered as incomplete until the close of the
meeting record.
(c) If a permit is denied, the letter of denial shall state the reason(s) for denial and any reasonable measures
which the applicant may take to make the application approvable.
' (d) Permits shall be issued or renewed for a period of time deemed reasonable by the Director.
'History Note: Statutory Authority G.S. 143-215.1; 143-215.3(a);
' E, f . September 1, 1995.
'.1011 MODIFICATION AND REVOCATION OF PERMITS
' Any permit issued by the Division pursuant to these Rules is subject to revocation, or modification upon 60
days notice by. the Director in whole or part for good cause including but not limited to:
(1) violation of any terms or conditions of the permit;
(2) obtaining a permit by misrepresentation or failure to disclose fully all relevant facts;
(3) refusal of the permittee to allow authorized employees of the Department of Environment, Health,
and Natural Resources upon presentation of credentials:
'(a) to enter upon permittee's premises on which a system is located in which any records are required
' to be kept under terms and conditions of the permit;
(b) to have access to any copy and records required to be kept under terms and conditions of the
permit;
(c) to inspect any monitoring equipment or method required in the permit; or
(d) to sample any discharge of pollutants;
I(4) failure to pay the annual fee for administering and compliance monitoring.
History Note: Statutory Authority G.S. 143-215.1; 143-215.3(a);
f Ejf. September 1, 1995.
(' .1012 DELEGATION OF AUTHORITY
For permits issued by the Division, the Director is authorized to delegate any or all of the functions
contained in these Rules except the following:
(1) denial of a permit application;
(2) revocation of a permit not requested by the permitter; or
I' (3) modification of a permit not requested by the perminee.
History Note: Statutory Authority G. S. 143-215.3(a);
IEff. September 1, 1995.
' .1013 GENERAL PERMITS
I(a) In accordance with the provisions of G.S. 143.215.1(b)(3) and (4), general permits ' may be developed by the Division and issued by the Director for categories of activities covered in this Section. All activities
in the State that received a "Certificate of Coverage" for that category from the Division shall be deemed
Icovered under that general permit. Each of the general permits shall be issued individually under G.S.
' 143-215.1. using all procedural requirements specified for state permits including. application and public
notice. Activities covered under general permits, developed in accordance with this Rule, shall be subject to
the same standards and limits, management practices, enforcement authorities, and rights and privileges as
specified in the general permit. Procedural requirements for application and permit approval, unless
specifically designated as applicable to individuals proposed to be covered under the general permits, apply
only to the issuance of the general permits. After issuance of the general permit by the Director, activities
!' in the applicable categories may request coverage under the general permit, and the Director or his designee
i
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shall grant appropriate certification. General permits may be written to regulate categories of other activities
that all:. involve the same or substantially similar operations; have similar characteristics; require the same
limitations or operating conditions; require the same or similar monitoring; and in the opinion of the Director
are more appropriately controlled by a general permit.
(b) No provision in any general permit issued under this Rule shall be interpreted to allow the permittee
to violate state water quality standards or other applicable environmental standards.
(c) For a general permit to apply to an activity, a Notice of Intent to be covered by the general permit must
be submitted to the -Division using forms provided by the Division and, as appropriate, following the
application procedures specified in this Section. If all requirements are met, coverage under the general
permit may be granted. If all requirements are not met, a long form application and full application review
procedure shall be required.
(d) General permits may be modified and reissued by the Division as necessary. Activities covered by
general permits need not submit new Notices of Intent or renewal requests unless so directed by the Division.
If the Division chooses not to renew a general permit, all facilities covered under that general permit shall be
notified to submit applications for individual permits.
(e) All previous state water quality permits issued to a facility which can be covered by a general permit,
whether for construction or operation, are revoked upon request of the permittee, termination of the individual
permit and issuance of the Certification of Coverage.
(f) Anyone engaged in activities covered by the general permit rules but not permitted in accordance with
this Section shall be considered in violation in G.S. 143-215.1.
(g) Any individual covered or considering coverage under a general permit may choose to pursue an
individual permit for any activity covered by this Section.
(h) The Director may require any person, otherwise eligible for coverage under a general permit, to apply
for an individual permit by notifying that person that an application is required. Notification shall consist of
a written description of the reason(s) for the decision, appropriate permit application forms and application
instructions, a statement establishing the required date for submission of the application. and a statement
informing the person that coverage by the general permit shall automatically terminate upon issuance of the
individual permit. Reasons for requiring application for an individual permit may be:
(1) the activity is a significant contributor of pollutants:
(2) conditions at the permitted site change, altering the constituents or characteristics of the site such
that the activity no longer qualifies for coverage under a general permit;
(3) noncompliance with the general permit;
(4) noncompliance with Commission Rules:
(5) a change has occurred in the availability of demonstrated technology or practic:s for the control
or abatement of pollutants applicable to the activity: or
(6) a determination that the water of the stream receiving stormwater runoff from the site is not
meeting applicable water quality standards.
lii Any interested person may petition the Director to take an action under Paragraph (b) of this Rule to
require an individual permit.
(j) General permits may be modified, terminated. or revoked and reissued in accordance vith the authority
and requirements of Rules .1010 and .1011 of this Section. -
History Note: Stattttory Authoring G.S. 143-215.1. 143-21-.3(a).
Eff. September 1, 1995.
500 copies of this public document were printed at a cost of $ 144.00 or
$.29 per copy.
A*ORTH CAROLLVA ADMIMSTRATIVE CODE 12/IS/95 Page 12

APPENDIX B
North Carolina
Stormwater Management Permit

OFFICE USE ONLY
Date Received Fee Paid Permit Number
I'
.1
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
This form may be photocopied for use as an original
I. GENERAL INFORMATION
1. Applicants name (specify the name of the corporation, individual, etc. who owns the project):
2. Print Owner/Signing Official's name and title (person legally responsible for facility and compliance):
3. Mailing Address for person listed in item 2 above:
City: State: Zip:
Telephone Number: i
4. Project Name (subdivision, facility, or establishment name -should be consistent with project name on
plans, specifications, letters, operation and maintenance agreements, etc.):
S. Location of Project (street address):
City: County:
6. Directions to project (from nearest major intersection):
7. Latitude:
Longitude:
8. Contact person who can answer questions about the project:
Name: Telephone Number:
II. PERMIT INFORMATION:
of project -
1. Specify whether project is (check one): New Renewal Modification
1
Form SNVU-101 Version 3.99 Page 1 of 4

2. If this application is being submitted as the result of a renewal or modification to an existing permit, list the
existing permit number and its issue date (if known)
3. Specify the type of project (check one):
Low Density High Density Redevelop General Permit Other
4. Additional Project Requirements (check applicable blanks): I
_CAMA Major _Sedimentation/Erosion Control 404/401 Permit _NPDES Stormwater
Information on required state permits can be obtained by contacting the Customer Service Center at '
1-877-623-6748.
III. PROJECT INFORMATION I
1. In the space provided below, summarize how stormwater will be treated. Also attach a detailed narrative
(one to two pages) describing stormwater management for the project
2. Stormwater runoff from this project drains to the River. basin. '
3. Total Project Area: acres
5. How many drainage areas does the project have?
4. Project Built Upon Area: %
6. Complete the following information for each drainage area. If there are more than two drainage areas in the
project, attach an additional sheet with the information for each area provided in the same format as below.
hI'
u
I
" Impervious area is defined as the built upon area including, but not limited to, buildings, roads, parking areas,
sidewalks, gravel areas, etc. I
Form SWU-101 Version 3.99 Page 2 of 4 1

7. How was the off -site impervious area listed above derived.
^� IV. DEED RESTRICTIONS AND PROTECTIVE COVENANTS
The following italicized deed restrictions and protective covenants are required to be recorded for all
subdivisions, outparcels and future development prior to the sale of any lot. If lot sizes vary significantly, a
' table listing each lot number, size and the allowable built -upon area for each lot must be provided as an
attachment.
1. The following covenants are intended to ensure ongoing compliance with state stormwater management permit
number as issued by the Division of Water Quality. These covenants may
not be changed or deleted without the consent of the State.
' 2. No more than s uare eet o an lot shall be covered structures or impervious materials.
q f f y � p
Impervious materials include asphalt, gravel, concrete, brick, stone, slate or similar material but do not include wood
decking or the water surface of swimming pools.
3. Swales shall not be filled in, piped, or altered except as necessary to provide driveway crossings.
r� 4. Built -upon area in excess of the permitted amount requires a state stormwater management permit modification prior to
.r
construction.
5. All permitted runoff from outparcels or future development shall be directed into the permitted stormwater control
system. These connections to the stormwater control system shall be performed in a manner that maintains the
integrity and performance of the system as permitted.
By your signature below, you certify that the recorded deed restrictions and protective covenants for this project
shall include all the applicable items required above, that the covenants will be binding on all parties and
persons claiming under them, that they will run with the land, that the required covenants cannot be changed or
deleted without concurrence from the State, and that they will be recorded prior to the sale of any lot.
V. SUPPLEMENT FORMS
The applicable state stormwater management permit supplement form(s) listed below must be submitted for
each BMP specified for this project. Contact the Stormwater and General Permits Unit at [phone] for the
status and availability of these forms.
Form SWU-102 Wet Detention Basin Supplement
Form SWU-103 Infiltration Basin Supplement
Form SWU-104 Low Density Supplement
Form SWU-105 Curb Outlet System Supplement
Form SWU-106 Off -Site System Supplement
' Form SWU-107 Underground Infiltration Trench Supplement
Form SWU-108 Neuse River Basin Supplement
Form SWU-109 Innovative Best Management Practice Supplement
Form SWU-101 Version 3.99 Pane 3 of 4

VI. SUBMITTAL REQUIREMENTS
Only complete application packages will be accepted and reviewed by the Division of Water Quality (DWQ).
A complete package includes all of the items listed below, The complete application package should be
submitted to the appropriate DWQ Regional Office.
1. Please indicate that you have provided the following required information by initialing in the space
'
provided next to each item.
Initials
• Original and one copy of the Stormwater Management Permit Application Form
• One copy of the applicable Supplement Form(s) for each BMP
'
• Permit application processing fee of $420 (payable to NCDENR)
• Detailed narrative description of stormwater treatment/management
• Two copies of plans and specifications, including:
'
- Development/Project name
- Engineer and firm
-Legend
'
- North arrow
- Scale
- Revision number & date
- Mean high water line
'
- Dimensioned property/project boundary
- Location map with named streets or NCSR numbers
- Original contours, proposed contours, spot elevations, finished floor elevations
,
- Details of roads, drainage features, collection systems, and stormwater control measures
- Wetlands delineated, or a note on plans that none exist
- Existing drainage (including off -site), drainage easements, pipe sizes, runoff calculations
- Drainage areas delineated
- Vegetated buffers (where required)
S 0, a-
,
VII. AGENT AUTHORIZATION
If you wish to designate authority to another individual or firm so that they may provide information on your
,
behalf, please complete this section.
Designated agent (individual or firm):
'
Mailing Address:
City: State: Zip:
'
Phone: ( ) Fax: ( )
VIII. APPLICANT'S CERTIFICATION
I, (print or type name of person listed in General Information, item 2)
'
certify that the information included on this permit application form is, to the best of my knowledge, correct and
that the project will be constructed in conformance with the approved plans, that the required deed restrictions
and protective covenants will be recorded, and that the proposed project complies with the requirements of 15A I
NCAC 2H .1000.
Signature Date: I
Form SWU-101 Version 3.99 Page 4 of 4 '

APPENDIX C
Public Information Flyers

III .:� I.� I : cK�� l 1\Y111�'1
WHAT IS STORMWATER RUNOFF?
' Stormwater runoff is the rain that runs off streets, rooftops, parking lots, lawns
and other land surfaces. As communities develop more impervious surfaces are
created and less rainfall can soak into the ground. This increases flooding and
streambank erosion.
POLLUTANTS IN STORMWATER
Stormwater picks up pollutants as it flows across the ground. Some of these
pollutants include:
r F1J};4 • Sediment Bacteria from Leaking Septic Tanks
• Pesticides and Fertilizers • Bacteria from Animal Wastes
' • Oil and Grease • Waste from Boats
• Solvents and Cleaners
1
Sometimes pollutants are illegally dumped into storm drains and waterways.
WHAT CAN YOU DO TO PREVENT STORMWATER POLLUTION AND
DECREASE RUNOFF?
• Minimize impervious surfaces to reduce runoff.
• Divert roof drains to vegetated areas on your property, not directly onto paved surfaces. This
increases infiltration and decreases runoff.
• Divert runoff from pavement to grassy, planted or wooded areas of your property, so stormwater can
seep slowly into the ground.
• Retain or create buffers (50 to 100 feet where possible) of vegetation between waterways and
impervious areas to help filter out pollutants and increase infiltration.
• Stop soil erosion — plant vegetation on all bare areas.
• Design new construction to prevent runoff and stormwater pollution.
• Properly use and store all household chemicals.
• Clean up spilled solvents, brake fluids, grease, etc. Do not wash them into the street where they will
eventually end up in local waterways.
• Properly dispose of household hazardous wastes. Do not dump them on the ground or in the storm
drain.
• Clean litter from the street, storm drains, and drainage ditches near your home and along waterways
to keep it out of the water. This also helps prevent clogged storm drains and waterways help reduce
the chance of flooding.
• Report any pollution, illegal dumping or soil erosion that you see to authorities.
If you have any questions or comments about the Stormwater Management Program for Dare County,
please contact Donna Creef with the Dare County Planning Department at [phone].

( Ktj IV 1A
0) Oft by
l ��► I'� � I ���F43 1010:11ma [ 1 wwwoulIM"Ol'�
WHAT IS STORMWATER MANAGEMENT?
Stormwater runoff management involves utilizing control principles and practices to
reduce stormwater runoff and stormwater pollution. The current approach to solving
these problems is through minimizing the generation of runoff and pollutants,
combined with managing runoff and pollutants to minimize its impacts in a cost-
effective manner.
'PREVENTATIVE MEASURES
Preventative measures include non-structural best management practices (BMPs) that help prevent runoff and
the contamination of runoff through controlling the sources. These measures include:
' Stormwater Ordinances/Policies
Establishing greenways along waterways, limiting the amount of impervious surfaces, setting minimum lot
'sizes, restricting fill height on lots, requiring building setbacks and vegetative buffers along streams,
discharging downspouts from roof gutters into vegetated areas, requiring runoff from paved areas to flow
through vegetated buffers prior to entering waterways, prohibiting the filling of drainage swales.
' Public Education
Changing citizen behavior and practices through education is the key to decreasing stormwater runoff and
stormwater pollution. Educating the public and town employees about stormwater problems and BMPs will
' help minimize runoff and protect water quality.
Pollution Prevention
'Practicing preventative maintenance to reduce spills and leaks, covering material stored outside to prevent
exposure to rainfall, and maintaining sanitary sewers and septic tanks are all methods of pollution prevention.
'CONTROL MEASURES
Control measures include structural best management practices (BMPs) that control the volume and peak
discharge rate and/or reduce the concentration of pollutants in stormwater runoff. These measures include:
Vegetative Practices
Grassed swales help to reduce stormwater flows and pollution. Grassed swales maximize infiltration and
' filtration. The vegetation "captures" pollutants, preventing them from entering the waterways.
'Infiltration Devices
A portion of the stormwater runoff is retained in the infiltration facility, allowing it to infiltrate into the soil, and
or evaporate into the air. These devices will reduce the amount of runoff and also the amount of pollutants.
' Retention Ponds
A portion of the stormwater runoff is retained in these facilities in order to reduce the amount of runoff entering
the waterways at the time of the storm. The water is slowly released over time. Some of the pollutants settle to
' the bottom of the facility, thus reducing the amount of pollutants in the stormwater.
These and other practices will be evaluated for use by Dare County. If you have any questions or comments
' about the Stormwater Management Program for Dare County, please contact Donna Creef with the Dare County
Planning Department at [phone].

APPENDIX D
North Carolina Sewage Treatment
and Disposal Regulations

I' ENR - ENVIRONMENTAL HEALTH TI SA: 18A .1900
' SECTION .1900 - SEWAGE TREATMENT AND DISPOSAL SYSTEMS
Rules.] 901 - .1968 of Title 15A Subchapter 18A of the North Carolina Administrative Code (T15A.18A .1901 -.1968);
has been transferred and recodified from Rules .1901 - .1968 of Title 10 Subchapter l0A of the North Carolina
Administrative Code (T10.10A .1901 - .1968), effective April 4, 1990.
.1901
PURPOSE
.1902
PROPER DISPOSAL
.1903
DEFINITIONS
.1904
SEWAGE DISPOSAL REQUIREMENTS
I,
.1905
PRIVY AND SEPTIC TANK CONSTRUCTION
.1906
PREFABRICATED TANKS
.1907
MINIMUM STANDARDS FOR PREFABRICATED SEPTIC TANKS
f,
.1908
SITE EVALUATION
.1909
APPLICATION RATES
.1910
SITE CLASSIFICATION
.1911
SPACE REQUIREMENTS
.1912
LOCATION OF SEPTIC TANK SYSTEMS AND PRIVIES
.1913
MAINTENANCE OF PRIVIES
.1914
MAINTENANCE OF SEPTIC TANK SYSTEMS
.1915
PERMITS
.1916
RESPONSIBILITIES
.1917
TECHNICAL GUIDE
.1918
.1919
SITE FACTORS
TOPOGRAPHY
.1920
SOIL CHARACTERISTICS
.1921
PERCOLATION TESTS
!'
.1922
DETERMINATION OF SOIL SUITABILITY
.1923
AVAILABLE SPACE
.1924
OTHER APPLICABLE FACTORS
.1925
.1926
ESTIMATES OF SEWAGE QUANTITIES
POSSIBLE MODIFICATIONS OF INITIAL CLASSIFICATIONS
.1927
INTERPRETATION AND TECHNICAL ASSISTANCE
.1928
APPLICABILITY OF RULES
.1929
EXEMPTION
I
.1930
DISUSE OF SEWAGE SYSTEM
.1931
VIOLATIONS
.1932
CONFLICTING RULES REPEALED
.1933
SEVERABILITY
History Note: Authority G.S. 130-160; 166.23 through 166.28;
I' Eff. July 1, 1977,
Readopted Eff. December S, 1977;
Amended Eff. July 1, 1982; March 31, 1981; June 30, 1980;
Repealed Eff. July 1, 1982.
.1934 SCOPE
The rules contained in this Section shall govern the treatment and disposal of domestic type sewage from septic tank
l' systems, privies, incinerating toilets, mechanical toilets, composting toilets, recycling toilets, or other such systems serving
II single or multiple -family residences, places of business, or places of public assembly, the effluent from which is designed
not to discharge to the land surface or surface waters.
I' History Note: AuthorityG.S. 130A-335(e);
Eff. July 1, 1982;
i' Amended Eff. December], 1990.
' NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page I

I' ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
.1935
DEFINITIONS
following definitions shall apply throughout this Section:
IThe
' (1)
"Alluvial Soils" means stratified soils without distinct horizons, deposited by flood waters.
(2)
"Alternative System" means any approved ground absorption sewage treatment and disposal system other than
an approved privy or an approved septic tank system.
I, (3)
"Approved" means that which has been considered acceptable to the State or local health department.
(4)
"Approved Privy" means a fly -tight structure consisting of a pit, floor slab, and seat riser constructed i n
accordance with Rule .1959 of this Section.
"Approved Public or Community Sewage System" means a single system of sewage collection, treatment, and
I(5)
'
disposal owned and operated by a sanitary district, a metropolitan sewage district, a water and sewer authority,
a county or municipality, or a public utility, constructed and operated in compliance with applicable requirements
of the Division of Environmental Management.
"Areas
(6)
subject to frequent flooding" means those areas inundated at a 10-year or less frequency and includes
'
alluvial soils and areas subject to tidal or storm overwash.
(7)
"Collection sewer" means gravity flow pipelines, force mains, effluent supply lines, and appliances appurtenant
thereto, used for conducting wastes from building drains to a treatment system or to a ground absorption sewage
I'
treatment and disposal system.
(8)
"Designated wetland" means an area on the land surface established under the provisions of the Coastal Area
(9)
Management Act or the Federal Clean Water Act.
"Design unit" means one or more dwelling units, places of business, or places of public assembly on:
(a) a single lot or tract of land;
(b) multiple lots or tracts of land served by a common ground absorption sewage treatment and disposal
system; or
(c) a single lot or tract of land or multiple lots or tracts of land where the dwelling units, places of business
or places of public assembly are under multiple ownership (e.g. condominiums) and are served by a ground
absorption system or multiple ground absorption systems which are under common or joint ownership or
control.
(10)
"Dwelling unit" means any room or group of rooms located within a structure and forming a single, habitable unit
with facilities which are used or intended to be used for liv ing, sleeping, bathing, toilet usage, cooking, and eating.
I, (1 1)
"Effluent" means the liquid discharge of a septic tank or other sewage treatment device.
(12)
"Ground absorption sewage treatment and disposal system" means a system that utilizes the soil for the subsurface
disposal of partially treated or treated sewage effluent.
"Horizon" means a layer of soil, approximately parallel to the surface, that has distinct characteristics produced
I(13)
'
by soil forming processes.
(14)
"Local health department" means any county, district, or other health department authorized to be organized under
the General Statutes of North Carolina.
I' (15)
"Mean high water mark" means, for coastal waters having six inches or more lunar tidal influence, the average
height of the high water over a 19 year period as may be ascertained from National Ocean Survey or U.S. Army
Corps of Engineers tide stations data or as otherwise determined under the provisions of the Coastal Are a
Management Act.
' (16)
"Naturally occurring soil" means soil formed in place due to natural weathering processes and being unaltered
by filling, removal, or other man -induced changes other than tillage.
(17)
"Nitrification field" means the area in which the nitrification lines are located.
(, (18)
"Nitrification lines" means approved pipe, specially designed porous blocks, or other approved materials which
receive partially treated sewage effluent for distribution and absorption into the soil beneath the ground surface.
(19)
"Nitrification trench", also referred to as a sewage absorption trench, means a ditch into which a single
f,
nitrification line is laid and covered by soil.
II(20)
"Non -ground absorption sewage treatment system" means a facility for waste treatment designed not to discharge
to the soil, land surface, or surface waters, including but n of limited to, approved vault privies, incinerating toilets,
mechanical toilets, composting toilets, chemical toilets, and recycling systems.
(21)
"Organic soils" means those organic mucks and peats consisting of more than 20 percent organic matter (by dry
weight) and 18 inches or greater in thickness.
(22)
"Parent material" means the mineral matter that is in its present position through deposition by water, wind,
gravity or by decomposition of rock and exposed at the land surface or overlain by soil or saprolite.
'
(23)
"Ped" means a unit of soil structure, such as an aggregate, crumb, prism, block, or granule formed by natura I
processes.
' (24)
"Perched water table" means a saturated zone, generally above the natural water table, as identified by drainage
mottles caused by a restrictive horizon.
'
NORTH
CAROLINA ADMINISTRATIVE CODE 01121199 Page 2

I' ENR - ENVIRONMENTAL HEALTH T1 SA: I8A .1900
(25) "Person" means any individual, firm, association, organization, partnership, business trust, corporation, company,
I' or unit of local government.
(26) "Place of business" means any store, warehouse, manufacturing establishment, place of amusement or recreation,
service station, foodhandling establishment, or any other place where people work or are served.
I (27) "Place of public assembly" means any fairground, auditorium, stadium, church, campground, theater, school, or
' any other place where people gather or congregate.
(28) 'Privy building" means and includes any and all buildings which are used for privacy in the acts of urination and
defecation which are constructed over pit privies and are not connected to a ground absorption sewage treatment
and disposal system or a public or community sewage system.
' (29) "Public management entity" means a city (G.S. 160A, Article 16), county (G.S. 153A, Article 15), interloca I
contract (G.S. 153A, Article 16), joint management agency (G.S. 160A-461 -462), county service district (G.S.
153A, Article 16), county water and sewer district (G.S. 162A, Article 6), sanitary district (G.S. 130A, Article
' 2), water and sewer authority (G.S. 162A, Article 1), metropolitan water district (G.S. 162A, Article 4) ,
metropolitan sewerage district (G.S. 162A, Article 5), public utility [G.S. 62-3(23)], county or district healt h
department (G.S. 130A, Article 2), or other public entity legally authorized to operate and maintain on -site
(' sewage systems.
(30) "Relocation" means the displacement of a residence, place of business, or place of public assembly from on e
location to another.
1 (31) "Repair area" means an area, either in its natural state o r which is capable of being modified, consistent with these
' Rules, which is reserved for the installation of additional nitrification fields and is not covered with structures or
impervious materials.
(32) "Residence" means any home, hotel, motel, summer camp, labor work camp, mobile home, dwelling unit in a
I' multiple -family structure, or any other place where people reside.
(33) 'Restrictive horizon" means a soil horizon that is capable of perching ground water or sewage effluent and that
is brittle and strongly compacted or strongly cemented with iron, aluminum, silica, organic matter, or other
Icompounds. Restrictive horizons may occur as fragipans, iron pans or organic pans, and are recognized by their
' resistance in excavation or in using a soil auger.
(34) 'Rock" means the body of consolidated or partially consolidated material composed of minerals at or below the
land surface. Rock includes bedrock and partially weathered rock that is relatively hard and cannot be dug with
I' hand tools. The upper boundary of rock is "saprolite", "soil", or the land surface.
(35) "Sanitary system of sewage treatment and disposal" means a complete system of sewage collection, treatment and
disposal, including approved privies, septic tank systems, connection to public or community sewage systems,
I' incinerators, mechanical toilets, composting toilets, recycling toilets, mechanical aeration systems, or other such
systems.
(36) "Saprolite" means the body of porous material formed in place by weathering of igneous or metamorphic rocks.
Saprolite has a massive, rock -controlled structure, and retains the fabric (arrangement of minerals) of its parent
' rock in at least 50 percent of its volume. Saprolite can be dug with hand tools. The lower limit of saprolite is
"rock" and its upper limit is "soil" or the land surface. The term "saprolite" does not include sedimentary parent
materials.
(37) "Septic tank" means a water -tight, covered receptacle designed for primary treatment of sewage and constructed
to:
(a) receive the discharge of sewage from a building;
(b) separate settleable and floating solids from the liquid;
' (c) digest organic matter by anaerobic bacterial action;
(d) store digested solids through a period of detention; and
(e) allow clarified liquids to discharge for additional treatment and final disposal.
(38) "Septic tank system" means a subsurface sanitary sewage system consisting of a septic tank and a subsurface
disposal field.
(39) "Sewage" means the liquid and solid human waste and liquid waste generated by water -using fixtures and
appliances, including those associated with food handling. The term does not include industrial process
' wastewater or sewage that is combined with industrial process wastewater.
(40) "Site" means the area in which the sewage treatment and disposal system is to be located and the area required
to accommodate repairs and replacement of nitrification field and permit proper functioning of the system.
' (41) "Soil" means the naturally occurring body of porous mineral and organic materials on the land surface. Soil is
composed of sand-, silt-, and clay -sized particles that are mixed with varying amounts of larger fragments and
some organic material. Soil contains less than 50 percent of its volume as rock, saprolite, or coarse -earth fraction
' (mineral particles greater than 2.0 millimeters). The upper limit of the soil is the land surface, and its lower limit
is "rock", "saprolite", or other parent materials.
' NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 3

I' ENR - ENVIRONMENTAL HEALTH T1 SA: 18A .1900
(42) . "Soil structure" means the arrangement of primary soil particles into compound particles, peds, or clusters that
are separated by natural planes of weakness from adjoining aggregates.
I' (43) "Soil textural classes" means soil classification based upon size distribution of mineral particles in the fine -earth
fraction less than two millimeters in diameter. The fine -earth fraction includes sand (2.0 - 0.05 mm in size), silt
(less than 0.05 mm - 0.002 mm or greater in size), and clay (less than 0.002 mm in size) particles. The specific
I' textural classes are defined as follows and as shown in Soil Taxonomy, Appendix 1, which is hereby adopted by
reference in accordance with G.S. 15013-14(c):
(a) "Sand" means soil material that contains 85 percent or more of sand; the percentage of silt plus 1.5 times
I' the percentage of clay shall not exceed 15.
(b) "Loamy sand" means soil material that contains at the upper li mit 85 to 90 percent sand, and the percentage
silt plus 1.5 times the percentage of clay is not less than 15; at the lower limit it contains not less than 70
I to 85 percent sand, and the percentage of silt plus twice the percentage of clay does not exceed 30.
' (c) "Sandy loam" means soil material that contains either 20 percent clay or less, and the percentage of silt plus
twice the percentage of clay exceeds 30, and contains 52 percent or more sand; or less than seven percent
clay, less than 50 percent silt, and between 43 and 52 percent sand.
' (d) "Loam" means soil material that contains seven to 27 percent clay, 28 to 50 percent silt, and less than 52
percent sand.
(e) "Silt loam" means soil material that contains 50 percent or more silt and 12 to 27 percent clay; or contains
I, 50 to 80 percent silt and less than 12 percent clay.
(f) "Silt" means soil material that contains 80 percent or more silt and less than 12 percent clay.
(g) "Sandy clay loam" means soil material that contains 20 to 35 percent clay, less than 28 percent silt, and
45 percent or more sand.
(' (h) "Clay loam" means soil material that contains 27 to 40 percent clay and 20 to 45 percent sand.
(i) Silty clay loam" means soil material that contains 27 to 40 percent clay and less than 20 percent sand.
0) "Sandy clay" means soil material that contains 35 percent or more clay and 45 percent or more sand.
I' (k) "Silty clay" means soil material that contains 40 percent or more clay and 40 percent or more silt.
(1) "Clay" means soil material that contains 40 percent or more clay, less than 45 percent sand, and less than
40 percent silt.
(44) "State" means the Department of Environment, Health, and Na tural Resources, Division of Environmental Health.
I' (45) "Stream" means a natural or manmade channel, including groundwater lowering ditches and devices, in which
water flows or stands most of the year.
(46) "Subsurface disposal' means the application of sewage effluent beneath the surface of the ground by distribution
I' through approved nitrification lines.
History Note: Authority G.S. 130A-335(e) and (n;
Eff. July 1, 1982;
(, Amended Eff. July 1, 1995; January 1, 1990; August 1, 1988, April 1, 1985.
.1936 REQUIREMENTS FOR SEWAGE TREATMENT AND DISPOSAL
I' History Note: Authority G.S.130A-335(e);
Eff. July 1, 1982;
Repealed Eff. January 1, 1990.
.1937 PERMITS
(a) Any person owning or controlling a residence, place of business, or place ofpublic assembly containing water -using
I' fixtures connected to a water supply source shall discharge all wastewater directly to an approved wastewater system
permitted for that specific use.
(b) An Improvement Permit, Authorization for Wastewater System Construction (Construction Authorization) an d
Operation Permit, shall be required in accordance with G.S. 130A-336, G.S. 130A-337 and G.S. 130A-338. Rule .1949
' of this Section shall be used to determine whether subsequent additions, modifications, or change in the type of facility
increase wastewater flow or alter wastewater characteristics.
(c) An application for an Improvement Permit or Construction Authorizat ion, as applicable, shall be submitted to the local
(' health department for each site prior to the construction, location, or relocation of a residence, place of business, or place
of public assembly. Applications for systems required to be designed by a professional engineer and applications for
industrial process wastewater systems shall meet the provisions of Rule .1938 of this Section.
' (d) The application for an Improvement Permit shall contain at least the following information: owner's name, mailing
address, and phone number, location of property, plat of property or site plan, description of existing and proposed facilities
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I' ENR - ENVIRONMENTAL HEALTH T1 SA: 18A .1900
or structures, number of bedrooms, or number of persons served, or other factors required to determine wastewater system
Idesign flow or wastewater characteristics, type of water supply including the location of proposed or existing well(s), and
' signature of owner or owner's legal representative. The applicant shall identify property lines and fixed reference points
in the field. The applicant shall make the site accessible for an evaluation as required in Rule.] 939 of this Section. The
applicant shall notify the local health department on the application of the following:
(1) the property contains previously identified jurisdictional wetlands:
(2) wastewater other than sewage will be generated; or
(3) the site is subject to approval by other public agencies.
I(e) The application for a Construction Authorization shall contain:
' (1) the information required in Paragraph (d) of this Rule; however, a plat or site plan shall not be required with the
application for a Construction Authorization to repair a previously permitted system when the repairs will be
I accomplished on property owned and controlled by the applicant and for which the property lines are readily
' identifiable in the field;
(2) the locations of the proposed facility, appurtenances, and the site for the system showing setbacks to property
line(s) or other fixed reference point(s); and
(3) the proposed system type as specified by the owner or owner's legal representative and that meets the conditions
of the Improvement Permit, the provisions of these Rules, and G.S. 130A, Article 11.
(f) An authorized agent of DENR shall issue an Improvement Permit after determining that the site is suitable o r
Iprovisionally suitable and that a system can be installed so as to meet the provisions of these Rules. The Improvement Permit
' shall include those items required in G.S. 130A-336(a). An Improvement Permit for which a plat is provided shall be valid
without expiration and an Improvement Permit for which a site plan is provided shall be valid for 60 months from the date
of issue as provided in G.S. 130A-335(f) and G.S. 130A-336(a). The Improvement Permit is transferable to subsequent
owners except as provided in G.S. 130A-335(f) and G.S. 130A-336(a).
(g) The Construction Authorization as provided in G.S. 130A-335(f) and G.S. 130A-336(b) shall be valid for a period
equal to the period ofvalidity of the Improvement Permit, not to exceed 60 months. Site modifications required as conditions
Iof an Improvement Permit shall be completed prior to the issuance of a Construction Authorization. The Constructio n
' Authorization shall be issued by an authorized agent for the installation of a wastewater system when it is found that th e
Improvement Permit conditions and rules of this Section are met. The Construction Authorization shall contain conditions
regarding system type, system layout, location, and installation requirements. The property owner shall ensure that a
I' Construction Authorization is obtained and is valid prior to the construction or repair of a system. The property owner shall
obtain a Construction Authorization prior to the construction, location, or relocation of a residence, place of business, or
place of public assembly. If the installation has not been completed during the period of validity of the Construction
I Authorization, the information submitted in the application for a Permit or Construction Authorization is found to have been
incorrect, falsified or changed, or the site is altered, the Permit or Construction Authorization shall become invalid, and may
be suspended or revoked. When a Permit or Construction Authorization has become invalid, expired, suspended, or revoked,
the installation shall not be commenced or completed until a new Permit or Construction Authorization has been obtained.
I' Revised Construction Authorizations shall be issued for sites where Improvement Permits are valid without expiration in
compliance with G.S. 130A-335(fl).
(h) Prior to the issuance of a Construction Authorization for a wastewater system to serve a condominium or other
Imultiple -ownership development where the system will be under common or joint control, a draft agreement (tri-party)
' among the local health department, developer, and a proposed non-profit, incorporated owners association shall be submitted
to the local health department for approval. Prior to the issuance of an Operation Permit for a system requiring a tri-party
agreement, the agreement shall be executed among the local health department, developer, and a non-profit, incorporated
(, owners association and filed with the local register of deeds. The tri-party agreement shall address ownership transfer of
ownership, maintenance, repairs, operation, and the necessary funds for the, continued satisfactory performance of th e
wastewater system, including collection, treatment, disposal, and other appurtenances.
I' (i) No residence, place of business, or place of public assembly shall be occupied nor shall any wastewater system be
covered or placed into use until an authorized agent issues an Operation Permit. The Operation Permit shall not be issued
or reissued until the authorized agent finds that the system is in compliance with Article 11 of G.S. Chapter 130A, these
IRules, and all conditions prescribed by the Improvement Permit, and Construction Authorization. The Operation Permit
' shall specify the system type in accordance with Table V(a) of Rule .1961 of this Section, and shall include conditions for
system performance, operation, maintenance, monitoring and reporting. At the review frequency specified in Rule .1961,
Table V(a) of this Section, an authorized agent shall determine whether a system in compliance with the conditions of the
I' Operation Permit, these Rules, and Article 1 I of G.S. Chapter 130A. An authorized agent may modify, suspend or revoke
the Operation Permit or seek other remedies under Article 2, Chapter 130A, if the system is not in compliance with Article
11 of G.S. Chapter 130A, these Rules, and all conditions imposed by the Operation Permit.
I, 0) For a Type V or VI system as specified in Rule .1961, Table V(a) of Paragraph (b)(9) of this Section, the Operation
Permit shall expire either;
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IENR - ENVIRONMENTAL HEALTH TI SA: 18A .1900
' (1) 60 months after the Operation Permit is issued for any system instal led on or after the effective date of these Rules
I or
' (2) 60 months after the effective date of these Rules for any system with a valid Operation Permit issued prior to the
effective date of these Rules.
(k) Upon determining that an existing wastewater system including all subsystems and system components in a
I' manufactured home park has a valid Operation Permit and is in compliance with Article 11 of G.S. Chapter 130A, these
Rules, and permit conditions, an authorized agent shall issue a written authorization for a manufactured home to be connected
to the existing system.
(1) Any person other than the owner or controller of a residence, place of business, or place of public assembly, wh o
' engages in the business of constructing, installing, or repairing wastewater systems shall register with the local health
department in each county where he operates before constructing, installing, or repairing wastewater systems.
(m) An authorized agent shall prepare a written report with reference to the site and soil conditions required to b e
I, evaluated pursuant to this Section. When a permit is denied, the report shall be provided to the applicant. If modifications
or alternatives are available, information shall be provided to the applicant. The report shall be signed and dated by an
authorized agent of the State.
I' History Note: Authority G.S. 130A-335(e),(9;
Eff. July 1, 1982;
IAmended Eff. August 1, 1991; January 1, 1990; January 1, 1984;
' Temporary Amendment Eff. January 20, 1997,
Amended Eff. August 1, 1998.
.1938 RESPONSIBILITIES
(a) The permitting of wastewater system shall be the responsibility of agents authorized by the State in accordance with
G.S. 130A-40,13OA-50, and registered with the State of North Carolina Board of Sanitarian Examiners if required in G.S.
I90A Article 4.
' (b) The person owning or controlling the system shall be responsible for assuring compliance with the laws, rules, and
permit conditions regarding system location, installation, operation, maintenance, monitoring, reporting, and repair.
(c) Prior to the issuance of an Improvement Permit or Construction Authorization, plans and specifications may b e
(' required by the local health department where there is an unsuitable soil or unsuitable characteristic and shall be required
for drainage systems serving two or more lots. These plans and specifications shall be required to be prepared by a person
or persons who are licensed or registered to consult, investigate, evaluate, plan or design wastewater systems, soil and rock
Icharacteristics, ground water hydrology, or drainage systems if required in G.S. 89C, 89E, 89F, and 90A Article 4.
' (d) Any wastewater system which meets one or more of the following conditions shall be designed by a registered
professional engineer if required by G.S. 89C:
(1) The system is designed to handle over 3,000 gallons per day, as determined in Rule .1949(a) or (b) of this Section,.
I' except where the system is limited to an individual septic tank system serving an individual dwelling unit or
several individual septic tank systems, each serving an individual dwelling unit.
(2) The system requires pretreatment before disposal, other than by a conventional septic or other system approved
Iunder Rule .1957 or. 1969 of this Section.
' (3) The system requires use of sewage pumps prior to the septic tank or other pretreatment system, except for systems
subject to the North Carolina Plumbing code or which consist of grinder pumps and associated pump basins that
I are approved and listed in accordance with standards adopted by the National Sanitation Foundation.
' (4) The individual system is required by Rule. 1952 of this Section to use more than one pump or siphon in a single
pump tank.
(5) The system includes a collection sewer, prior to the septic tank or other pretreatment system, which serves two
I' or more buildings, except for systems subject to the North Carolina Plumbing Code.
(6) The system includes structures which have not been pre-engineered.
(7) The system is designed for the collection, treatment and disposal of industrial process wastewater, except under
the following circumstances:
' (A) the State -has determined that the wastewater generated by the proposed facility has a pollutant strength
which is lower than or equal to domestic sewage, and does not require specialized pretreatment or
management, or
(' (B) the State has pre -approved a predesigned pretreatment system or process and management method
proposed by the facility owner which shall enable the industrial process wastewater to have a pollutant
strength which is lower than or equal to domestic sewage.
(8) Any other system serving a business or multi -family dwelling so specified by the local health department.
' (e) The State shall review and approve the system layout on a site plan or plat, plans and specifications for all systems
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ENR - ENVIRONMENTAL HEALTH Tl SA: 18A .1900
serving a design unit with a design flow greater than 3,100 gallons per day, as determined in Rule .1949(a) or (b) of this
ISection, except:
' (1) where the system is limited to an individual septic tank system serving an individual dwelling unit or several
individual septic tank systems, each serving an individual dwelling unit, or
I(2) where the system consists of individual septic tank systems, each serving an individual facility, and which meets
' all of the following criteria;
(A) each individual system's design flow does not exceed 1500 gallons per day, as determined in Rule .1949(a)
or (b) of this Section,
(B) the site for the nitrification field and repair area for each individual system is at least 20 feet from any other
individual system site, and
(C) the design wastewater loading on the lot or tract of land containing the design unit is less than 1,500
Igallons per day per acre for new or expanded systems and 3,000 gallons per day/acre for malfunctioning
' systems.
(f) The state shall also review and approve plans and specifications for any industrial process wastewater system required
by this Section to be designed by a registered professional engineer and any other system so specified by the local health
(' department.
(g) For systems that require State review and approval:
(1) An improvement permit shall not be issued unless the site plan or plat and system layout, including details for any
Iproposed site modifications, are approved. A Construction Authorization shall not be issued unless plans and
' specifications, including methods of operation and maintenance, are approved.
(2) Prior to issuance of the operation permit for a system required to be designed by a registered professional
engineer, the owner shall submit to the local health department a statement signed by a registered professional
I, engineer stating that construction is complete and in accordance with approved plans and specifications and
approved modifications. Periodic observations of construction and a final inspection for design compliance by
the certifying registered professional engineer or his representative shall be required for this statement. The
Istatement shall be affixed with the registered professional engineer's seal.
' (h) Plans and specifications required to be prepared by a registered professional engineer shall contain the information
necessary for construction of the system in accordance with applicable rules and laws and shall include any of the following,
determined to be applicable by the local health department or the State:
(1) the seal, signature, and the date on all plans and the first sheet of specifications; specifications and reports
prepared by the design engineer and licensed or registered professionals who contributed to the plans,
specifications, or reports;
(2) a description of the facilities served and the calculations and basis for the design flow proposed;
(3) a site plan based on a surveyed plat showing all system components, public water supply sources within 500 feet,
private water supplies and surface water supplies within 200 feet, water lines serving the project and within 10
feet of all components, building foundations, basements, property lines, embankments or cuts of two feet or more
' in vertical height, swimming pools, storm sewers, interceptor drains, surface drainage ditches, and adjacent
nitrification fields;
(4) specifications describing all materials to be used, methods of construction, means for assuring the quality and
I' integrity of the finished product, and operation and maintenance procedures addressing requirements for the
system operator, inspection schedules, residuals management provisions, process and performance monitoring
schedules, and provisions for maintaining mechanical components and nitrification field vegetative cover;
(5) plan and profile drawings for collection sewers, force mains and supply lines, showing pipe diameter, depth of
' cover, cleanout and manhole locations, invert and ground surface elevations, valves and other appurtenances,
lateral connections, proximity to utilities and pertinent features such as wells, water lines, storm drains, surface
waters, structures, roads, and other trafficked areas;
I' (6) plans for all tanks, showing capacity, invert and ground elevations, access manholes, inlet and outlet details, and
plans for built -in -place or nonstate-approved, precast tanks, also showing dimensions, reinforcement details,
liquid depth, and other pertinent construction features;
(7) calculations for pump or siphon sizing, pump curves, and plan and profile drawings for lift stations and effluent
dosing tanks, showing anti -buoyancy provisions, pump or siphon locations, discharge piping, valves, vents, pump
controls, pump removal system, electrical connection details, and activation levels for pumps or siphons and
high-water alarms;
' (8) plan and profile drawings for wastewater treatment plants and other pretreatment systems, including cross-section
views of all relevant system components, and data and contact lists from comparable facilities for any
non-standard systems;
' (9) plans for nitrification field and repair area, based on an evaluation and report prepared by a person licensed or
registered to practice soil science, if required in G.S. 89F showing the following:
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ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
(A) field locations with existing and final relative contour lines based on field measurements at intervals not
` exceeding two feet or spot elevations if field areas are essentially flat or of uniform grade;
I(B) field layout, pipe sizes, length, spacing, connection and clean out details, invert elevations of flow
distribution devices and laterals, valves, and appurtenances;
(C) trench plan and profile drawings and flow distribution device details; and
I' (D) location and design of associated surface and groundwater drainage systems; and
(10) any other information required by the local health department or the State.
(i) The entire wastewater sewage system shall be on property owned or controlled by the person owning or controlling
the system. Necessary easements, right of ways, or encroachment agreements, as applicable, shall be obtained prior to the
issuance of a Construction Authorization for the system installation or repair. Terms of the easement, right-of-way o r
encroachment agreement shall provide that the easement, right-of-way, or encroachment agreement:
(1) is appurtenant to specifically described property and runs with the land and is not affected by change of ownership
I' or control;
(2) is valid for as long as the wastewater system is required for the facility that it is designed to serve;
(3) describes and specifies the uses being granted and shall include ingress and egress, system installation, operation,
(' maintenance, monitoring, and repairs:
(4) specifies by metes and bounds description or attached plat, the area or site required for the wastewater system and
appurtenances including a site for any required system replacement; and
I(5) shall be recorded with the register of deeds in the county where the system and facility is located.
' History Note: Authority G.S. 89C; 89E, 89F,• 90A; 130A-335(e), (1);
Eff. July 1, 1982;
(� Amended Eff. January], 1990; April 1, 1985;
Temporary Amendment Eff. January 20, 1997,
Amended Eff. August], 1998.
I' .1939 SITE EVALUATION
(a) The local health department shall investigate each proposed site. The investigation shall include the evaluation of the
following factors:
(1) topography and landscape position;
(2) soil characteristics (morphology);
(3) soil wetness;
(' (4) soil depth;
(5) restrictive horizons; and
(6) available space.
(b) Soil profiles shall be evaluated at the site by borings or other means of excavation to at least 48 inches or to a n
UNSUITABLE characteristic and a determination shall be made as to the suitability of the soil to treat and absorb septic tank
effluent. Applicants may be required to dig pits when necessary for proper evaluation of the soil at the site.
(c) Site evaluations shall be made in accordance with Rules .1940 through .1948 of this Section. Based on this
evaluation, each of the factors listed in Paragraph (a) of this Rule shall be classified as SUITABLE (S), PROVISIONALLY
SUITABLE (PS), or UNSUITABLE (U).
(d) The local health department shall determine the long-term acceptance rate to be used for sites classified SUITABLE
OR PROVISIONALLY SUITABLE in accordance with these rules.
' History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
I' Amended Eff. January 1, 1990.
.1940 TOPOGRAPHY AND LANDSCAPE POSITION
I (a) Uniform slopes under 15 percent shall be considered SUITABLE with respect to topography.
(b) Uniform slopes between 15 percent and 30 percent shall be considered PROVISIONALLY SUITABLE with respect
to topography.
(c) Slopes greater than 30 percent shall be considered UNSUITABLE as to topography. Slopes greater than 30 percent
(� may be reclassified as PROVISIONALLY SUITABLE after an investigation indicates that a modified system may be
installed in accordance with Rule .1956 of this Section; however, slopes greater than 65 percent shall not be reclassified as
PROVISIONALLY SUITABLE.
(d) Complex slope patterns and slopes dissected by gullies and ravines shall be considered UNSUITABLE with respect
to topography.
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ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
(e) Depressions shall be considered UNSUITABLE with respect to landscape position except when the site complies
Iessentially with the requirements of this Section and is specifically approved by the local health department.
' (f) The surface area on or around a ground absorption sewage treatment and disposal system shall be landscaped to
provide adequate drainage if directed by the local health department. The interception of perched or lateral ground -water
movement shall be provided where necessary to prevent soil saturation on or around the ground absorption sewage treatment
and disposal system.
(g) A designated wetland shall be considered UNSUITABLE with respect to landscape position, unless the proposed use
is specifically approved in writing by the U.S. Army Corps of Engineers or the North Carolina Division of Coasta I
I' Management.
HistoryNote: Authority G.S. 130A-335(e);
IEff. July 1, 1982; \
' Amended Eff. January 1, 1990.
.1941 SOIL CHARACTERISTICS (MORPHOLOGY)
(a) The soil characteristics which shall be evaluated by the local health department are as follows:
(1) Texture - The relative proportions of sand, silt, and clay sized mineral particles in the fine -earth fraction of the
soil are referred to as soil texture. The texture ofthe different horizons of soils shall be classified into four general
groups and 12 soil textural classes based upon the relative proportions of sand, silt, and clay sized mineral
' particles.
(A) SOIL GROUP I - SANDY TEXTURE SOILS. The sandy group includes the sand and loamy sand soil
textural classes and shall be considered SUITABLE with respect to texture.
I (B) SOIL GROUP II - COARSE LOAMY TEXTU RE SOILS. The coarse loamy group includes sandy loam
and loam soil textural classes and shall be considered SUITABLE with respect to texture.
(C) SOIL GROUP III - FINE LOAMY TEXTURE SOILS. The fine loamy group includes silt, silt loam ,
sandy clay loam, clay loam, and silty clay loam textural classes and shall be considered PROVISIONALLY
' SUITABLE with respect to texture.
(D) SO1L GROUP IV - CLAYEY TEXTURE SOILS. The clayey group includes sandy clay, silty clay, and
clay textural classes and shall be considered PROVISIONALLY SUITABLE with respect to texture.
(E) The soil textural class shall be determined in the field by hand texturing samples of each soil horizon in
the soil profile using the following criteria:
(i) Sand: Sand has a gritty feel, does not stain th a fingers, and does not form a ribbon or ball when wet
or moist.
' (ii) Loamy Sand: Loamy sand has a gritty feel, stains the fingers (silt and clay), forms a weak ball, and
cannot be handled without breaking.
(iii) Sandy Loam: Sandy loam has a gritty feel and forms a ball that can be picked up with the fingers
(' and handled with care without breaking.
(iv) Loam: Loam may have a slightly gritty feel but does not show a fingerprint and forms only short
ribbons of from 025 inch to 0.50 inch in len gth. Loam will form a ball that can be handled without
!, breaking.
(v) Silt Loam: Silt loam has a floury feel when moist and will show a fingerprint but will not ribbon
and forms only a weak ball.
(vi) Silt: Silt has a floury feel when moist and sticky when wet but will not ribbon and forms a ball that
will tolerate some handling.
(vii) Sandy Clay Loam: Sandy clay loam has a gritty feel but contains enough clay to form a firm ball
and may ribbon to form 0.75-inch to one -inch long pieces.
I, (viii) Silty Clay Loam: Silty clay loam is sticky when moist and will ribbon from one to two inches.
Rubbing silty clay loam with the thumbnail produces a moderate sheen. Silty clay loam produces
a distinct fingerprint.
(ix) Clay Loam: Clay loam is sticky when moist. Clay loam forms a thin ribbon of one to two inches
in length and produces a slight sheen when rubbed with the thumbnail. Clay loam produces a
nondistinct fingerprint.
(x) Sandy Clay: Sandy clay is plastic, gritty, and sticky when moist and forms a firm ball and produces
' a thin ribbon to over two inches in length.
(xi) Silty Clay: Silty clay is both plastic and sticky when moist and lacks any gritty feeling. Silty clay
forms a firm ball and readily ribbons to over two inches in length.
(xii) Clay: Clay is both sticky and plastic when moist, produces a thin ribbon over two inches in length,
' produces a high sheen when rubbed with the thumbnail, and forms a strong ball resistant to
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IFENR - ENVIRONMENTAL HEALTH T1 SA: 18A .1900
breaking.
(, (F) The Department may substitute laboratory determination of the soil textural class as defined in these Rules
Iby particle -size analysis of the fine -earth fraction (less than 2.0 mm in size) using the sand, silt, and clay
particle sizes as defined in these Rules for field testing when conducted in accordance with AST M
(American Society for Testing and Materials) D-422 procedures for sieve and hydrometer analyses which
I, are hereby adopted by reference in accordance with G.S. 15013-14(c). For fine loamy and clayey soil s
jj (Groups III and IV), the dispersion time shall be increased to 12 hours. Copies may be inspected in and
copies obtained from the Department of Environment, Health, and Natural Resources, Division o f
I' Environmental Health, P.O. Box 27687, Raleigh, North Carolina 27611-7687.
(2) Soil Structure - The following types of soil structure shall be evaluated:
(A) CRUMB AND GRANULAR SOIL STRUCTURE - Soils which have crumb or granular structure shall
be considered SUITABLE as to structure.
' (B) BLOCK -LIKE SOIL STRUCT URE - Block -Like Soil Structure with peds 2.5 cm (1 inch) or less in size
shall be considered PROVISIONALLY SUITABLE as to structure. Block -like soil structure with peds
greater than 2.5 cm (1 inch) in size within 36 inches of the naturally occurring soil surface shall be
{ considered UNSUITABLE as to structure.
PLATY SOIL STRUCTURE - soils which have platy soil structure within 36 inches of the natural) y
occurring soil surface shall be considered UNSUITABLE as to structure.
(D) PRISMATIC SOIL STRUCTURE - Soils which have prismatic soil structure within 36 inches ofth e
naturally occurring soil surface shall be considered UNSUITABLE as to structure.
(E) ABSENCE OF SOIL STRUCTURE - Soils which are single grained and exhibit no structural aggregates
shall be considered SUITABLE as to structure. Soils which are massive and exhibit no structural peds
within 36 inches of the naturally occurring soil surface shall be considered UNSUITABLE as to structure.
(F) Structure shall be evaluated using Soil Taxonomy, Appendix I, which is hereby adopted by reference in
accordance with G.S. 15013-14(c). Copies may be ins pected in, and copies obtained from, the Department
(, of Environment, Health, and Natural Resources, Division of Environmental Health, P.O. Box 27687,
Raleigh, NC 27611-7687.
(3) Clay Mineralogy - Along with soil texture, the mineralogy of the clay -sized fraction determines the degree to
which some soils swell when wetted and thereby affects the size and number of pores available for movement of
I' sewage effluent through the soil. There are two major types of clays, including the 1:1 clays, such as Kaolinite,
which do not shrink or swell extensively when dried or wetted; and the 2:1 clays, including mixed mineralogy
clays, such as clays containing both Kaolinite and Montmorillonite that will shrink and swell when dried and
wetted. The type of clay minerals in the clay -sized fraction shall be determined by a field evaluation of moist soil
consistence or of wet soil consistence using Soil Taxonomy, Appendix I, which is hereby adopted by reference
in accordance with G.S.150B-14(c). The Department may substitute laboratory determination of the expansive
clay mineralogy as defined in these Rules for field testing when conducted in accordance with ASTM D-4318,
procedures A and B, for the determination of liquid limit, plastic limit, and plasticity index of soils. Thes e
procedures are hereby adopted by reference in accordance with G.S. 15013-14(c). If the liquid limit exceeds 50
percent and the plasticity index exceeds 30, the soil shall be considered as having an expansive clay mineralogy.
I' Copies may be inspected in, and copies obtained from, the Department of Environment, Health, and Natura I
Resources, Division of Environmental Health, P.O. Box 27687, Raleigh, NC 27611-7687.
(A) SLIGHTLY EXPANSIVE CLA Y MINERALOGY - Soils which have loose, very friable, friable or firm
' moist soil consistence, or have slightly sticky to sticky or nonplastic, slightly plastic to plastic wet soil
consistence, are considered to have predominantly L I clay minerals and shall be considered SUITABLE
as to clay mineralogy.
(B) EXPANSIVE CLAY MINERALOGY - Soils which have either- very firm or extremely firm moist soil
consistence, or have either very sticky or very plastic wet soil consistence, are considered to have
I predominantly 2:1 clay minerals (including mixed mineralogy clays) and shall be considered
UNSUITABLE as to clay mineralogy.
(4) Organic Soils - Organic soils shall be considered UNSUITABLE.
(b) Where the site is UNSUITABLE with respect to structure or clay mineralogy, it may be reclassified
PROVISIONALLY SUITABLE after an investigation indicates that a modified or alternative system may be installed in
accordance with Rule .l 956 or Rule .1957 of this Section.
History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
' Amended Eff. January /, 1990.
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(' ENR - ENVIRONMENTAL HEALTH TI SA: 18A .1900
.1942 SOIL WETNESS CONDITIONS
I(a) Soil wetness conditions caused by a seasonal high-water table, perched water table, tidal water, seasonally saturated
' soils or by lateral water movement shall be determined by observation of colors of chroma 2 or less (Munsell color chart)
in mottles or a solid mass. If drainage modifications have been made, the Department may make a determination of the soil
wetness conditions by direct observation of the water surface during periods of typically high water elevations. However,
colors of chroma 2 or less which are relic from minerals of the parent material shall not be considered indicative of a soil
wetness condition. Sites where soil wetness conditions are greater than 48 inches below the naturally occurring soil surface
shall be considered SUITABLE with respect to soil wetness. Sites where soil wetness conditions are between 36 inches and
48 inches below the naturally occurring soil surface shall be considered PROVISIONALLY SUITABLE with respect to soil
wetness. Srtes•where-soil wetness conditions are less than 36 inches below the naturally occurring soil surface shall b e
considered UNSUITABLE with respect to soil wetness.
(b) Where the site is UNSUITABLE with respect to soil wetness conditions, it may be reclassified PROVISIONALLY
' SUITABLE after an investigation indicates that a modified or alternative system can be installed in accordance with Rule
.1956 or Rule. 1957 of this Section.
History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
Amended Eff. January 1, 1990.
I.1943 SOIL DEPTH
' (a) Soil depths to saprolite, rock, or parent material greater than 48 inches shall be considered SUITABLE as to soi I
depth. Soil depths to saprolite, rock, or parent material between 36 inches and 48 inches shall be considered
PROVISIONALLY SUITABLE as to soil d epth. Soil depths to saprolite, rock, or parent material less than 36 inches shall
be classified UNSUITABLE as to soil depth.
(b) Where the site is UNSUITABLE with respect to depth, it may be reclassified PROVISIONALLY SUITABLE after
a special investigation indicates that a modified or alternative system can be installed in accordance with Rule .1956 or Rule
1957 of this Section.
History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
Amended Eff. August 1, 1988.
I, .1944 RESTRICTIVE HORIZONS
(a) Soils in which restrictive horizons are three inches or more in thickness and at depths greater than 48 inches below
the naturally occurring soil surface shall be considered SUITABLE as to depth to restrictive horizons. Soils in whic h
restrictive horizons are three inches or more in thickness and at depths between 36 inches and 48 inches shall be considered
(' PROVISIONALLY SUITABLE as to depth to restrictive horizons. Soils in which restrictive horizons are three inches or
more in thickness and at depths less than 36 inches shall be considered UNSUITABLE as to depth to restrictive horizons.
(b) Where the site is UNSUITABLE with respect to restrictive horizons, it may be reclassified PROVISIONALL Y
(' SUITABLE after an investigation indicates that a modified or alternative system can be installed in accordance with Rules
.1956 or .1957 of this Section.
History Note: Authority G.S. 130A-335(e);
' Eff. July 1, 1982;
Amended Eff. January 1, 1990; October 1, 1983.
(, .1945 AVAILABLE SPACE
(a) Sites shall have sufficient available space to permit the installation and proper functioning of ground absorption
sewage treatment and disposal systems, based upon the square footage of nitrification field required for the long-term
!' acceptance rate determined in accordance with these Rules.
I(b) Sites shall have sufficient available space for a repair area separate from the area determined in Paragraph (a) of this
Rule. The repair area shall be based upon the area of the nitrification field required to accommodate the installation of a
replacement system as specified in Rule .1955, .1956, or .1957 of this Section. Prior to issuance of the initial Improvement
Permit for a site, the local health department shall designate on the permit the original system layout, the repair area, and
the type of replacement system.
(c) The repair area requirement of Paragraph (b) of this Rule shall not apply to a lot or tract of land:
(' (1) which is specifically described in a document on file with the local health department on July 1, 1982, or which
is specifically described in a recorded deed or a recorded plat on January 1, 1983; and
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' (2) which is of insufficient size to satisfy the repair area requirement of Paragraph b of this Rule as determined b
9() Y
the local health department; and
' (3) on which a ground absorption sewage treatment and disposal system with a'design daily flow of:
(A) no more than 480 gallons is to be installed, or
(B) more than 480 gallons is to be installed if application for an improvement permit which meets the
requirements of Rule. I 937(c) of this Subchapter is received by the local health department on or before
April 1, 1983.
(d) Although a lot or tract of land is exempted under Paragraph (c) from the repair area requirement of Paragraph (b),
the maximum feasible area, as determined by the local health department, shall be allocated for a repair area.
History Note: Authority G.S. 130A-335(e) and (/);
Eff. July 1, 1982;
Amended Eff. February 1, 1992; July 1, 1983; January], 1983.
.1946 OTHER APPLICABLE FACTORS
The site evaluation shall include consideration of any other applicable factors involving accepted public health principles,
such as, but need not be limited to:
(1) The proximity of a large -capacity water -supply well, the cone of influence of which would dictate a larger
separation distance than the minimum distance specified in Rule. 1950 of this Section;
' (2) The potential public health hazard due to possible failures of soil absorption systems when specifically identified,
would dictate larger separation distances than the minimums specified in Rule .1950 and Rule .1955(m) of this
Section;
(3) The potential public health hazard of possible massive failures of soil absorption systems proposed to serve large
numbers of residences, as in residential subdivisions or mobile home parks;
(4) For sites serving systems designed to handle over 3,000 gallons per day, as determined in Rule .1949 (a) or (b)
of this Section, which include one or more nitrification fields with a design flow of greater than 1500 gallons per
' day, the applicant shall submit sufficient site -specific data to predict the height of the water table mound that will
develop beneath the field (level sites) and the rate of lateral and vertical flow away from the nitrification trenches
(sloping sites). The data submitted may include soil borings to depths greater than 48 inches, permeability and
t' hydraulic conductivity measurements, water level readings, and other information determined to be necessary by
tt the local health department or the State. The site shall be considered UNSUITABLE if the data indicate that the
groundwater mound which will develop beneath the site cannot be maintained two feet or more below the bottom
of the nitrification trenches or it is determined that effluent is likely to become exposed on the ground surface
' within, or adjacent to, the nitrification field.
History Note: Authority G.S. 130A-335(e);
(, Eff July 1, 1982;
Amended Eff. January 1, 1990.
.1947 DETERMINATION OF OVERALL SITE SUITABILITY
All of the criteria in Rules .1940 through .1946 of this S ection shall be determined to be SUITABLE, PROVISIONALLY
SUITABLE, or UNSUITABLE, as indicated. If all criteria are classified the same, that classification will prevail. Where
there is a variation in classification of the several criteria, the most limiting uncorrectable characteristics shall be used to
I' determine the overall site classification.
`` History Note: Authority G.S. 130A-335(e);
I' Eff. July 1, 1982;
I Amended Eff. January 1, 1990.
.1948 SITE CLASSIFICATION
(a) Sites classified as SUITABLE may be utilized for a ground absorption sewage treatment and disposal syste m
consistent with these Rules. A suitable classification generally indicates soil and site conditions favorable for the operation
of a ground absorption sewage treatment and disposal system or have slight limitations that are readily overcome by proper
design and installation.
(b) Sites classified as PROVISIONALLY SUITABLE may be utilized for a ground absorption sewage treatment and
disposal system consistent with these Rules but have moderate limitations. Sites classified Provisionally Suitable require
(, some modifications and careful planning, design, and installation in order for a ground absorption sewage treatment an d
disposal system to function satisfactorily.
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I' ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
(c) Sites classified UNSUITABLE have severe limitations for the installation and use of a properly functioning ground
(' absorption sewage treatment and disposal system. An improvement permit shall not be issued for a site which is classified
as UNSUITABLE. However, where a site is UNSUITABLE, it may be reclassified PROVISIONALLY SUITABLE if a
special investigation indicates that a modified or alternative system can be installed in accordance with Rules .1956 or .1957
of this Section.
(d) A site classified as UNSUITABLE may be used for a ground absorption sewage treatment and disposal syste m
specifically identified in Rules .1955, .1956, or .1957 of this Section or a system approved under Rule .1969 if writte n.
documentation, including engineering, hydrogeologic, geologic or soil studies, indicates to the local health department that
(' the proposed system can be expected to function satisfactorily. Such sites shall be reclassified as PROVISIONALL Y
SUITABLE if the local health department determines that the substantiating data indicate that:
(1) a ground absorption system can be installed so that the effluent will be non-pathogenic, non-infectious, non -toxic,
and non -hazardous;
(2) the effluent will not contaminate groundwater or surface water; and
(3) the effluent will not be exposed on the ground surface or be discharged to surface waters where it could come in
contact with people, animals, or vectors.
I' The State shall review the substantiating data if requested by the local health department.
History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
Amended Eff. April], 1993; January], 1990.
.1949 SEWAGE FLOW RATES FOR DESIGN UNITS t.
(a) In determining the volume of sewage from dwelling units, the flow rate shall be 120 gallons per day per bedroom.
The minimum volume of sewage from each dwelling unit shall be 240 gallons per day and each additional bedroom above
two bedrooms shall increase the volume of sewage by 120 gallons per day. In determining the number of bedrooms in a
I' dwelling unit, each bedroom and any other room or addition that can reasonably be expected to function as a bedroom shall
be considered a bedroom for design purposes. When the occupancy of a dwelling unit exceeds two persons per bedroom,
the volume of sewage shall be determined by the maximum occupancy at a rate of 60 gallons per person per day.
(b) Table No. I shall be used to determine the minimum design daily flow of sewage required in calculating the design
I, volume of sanitary sewage systems to serve selected types of establishments. The minimum design volume of sewage from
any establishment shall be 100 gallons per day. Design of sewage treatment and disposal systems for establishments not
identified in this Rule shall be determined using available flow data, water -using fixtures, occupancy or operation patterns,
and other measured data.
TABLE NO. I
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TYPE OF ESTABLISHMENT
DAILY FLOW FOR DESIGN
('
Airports
5 gal/passenger
(Also R.R. stations, bus terminals --not
including food service facilities)
Barber Shops
50 gal/chair
Bars, Cocktail Lounges (Not including
food service)
20 gal/seat
Beauty Shops (Style Shops)
125 gal/chair
i'
Bowling Lanes
50 gal/lane
!!
Businesses (other than those listed
elsewhere in this table)
25 gal/employee
Camps
Construction or Work Camps
60 gal/person
40 gal/person
(with chemical
toilets)
Summer Camps
60 gal/person
Campgrounds — With Comfort Station
100 gal/campsite
(Without water and sewer hookups)
Travel Trailer/Recreational Vehicle Park
120 gal/space
(With water and sewer hookups)
'
I
Churches (Not including a Kitchen, Food Service
Facility, Day Care or Camp)
3 gal/seat
Churches (With a Kitchen but, not including a Food
5 gal/seat
Service Facility, Day Care, or Camp)
Country Clubs
20 gal/member
Day Care Facilities
15 gal/person
Factories (Exclusive of industrial waste)
25 gal/person/shift
Add for showers
10 gal/person/shift
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TI SA: 18A .1900
Food Service Facilities
40 gal/seat or
Restaurants
40 gal/l5 ft= of
dining area, whichever
is greater
24-hour Restaurant
75 gal/seat
I'
Food Stands
(1) Per 100 square feet of food stand floor space
50 gal
(2) Add per food employee
25 gal
I,
Other Food Service Facilities
5 gal/meal
Hospitals
300 gal/bed
Marinas
10 gal/boat slip
With bathhouse
30 gal/boat slip
Meat Markets
(1) Per 100 square feet of market floor space
50 gal
(2) Add per market employee
25 gal
Motels/Hotels
120 gal/room
With cooking facilities
175 gal/room
Offices (per shift)
25 gal/person
Residential Care Facilities
60 gal/person
Rest Homes and Nursing Homes
With laundry
120 gal/bed
Without laundry
60 gal/bed
Schools
Day Schools
15 gal/student
With cafeteria, gym, and showers
12 gal/student
With cafeteria only
10 gal/student
With neither cafeteria nor showers
60 gal/person
Boarding Schools
250 gal/water
Service Stations
closet or urinal
24-hour Service Stations
325 gal/water closet
Stores, Shopping Centers, and Malls
120 gal/l000 ft'
(Exclusive of food service and
of retail sales area
meat markets)
Stadium, Auditorium, Theater, Drive-in
5 gal/seat or space
Swimming Pools, Spas, and Bathhouses
10 gal/person
fl
(c) An adjusted design daily sewage flow may be granted by the local health
department upon a showing as specified in
Subparagraphs (c)(1) through (c)(2) that a sewage system is adequate to meet actual daily water consumption from a facility
included in Paragraph (b) of this Rule.
(1) Documented data from that facility or a comparable facility justifying a flow rate reduction shall be submitted to
the local health department and the State. The submitted data shall consist of at least 12 previous consecutive
monthly total water consumption readings and at least 30 consecutive daily water consumption readings. The
daily readings shall be taken during a projected normal or above normal sewage flow month. A peaking factor
shall be derived by dividing the highest monthly flow as indicated from the 12 monthly readings by the sum of
't the 30 consecutive daily water consumption readings. The adjusted design daily sewage flow shall be determined
by taking the numerical average of the greatest ten percent of the daily readings and multiplying by the peaking
factor. Further adjustments shall be made in design sewage flow rate used for sizing nitrification fields and
pretreatment systems when the sampled or projected wastewater characteristics exceed those of domestic sewage,
such as wastewater from restaurants or meat markets.
(2) An adjusted daily sewage flow rate may be granted contingent upon use of extreme water -conserving fixtures,
such as toilets which use 1.6 gallons per flush or less, spring -loaded faucets with flow rates of one gallon pe r
minute or less, and shower -heads with flow rates of two gallons per minute or less. The amount of sewage flow
rate reduction shall be determined by the local health department and the State based upon the type of fixtures and
documentation of the amount of flow reduction to be expected from the proposed facility. Adjusted daily flow
' rates based upon use of water -conserving fixtures shall apply only to design capacity requirements of dosing and
distribution systems and nitrification fields. Minimum pretreatment capacities shall be determined by the design
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I' ENR - ENVIRONMENTAL HEALTH T1 SA: 18A .1900
flow rate of Table I of this Rule.
History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
Amended Eff. January 1, 1990; January 1, 1984.
.1950 LOCATION OF SANITARY SEWAGE SYSTEMS
(a) Every sanitary sewage treatment and disposal system shall be located at least the minimum horizontal distance from
I' the following:
(1) Any private water supply source, including any well or spring 100 feet;
(2) Any public water supply source 100 feet;
' (3) Streams classified as WS-I 100 feet;
(4) Waters classified as S.A. 100 feet, from mean high water mark;
(5) Other coastal waters 50 feet, from mean high water mark;
(6) Any other stream, canal, marsh, or other surface waters 50 feet;
(7) Any Class I or Class II reservoir 100 feet, from normal pool elevation;
(8) Any permanent storm water retention pond 50 feet, from flood pool elevation;
(9) Any other lake or pond 50 feet, from normal pool elevation;
' (10) Any building foundation 5 feet;
(11) Any basement 15 feet;
(12) Any property line 10 feet;
(13) Top of slope of embankments or cuts of 2 feet or more vertical height 15 feet;
I' (14) Any water line 10 feet;
(15) Drainage Systems:
(A) Interceptor drains, foundation drains, and storm water diversions
I' (i) upslope 10 feet,
(ii) sideslope 15 feet, and
(iii) downslope 25 feet;
(B) Groundwater lowering ditches and devices 25 feet;
(16) Any swimming pool 15 feet;
(17) Any other nitrification field (except repair area) 20 feet;
(b) Ground absorption sewage treatment and disposal systems may be located closer than 100 feet from a private water
supply, except springs and uncased wells located downslope and used as a source of drinking water, for repairs, spac e
limitations, and other site -planning considerations but shall be located the maximum feasible distance and in no case less
than 50 feet.
(c) Nitrification fields and repair areas shall not be located under paved areas or areas subject to vehicular traffic. I f
(' effluent is to be conveyed under areas subject to vehicular traffic, ductile iron or its equivalent pipe shall be used. However,
pipe specified in Rule.] 955 (e) maybe used if a minimum of 30 inches of compacted cover is provided over the pipe.
(d) In addition to the requirements of Paragraph (a) of this Rule, sites to be used for subsurface disposal for design units
with flows over 3,000 gallons per day, as determined in Rule .1949 (a) or (b) of this Section, which include one or more
nitrification fields with individual capacities of greater than 1,500 gallons per day, shall be located at least the minimu m
horizontal distance from the following:
(1) Any Class I or II reservoir or any public water supply source utilizing a shallow (under 50 feet) groundwater
I' aquifer 500 feet;
(2) Any other public water supply source, unless determined to utilize a confined aquifer 200 feet;
(3) Any private water supply source, unless determined to utilize a confined aquifer 100 feet;
(4) Waters classified as SA 200 feet, from mean high water mark;
(5) Any waters classified as WS-I 200 feet;
(6) Any surface waters classified as WS-II, WS-III, B, or SB 100 feet; and
' (7) Any property line 25 feet.
I (e) Collection sewers, force mains, and supply lines shall be located at least the minimum horizontal distance from the
following:
I,
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(1) Any public water supply source, including wells, springs,
and Class I or Class 11 reservoirs
(2) Any private water supply source, including wells and springs
leakproof pipe,
(3) Any waters classified as WS-1, WS-II,
WS-III, B, SA, or SB
(4) Any other stream, canal, marsh, coastal
waters, lakes and other impoundments, or other surface waters
(5) Any basement
(6) Any property line
(7) Top of slope of embankments or cuts of
two feet or more vertical height
(8) Drainage Systems:
(A) Interceptor drains, storm drains, and storm water
diversions
(B) Ground -water lowering ditches and devices
(9) Any swimming pool
(10) Any other nitrification field
100 feet, unless constructed
of leakproof pipe, such as
ductile iron pipe with mechanical
joints equivalent to water main
standards, in which case the
minimum setback may be reduced
to 50 feet;
50 feet, unless constructed of
similar such as ductile iron pipe with
mechanical joints equivalent to water
main standards, in which
case the minimum setback may be
reduced to 25 feet;
50 feet, unless constructed of
similar leakproof pipe, such as
ductile iron pipe with mechanical
joints equivalent to water main
standards, in which case the
minimum setback may be reduced
to 10 feet;
10 feet;
10 feet;
5 feet;
10 feet;
5 feet;
10 feet;
10 feet;
5 feet;
(f) Sewer lines may cross a water line if 18 inches clear separation distance is maintained, with the sewer line passing
under the water line. When conditions prevent an 18-inch clear separation from being maintained or whenever it is necessary
for the water line to cross under the sewer, the sewer line shall be constructed of ductile iron pipe or its equivalent and the
water line shall be constructed of ferrous materials equivalent to water main standards for a distance of at least ten feet on
each side of the point of crossing, with full sections of pipe centered at the point of crossing.
(g) Sewer lines may cross a storm drain if:
(1) 12 inches clear separation distance is maintained; or
(2) the sewer is of ductile iron pipe or encased in concrete or ductile iron pipe for at least five feet on either side of
the crossing.
(h) Sewer lines may cross a stream if at least three feet of stable cover can be maintained or the sewer line is of ductile
iron pipe or encased in concrete or ductile iron pipe for at least ten feet on either side of the crossing and protected against
the normal range of high and low water conditions, including the 100-year flood/wave action. Aerial crossings shall be by
ductile iron pipe with mechanical joints or steel pipe. Pipe shall be anchored for at least ten feet on either side of the
crossing.
(i) Septic tanks, lift stations, wastewater treatment plants, sand filters, and other pretreatment systems shall not be located
in areas subject to frequent flooding (areas inundated at a ten-year or less frequency) unless designed and installed to b e
watertight and to remain operable during a ten-year storm. Mechanical or electrical components of treatment systems shall
be above the 100-year flood level or otherwise protected against a 100-year flood.
History Note: Authority G.S. 130A-335(e) and 69;
Eff. July 1, 1982;
Amended Eff. January 1, 1990; October 1, 1982.
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.1951 APPLICABILITY OF RULES
(a) Except as required in Paragraph (b) of this Rule, the minimum horizontal distance requirements in Rule. I 950(a)(4),
(11), (12), or (13) shall not apply to the installation of a single septic tank system serving a single-family residence not to
exceed four bedrooms on a lot or tract of land:
(1) which, on July 1, 1977, is specifically described in a deed, contract, or other instrument conveying fee title o r
which is specifically described in a recorded plat;.and
(2) which, on July 1, 1977, is of insufficient size to satisfy the minimum horizontal distance requirements in Rule
.1950(a)(4), (11), (12), or (13) of this Section; and
(3) which, on the date system construction is proposed to begin, is not capable of being served by a community or
public sewerage system.
(b) For those lots or tracts of land described in Rule .1951(a) of this Section, where any of the minimum horizonta 1
distance requirements prescribed in Rule .1950(a)(4), (11), (12), or (13) of this Section can be met, such minimu m
horizontal distances.shall be required.
(c) For those lots or tracts of land described in Rule .1951(a) of this Section, where a specific minimum horizontal
distance requirement prescribed in Rule. I 950(a)(4), (11), (12), or (13) of this Section cannot be met, the maximum feasible
horizontal distance, as determined by the local agency, shall be required. Provided, however, that at least the followin g
minimum horizontal distances shall be required in all cases:
(1) Rule .1950(a)(4) of this Section, the minimum horizontal distance shall be not less than 50 feet;
(2) Rule .1950(a)(11) of this Section, the minimum horizontal distance shall be not less than 8 feet;
(3) Rule .1950(a)(12) and (13) of this Section, the minimum horizontal distance shall be not less than 5 feet.
(d) All other provisions of this Section except as exempted by this Rule shall apply to the lots or tracts of land described
in Rule .1951(a) of this Section. Any rules and regulations of the Commission for Health Services or any local board o f
health in effect on June 30, 1977, which establish greater minimum distance requirements than those provided for in this
Section, shall remain in effect and shall apply to a lot or tract of land to which Rule .1950(a)(4), (11), (12), or (13) of this
Section do not apply.
(e) It shall be the responsibil ity of any owner of a lot or tract of land, who applies for a permit required by Rule .1937 of
this Section, and who seeks, under the provisions of Rule .1951(a) of this Section, to exempt his lot or tract of land from any
of the minimum horizontal distance requirements of Rule .1950(a)(4), (11), (12), or (13) of this Section to provide to the
local health department necessary records of title to the lot or tract of land for which the exemption is sought in order that
the local agency may determine whether the applicant is entitled to any such exemption.
(f) For those lots or tracts of land which, on the effective date of this Section, are specifically described in a deed o r
recorded plat, and the minimum horizontal distance requirements prescribed in Rule . I 950(a)(1 5)(B) cannot be met, the
maximum feasible horizontal distance, as determined by the local health department, shall be required, but shall not be less
than ten feet.
I' History Note: Authority G.S. 130A-335(e);
E, ff. July 1, 1982;
Amended Eff. January], 1990.
.1952 EFFLUENT FILTER, DOSING TANK AND LIFT STATION DESIGN
(a) A septic tank or dosing tank shall be watertight, structurally sound, and not subject to excessive corrosion or decay.
Septic tanks shall be of two -compartment design. The inlet compartment of a two -compartment tank shall hold between
two-thirds and three -fourths of the total tank capacity. Septic tanks shall have an approved effluent filter and access devices.
The effluent filter shall function without a bypass of unfiltered wastewater, sludge or scum. The effluent filter case shall be
designed to function as a sanitary tee with the inlet extending down to between 25 and 40 percent of the liquid depth. The
requirement(s) for an effluent filter and access devices shall apply to septic tanks for which a Construction Authorization
is issued on or after January 1, 1999. A properly designed dosing siphon or pump shall be used for discharging sewag e
effluent into nitrification lines when the total length of such lines exceeds 750 linear feet in a single system and as required
I' for any pressure -dosed system. When the design daily flow from a single system exceeds 3,000 gallons per day or when the
total length of nitrification lines exceeds 2,000 linear feet in a single system, alternating siphons or pumps shall be used
which shall discharge to separate nitrification fields. The dose volume from pump or siphon systems shall be of such design
so as to fill the nitrification lines from 66 percent to 75 percent of their capacity at each discharge except as required for
low-pressure distribution systems. The discharge rate from dosing systems shall be designed to maximize the distribution
of the effluent throughout the nitrification field. Septic tanks installed where the top will be deeper than six inches below
the finished grade shall have an access manhole over each compartment with cover, extending to within six inches of the
j' finished grade, having a minimum opening adequate to accommodate the installation or removal of the septic tank lid,
`` septage removal, and maintenance of the effluent filter. When the top of the septic tank or access manhole is below th e
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IENR - ENVIRONMENTAL HEALTH T15A :18A.1900
finished grade, the location of each manhole shall be visibly marked at finished grade. Any system serving a design unit
Iwith a design sewage flow greater than 3,000 gallons per day shall have access manholes that extend at least to finished grade
' and be designed and maintained to prevent surface water inflow. The manholes shall be sized to allow proper inspection
and maintenance. All dosing tanks shall have a properly functioning high-water alarm. The alarm shall be audible and
Ivisible by system users and weatherproof if installed outdoors. The alarm circuit shall be provided with a manual disconnect
' in a watertight, corrosion -resistant outside enclosure (NEMA 4X or equivalent) adjacent to the dosing tank.
(b) Minimum liquid capacities for septic tanks shall be in accordance with the following:
I (1) Residential Septic Tanks (for each individual residence or dwelling unit):
Number of Minimum Liquid Equivalent Capacity
Bedrooms Capacity Per Bedroom
3 or less 900 gallons 300 gallons
I' 4 1,000 gallons 250 gallons
5 1,250 gallons 250 gallons
I' (2) Septic tanks for large residences, multiple dwelling units, or places of business or public assembly shall be i n
accordance with the following:
(A) The minimum liquid capacity of septic tanks for places of business or places of public assembly with a
design sewage flow of 600 gallons per day or less shall be determined in accordance with the following:
V = 2Q; where V is the liquid capacity of the septic tank and Q is the design daily sewage flow.
(B) Individual residences with more than five bedrooms, multiple -family residences, individual septic tank
systems serving two or more residences, or any place of business or public assembly where the design
sewage flow is greater than 600 gallons per day, but less than 1,500 gallons per day, the liquid capacity
of the septic tank shall be designed in accordance with the following: V = 1.17Q + 500; where V is the
liquid capacity of the septic tank and Q is the design daily sewage flow. The minimum liquid capacity of
a septic tank serving two or more residences shall be 1,500 gallons.
' (C) Where the design sewage flow is between 1,500 gallons per day and 4,500 gallons per day, the liqui d
capacity of the septic tank shall be designed in accordance with the following: V = 0.75Q + 1,125; where
V is the liquid capacity of the septic tank and Q is the design daily sewage flow.
' (D) Where the design sewage flow exceeds 4,500 gallons per day, the septic tank shall be designed in
accordance with the following: V = Q; where V is the liquid capacity of the septic tank and Q is the design
daily sewage flow.
(E) The minimum liquid capacity requirements of Subparagraph (b)(2) of this Rule shall be met by use of a
' single two -compartment septic tank or by two tanks installed in series, provided the first tank is
constructed without a baffle wall and contains at least two-thirds of the total required liquid capacity.
(3) The minimum capacity of any septic tank shall be 750 gallons.
' (c) The following are minimum standards of design and construction of pump tanks and pump dosing systems:
(1) The liquid capacity of a pump tank shall be considered as the entire internal volume with no additional
requirement for freeboard. Pump tanks shall have a minimum liquid capacity in accordance with the following:
' (A) Pump tanks for systems with nitrification fields installed in Soil Group I, II, or III soils, as defined in these
Rules, shall have a minimum liquid capacity equal to two-thirds of the required septic tank liquid capacity.
(B) Pump tanks for systems installed in Group IV soils shall have a minimum liquid capacity equal to th e
required septic tank liquid capacity.
(C) The minimum liquid capacity of any pump tank shall be 750 gallons.
(D) An alternate method to determine minimum liquid capacity of a pump tank shall be to provide for th e
minimum pump submergence requirement (Subparagraph (c)(5) of this Rule), the minimum dose volume
requirement (Paragraph (a) of this Rule), and the minimum emergency storage capacity requirement. The
' emergency storage capacity requirement is determined based on the type of facility served, the
classification of surface waters which would be impacted by a pump tank failure, and the availability of
standby power devices and emergency maintenance personnel. The emergency storage capacity shall be
' the freeboard space in the pump tank above the high-water alarm activation level plus the available
freeboard space in previous tankage and in the collection system below the lowest ground elevation
between the pump tank and the lowest connected building drain invert. The minimum emergency storage
' capacity for residential systems and other systems in full-time use on sites draining into WS-I, WS-fI ,
WS-III, SA, SB, and B water s shall be 24 hours, without standby power, or 12 hours with standby power
manually activated, or four hours with standby power automatically activated or with a high-water alarm
automatically contacting a 24-hour maintenance service. The minimum emergency storage capacity for
systems not in full-time use and for all systems at sites draining into all other surface waters shall be 12
INORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 19

' ENR - ENVIRONMENTAL HEALTH TISA: 18A .1900
hours without standby power, or eight hours with standby power manually activated, or four hours with
standby power automatically activated or with a high-water alarm automatically contacting a 24-hour
' maintenance service.
(E) Notwithstanding Paragraphs (c)(1) (A)-(D), other criteria for pump tank capacity may be approved by the
local health department and the State for raw sewage lift stations, pressure sewer systems, and systems with
' design flows exceeding 3,000 gallons per day.
(2) The effluent pump shall be capable of handling at least one-half inch solids and designed to meet the discharge
rate and total dynamic head requirements of the effluent distribution system. The pump shall be listed by
Underwriter's Laboratory or an equivalent third party electrical testing and listing agency, unless the proposed
pump model is specified by a registered professional engineer.
(3) Pump discharge piping shall be of Schedule 40 PVC or stronger material and adequately secured. Fittings and
valves shall be of compatible corrosion -resistant material. A threaded union, flange, or similar disconnect device
shall be provided in each pump discharge line. All submersible pumps shall be provided with a
corrosion -resistant rope or chain attached to each pump enabling pump removal from the ground surface without
requiring dewatering or entrance into the tank. Valves shall also be readily accessible from the ground surface.
' (4) Antisiphon holes (three -sixteenth inch) shall be provided when the discharge or invert elevation of the distribution
system is below the high-water alarm elevation in the pump tank, or in accordance with pump manufacturer's
specifications. Check valves shall be provided when the volume of the supply line is greater than 25 percent of
the dosing volume, or in accordance with pump manufacturer's specifications. When provided, the antisiphon
hole shall be located between the pump and the check valve.
(5) Sealed mercury control floats or similar devices designed for detecting liquid levels in septic tank effluent shall
be provided to control pump cycles. A separate level sensing device shall be provided to activate the high-water
' alarm. Pump -off level shall be set to keep the pump submerged at all times or in accordance with the
manufacturers specifications. A minimum of 12 inches of effluent shall be maintained in the bottom of the pump
tank. The high-water alarm float shall be set to activate within six inches of the pump -on level. The lag pump
' float switch, where provided, shall be located at or above the high-water alarm activation level.
(6) Pump and control circuits shall be provided with manual circuit disconnects within a watertight,
corrosion -resistant, outside enclosure (NEMA 4X or equivalent) adjacent to the pump tank, securely mounted
at least 12 inches above the finished grade. The pump(s) shall be manually operable without requiring the use
' of special tools or entrance into the tank for testing purposes. Conductors shall be conveyed to the disconnect
enclosure through waterproof, gasproof, and corrosion -resistant conduits, with no splices or junction boxes
provided inside the tank. Wire grips, duct seal, or other suitable material shall be used to seal around wire and
wire conduit openings inside the pump tank and disconnect enclosure.
(7) For systems requiring duplex and multiplex pumps, a control panel shall be provided which shall include
short-circuit protection for each pump and for the control system, independent disconnects, automatic pum p
sequencer, hand -off -automatic (H-O-A) switches, run lights, and elapsed time counters for each pump. Alarm
' circuits shall be supplied ahead of any pump overload or short circuit protective devices. The control panel must
be in a watertight, corrosion -resistant enclosure (NEMA 4X or equivalent) unless installed within a weathertight
building. The panel shall be protected from intense solar heating.
' (8) Dual and multiple fields shall be independently dosed by separate pumps which shall automatically alternate. The
supply lines shall be "H" connected to permit manual alternation between fields dosed by each pump. "H "
connection valving shall be readily accessible from the ground surface, either from the pump tank access manhole
or in a separate valve chamber outside the pump tank. Other equivalent methods of dosing dual or multiple fields
' may be approved by the State.
(9) The pump tank shall have a properly functioning high-water alarm. The alarm circuit shall be supplied ahead of
any pump overload and short circuit protective devices. The alarm shall be audible and visible by system users
and weatherproof if installed outdoors in an enclosure (NEMA 4X or equivalent).
' (d) Siphons and siphon dosing tanks may be used when at least two feet of elevation drop can be maintained between the
siphon outlet invert and the inlet invert in the nitrification field distribution system.
' (1) Siphon dosing tanks shall be designed in accordance with the minimum dose requirements in this Rule and shall
meet the construction requirements of this Section. The siphon dose tank shall provide at least 12 inches o f
freeboard, and the inlet pipe shall be at least three inches above the siphon trip level. The high-water alarm shall
be set to activate within two inches of the siphon trip level.
(2) Siphon dosing tanks shall have a watertight access opening over each siphon with a minimum diameter of 24
inches and extending to finished grade and designed to prevent surface water inflow.
(3) The slope and size of the siphon discharge line shall be sufficient to handle the peak siphon discharge by gravity
' flow without the discharge line flowing full. Vents for the discharge lines shall be located outside of the dosing
tank or otherwise designed to not serve as an overflow for the tank.
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ENR - ENVIRONMENTAL HEAL TH T15A: 18A .1900
' 4 All siphon arts shall be installed in accordance with the ma materials must be
() P p manufacturer's specifications. All mate Ism s
Icorrosion -resistant, of cast iron, high density plastic, fiberglass, stainless steel, or equal.
' (5) Siphon dosing tanks shall have a properly functioning high-water alarm that is audible and visible by system users
and weatherproof if installed outdoors in an enclosure (NEMA 4X or equivalent).
(e) Raw sewage lift stations shall meet the construction standards of this Section and all horizontal setback requirements
' for sewage treatment and disposal systems in accordance with Rule .I950(a) of this Section unless the station is a sealed,
watertight chamber, in which case the setback requirements for collection sewers in Rule.1 950(e) of this Section shall apply.
Sealed, watertight chambers shall be of a single, prefabricated unit, such as fiberglass, with sealed top cover, and preformed
I' inlet and outlet pipe openings connected with solvent welds, 0-ring seals, rubber boots, stainless steel straps, or equivalent.
Dual pumps shall be provided for stations serving two or more buildings or for a facility with more than six water closets.
Pumps shall be listed by Underwriter's Laboratories or an equivalent third party electrical testing and listing agency, and shall
be grinder pumps or solids -handling pumps capable of handling at least three-inch spheres unless the station serves no more
t than a single water closet, lavatory, and shower, in which case two-inch solids handling pumps shall be acceptable.
Minimum pump capacity shall be 2.5 times the average daily flow rate. The dosing volume shall be set so that the pump -off
time does not exceed 30 minutes, except for stations serving single buildings, and pump run-time shall be from three to ten
I, minutes at average flow. Pump station emergency storage capacity and total liquid capacity shall be determined in
accordance with Paragraph (c)(1)(D) of this Rule except for a sealed, watertight chamber serving an individual building,
in which case a minimum storage capacity of eight hours shall be required. All other applicable requirements for pump tanks
Iand pump dosing systems in accordance with Paragraph (c) of this Rule shall also apply to raw sewage lift stations.
History Note: Authority G.S. 130.9-335 (e)69(f1)[2nd],-
Eff. July 1, 1982;
' Amended Eff. August 1, 1991; January 1, 1990;
Temporary Amendment Eff. January 1, 1999.
.1953 PREFABRICATED SEPTIC TANKS AND PUMP TANKS
' When prefabricated concrete tanks or tanks of other material are used, they shall be constructed in accordance with the
plans which have been approved by the State and shall comply with all requirements of this Section. At least three complete
Isets of plans and specifications for the initial design of the prefabricated septic tank or subsequent changes and modifications
' shall be submitted to the Department of Environment and Natural Resources, On -Site Wastewater Section, P.O. Box 29594,
Raleigh, North Carolina 27626-0594. Separate plans and specifications for the design of each septic tank or pump tank to
be produced shall be submitted to the On -Site Wastewater Section for approval. These plans and specifications shall show
Ithe design of the septic tank in detail, including:
' (1) All pertinent dimensions;
(2) Reinforcement material and location;
I(3) Material strength;
' (4) Liquid depth;
(5) Pipe penetration, joint material and method of sealing;
(6) Access manhole riser, lid, and other proposed appurtenances to the septic tank;
I (7) Approved effluent filter(s), filter support detail and filter access detail; and
(8) Other design features.
IHistory Note: Authority G.S. 130A-335 (e)(1)f1)[2nd];
' Eff July 1, 1982;
Amended Eff. January 1, 1990,
Temporary Amendment Eff. January 1, 1999.
(, .1954 MINIMUM STANDARDS FOR PRECAST REINFORCED CONCRETE TANKS
(a) The following are minimum standards of design and construction of precast reinforced concrete septic tanks:
I' (1) The minimum requirement for the liquid depth is 36 inches.
(2) A minimum of nine inches freeboard is required, the freeboard being the air space between the top of the liquid
and the bottom side of the lid or cap of the tank.
i (3) The length of the septic tank shall be at least twice as long as the width.
' (4) There shall be three inlet openings in the tank, one on the tank end and one on each sidewall of the inlet end of
the tank. The blockouts for these openings shall leave a concrete thickness of not less than one inch in the tank
wall. The blockouts shall be made for a minimum of four -inch pipe or a maximum of six-inch pipe. The outlet
' pipe penetration of the tank shall be through a resilient, watertight, sealed, non -corrosive and flexible connective
sleeve. The outlet pipe penetration shall be precast to be compatible with the connective sleeve. No pip e
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(' ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
(4) All siphon parts shall be installed in accordance with the manufacturer's specifications. All materials must be
corrosion -resistant, of cast iron, high density plastic, fiberglass, stainless steel, or equal.
' (5) Siphon dosing tanks shall have a properly functioning high-water alarm that is audible and visible by system users
and weatherproof if installed outdoors in an enclosure (NEMA 4X or equivalent).
I (e) Raw sewage lift stations shall meet the construction standards of this Section and all horizontal setback requirements
' for sewage treatment and disposal systems in accordance with Rule .I950(a) of this Section unless the station is a sealed,
watertight chamber, in which case the setback requirements for collection sewers in Rule .1950(e) of this Section shall apply.
Sealed, watertight chambers shall be of a single, prefabricated unit, such as fiberglass, with sealed top cover, and preformed
I' inlet and outlet pipe openings connected with solvent welds, O-ring seals, rubber boots, stainless steel straps, or equivalent.
Dual pumps shall be provided for stations serving two or more buildings or for a facility with more than six water closets.
Pumps shall be listed by Underwriter's Laboratories or an equivalent third party electrical testing and listing agency, and shall
Ibe grinder pumps or solids -handling pumps capable of handling at least three-inch spheres unless the station serves no more
' than a single water closet, lavatory, and shower, in which case two-inch solids handling pumps shall be acceptable.
Minimum pump capacity shall be 2.5 times the average daily flow rate. The dosing volume shall be set so that the pump -off
time does not exceed 30 minutes, except for stations serving single buildings, and pump run-time shall be from three to ten
I' minutes at average flow. Pump station emergency storage capacity and total liquid capacity shall be determined in
accordance with Paragraph (c)(1)(D) of this Rule except for a sealed, watertight chamber serving an individual building,
in which case a minimum storage capacity of eight hours shall be required. All other applicable requirements for pump tanks
and pump dosing systems in accordance with Paragraph (c) of this Rule shall also apply to raw sewage lift stations.
History Note: Authority G.S. 130A-335 (e)69(fl)[2nd],
Eff. July 1, 1982;
Amended Eff. August 1, 1991; January 1, 1990,
Temporary Amendment Eff. January 1, 1999.
t .1953 PREFABRICATED SEPTIC TANKS AND PUMP TANKS
When prefabricated concrete tanks or tanks of other material are used, they shall be constructed in accordance with the
plans which have been approved by the State and shall comply with all requirements of this Section. At least three complete
sets of plans and specifications for the initial design of the prefabricated septic tank or subsequent changes and modifications
' shall be submitted to the Department of Environment and Natural Resources, On -Site Wastewater Section, P.O. Box 29594,
Raleigh, North Carolina 27626-0594. Separate plans and specifications for the design of each septic tank or pump tank to
be produced shall be submitted to the On -Site Wastewater Section for approval. These plans and specifications shall show
I' the design of the septic tank in detail, including:
(1) All pertinent dimensions;
(2) Reinforcement material and location;
I(3) Material strength;
' (4) Liquid depth;
(5) Pipe penetration, joint material and method of sealing;
(6) Access manhole riser, lid, and other proposed appurtenances to the septic tank;
I t (7) Approved effluent filter(s), filter support detail and filter access detail; and
(8) Other design features.
History Note: Authority G.S. 130A-335 (e)69f1)[2nd],•
Eff. July 1, 1982; ,
Amended Eff. January 1, 1990,
Temporary Amendment Eff. January 1, 1999.
I' .1954 MINIMUM STANDARDS FOR PRECAST REINFORCED CONCRETE TANKS
(a) The following are minimum standards of design and construction of precast reinforced concrete septic tanks:
I' (1) The minimum requirement for the liquid depth is 36 inches.
`` (2) A minimum of nine inches freeboard is required, the freeboard being the air space between the top of the liquid
and the bottom side of the lid or cap of the tank.
(3) The length of the septic tank shall be at least twice as long as the width.
' (4) There shall be three inlet openings in the tank, one on the tank end and one on each sidewall of the inlet end of
the tank. The blockouts for these openings shall leave a concrete thickness of not less than one inch in the tank
wall. The blockouts shall be made for a minimum of four -inch pipe or a maximum of six-inch pipe. The outlet
' pipe penetration of the tank shall be through a resilient, watertight, sealed, non -corrosive and flexible connective
sleeve. The outlet pipe penetration shall be precast to be compatible with the connective sleeve. No pip e
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(' ENR - ENVIRONMENTAL HEALTH TI SA: 13A .1900
penetration points or openings shall be permitted below the tank liquid level.
(5) The inlet pipe in the tank shall be a straight pipe.
(6) The outlet shall be through an approved effluent filter secured in place in an effluent filter support case. The
effluent filter support case shall serve as a functioning sanitary tee with the bottom inlet extending down between
I 25 and 40 percent of the liquid depth. The approved effluent filter and support case shall be furnished by th e
' septic tank manufacturer. The invert of the outlet shall be at least two inches lower in elevation than the invert
of the inlet.
(7) Other equivalent methods of supporting the effluent filter and for making the pipe penetrations shall be approved
I' by the On -Site Wastewater Section.
(8) In order to obtain approval of an effluent filter, the filter manufacturer shall submit to the State the following
information with supporting documentation:
I(a) For each septic tank system that is designed to treat 3,000 gallons per day or less of sewage, a written
' certification that the effluent filter is designed, constructed, and performs in compliance with North
Carolina General Statute 130A-335.1(a)(1)(2)(3), and (4);
(b) Sizing as to capacity and wastewater strength for all models of proposed filters to be approved; and
(c) Specifications for application, installation, operation, and maintenance.
(9) All tanks shall be manufactured with a cast -in -place partition so that the tank contains two compartments. The
partition shall be located at a point not less than two- thirds nor more than three -fourths the length of the tank from
'the inlet end. The top of the partition shall terminate two inches below the bottom side of the tank top in order
' to leave space for air or gas passage between compartments. The top and bottom halves of the partition shall be
cast in such manner as to leave a water passage slot four inches high for the full width of the tank. The partition
(both halves) shall be reinforced by the placing of six-inch by six-inch No. 10 gage welded reinforcing wire. The
I' reinforcing wire shall be bent to form an angle of 90 degrees on the ends in order to form a leg not less than four
inches long. When the wire is placed in the mold the four -inch legs should lay parallel with the sidewall wire and
adjacent to it. It is recognized that there are other methods of constructing a partition or two -compartment tank.
Any method other than the one described will be considered on an individual basis for approval by the On -Site
Wastewater Section. However, the tank wall thickness must remain not less than two and one-half inches thick
throughout the tank except for the pipe penetrations.
I (10) Adequate access openings must be provided in the tank top. Access shall be provided for cleaning or rodding
' out of the inlet pipe, for cleaning or clearing the air or gas passage space above the partition, for pumping of each
compartment, and for the maintenance of the effluent filter. This shall be accomplished by properly locating two
manholes or access openings with each having a minimum opening of 15 inches by 15 inches or 17 inches i n
Idiameter as the opening cuts the plane of the bottom side of the top of the tank or other equidimensional opening
' with at least 225 square inches. The manhole covers shall be beveled on all sides in such manner as t o
accommodate a uniform load of 150 pounds per square foot without damage to the cover or the top of the tank.
I If the top of the tank is to be multislab construction, the slabs over the inlet of the tank, partition, and outlet of the
' tank must not weigh in excess of 150 pounds each. Multislab construction allows for the elimination of th e
manholes. Manhole covers, tank lids, access opening covers, or slabs shall have a handle of steel or other
rot -resistant material equivalent in strength to a No. 3 reinforcing rod (rebar).
I' (11) The concrete tank and tank lid shall be reinforced by using a minimum reinforcing of six-inch by six-inch No. 10
gage welded steel reinforcing wire in the top, bottom ends, and sides of the tank. The reinforcing wire shall be
lapped at least six inches. Concrete cover shall be required for all reinforcement. Reinforcement shall be placed
t to maximize the structural integrity of the tank. The tank, tank lid, riser and riser cover shall be able to withstand
a uniform live loading of 150 pounds per square foot in addition to all loads to which an underground tanks, riser,
or riser cover is normally subjected, such as the dead weight of the concrete and soil cover, active soil pressure
on tank walls, and the uplifting force of the ground water. Additional reinforcement shall be required when the
(' loads on a concrete tank, riser, or riser cover are exceeded by subjecting it to vehicular traffic or when the top of
the tank is placed deeper than three feet below the finished grade.
(12) The top, bottom, ends, and sides of the tank must have a minimum thickness of two and one-half inches.
(13) A minimum 28-day concrete compressive strength of 3,500 pounds per square inch shall be used in the
' construction of the septic tank, concrete access riser and riser cover. The concrete shall achieve a minimu in
compressive strength of 3,000 pounds per square inch prior to removal of the tank from the place of manufacture.
It shall be the responsibility of the manufacturer to certify that this condition has been met prior to shipment. A
(' septic tank shall be subject to testing to ascertain the strength of the concrete prior to its being approved for
installation. Recognized devices for testing the strength of concrete include a properly calibrated Schmidt
Rebound Hammer or Windsor Probe Test. Accelerated curing in the mold by use of propane gas or other fuels
is prohibited, except in accordance with accepted methods and upon prior approval of the State.
(14) After curing, tanks manufactured in two sections and as required, concrete risers shall be joined and sealed at the
1 NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 22

ENR - ENVIRONMENTAL HEALTH TI SA: 18A .1900
joint by using a mastic, butyl rubber, or other pliable sealant that is waterproof, corrosion -resistant, and approved
for use in septic tanks. The sealant shall have a minimum size of one inch nominal diameter or equivalent. Before
sealing, the joint shall be smooth, intact, and free of all deleterious substances. Tank halves shall be properl y
aligned to ensure a tight seal. The sealant shall be provided by the manufacturer.
(15) All tanks produced shall bear an imprint identifying the manufacturer, the serial number assigned to the
manufacturer's plans and specifications approved by the State, and the liquid or working capacity of the tanks.
This imprint shall be located to the right of the blockout made for the outlet pipe on the outlet end of the tank.
All tanks shall also be permanently marked with the date of manufacture adjacent to the tank imprint or on the
top of the tank directly above the imprint.
(16) Risers and access covers shall have a clear opening sized to allow for maintenance and removal of internal devices
of the septic tank and shall not allow accidental entry. The access cover and tank lid shall be designed,
constructed, and maintained to prevent unauthorized access. Risers shall be sealed watertight where they join the
top of the septic tank, and constructed to prevent water inflow through the lid or cover.
(b) Pump tanks shall meet the construction requirements of Paragraph (a) of this Rule with the following modifications.
(1) Tanks shall be cast with a single compartment, or, if a partition is provided, the partition shall be cast to contain
a minimum oftwo four -inch diameter circular openings, or equivalent, located no more than 12 inches above the
tank bottom.
(2) There shall be no requirement as to tank length, width, or shape, provided the tank satisfies all other requirements
of this Section.
(3) The invert of the inlet openings shall be located within 12 inches of the tank top. No freeboard shall be required
in the pump tank.
(4) After joining, tanks manufactured in two sections shall be plastered along the joint with hydraulic cement, cement
mortar, or other waterproofing sealant. Other methods of waterproofing tanks may be used as specifically
approved in the plans and specifications for the tank. Prior to backfilling, the local health department shall make
a finding that a two section tank is watertight if a soil wetness condition is present within five feet of the elevation
of the top of the tank.
(5) Tanks shall be vented and accessible for routine maintenance. A watertight access manhole with removable lid
shall be provided over the pump with a minimum diameter of 24 inches. The access manhole shall extend at least
to six inches above finished grade and be designed and maintained to prevent surface water inflow. Larger or
multiple manholes shall be provided when two or more pumps are required. Pumps shall be removable without
requiring entrance into the tank. Manhole lids and electrical controls shall be secured against unauthorized
access. Manhole risers shall be joined to the tank top and sealed in accordance with Paragraphs (a)(12) an d
(b)(4) of this Rule.
(6) All pump tanks shall bear an imprint identifying the manufacturer, pump tank serial number assigned by the
Division of Environmental Health, and the liquid or working capacity of the tank. The imprint shall be located
to the left of the outlet blockout. All tanks shall also be permanently marked with the date of manufacture adjacent
to the tank imprint or on the top of the tank directly above the imprint.
(c) Plans for prefabricated tanks, risers and riser covers, other than those approved under Paragraphs (a) or (b) of this
Rule shall be approved on an individual basis as determined by the information furnished by the designer which indicates
the tank, riser or riser cover will provide equivalent effectiveness as those designed in accordance with the provisions of
Paragraphs (a) and (b) of this Rule.
(d) Tanks other than approved prefabricated tanks shall be constructed consistent with the provisions of this Rule except
as follows:
(1) Cast -in -place concrete septic and pump tanks shall have a minimum wall thickness of six inches.
(2) Concrete block or brick masonry tanks shall have a minimum wall thickness of at least six inches when the design
volume is less than 1,000 gallons and a minimum wall thickness of at least eight inches when the design volume
is 1,000 gallons or more. All joints between masonry units shall be mortared using masonry cement mortar or
equivalent. The joints shall have a nominal thickness of three -eighths inch. All concrete block masonry tanks
shall have a minimum wall reinforcement of number three reinforcing bars on 20-inch centers, or equivalent. The
maximum allowable reinforcement spacing in either direction shall be four feet. All block wall cores shall be
filled with concrete with a minimum compressive strength of3,000 pounds per square inch. All tanks constructed
of block or brick shall be plastered on the inside with a 1:3 mix (one part cement, three parts sand) of Portland
cement at least three -eighths inch thick or the equivalent using other approved waterproofing material.
(3) The bottom of the built -in -place tank shall be poured concrete with a minimum thickness of four inches. Al I
built -in -place tanks shall be reinforced to satisfy the structural strength requirements of Paragraph (a)(9) of this
Rule. Reinforcement shall be placed in both directions throughout the entire tank, including top, bottom, walls,
and ends.
(e) Manufacturers of septic tanks, effluent filters, pump tanks, risers, and riser locators shall comply with the General
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I, ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
Statutes, this Section, and Approval conditions. If the approved products or materials are found to be in non-compliance,
Ithe Operation Permit shall not be issued or shall be denied. The State shall suspend or revoke the product approval upon
' a finding that the information submitted is falsified, the product has been subsequently altered, or subsequent experience with
the product results in altered conclusions about its design or performance. Suspension or revocation of the product approval
shall not affect systems previously installed pursuant to the approval.
I' History Note: Authority G.S. 130A-335 (e)(nfl)[2nd],
Eff. July 1, 1982;
Amended Eff. August 1, 1991; January 1, 1990,
Temporary Amendment Eff. January 1, 1999.
.1955 DESIGN INSTALLATION CRITERIA FOR CONVENTIONAL SEWAGE SYSTEMS
' (a) Conventional septic tank systems shall utilize a septic tank of approved construction with an approved effluent filter
and support case, access devices, and design volume which provides primary treatment of the sewage in accordance with
the provisions of these Rules. The effluent filter support case shall be solvent welded to a PVC Schedule 40 outlet pipe with
(' a minimum diameter of three inches inserted through the outlet connective sleeve creating a watertight and mechanically
sound joint and shall extend at least 24 inches beyond the tank outlet. The filter and support case shall be installed an d
maintained in accordance with the filter manufacturer's specifications. The effluent filter shall be accessible without the
operator entering the septic tank and removable by hand. The effluent filter shall be secured in the support case and located
' under the outlet access opening or manhole. When the top of the septic tank or access manhole is installed below finished
grade, the location of each access opening or manhole shall be visibly marked at finished grade. The visible marker(s) shall
be located over or within a five foot radius of each access opening or manhole. The marker(s) shall be identified as a septic
tank locator. When not placed over each access opening or manhole, the marker(s) shall indicate location of tank access
opening(s) or manhole(s). The filtered effluent from the septic tank shall be conveyed to an approved nitrification line where
the soil provides for final treatment and disposal of the sewage.
I(b) Table I1 shall be used in detennining the maximum long-term acceptance rate for septic tank systems of conventional
' trench design. The long-term acceptance rate shall be based on the most hydraulically limiting naturally occurring soi I
horizon within three feet of the ground surface or to a depth of one foot below trench bottom, whichever is deeper.
TABLE 11
SOIL GROUP SOIL TEXTURE CLASSES LONG-TERM
(USDA CLASSIFICATION) ACCEPTANCE RATE
gpd/ftz
I Sands Sand 1.2 - 0.8
(With S or PS Loamy Sand
' structure and
clay mineralogy)
II Coarse Loams Sandy Loam 0.8 - 0.6
(With S or PS Loam
structure and
clay mineralogy)
I' III Fine Loams Sandy Clay Loam 0.6 - 0.3
(With S or PS Silt Loam
I' structure and Clay Loam
clay mineralogy) Silty Clay Loam
Silt
IV Clays Sandy Clay 0.4 - 0.1
(With S or PS Silty Clay
structure and Clay
I' clay mineralogy)
` The long-term acceptance rate shall not exceed the mean rate for the applicable soil group for food service facilities, meat
I' markets, and other places of business where accumulation of grease can cause premature failure of a soil absorption system.
Long-term acceptance rates up to the maximum for the applicable soil group may be permitted for facilities where data from
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ENR - ENVIRONMENTAL HEALTH T1 SA: 18A.1900
comparable facilities indicates that the grease and oil content of the effluent will be less than 30 mg/l and the chemical
oxygen demand (COD) will be less than 500 mg/l.
' (c) The design daily sewage flow shall be divided by the long-term acceptance rate to determine the minimum area of
nitrification trench bottom. The total length of the nitrification line shall be determined by dividing the required area o f
nitrification trench bottom by the trench width, not to exceed 36 inches. Trenches shall be located not less than three times
the trench width on centers with a minimum spacing of five feet on centers.
(d) The local health department may permit the use of a bed system on sites where the soil texture can be classified into
either Soil Groups I, II, or III, meeting the other requirements of this Section, and only on lots which are limited b y
topography, space, or other site -planning considerations. In such cases, the number of square feet of bottom area needed
' shall be increased by 50 percent over what would be required for a trench system. Nitrification lines shall be at least 18
inches from the side of the bed and shall have lines on three-foot centers. When the design daily flow exceeds 600 gallons
per day, bed systems shall.not be used.
(e) The pipe or tubing used between the septic tank and the nitrification line shall be a minimum of three-inch nominal
size Schedule 40 polyvinyl chloride (PVC), polyethylene (PE), or acrylonitrile-butadiene-styrene (ABS) or equivalent with
a minimum fall of one -eighth inch per foot. However, three-inch or greater nonperforated polyethylene (PE) corrugated
I' tubing may be substituted for Schedule 40 pipe between a distribution device and the nitrification line if the following
conditions are met:
(1) the trench has a minimum bottom width of one foot;
(2) the trench bed is compacted, smooth, and at a uniform grade;
(3) the pipe is placed in the middle of the trench with a minimum of three inches of clearance between the pipe and
the trench walls;
(4) washed stone or washed gravel envelope is placed in the trench on both sides of the pipe and up to a point at least
two inches above the top of the pipe;
(5) a minimum of six inches of soil cover is placed and compacted over the stone or gravel envelope; and
(6) earthen dams consisting of two feet of undisturbed or compacted soil are placed at both ends of the trenc h
separating the trench from the distribution device and the nitrification line.
' All joints from the septic tank to the nitrification line shall be watertight.
(f) When four or six-inch diameter corrugated plastic tubing is used for nitrification lines, it shall be certified as complying
with ASTM F 405, Standard Specification for Corrugated Polyethylene (PE) Tubing and Fittings, which is hereby adopted
by reference in accordance with G.S. 15013-21.6. The corrugated tubing shall have three rows of holes, each hole between
one-half inch and three -fourths inch in diameter, and spaced longitudinally approximately four inches on centers. The rows
of holes may be equally spaced 120 degrees on centers around the periphery, or three rows may be located in the lower
portion of the tubing, the outside rows being approximately on 120-degree centers. The holes may be located in the same
' corrugation or staggered in adjacent corrugations. Other types of pipe may be used for nitrification lines provided the pipe
satisfies the requirements of this Section for hole size and spacing and the pipe has a stiffness equivalent to corrugated
polyethylene tubing (ASTM F405) or stronger. The nitrification line shall be located in the center of the nitrification trench.
I, (g) Nitrification trenches shall be constructed as level as possible but in no case shall the fall in a single trench bottom
exceed one-fourth inch in 10 feet as determined by an engineer's level or equivalent. When surface slopes are greater than
two percent, the bottom of the nitrification trenches shall follow the contour of the ground. An engineer's level or equivalent
shall be used for installation and inspection. The nitrification trench shall not exceed a width of three feet and a depth of
three feet, except as approved by the local health department.
(h) Rock used in soil absorption systems shall be clean, washed gravel or crushed stone and graded or sized in accordance
with size numbers 3, 4, 5, 57, or 6 of ASTM D-448 (standard sizes of coarse aggregate) which is hereby adopted by
reference in accordance with G.S.15013-21.6. Copies may be inspected in, and copies obtained from the Division o f
Environmental Health, P.O. Box 27687, Rale igh, North Carolina 27611-7687. The rock shall be placed a minimum of one
foot deep with at least six inches below the pipe and two inches over the pipe and distributed uniformly across the trench
I' bottom and over the pipe.
(i) The soil cover over the nitrification field shall be to a depth of at least six inches. The finished grade over th e
nitrification field shall be landscaped to prevent the ponding of surface water and runoff of surface water shall be diverted
away from the nitrification field. Soil cover above the original grade shall be placed at a uniform depth over the entir e
nitrification field, except as required to prevent the ponding of surface water, and shall extend laterally five feet beyond the
nitrification trench. The soil cover shall be placed over a nitrification field only after proper preparation of the original
ground surface. The type of soil cover and placement shall be approved by the local health department.
0) Effluent distribution devices, including distribution boxes, flow dividers, and flow diversion devices, shall be of sound
construction, watertight, not subject to excessive corrosion, and of adequate design as approved by the local health
department. Effluent distribution devices shall be separated from the septic tank and nitrification lines by a minimum of two
feet of undisturbed or compacted soil and shall be placed level on a solid foundation of soil or concrete to prevent differential
(, settlement of the device. The installer shall demonstrate that the distribution devices perform as designed.
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!' ENR - ENVIRONMENTAL HEALTH T1 SA: 18A .1900
f(k) Grease traps or grease interceptors shall be required at food service facilities, meat markets, and other places o f
business where the accumulation of grease can cause premature failure of a soil absorption system. The following design
' criteria shall be met:
(1) The grease trap shall be plumbed to receive all wastes associated with food handling and no toilet wastes;
(2) The grease trap liquid capacity shall be sufficient to provide for at least five gallons of storage per meal served
(' per day, or at least two-thirds of the required septic tank liqu id capacity, or a capacity as determined in accordance
with the following:
ILC = D x GL x ST x HR/2 x LF
where LC = grease trap liquid capacity (gallons)
D = number of seats in dining area
GL = gallons of wastewater per meal (1.5 single -service; 2.5 full service)
' ST = storage capacity factor = 2.5
HR = number of hours open
I, LF = loading factor = (1.25 interstate highway
1.0 other highways and recreational areas
0.8 secondary roads)
I' (3) Two or more chambers must be provided, with total length -to -width ratio at least 2:1. Chamber opening an d
outlet sanitary tee must extend down at least 50 percent of the liquid depth.
(4) Access manholes, with a minimum diameter of 24 inches, shall be provided over each chamber and sanitary tee.
The access manholes shall extend at least to finished grade and be designed and maintained to prevent surface
' water infiltration. The manholes shall also have readily removable covers to facilitate inspection, filter
maintenance, and grease removal.
(5) One tank or multiple tanks, in series, shall be constructed in accordance with Rules .1952, .1953, and .1954 of
' this Section, and the provisions of Paragraphs (k)(3) and (k)(4) of this Rule.
(6) Where it has been demonstrated that specially designed grease interceptors will provide improved performance,
the grease trap liquid capacity may be reduced by up to 50 percent.
I' (1) Stepdowns or drop boxes may be used where it is determined by the local health department that topography prohibits
the placement of nitrification trenches on level grade. Stepdowns shall be constructed of two linear feet of undisturbed soil
and constructed to a height which fully utilizes the upstream nitrification trench. Effluent shall be conveyed over the
Istepdown through nonperforated pipe or tubing and backfilled with compacted soil. Drop boxes shall be constructed so that
' the invert of the inlet supply pipe is one inch above the invert of the outlet supply pipe which is connected to the next lower
drop box. The top of the trench outlet laterals, which allow effluent to move to the nitrification lines, shall be two inches
below the invert of the outlet supply line. Area taken up by stepdowns and drop boxes shall not be included as part of the
(' minimum area required for nitrification trench bottoms.
(m) Nitrification trenches shall be installed with at least one foot of naturally occurring soil between the trench bottom
and saprolite, rock, or any soil horizon unsuitable as to structure, clay mineralogy or wetness. If the separation between the
Ibottom of the nitrification trench and any soil wetness condition is less than 18 inches, and if more than six inches of this
' separation consists of Group I soils, a low pressure pipe system shall be required.
(n) If sewage effluent pumps are used, the applicable requirements of Rule .1952 of this Section shall apply.
(o) Collection sewers shall be designed and constructed in accordance with the following minimum criteria:
I' (1) Building drains and building sewers shall be in accordance with the state plumbing code and approved by the
local building inspector.
(2) Pipe material shall be specified to comply with the applicable ASTM standards, with methods of joining and other
special installation procedures specified which are appropriate for the pipe to be used.
' (3) Gravity sewers shall be designed to maintain scour velocities of at least two feet per second with the pipe half full
and a minimum of one foot per second at the peak projected instantaneous flow rate. Force mains shall be sized
to I' obtain at least a two -foot per second scour velocity at the projected pump operating flow rate. (4) Infiltration and exfiltration shall not exceed 100 gallons per day per inch diameter per mile of gravity sewer pipe
or 20 gallons per day per inch diameter per mile of pressure pipe in force mains and supply lines.
(5) Three-foot minimum cover shall be provided for all sewers unless ferrous material pipe is specified. Ferrou s
(' material pipe or other pipe with proper bedding to develop design -supporting strength shall be provided where
sewers are subject to traffic -bearing loads.
(6) Manholes shall be used for sewers at any bends, junctions, and at least every 425 feet along the sewer lines. Drop
manholes are required where the inlet to outlet elevation difference exceeds 2.5 feet. Manhole lids shall b e
watertight if located below the 100-year flood elevation, within 100 feet of any public water supply source, or
NORTH CAROLINA ADMINISTRATIVE CODE. 01/21/99 Page 26

ENR - ENVIRONMENTAL HEALTH T1 SA: I8A .1900
11
11
within 50 feet of any private water supply source or any surface waters classified WS-1, WS-11, WS-111, SA, SB,
or B.
(7) Cleanouts may be used instead of manholes for four -inch and six-inch sewers serving one or two buildings or as
otherwise allowed by the North Carolina Plumbing Code. When used, cleanouts are required at least every 50
feet for four -inch sewers and every 100 feet for six-inch sewers and at all junctions and bends which exceed 45
r, degrees.
I) (8) Additional ventilation provisions may be required for collection sewers. Air relief valves shall be provided as
needed for force mains.
(p) Alternating dual field nitrification systems may be utilized where soils are limited by high clogging potentials (Soil
' Groups III and N) and where the potential for malfunction and need for immediate repair is required. Alternating dua I
nitrification fields shall be designed with two complete nitrification fields, each sized a minimum of 75 percent of the total
area required for a single field and separated by an effluent flow diversion valve. The diversion valve shall be constructed
I' to resist 500 pounds crushing strength, structurally sound, and shall be resistant to corrosion. Valves placed below ground
level shall be provided with a valve box and suitable valve stem so that they may be operated from the ground surface.
t History Note: Authority G.S. 130A-335 (e)09(f1)[2nd],
Eff. July 1, 1982;
Amended Eff. August 1, 1991; January 1, 1990; August 1, 1988; February 1, 1987;
Temporary Amendment Eff. January 1, 1999.
.1956 MODIFICATIONS TO SEPTIC TANK SYSTEMS
The following are modifications to septic tank systems or sites which may be utilized singly or in combination to overcome
selected soil and site limitations. Except as required in this Rule, the provisions for design and installation of Rule .1955
of this Section shall apply:
(1) SHALLOW SYSTE MS: Sites classified UNSUITABLE as to soil depth or soil wetness may be reclassified as
' PROVISIONALLY SUITABLE with respect to soil depth or soil wetness conditions by utilizing shallow
placement of nitrification trenches in the naturally occurring soil. Shallow trenches may be used where at least
24 inches of naturally occurring soil are present above saprolite, rock, or soil wetness conditions and all other
factors are PROVISIONALLY SUITABLE Or SUITABLE. Shallow trenches shall be designed and constructed to
meet the vertical separation requirements in Rule .I955(m) of this Section. The long-term acceptance rate shall
be based on the most hydraulically limiting naturally occurring soil horizon within 24 inches of the ground surface
(' or to a depth of one foot below the trench bottom, whichever is deeper. Soil cover above the original grade shall
be placed at a uniform depth over the entire nitrification field and shall extend laterally five feet beyond the
nitrification trench. The soil cover shall be placed over a nitrification field only after proper preparation of the
original ground surface. The type and placement of soil cover shall be approved by the local health department.
(2) DRAINAGE AND RESTRICTI VE HORIZONS: Sites classified UNSUITABLE as to soil wetness conditions
or restrictive horizons may be reclassified PROVISIONALLY SUITABLE as to soil wetness conditions or
restrictive horizons when:
I' (a) Soils are Soil Groups I or II with SUITABLE structure, and clay mineralogy;
(( (b) Restrictive horizons, if present, are less than three inches thick or less than 12 inches from the soil surface;
(c) Modifications can be made to meet the requirements in Rule .I955(m) of this Section for the separation
between the water table and the bottom of the nitrification tre rich at all times and when provisions are made
' for maintenance of the drainage systems;
(d) Easements are recorded and have adequate width for egrets and ingress for maintenance of drainage
systems serving two or more lots;
I' (e) Maintenance of the drainage system is made a condition of any permit issued for the use or operation of
a sanitary sewage system; and
(f) Drainage may be used in other types of soil when the requirements of Rule .I 957(c) in this Section are met.
(3) GRAVELLESS TRENCHES: Modified nitrification trenches or line s, including large diameter pipe (greater than
four inches I.D.), and specially designed porous block systems may be permitted by the local health department.
(a) Gravelless nitrification trench systems may be substituted for conventional trench systems on any site found
to be suitable or provisionally suitable in accordance with Rules .1940 to .1948 of this Section to eliminate
the need for gravel, minimize site disturbance, or for other site planning considerations. Gravelless
nitrification trench systems shall not be used, however, where wastes contain high amounts of grease and
oil, such as restaurants.
(' (i) Large diameter pipe systems shall consist of eight -inch or 10-inch (inside diameter), corrugated,
polythylene tubing encased in a nylon, polyester, or nylon/polyester blend filter wrap installed in
I' NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 27

ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
' a nitrification trench, 12 or more inches wide and backfilled with soil classified as soil group 1,11,
or I11. Nitrification area requirement shall be determined in accordance with Rules .1955(b) and
' .1955(c), or in Rule .1956(6xb), Table III of this Section, when applicable, with eight -inch tubing
considered equivalent to a two -foot -wide conventional trench and 10-inch tubing considered
equivalent to a two and one -half -foot -wide conventional trench. The long-term acceptance rate
shall not exceed 0.8 gallons per day per square foot. Tubing and fittings shall comply with the
requirements ofASTM F-667, which is hereby incorporated by reference including any subsequent
amendments and editions. Copies of the standards may be inspected in and copies obtained from
the Divison of Environmental Health, P.O. Box 27687, Raleigh, NC 27611-7687 at no cost. The
corrugated tubing shall have two rows of holes, each hole between three -eighths and one -half -inch
in diameter, located 120 degrees apart along the bottom half of the pipe (each 60 degrees from the
bottom center line) and staggered so that one hole is present in the valley of each corrugation. The
tubing shall be marked with a visible top location indicator, 120 degrees away from each row of
holes. Filter wrap shall be spun, bonded, or spunlaced nylon, polyester, or nylon/polyester blend
nylon filter wrap meeting the following minimum requirements:
Unit Weight: Oztyd'= 1.0
Sheet Grab Tensile: MD - 23 lbs.
Trapezoid Tear: MD - 6.2 lbs.
XD -5.1 lbs.
' Mullen Burst:
PSI — 40
Kpa = 276 .
Frazier Air Perm, CFM/ft ] 0.5 "H2O: 500"
Corrugated Tubing shall be covered with filter wrap at the factory and each joint shall be immediately encased in a black
' polyethylene sleeve which shall continue to encase the large diameter pipe and wrap until just prior to installation in the
trench. Large diameter pipe systems shall be installed in accordance with this Rule and the manufacturer's guidelines. The
trench bottom and pipe shall be level (with a maximum fall of one inch in 100 feet). Filter wrap encasing the tubing shall
not be exposed to sunlight (ultraviolet radiation) for extended periods. Rocks and large soil clumps shall be removed from
backfill material prior to being used. Clayey soils (soil group IV) shall not be used for backfill. The near end of the large
diameter pipe shall have an eight -inch by four -inch offset adaptor (small end opening at top) suitable for receiving the pipe
from the septic tank or distribution device and making a mechanical joint in the nitrification trench.
' (ii) A Prefabricated, Permeable Block Panel System (PPBPS), untilizing both horizontal and vertical
air chambers and special construction to promote downline and horizontal distribution of effluent,
may be used under the following conditions:
(A) the soil and site criteria of this Section shall be met;
(B) in calculating the required linear footage for a PPBPS's nitrification field, the linear footage
for the nitrification line as determined in Rule .1955 (b) and (c), or in Rule .1956 (6)(b) ,
t' Table III of this Section when applicable, shall be multiplied by 0.5 for a 16 inch PPBPS;
II(C) installation of the PPBPS shall be in accordance with these Rules except:
(I) the PPBPS trench shall be located not less -than eight feet on centers;
I (II) the installation shall be in accordance with the manufacturer's specifications; ' and (III) the sidewalls of nitrification trenches placed in Group IVa soils shall be raked to
open pores which were damaged or sealed during excavation;
(D) where design sewage flow is more than 480 gallons per day, the system shall be
pressure -dosed; and
(E) the long-term acceptance rate shall not exceed 0.8 gallons per day per square foot.
(b) Other types of nitrification trenches or lines may be approved by the local health department on a
site -specific basis in accordance with Rule .1969 of this Section.
' (4) INTERCEPTOR DRAINS: Sites classified as UNSUITABLE as to soil wetness conditions because of the
presence of lateral water movement may be reclassified PROVISIONALLY SUITABLE as to soil wetnes s
conditions when such water is intercepted and diverted to prevent saturation of the soil absorption system.
I' (5) STEEP SLOPES: Stable slopes g reater than 30 percent may be reclassified as PROVISIONALLY SUITABLE
�' NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 28

I' ENR - ENVIRONMENIAL HEALTH T15A: 18A .1900
when:
(a) The soil characteristics can be classified as SUITABLE or PROVISIONALLY SUITABLE to a depth of
I' at least one foot below the bottom of the nitrification trench at the upslope side of the trench;
(b) Surface water runoff is diverted around the nitrification field if necessary to prevent scouring or erosion
of the soil over the field; and
(c) The finished grade over the nitrification field site is returned to the original topography and adequately
seeded, unless otherwise specified by the local health department.
(6) SAPROLITE SYSTEM: Sites classified UNSUITABLE as to soil depth, with saprolite present, may b e
I' reclassified PROVISIONALLY SUITABLE as to soil depth when the provisions of this Paragraph are met.
(a) An investigation of the site using pits at locations specified by the local health department shall be
conducted. The following physical properties and characteristics shall be present in the two feet of
saprolite below the proposed trench bottom:
I' (i) the saprolite texture shall be sand, loamy sand, sandy loam, loam, or silt loam;
(ii) clay mineralogy shall be suitable;
(iii) greater than two-thirds of the material shall have a moist consistence of loose, very friable, friable,
or firm;
(iv) the saprolite wet consistence shall be nonsticky or slightly sticky and nonplastic or slightly plastic;
(v) the saprolite shall be in an undisturbed, naturally occurring state; and
(vi) the saprolite shall have no open and continuous joints, quartz veins, or fractures relic of parent rock
I' to a depth of two feet below the proposed trench bottom.
(b) Table III shall be used in determining the long-term acceptance rate for septic tank systems installed
pursuant to Paragraph (6) of this Rule. The long-term acceptance rate shall be based on the mos t
hydraulically limiting, naturally occurring saprolite to a depth of two feet below trench bottom.
TABLE III
SAPROLITE SAPROLITE LONG-TERM
' GROUP TEXTURAL CLASSES ACCEPTANCE RATE
Sands Sand 0.8 - 0.6
Loamy Sand 0.7 - 0.5
II Loams Sandy Loam 0.6 0.4
Loam 0.4 - 0.2
Silt Loam 0.3 - 0.1
If a low pressure pipe system is used, the long term acceptance rate in Table III shall be reduced by one-half and the
system shall be designed in accordance with Rule .I957(a) of this Section, except that Rule .1957 (a)(2)(B) and Rule
.l 957(a)(3) shall not apply. Saprolite textural classifications shall be determined from disturbed materials and
determined by Rule. 1941 (a)(1) of this Section. Low-pressure distribution shall be used when the total length of
nitrification lines exceeds 750 feet in a single system.
(c) The design daily flow shall not exceed 1000 gallons.
(d) The nitrification field shall be constructed using nitrification trenches with a maximum width of three
feet and a maximum depth of three feet on the downslope side of the nitrification trench. The bottom of
a nitrification trench shall be a minimum of two feet above rock or saprolite that does not meet the
requirements of Subparagraph (6)(a) of this Rule. However, where SUITABLE or
PROVISIONALLY SUITABLE soil underlies the trench bottom, this separation distance may be
I' reduced by subtracting the actual soil depth beneath the trench bottom from 24 inches to establish the
minimum separation distance from the trench bottom to rock.
(e) The bottom of any nitrification trench shall be a minimum of two feet above any wetness condition.
(f) Surface and subsurface interceptor drains shall be required on sites with more slowly permeable
I horizons above the usable saprolite to intercept laterally flowing waters or perched waters.
(g) Exceptions to the provisions of Rule .1950(a) found in Rule .1950 and .1951 of this Section shall not
apply to systems installed pursuant to this Paragraph [Rule .1956(6)].
(h) Other saprolite systems may be approved on a site -specific basis in accordance with Rule.] 948(d) of
this Section.
I' History Note: Authority G.S. 130A-335(e) and (/);
Eff. July 1, 1982;
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ENR - ENVIRONMENTAL HEALTH T1 SA: 18A .1900
' Amended Eff. July 1, 1995; April 1, 1993; January 1, 1990; August 1, 1988.
I, .1957 DESIGN CRITERIA FOR DESIGN OF ALTERNATIVE SEWAGE SYSTEMS
(a) LOW-PRESSURE PIPE SYSTEMS: Low-pressure pipe (LPP) systems with a two to five-foot pressure head
may be utilized on sites which are SUITABLE or PROVISIONALLY SUITABLE for conventional or modified systems
and on sites where soil and site conditions prohibit the installation of a conventional or modified septic tank system if the
requirements of this Paragraph are met.
(I) The LPP system shall consist of the following basic components:
(A) a network of small -diameter (one to two inches) perforated PVC 160 psi pipe or equivalent placed in
' naturally occurring soil at shallow depths (generally 12 to 18 inches) in narrow trenches not less than
eight inches in width and spaced not less than five feet on center. Trenches shall include at least five
inches of washed stone or washed gravel below the pipe and two inches above the pipe; and four
(' inches of soil cover.
(B) a properly designed, two -compartment septic tank or other approved pretreatment system, and a
pumping or dosing tank;
I' (C) a watertight supply manifold pipe, of Schedule 40 PVC or equivalent, for conveying effluent from the
dosing chamber to the low-pressure network.
(2) The soil and site criteria for LPP systems shall meet the following minimum requirements:
(A) LPP nitrification fields shall not be installed on slopes in excess of ten percent unless special design
I' procedures to assure proper distribution of effluent over the nitrification field are approved.
Landscaping of the LPP distribution field shall be constructed to shed rainwater or runoff. All other
requirements of Rule .1940 of this Section shall be met.
(' (B) Site suitability for an LPP system shall be based on the first 24 inches of soil beneath the naturally
occurring soil surface. This 24 inches shall consist of SUITABLE or PROVISIONALLY SUITABLE
soil as determined in accordance with Rules .1941 through .1944 and .1956 of this Section.
(C) Location of the septic tank, other approved pretreatment unit, pumping or dosing chamber, and
nitrification field shall be in accordance with Rule .1950 of this Section. Horizontal distances from the
nitrification field shall be measured from a margin two and one-half feet beyond the lateral and
manifold pipes.
(D) There shall be no soil disturbance of the site or repair area for an LPP system except the minimum
required for installation.
(E) The available space requirements of Rule .1945 of this Section shall apply.
(3) Table IV shall be used in determining the long-term acceptance rate for LPP systems. The long-term
acceptance rate shall be based on the most hydraulically limiting, naturally occurring soil horizon within two
feet of the ground surface or to a depth of one foot below the trench bottom, whichever is deeper.
r
' NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 30

ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
TABLE IV
SOIL GROUP
SOIL TEXTURAL CLASSES
LONG-TERM
(USDA CLASSIFICATION)
ACCEPTANCE RATE
gpd/ft
I
Sands
Sand
0.6 - 0.4
(With S or PS
Loamy Sand
structure and
clay mineralogy)
II
Coarse Loams
Sandy Loam
0.4 - 0.3
(With S or PS
Loam
structure and
clay mineralogy)
III
Fine Loams
Sandy Clay Loam
0.3 - 0.15
(With S or PS
Silt Loam
structure and
Clay Loam
clay mineralogy)
Silty Clay Loam
Silt
IV
Clays
Sandy Clay
0.2 - 0.05
(With S or PS
Silty Clay
structure and
Clay
clay mineralogy)
The long-term acceptance rate shall not exceed the mean rate for the applicable soil group for food service facilities,
meat markets, and other places of business where accumulation of grease can cause premature failure of a soil
absorption system. Long-term acceptance rates up to the maximum for the applicable soil group may be permitted for
facilities where data from comparable facilities indicates that the grease and oil content of the effluent will be less than
30 mg/I and the chemical oxygen demand (COD) will be less than 500 mg/1.
(4) In calculating the number of square feet for the nitrification field, the design sewage flow shall be divided by
the long-term acceptance rate from Table IV. In calculating the minimum length of trenches in the UP
system, the total square footage of the nitrification field shall be divided by five feet.
(5) Low-pressure systems shall be designed for uniform distribution of effluent. The trenches shall be level and
parallel to the ground elevation contours.
(A) The maximum lateral length shall yield no more than a ten -percent difference in discharge rate between
the first and last hole along the lateral.
(B) Minimum hole size shall be 5/32-inch for at least two-thirds of the field lateral lines. Smaller holes (no
less than 1/8-inch) may be used in no more than one-third of the lateral lines where necessary to
balance flow distribution on sloping sites. However, for systems serving restaurants, foodstands, meat
markets and other establishments where effluent is expected to have a high clogging potential, the
minimum hole size shall be 5/32-inch.
(C) Maximum hole spacing shall be as follows: Soil Group I, five feet; Soil Group I1, six feet; Soil Group
III, eight feet; and Soil Group IV, ten feet.
(D) The following design provisions are required for sloping sites:
(i) Separately valved manifolds are required for all subfield segments where the elevation
difference between the highest and lowest laterals exceeds three feet.
(ii) The hole spacing, hole size or both shall be adjusted to compensate for relative head differences
between laterals branching off a common supply manifold and to compensate for the bottom
lines receiving more effluent at the beginning and end of a dosing cycle. The lateral network
shall be designed to achieve a ten to 30 percent higher steady state (pipe full) flow rate into the
upper lines, relative to the lower lines, depending on the amount of elevation difference.
(iii) Maximum elevation difference between the highest and lowest laterals in a field shall not exceed
11 NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 31

ENR - ENVIRONMENTAL HEALTH TISA: 13A .1900
ten feet unless the flow is hydraulically split between subfield segments without requiring
simultaneous adjustment of multiple valves.
' (E) Tum-ups shall be provided at the ends of each lateral, constructed of Schedule 40 PVC pipe or
equivalent, and protected with sleeves of larger diameter pipe (six inches or greater). Tum-ups and
sleeves shall be cut off and capped at or above the ground surface, designed to be protected from
1, damage, and easily accessible.
t( (F) The supply manifold shall be sized large enough relative to the size and number of laterals served so
that friction losses and differential entry losses along the manifold do not result in more than a 15
percent variation in discharge rate between the first and last laterals.
(i) The ratio of the supply manifold inside cross sectional area to the sum of the inside cross
sectional areas of the laterals served shall exceed 0.7:1.
(ii) The reduction between the manifold and connecting laterals shall be made directly off the
manifold using reducing tees.
(iii) Cleanouts to the ground surface shall be installed at the ends of the supply manifold.
(G) Gate valves shall be provided for pressure adjustment at the fields whenever the supply line exceeds
100 feet in length. Valves shall be readily accessible from the ground surface and adequately protected
in valve boxes.
(6) Septic tanks, pump tanks, pump dosing systems, siphons, and siphon dosing tanks shall be provided in
accordance with Rule .1952 of this Section.
(A) Design flow rate shall be based upon delivering two feet to five feet of static pressure head at the distal
end of all lateral lines.
(B) Dose volume shall be between five and ten times the liquid capacity of the lateral pipe dosed, plus the
liquid capacity of the portions of manifold and supply lines which drain between doses.
(b) FILL SYSTEM: A fill system (including new and existing fill) is a system in which all or part of the nitrification
trench(es) is installed in fill material. A fill system, including an existing fill site, may be approved where soil and site
conditions prohibit the installation of a conventional or modified septic tank system if the requirements of this Paragraph
are met.
(1) Fill systems may be installed on sites where at least the first 18 inches below the naturally occurring soil
surface consists of soil that is suitable or provisionally suitable with respect to soil structure and clay
mineralogy, and where organic soils, restrictive horizons, saprolite or rock are not encountered. Further, no
soil wetness condition shall exist within the first 12 inches below the naturally occurring soil surface and a
groundwater lowering system shall not be used to meet this requirement. Fill systems shall not be utilized on
designated wetlands unless the proposed use is specifically approved in writing by the designating agency.
The following requirements shall also be met:
(A) Nitrification trenches shall be installed with at least 24 inches separating the trench bottom and any soil
horizon unsuitable as to soil structure, clay mineralogy, organic soil, rock or saprolite. However, if a
low pressure pipe system is used, the minimum separation distance shall be 18 inches.
(B) Nitrification trenches shall be installed with at least 18 inches separating the trench bottom and any soil
wetness condition. This separation requirement for soil wetness conditions may be met with the use of
a groundwater lowering system only in Soil Groups I and II, with suitable structure and clay
mineralogy. However, if a low pressure pipe system is used, the minimum separation distance shall be
12 inches.
(C) Systems shall be installed only on sites with uniform slopes less than 15 percent. Storm water
diversions and subsurface interceptor drains or swales may be required upslope of the system.
(D) The long-term acceptance rate shall be based on the most hydraulically limiting soil horizon within 18
inches of the naturally occurring soil surface or to a depth one foot below the trench bottom, whichever
is deeper. The lowest long-term acceptance rate for the applicable soil group shall be used for systems
installed pursuant to this Rule. However, the long-term acceptance rate shall not exceed 1.0 gallons per
day per square foot for gravity distribution or 0.5 gallons per day per square foot for low-pressure pipe
systems installed on sites with at least 18 inches of Group 1 soils below the naturally occurring soil
surface or to a depth of one foot below the trench bottom, whichever is deeper.
(E) If the fill system uses low-pressure pipe distribution, all the requirements of Paragraph (a) of this Rule,
except Paragraph (a)(2)(B), shall apply. Systems with a design daily flow greater than 480 gallons per
day shall use low-pressure pipe distribution.
(F) Fill material shall have such soil texture to be classified as sand or loamy sand (Soil Group I) up to the
top of the nitrification trenches. The final six inches of fill used to cover the system shall have a finer
texture (such as Group II, III) for the establishment of a vegetative cover. Existing fill material shall
have no more than ten percent by volume of fibrous organics, building rubble, or other debris and shall
NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 32

ENR - ENVIRONMENTAL HEAL TH TI SA: 18A .1900
u
u
11
11
II
II
11 2
II
u
II
11
II
11
II
n
not have discreet layers containing greater than 35 percent of shell fragments.
(G) Where fill material is added, the fill material and the existing soil shall be mixed to a depth of six
inches below the interface. Heavy vegetative cover or organic litter shall be removed before the
additional fill material is incorporated.
(H) The fill system shall be constructed as an elongated berm with the long axis parallel to the ground
elevation contours of the slope.
(I) The side slope of the fill shall not exceed a rise to run ratio of 1:4. However, if the first 18 inches
below the naturally occurring soil surface is Group I soil, the side slope of the fill shall not exceed a
rise to run ratio of 1:3.
(J) The outside edge of the nitrification trench shall be located at least five feet horizontally from the top of
the side slope.
(K) The fill system shall be shaped to shed surface water and shall be stabilized with a vegetative cover
against erosion.
(L) The setback requirements shall be measured from the projected toe of the slope. However, if this
setback cannot be met, the setback requirements shall be measured from a point five feet from the
nearest edge of the nitrification trench if the following conditions are met:
(i) Slope of the site shall not exceed two percent;
(ii) The first 18 inches of soil beneath the naturally occurring soil surface shall consist of Group I
soils;
(iii) The lot or tract of land was recorded on or before December 31, 1989; and
(iv) A condition is placed upon the Improvement Permit to require connection to a public or
community sewage system within 90 days after such system is available for connection and after
it is determined that 300 feet or less of sewer line is required for connection.
(M) The available space requirements of Rule .1945 of this Section shall apply.
An existing fill site that does not meet the requirements of Paragraph (b)(1) of this Rule may be utilized for a
sanitary sewage system if the following requirements are met:
(A) Substantiating data are provided by the lot owner (if not readily available to the local health
department) indicating that the fill material was placed on the site prior to July 1, 1977.
(B) The fill material placed on the site prior to July 1, 1977 shall have such soil texture to be classified as
sand or loamy sand (Group I) for a depth of at least 24 inches below the existing ground surface. This
fill material shall have no more than ten percent by volume of fibrous organics, building rubble, or
other debris. This fill shall not have discreet layers containing greater than 35 percent of shell
fragments. However, if at least 24 inches of Group I fill material was in place prior to July 1, 1977,
additional fill with soil texture classified as Group I may be added to meet the separation requirements
of Paragraph (b)(2)(D) of this Rule.
(C) Soil wetness conditions, as determined by Rule .1942(a) in this Section, are 18 inches or greater below
the ground surface of the fill placed on the lot prior to July 1, 1977. This requirement shall be met
without the use of a groundwater lowering system.
(D) Low-pressure pipe distribution shall be used and shall meet all the requirements of Paragraph (a) of
this Rule, except (a)(2)(B). The long-term acceptance rate shall not exceed 0.5 gallons per day per
square foot. However, for existing fill sites with 48 inches of Group I soils, conventional nitrification
trenches utilizing a maximum long-term acceptance rate of 1.0 gallons per day per square foot may be
installed in lieu of low-pressure pipe systems. The minimum separation distance between the trench
bottom and any soil wetness condition or any soil horizon unsuitable as to soil structure, clay
mineralogy, organic soil, rock, or saprolite shall be 24 inches for low pressure pipe systems and 48
inches for conventional systems. This separation requirement may be met by adding additional Group I
soil, but shall not be met with the use of a groundwater lowering system. Where fill is to be added, the
requirements of Paragraphs (b)(1)(C), (F), (G), (H), (J), (K), of this Rule and the following
requirements shall be met:
(i) The side slope of the fill shall not exceed a side slope ratio of 1:3, and;
(ii) The setback requirements shall be measured from the projected toe of the slope. However, if
this setback cannot be met, the setback requirements shall be measured from a point five feet
from the nearest edge of the nitrification trench if the following conditions are met:
(1) Slope of the site shall not exceed two percent;
(11) The lot or tract of land was recorded on or before December 31, 1989; and
(111) A condition is placed upon the Improvement Permit to require connection to a public or
community sewage system within 90 days after such system is available for connection
and after it is determined that 300 feet or less of sewer line is required for connection.
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ENR - ENVIRONMENTAL HEALTH TI SA: 18A .1900
'(E) The available space requirements of Rule. 1945 of this Section shall apply.
(F) The design flow shall not exceed 480 gallons per day.
' (3) Other fill systems may be approved by the local health department on a site -specific basis in accordance with
Rule. 1948(d) of this Section.
(c) Individual aerobic sewage treatment units (ATUs) shall be sited, designed, constructed and operated in
accordance with this Rule to serve a design unit with a design flow rate of up to 1500 gallons per day, as determined in
Rule .1949(a) or.] 949(b) of this Section. ATUs shall not be used, however, where wastes contain high amounts of
grease and oil, including restaurants and food service facilities. The strength of the influent wastewater shall be similar
to domestic sewage with Biological Oxygen Demand (BOD) and suspended solids not to exceed'300 parts per million.
ATUs shall comply with the requirements of the National Sanitation Foundation (NSF) Standard 40 for Individual
11 Aerobic Wastewater Treatment Plants and shall be classified as meeting Class I effluent quality. NSF Standard 40 for
Individual Aerobic Wastewater Treatment Plants is hereby incorporated by reference including any subsequent
amendments and editions. Copies of the standards may be inspected in and copies obtained from the Division of
Environmental Health, P.O. Box 27687, Raleigh, N.C. 27611-7687 at no cost. ATUs shall bear the NSF mark and the
NSF listed model number or shall bear the. certification mark and listed model number of a third parry certification
program accredited by the American National Standards Institute (ANSI), pursuant to ANSI Policy and Procedures for
Accreditation of Certification Programs to certify ATUs in accordance with NSF Standard Number 40. The ANSI
Policy and Procedures for Accreditation of Certification Programs is hereby incorporated by reference including any
subsequent amendments and editions. Copies of the standard may be inspected in and copies obtained from the Division
C' of Environmental Health, P.O. Box 27687, Raleigh, N.C. 27611-7687 at no cost. ATUs shall only be permitted where
!! the unit is to be operated and maintained by a certified wastewater treatment facility operator employed by or under
contract to the county in which the unit is located, and in accordance with this Rule.
E (1) ATUs shall be constructed and installed in accordance with the plans which have been approved by the
Division of Environmental Health and shall comply with all requirements of this Rule. Procedures for plan
review and approval shall be in accordance with Rule .1953 of this Section.
(2) The rated capacity of ATUs listed as complying with NSF Standard 40 shall not be less than the design daily
h' flow as determined by Rule .1949(a) or. I 949(b) of this Section.
C (3) The following are minimum standards of design and construction of ATUs:
(A) Boockouts in concrete ATU inlet openings shall leave a concrete thickness not less than one inch in the
plant wall. Inlet and outlet blockouts shall be made for a minimum of four inch pipe and a maximum of
six inch pipe. No blockouts or openings shall be permitted below the liquid level of the ATU. .
(B) The inlet into the ATU shall be a straight pipe.
(C) The invert of the outlet shall be at least two inches lower in elevation than the invert of the inlet.
(D) Interior baffle walls in concrete units shall be reinforced by the placing of six-inch by six-inch No. 10
.gauge welded reinforcing wire. The reinforcing wire shall be bent to form an angle of 90 degrees on
the ends in order to form a leg not less than four inches long. When the wire is placed in the mold, the
four inch legs shall lay parallel with the side wall wire and adjacent to it.
(E) Access openings shall be provided in the ATU top. Access shall be provided for cleaning or rodding
out the inlet pipe, for cleaning or clearing air or gas passage spaces, as an entrance for inserting the
suction hose in compartments that are required to be pumped out, to allow for sampling the effluent,
and for access to repair or maintain any system components requiring repair and maintenance. All
access openings shall have risers sealed to the top of the ATU and extended at least to six inches above
finished grade and designed and maintained to prevent surface water inflow. Rule .1950(i) of this
Section shall also be met. ,
(F) Concrete ATUs shall be constructed in accordance with Rule .1954(a)(9), (10), (1 I) and (12) and
.1954(b)(4) of this Section.
(G) Fiberglass reinforced plastic ATUs shall be constructed with materials capable of resisting corrosion,
from sewage and sewage gases, and the active and passive loads on the unit walls.
(i) ATUs shall have the following minimum physical properties:
Ultimate tensile strength: 12,000 psi
Flexural strength: 19,000 psi
Flexural modulus of elasticity: 800,000 psi
(ii) A vacuum test shall be performed on at least one ATU of each model number by an independent
NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 34

ENR - ENVIRONMENTAL HEALTH TISA: 18A .1900
testing laboratory, in accordance with ASTM D-4021, Standard Specification for Glass -Fiber
Reinforced Polyester Underground Petroleum Storage Tanks, which is hereby incorporated by
I' reference including any subsequent amendments and editions. Copies of the standards may be
inspected in and copies obtained from the Division of Environmental Health, P.O. Box 27687,
Raleigh, N.C. 27611-7687 at no cost. Unit must withstand negative pressure of 2.5 pounds per
square inch (69.3 inches of water) without leakage or failure. Test results shall be included with
the specifications that are provided to the state for approval.
(iii) Composition of the finished unit shall be at least 30 percent fiberglass reinforcement by weight.
Minimum wall thickness shall be one-fourth inch. However, a wall thickness of not less than
three -sixteenth inch may be allowed in small, isolated areas of the ATU.
(iv) Interior and exterior surfaces shall have no exposed fibers or projections, no blisters larger than
one-fourth inch in diameter, and no pores or indentations deeper than one -sixteenth inch. The
tank shall be watertight.
(H) Prefabricated ATUs other than precast reinforced concrete or fiberglass reinforced plastic units shall
be approved on an individual basis based on information furnished by the designer which indicates the
unit will provide effectiveness equivalent to reinforced concrete or fiberglass reinforced plastic units.
(I) ATVs shall bear an imprint identifying the manufacturer, serial number assigned to the manufacturer's
plans and specifications approved by the Division of Environmental Health, and the liquid or working
capacity of the unit. The imprint shall be located to the right of the blockout or opening made for the
outlet pipe on the outside of the unit. ATUs shall also be permanently marked with the date of
manufacture adjacent to the unit imprint or on the top of the unit directly above the imprint.
(J) The design, construction, and operation of ATUs shall prevent bypass of wastewater.
(K) Electrical circuits to the ATU shall be provided with manual circuit disconnects within a watertight,
corrosion -resistant, outside enclosure (NEMA 4X or equivalent) adjacent to the ATU securely
mounted at least 12 inches above the finished grade. Control panels provided by the manufacturer
shall be installed in a watertight, corrosion -resistant enclosure (NEMA 4X or equivalent) adjacent to
the unit or on the side of the facility readily visible from the unit and accessible by maintenance
personnel. Conductors shall be conveyed to the disconnect enclosure and control panel through
waterproof, gasproof, and corrosion -resistant conduits. Splices and wire junctions, if needed, shall be
made outside the ATU in a watertight, corrosion -resistant enclosure (NEMA 4X or equivalent)
securely mounted adjacent to the unit at least 12 inches above the finished grade. Wire grips, duct seal,
or other suitable material shall be used to seal around wire and wire conduit openings inside the ATU
and disconnect enclosure. The ATU shall have an alarm device or devices to warn the user or operator
of a unit malfunction or a high water condition. The alarm shall be audible and visible by system users
and securely mounted adjacent to the ATU, on the side of the facility in clear view of the unit, or inside
the finished occupied space of the facility. If mounted outside, the alarm shall meet NEMA 4X
standards or equivalent. The alarm circuit or circuits shall be supplied ahead of any ATU electrical
control circuit overload and short circuit protective devices.
(4) A settling tank shall be required prior to an ATU serving a design unit with a design daily flow greater than
' 500 gallons, as determined in Rule. I 949(a) or .I 949(b) of this Section. The liquid capacity of the settling
tank shall be at least equal to the design daily flow as determined in Rule .1949(a) or (b) of this Section. The
settling tank may either be an approved prefabricated septic tank or another tank specially designed for a
specific individual aerobic sewage treatment plant and approved by the Division of Environmental Health as a
I, part of the plans for the plant.
(5) Ground absorption systems receiving effluent from approved ATUs may be used on sites classified as suitable
or provisionally suitable for conventional, modified, or alternative systems in accordance with this Section.
The following modifications to siting and design criteria shall be acceptable:
(A) The minimum horizontal setback requirements of Rule .1950(a) of this Section shall be met, except as
follows:
(i) Any private water supply source, except any uncased well or spring ...... 50 feet.
(ii) Streams classified as WS.1....................................... 70 feet.
(iii) Waters classified as SA 70 feet.
(iv Other coastal waters not classified as SA ........................... 35 feet.
(v) Any other stream, canal, marsh, or other surface waters ....:.::..:..::. 35 feet.
(vi) Any Class I or Class II reservoir . 70 feet,
from normal pool elevation.
(vii) Any permanent storm water retention pond .......................... 35 feet,
from flood pool elevation.
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ENR -ENVIRONMENTAL HEALTH T15A: 18A .1900
(viii) Any other lake or pond .......................................... 35 feet,
' from normal pool elevation.
(B) The requirements of Rules .1955(m), A956(1), .1956(2), .1956(6), .1957(b)(1), and .1957(b)(2) of
this Section shall be met, except as follows:
(i) A low-pressure pipe system shall not be required where the separation between the bottom of
' the nitrification trench and any soil wetness condition is at least 12 inches, but less than 18
inches, and more than six inches of this separation consists of Group I soils.
(ii) The restriction in Rule .1956(6)(a)(v) of this Section that saprolite be overlain by at least one
' foot of suitable or provisionally suitable naturally occurring soil shall not apply.
(iii) For new fill systems, a low pressure pipe system shall not be required in order for the minimum
separation distance between the trench bottom and any unsuitable soil horizon, rock, or saprolite
to be reduced to 18 inches.
(iv) For existing fill systems, the minimum separation requirements of Rule .1957(b)(2)(D) of this
Section shall be reduced from 48 to 36 inches for conventional systems and from 24 to 18
inches for low-pressure pipe system.
(C) The maximum long-term acceptance rate shall be increased by 25 percent for any ground absorption
system in soils which are Groups I or II with suitable structure and clay mineralogy. No other
reductions in linear footage of nitrification trench or system area shall be applied, except where based
on an adjusted design daily sewage flow rate granted in accordance with Rule .1949(c) of this Section.
i' (6) Prior to issuance of an Operation Permit for an ATU, the manufacturer or his licensed. representative shall
certify that the unit has been properly installed and a contract for operation and maintenance shall have been
executed between the unit owner and the county in accordance with Rule .1961(b) of this Section. It shall be
a condition of the Operation Permit that subsequent owners of an ATU execute such a contract.
The contract shall include the specific requirements for maintenance and operation, responsibilities for maintenance and
operation, responsibilities of the owner and system operator, provisions that the contract shall be in effect for as long as
the system is in use, and other requirements for the continued proper performance of the ATU.
A condition of the Operation Permit shall be that the unit continue to perform in accordance with Class I effluent quality
requirements of the National Sanitation Foundation (NSF) Standard Number 40 effective on the date the improvement
permit was issued.
(7) Performance monitoring shall be carried out by the operator.
(A) During each inspection, the operator shall confirm proper mechanical performance, conducts visual
check for unusual color, clogging, oily film, odors, foam, measure settleable aeration chamber solids,
' and ascertain the need for removing solids, backwash and cleaning of filters, and other maintenance
I activities. The ground absorption system shall also be inspected and an evaluation of performance
I shall be made. The operator shall take the necessary steps to assure that needed maintenance is carried
out.
(B) Semi-annually, samples shall be collected by the system operator and analyzed by a state -approved
wastewater testing laboratory of the effluent for Five -Day Biological Oxygen Demand, Suspended
Solids, and pH. The aeration tank shall be sampled for mixed liquor suspended solids.
' (C) Performance monitoring results shall be reported to the local health department and the state quarterly.
(D) Remedial action and additional sampling shall be required if monitoring results or inspection indicate
that Class I effluent standards are not met.
History Note: Authority G.S. 130A-335(e), (n; 130A-342,
Eff. July 1, 1982;
Amended Eff. April 1, 1993; May 1, 1991; December 1, 1 990;- January 1, 1990.
I' .1958 NON -GROUND ABSORPTION SEWAGE TREATMENT SYSTEMS
(a) Where an approved privy, an approved septic tank system, or a connection to an approved public or community
sewage system is impossible or impractical, this Section shall not prohibit the state or local health department from
permitting approved non -ground absorption treatment systems utilizing heat or other approved means for reducing the
toilet contents to an inert or stabilized residue or to an otherwise harmless condition, rendering such contents
noninfectious or noncontaminating. Alternative systems shall be designed to comply with the purposes and intent of this
Section.
(b) Holding tanks shall not be considered as an acceptable sewage treatment and disposal system. An improvement
permit shall not be issued for a sewage holding tank for any new construction. However, an Authorization to Construct
may be issued for a holding tank for pumping and hauling of wastewater effluent to a wastewater system approved under
this Section when the owner has provided a showing that a malfunctioning system cannot otherwise be repaired by
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' ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
connection to a system approved under this Section or to a system approved under the rules of the Environmental
Management Commission. Pumping and hauling wastewater effluent shall be performed by a septage management firm
permitted in accordance with G.S. 130A-291.1.
(c) Incinerating, composting, vault privies, and mechanical toilets shall be approved by the state agency or local
health department only when all of the wastewater is handled by a system approved under this Section.
' (d) Sewage recycling systems which discharge treated waste -water meeting the state drinking water standards may be
used only for toilet flushing and recycled sewage shall not be used for body contact or human consumption. Such
systems must be approved by the state or local health department.
(e) Chemical or portable toilets for human waste may be approved in accordance with G.S. 130A-335. Chemical or
portable toilets shall have a watertight waste receptacle constructed of nonabsorbent, acid resistant, noncorrosive
material.
' History Note: Authority G.S. 89C, 89E; 89F; 90A; 130A-335
Eff. July 1, 1982;
Amended Eff. August 1, 1991; January 1, 1990,
Temporary Amendment Eff. January 20, 1997,
Amended Eff. August], 1998.
' .1959 PRIVY CONSTRUCTION
An "approved privy" shall consist of a pit, floor slab, and seat assembly housed in a building which affords privacy
and reasonable protection from the weather.
(1) The pit shall consist of an excavation at least 42 inches square and in no case shall the bottom of an
excavation be closer than one foot from the seasonally high water table or rock.
(2) The pit shall be properly curbed to prevent caving. In sandy or loose soil, the curb should extend the full
depth of the pit. In tight soils, partial curbing is acceptable if it prevents caving.
(3) The privy floor slab shall be constructed of reinforced concrete. Where it is impractical to secure or construct
reinforced concrete floor assemblies, wood construction shall be acceptable provided the floor slab is made of
rough sub -flooring and covered with tight tongue -and -groove flooring or other type flooring materials to
provide strength and prevent entrance of flies and mosquitoes to the privy pit. Where wood construction is
used, floors shall be anchored to at least four -inch by four -inch sills.
(4) Wood used for riser, seat assemblies, and the floor slab shall be tongue -and -groove or plywood (exterior or
marine) material.
I, (5) Privies shall not be used for the disposal of water -carried sewage.
II History Note: Authority G.S. 130A-335(e);
I' Eff. July 1, 1982;
Amended Eff. December], 1990.
.1960 MAINTENANCE OF PRIVIES
(a) Any person owning or controlling the property upon which a privy is located shall be responsible for these
requirements:
(1) The privy building shall afford a reasonable degree of protection from bad weather conditions.
' (2) When the pit becomes filled to within 18 inches of the top of the ground, the privy building shall be moved to
1 a new pit and the old pit completely covered with earth.
I (3) If the pit caves in, a new pit shall be provided.
(b) The tenant or person occupying the property shall be responsible for these requirements:
(1) The walls, floors, and seat of the privy and grounds immediately adjacent to the building shall be kept in a
clean and decent condition.
(2) Fowl and other animals shall not be harbored in the privy building.
( (3) Seat cover shall be hinged and closed at all times when the privy is not in use.
(' (4) Flies shall be excluded from the pit at all times.
(5) Ashes, garbage, and trash shall be kept out of the pit.
11
11
History Note: Authority G.S. 130A-335(e) and (0;
Eff. July 1, 1982;
Amended Eff. January], 1990.
.1961 MAINTENANCE OF SEWAGE SYSTEMS
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ENR - ENVIRONMENTAL HEALTH TI SA: 18A .1900
(a) Any person owning or controlling the property upon which a ground absorption sewage treatment and disposal
' system is installed shall be responsible for the following items regarding the maintenance of the system:
I (1) Ground absorption sewage treatment and disposal systems shall be operated and maintained to prevent the
following conditions:
(A) a discharge of sewage or effluent to the surface of the ground, the surface waters, or directly into
groundwater at any time; or
(B) a back-up of sewage or effluent into the facility, building drains, collection system, or freeboard volume
of the tanks; or
(C) a free liquid surface within three inches of finished grade over the nitrification trench for two or more
observations made not less than 24 hours apart. Observations shall be made greater than 24 hours
after a rainfall event.
The system shall be considered to be malfunctioning when it fails to meet one or more of these requirements,
either continuously or intermittently, or if it is necessary to remove the contents of the tank(s) at a frequency
greater than once per month in order to satisfy the conditions of Parts (A), (B), or (C) of this Paragraph.
Legal remedies may be pursued after an authorized agent has observed and documented one or more of the
malfunctioning conditions and has issued a notice of violation.
(2) Ground absorption sewage treatment and disposal systems shall be checked, and the contents of the septic
tank removed, periodically from all compartments, to ensure proper operation of the system. The contents
' shall be pumped whenever the solids level is found to be more than 1/3 of the liquid depth in any
compartment.
(b) System management in accordance with Tables V(a) and V(b) of this Rule shall be required for all systems
installed or repaired after July 1, 1992. After July 1, 1992, system management in accordance with Tables V(a) and
V(b) shall be required for all existing Type V and Type VI systems.
(c) No Improvement Permit or Construction Authorization shall be issued for Type IV, Type V, or Type VI systems,
unless a management entity of the type specified in Table V(b) is specifically authorized, funded, and operational to
carry out this management program in the service area where the proposed system is to be located.
(d) A local health department may be the public management entity only for systems classified Type IV, V(a) and
V(b) and only when specifically authorized by resolution of the local board of health.
(e) A contract shall be executed between the system owner and a management entity prior to the issuance of an
Operation Permit for a system required to be maintained by a public or private management entity, unless the system
owner and certified operator are the same. The contract shall include the specific requirements for maintenance and
operation, responsibilities of the owner and system operator, provisions that the contract shall be in effect for as long as
the system is in use, and other requirements for the continued proper performance of the system. It shall also be a
condition of the Operation Permit that subsequent owners of the system execute such a contract.
(f) Inspections of the system shall be performed by a management entity at the frequency specified in Table V(b)
The management entity shall report the results of their inspections to the local health department at the specified
reporting frequency. However, where inspections indicate the need for system repairs, the management entity shall
notify the local health department within 48 hours in order to obtain a Construction Authorization for the repairs.
(g) The management entity shall be responsible for assuring routine maintenance procedures and monitoring
requirements in accordance with the conditions of the Operation Permit and the contract.
(h) Sewage systems with multiple components shall be classified by their highest or most complex system type in
accordance with Table V to determine local health department and management entity responsibilities.
(i) Sewage systems not identified in this Rule shall be classified by the Division of Environmental Health after
consultation with the appropriate commission governing operators of pollution control facilities.
6) The local health department shall routinely review the performance and operation reports submitted in' accordance
with Table V(b) of this Rule and shall perform an on -site inspection of the systems as required in Table V(a).
(k) The certified operator shall hold a valid and current certificate from the appropriate commission, and nothing in-
this Section shall preclude any requirements for system operators, in accordance with Article 3 of G.S. 90A.
A
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ENR - ENVIRONMENTAL HEALTH
T1 SA: 18A .1900
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TABLE V(a)
LOCAL HEALTH DEPARTMENT RESPONSIBILITIES
Minimum
System
System
System
Permits
Review
Classification
Description
Required
Frequency
Type I
a. Privy
Improvement
N/A
b. Chemical toilet
Permit, Construction
c. Incinerating toilet
Authorization, and
d. Other toilet system
Operation Permit
e. Grease trap
Type II
a. Conventional septic system
Improvement
N/A
(single-family or 480 GPD
Permit, Construction
or less)
Authorization, and
b. Conventional septic system
Operation Permit
with 750 linear feet of
nitrification line or less
c. Conventional system with shallow
placement
Type III
a. Conventional septic system
Improvement
5 yrs. (IIIb
>480 GPD (excluding single-
Permit, Construction
only)
family residence)
Authorization, and
b. Septic system with single effluent
Operation Permit
pump or siphon
c. Gravity fill system
d. Dual gravity field system
e. PPBPS system, gravity dosed
f. Large diameter pipe system
g. Other non -conventional trench
systems
Type IV
a. Any system with LPP distribution b.
Improvement
System with more than I pump or
Permit, Construction
3 yrs.
siphon
Authorization, and
Operation Permit
a. Sand filter pretreatment system
Improvement
Type V
b. Any >3000-GPD septic tank
Permit, Construction
12 mos.
system with a nitrification field
Authorization, and
designed for > 1500 GPD
Operation Permit
c. Aerobic Treatment Unit (ATU)
d. Other mechanical, biological, or
chemical pretreatment plant
(>3000-GPD)
Type VI
a. Any >3000-GPD system with
Improvement
6 mos.
mechanical, biological or chemical
Permit, Construction
pretreatment system plant
Authorization, and
b. Wastewater reuse/recycle
Operation Permit
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' ENR - ENVIRONMENTAL HEALTH TI SA: 18A .1900
TABLE V(b)
(' MANAGEMENT ENTITY RESPONSIBILITIES
' Minimum System
I System Management Inspection/Maintenance Reporting
Classification Entity Frequency Frequency
Type I
Owner
N/A
N/A
Type lI
Owner
N/A
N/A
I'
j
Type III
Owner
N/A
N/A
Type IV
Public Management Entity
2/yr
12 mos.
with a Certified Operator
('
or a private Certified
Operator
Type V
Public Management Entity
a. 2/yr (0-1500 GPD)
6 mos.
with a Certified Operator
4/yr (1500-3000 GPD)
or a private Certified
12/yr (3000-10000 GPD)
Operator
1/wk (>10000 GPD)
b. 12/yr (3000-10000 GPD)
I/wk (>10000 GPD)
c. 4/yr.
'
d. 12/yr.
Type VI
Public Management Entity
a. 1/wk (3000-10000 GPD)
3 mos.
with a Certified Operator
2/wk (10000-25000 GPD)
I'
3/wk (25000-50000 GPD)
5/wk (>75000 GPD)
b. 12/yr
(1) A sewage collection, treatment, and disposal system that creates or has created a public health hazard or nuisance
I' by surfacing of effluent or discharge directly into groundwater or surface watdrs, or that is partially or totally destroyed
shall be repaired within 30 days of notification by the state or local health department unless the notification otherwise
specifies a repair period in writing. If a system described in the preceding sentence has for any reason been
disconnected, the system shall be repaired prior to reuse. The state or local health department shall use its best
professional judgement in requiring repairs that will reasonably enable the system to function properly. If, for any
reason, a sewage collection, treatment, and disposal system is found to be nonrepairable, or is no longer required, the
system shall not be used, and may be required to have any contents removed, collapse any components and backfill, or
I otherwise secured as directed by the authorized agent to protect the public health and safety.
(m) When necessary to protect the public health, the state or local health department may require the owner or
controller of a malfunctioning system to pump and haul sewage to an approved wastewater system during the time
Ineeded to repair the system.
History Note: Filed as a Temporary Amendment Eff. July 3, 1991, for a period of 180 days to expire on
December 30, 1991;
Filed as a Temporary Amendment Eff. June 30, 1990, for a period of 180 days to expire on
December 27, 1990;
Authority G.S. 130A-335(e),10;
I Eff. July 1, 1982;
Amended Eff. August 1, 1991; October 1, 1990; January 1, 1990; August 1, 1988,
Temporary Amendment Eff. January 20, 1997,
Amended Eff. August], 1998.
11 NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 40

(' ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
.1962 APPLICABILITY
I' The provisions of this Section shall not apply to properly functioning sewage collection, treatment, and disposal
systems in use or for which a valid permit to install a system has been issued prior to July 1, 1977. This provision is
applicable only where the sewage flow and sewage characteristics are unchanged. This provision does not affect the
requirements for system operation, maintenance, and management in accordance with Rule .1961 of this Section.
I' History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
Amended Eff. August], 1991; December 1, 1990.
.1963 DISUSE OF SEWAGE SYSTEM
I' History Note: Authority G.S.130A-335(e);
Eff. July 1, 1982;
Repealed Eff. August 1, 1981
(, .1964 INTERPRETATION AND TECHNICAL ASSISTANCE
(a) The provisions of this Section shall be interpreted, as applicable, in accordance with the recognized principles and
I' practices of soil science, geology, engineering, and public health.
(b) The State will provide technical assistance. Local health departments may obtain technical information and
assistance from appropriate personnel as may be needed for interpretation of this Section.
I, History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
Amended Eff. January], 1990.
I' .1965 APPEALS PROCEDURE
Appeals concerning the interpretation and enforcement of the rules in this Section shall be made in accordance with
G.S. 150B and 10 NCAC I B.
History Note: Authority G.S. 130A-335(e);
Eff. July 1, 1982;
Amended Eff. February 1, 1987.
.1966 SEVERABILITY
If any provision of these Rules or the application thereof to any person or circumstance is held invalid, the remainder
of the rules or the application of such provisions to other persons or circumstances shall not be affected thereby.
History Note: Authority G.S. 130A-335(e);
I' Eff. July 1, 1982.
.1967 INJUNCTIONS
I' A person who violates any rule of this Section is subject to the injunctive relief provisions of G.S. 130A-18.
History Note: Authority G.& 130A-335(e);
Eff. July 1, 1982;
Amended Eff. January], 1985.
.1968 PENALTIES
A person who violates any rule of this Section is subject to the penalty provisions contained in G.S. 130A-22(c)
(Administrative Penalties), 130A-23 (Suspension and Revocation of Permits), and 130A-25 (Criminal Penalties).
I' History Note: Authority G.S. 130A-335(e); -
Eff. July 1, 1982;
Amended Eff. January 1, 1985.
11
1969 EXPERIMENTAL AND INNOVATIVE SYSTEMS, COMPONENTS, OR DEVICES
Experimental and innovative (E & I) systems are any wastewater systems, system components, or. devices that are not
11 NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 41

' ENR ENVIRONMENTAL HEALTH TI SA: 18A .1900
specifically described in Rules .1955, .1956, .1957, or .1958 of this Section, including any system for which reductions
' are proposed in the minimum horizontal or vertical separation requirements or increases are proposed to the maximum
long-term acceptance rates of this Section. This Rule shall provide for the approval and permitting of E & I systems.
(1) An application shall be submitted in writing to the State for an E & I system. The application shall include the
' following, as applicable:
(a) specification of the type of approval requested as either innovative, experimental or both;
(b) description of the system, including materials used in construction, and its proposed use;
(c) summary of pertinent literature, published research, and previous experience and performance with the
system;
(d) results of any available testing, research or monitoring of pilot systems or full-scale operational systems
conducted by a third party research or testing organization;
' (e) identity and qualifications of any proposed research or testing organization and the principal
investigators, and an affidavit certifying that the organization and principal investigators have no
conflict of interest and do not stand to gain financially from the sale of the E & I system;
(f) objectives, methodology, and duration of any proposed research or testing;
' (g) specification of the number of systems proposed to be installed, the criteria for site selection, and
system monitoring and reporting procedures;
(h) operation and maintenance procedures, system classification, proposed management entity and system
operator;
(i) procedure to address system malfunction and replacement or premature termination of any proposed
research or testing; and
(j) notification of any proprietary information, system, component, or device.
I' (2) The State shall review all applications submitted and evaluate at least the following:
(a) the completeness of the application, and whether additional information is needed to continue the
review;
(' (b) whether the system meets the standards of an innovative system under Paragraph (3) of this Rule, or
whether the system meets the standards of an experimental system under Paragraph (4) of this Rule, as
applicable.
(3) INNOVATIVE SYSTEMS: Innovative systems shall be reviewed and approved by the State, and the local
I' health department may permit innovative systems in accordance with the following:
(a) The State shall approve the system as an innovative system if the following standards have been met;
(i) The system, shall have been demonstrated to perform equal or superior to a system, which is
(' described in Rules .1955, .1956, .1957 or.] 958, based upon controlled pilot -scale research
studies or statistically -valid monitoring of full-scale operational systems.
Materials used in construction shall be equal or superior in physical properties and chemical
durability, compared to materials used for similar proposed systems, specifically described in
I' Rules .1955, .1956, .1957 or .1958. -
(b) When a system is approved as innovative by the State, the applicant shall be notified in writing. Such
notice shall include any conditions for use, monitoring, and operation.
(' (c) A local health department shall issue an Improvement Permit for any innovative system approved by
the State upon a finding that the provisions of this Rule including any conditions are met. Use of an
innovative system and any conditions shall be described on the Improvement Permit and the Certificate
of Completion or Operation Permit.
I (4) EXPERIMENTAL SYSTEMS: A system may be approved for use as an experimental system as part of a
research or testing program which has been approved by the State. The research or testing program shall be
conducted by a third party research or testing organization which has knowledge and experience relevant to
(' the proposed research or testing and has no conflict of interest and does not stand to gain financially from the
sale of the proposed system.
(a) To be approved by the State, the proposed research or testing program shall include the following:
(i) The research program shall be designed such that, if the objectives are met, the system would
satisfy the standards for approval as an innovative system under Paragraph (3) of this Rule.
(ii) Research design and testing methodology shall have a reasonable likelihood of meeting the
objectives.
I, (b) The State shall notify the applicant and the applicable local health departments when the proposed
research or testing program has been approved for an experimental system. Such notice shall include,
but not be limited to, conditions for siting, operation, monitoring and maintenance, and number of
(' systems which can installed.
(c) A local health department may issue an Improvement Permit for an experimental system when the
I' NORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 42

' ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
following conditions are met:
' (i) There is an application for an Improvement Permit in accordance with Rule .1937(c) of this
Section, with the proposed use of an experimental system specified.
(ii) The proposed site is included as part of an approved research or testing program and any
conditions specified for use of the system have been met.
(iii) When an experimental system is proposed to serve a residence, place of business or place of
public assembly, there shall be a repair area using a non -experimental backup system in
accordance with the provisions of Rule .1945(b) of this Section, except:
' (A) When an existing and properly functioning wastewater system is available for immediate
use, including connection to a public or community wastewater system; or
(B) When the experimental system is used as a repair to an existing malfunctioning system;
' or
(C) When the experimental system is to serve a vehicular, portable structure built on a
chassis and designed to be used as a residence, place of business, or place of public
assembly without a permanent foundation, in which case sufficient available space shall
' be reserved for the installation of a replacement system at least equal to the initial
experimental system.
(iv) When an experimental system is proposed which shall not serve a residence, place of business,
' or place of public assembly, a repair area or backup system shall not be required.
(v) The application for an experimental system shall include statements that the property owner is
aware of its experimental nature, that the local health department and State do not guarantee or
warrant that these systems will function in a satisfactory manner for any period of time, and that
use of the system may need to be discontinued if the system malfunctions and is found to be non -
repairable, or if the proposed research or testing program is prematurely terminated. Such
statements shall be signed by the owner.
' (vi) The owner of the site on which an experimental system is proposed shall execute a easement
granting rights of access to the system at reasonable hours for monitoring and evaluation to the
research or testing organization. This easement shall specify that it is granted for the purposes
of researching and testing an experimental wastewater system and shall remain valid as long as
' the system is to be part of the proposed research or testing program. The easement shall be
recorded with the county register of deeds.
(vii) Provisions shall be made for operation and maintenance of the system.
' (viii) Any special conditions required for the installation of the experimental system shall be specified
in the Improvement Permit. Use of an experimental system and any conditions shall be
described on the Improvement Permit and any subsequent operation permits, with provisions for
a repair area and backup system specified. A condition of the Improvement Permit shall be that
the installation be under the direct field supervision of the research or testing organization.
(ix) The proposed Improvement Permit and any subsequent operation permits for experimental
systems shall be reviewed by the State and found to be consistent with the approved research or
testing program prior to issuance by the local health department.
j 1 (d) Upon completion of the installation and prior to use, an Experimental System Operation Permit (ESOP) shall be
issued by the local health department. The ESOP shall be valid for a specified period of time not to exceed five years.
Special maintenance, monitoring and testing requirements shall be specified as permit conditions, in accordance with the
!' approved research or testing program. Failure to carry out these conditions shall be grounds for permit suspension or
revocation.
(e) Prior to expiration of the ESOP and based upon satisfactory system performance as determined during the
I' research or testing program, the local health department shall issue an Operation Permit. Premature termination of the
research or testing program shall be grounds for ESOP suspension or revocation.
(f) Upon completion of monitoring, research and testing, the research or testing organization shall prepare a final
I' report including recommendations on future use of the system. If the State determines that the results indicate that the
standards of Paragraph (3) of this Rule are met, the State shall approve the use as an innovative system.
(5) Any proposed changes or modifications in the E & I system shall be submitted for review and approval by the
I' State.
(6) The State shall suspend or revoke the approval of an E & I system upon a finding as follows:
(a) The information submitted in the application is falsified.
(b) subsequent experience with the system results in altered conclusions about system performance or
I' design.
(7) Suspension or revocation of an E & I System approval shall not affect systems previously installed pursuant to
INORTH CAROLINA ADMINISTRATIVE CODE 01121199 Page 43

' ENR - ENVIRONMENTAL HEALTH T15A: 18A .1900
the approval.
' History Note: Authority G. S. 130A-335(e), (n; 130A-343;
_ Eff. April 1, 1993.
�J
I� ..
I�
I�
I�
I' NORTH CAROLINA ADMINISTRATIVE CODE 01/21/99Page 44

APPENDIX E
Dare County
Soil Characteristics

M
Appendix E
Soil Characteristics
Dare County, North Carolina
Soil Type
Symbol
Soil Name
Slope
Sanitary Facility Rating
Permeability
High Water Table Depth
(Feet)
Hydric
Condition
Depth (In) Inches/Hour
Sanderling/Duck
BnD
Beaches-Newhan complex
0 to 25 percent
Not rated.
Not available.
Not available.
No
COB
Corolla fine sand
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
CuA
Currituck mucky peat
0 to 1 percent
Severe: flooding, wetness,
poor filter.
0-40
40 - 65
0.6 - 6.0
6.0-20.0
+1 -1.0
Yes
DtA
Duckston fine sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 20
0 -1.0
No
DuE
Dune land
2 to 40 percent
Severe: poor filter, slope.
0 - 60
> 20
> 6.0
No
DwE
Dune land-Newhan complex
2 to 40 percent
Severe: poor filter, slope.
0 - 60
> 20
> 6.0
No
FrD
Fripp fine sand
2 to 30 percent
Severe: poor filter, slope.
0 - 80
6.0-20
> 6.0
No
NeC
Newhan fine sand
0 to 10 percent
Severe: poor filter.
0 - 80
>20
> 6.0
No
OsA
Osier fine sand
0 to 2 percent
Severe: wetness, poor filter.
0-3
3 - 80
6.0-20
>20
0 -1.0
Yes
Colington
CnA
Conaby muck
0 to 2 percent
Severe: wetness.
0 - 14
14-60
0.2 - 2.0
2.0-6.0
0 -1.5
Yes
COB
Corolla fine sand
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
CuA
Currituck mucky peat
0 to 1 percent
Severe: flooding, wetness,
poor filter.
0-40
40 - 65
0.6 - 6.0
6.0-20.0
+1 - 1.0
Yes
FrD
Fripp fine sand
2 to 30 percent
Severe: poor filter, slope.
0 - 80
6.0-20
> 6.0
No
OsA
Osier fine sand
0 to 2 percent
Severe: wetness, poor filter.
0-3
3 - 80
6.0-20
>20
0 -1.0
Yes
OuB
Ousley fine sand
0 to 5 percent
Severe: flooding, wetness,
poor filter.
0 - 80
6.0-20
1.5 - 3.0
No
PSB
Psamments
0 to 6 percent
I Not rated.
----
----
----
No
North Roanoke IslandlManteo
BaC
Baymeade fine sand
1 to 10 percent
Severe: poor filter.
0 - 32
32-46
46-80
6.0-20
2.0-6.0
6.0-20
4.0 - 5.0
No
BvA
Belhaven muck
0 to 2 percent
Severe: wetness, peres
slowly.
0 - 38
38 - 47
47-72
0.2 - 6.0
2.0 - 6.0
0.2-0.6
0 -1.5
Yes

Appendix E
Soil Characteristics
Dare County, North Carolina
Soil Type
Soil Name
Slope
Sanitary Facility Rating Permeability
High Water Table Depth
Hydric
Symbol
Depth (In) Inches/Hour
(Feet)
Condition
I
North Roanoke Island/Manteo (continued)
FrD
Fripp fine sand
2 to 30 percent
Severe: poor filter, slope.
0 - 80
6.0 - 20
> 6.0
No
HoA
Hobonny muck
0 to 1 percent
Severe: flooding, wetness.
0 -16
0.6 - 6.0
+1 - 0
Yes
16-72
0.6-2.0
IcA
Icaria loamy fine sand
0 to 2 percent
Severe: wetness..
0 -12
0.6 - 6.0
0 -1.0
Yes
12-33
0.6-2.0
33-72
2.0-6.0
JoA
Johns loamy sand
0 to 2 percent
Severe: wetness, poor filter.
0 -13
2.0 - 6.0
1.5 - 3.0
No
13-26
0.6-2.0
26-72
6.0-20.0
LeA
Leon fine sand
0 to 2 percent
Severe: wetness, poor filter,
0 - 15
6.0 - 20.0
0 -1.0
flooding.
15 - 23
6.0 - 20.0
23-72
0.6-6.0
OsA
Osier fine sand
0 to 2 percent
Severe: wetness, poor filter.
0-3
6.0 - 20
0 - 1.0
Yes
3 - 80
>20
OuB
Ousley fine sand
0 to 5 percent
Severe: flooding, wetness,
0 - 80
6.0 - 20
1.5 - 3.0
No
poor filter.
PoA
Ponzer muck
0 to 2 percent
Severe: wetness, peres
0 - 24
0.06 - 2.0
0 -1.0
Yes
slowly.
24 - 57
0.2 - 2.0
57 - 72
----
PsB
Psamments
0 to 6 percent
Not rated.
----
----
----
No
South Roanoke Island/Wanchese
BaC
Baymeade fine sand
1 to 10 percent
Severe: poor filter.
0 - 32
6.0 - 20
4.0 - 5.0
No
32-46
2.0-6.0
46-80
6.0-20
BvA
Belhaven muck
0 to 2 percent
Severe: wetness, peres
0 - 38
0.2 - 6.0
0 -1.5
Yes
slowly.
38 - 47
2.0 - 6.0
47-72
0.2-0.6
FrD
Fripp fine sand
2 to 30 percent
Severe: poor filter, slope.
0 - 80
6.0 - 20
> 6.0
No
HoA
Hobonny muck
0 to 1 percent
Severe: flooding, wetness.
0 -16
0.6 - 6.0
+1 - 0
Yes
16-72
0.6-2.0
IcA
Icaria loamy fine sand
0 to 2 percent
Severe: wetness.
0 -12
0.6 - 6.0
0 -1.0
Yes
12-33
0.6-2.0
33-72
2.0-6.0

M
Appendix E
Soil Characteristics
Dare County, North Carolina
Soil Type Soil Name Slope Sanitary; Facility Rating
Symbol
Permeability
High Water Table Depth
(Feet)
Hydric
Condition
Depth' (In)
Inches/Hour
South Roanoke Island/Wanchese (continued)
JoA
Johns loamy sand
0 to 2 percent
Severe: wetness, poor filter.
0 -13
13-26
26-72
2.0 - 6.0
0.6-2.0
6.0-20.0
1.5 - 3.0
No
LeA
Leon fine sand
0 to 2 percent
Severe: wetness, poor filter,
flooding.
0 -15
15 - 23
23-72
6.0-20.0
6.0-20.0
0.6-6.0
0 -1.0
OsA
Osier fine sand
0 to 2 percent
Severe: wetness, poor filter.
0-3
3 - 80
6.0-20
>20
0 -1.0
Yes
OuB
Ousley fine sand
0 to 5 percent
Severe: flooding, wetness,
poor filter.
0 - 80
6.0-20
1.5 - 3.0
No
PoA
Ponzer muck
0 to 2 percent
Severe: wetness, peres
slowly.
0 - 24
24 - 57
57 - 72
0.06 - 2.0
0.2 - 2.0
----
0 - 1.0
Yes
PsB
Psamments
0 to 6 percent
Not rated.
----
----
----
No
Rodanthe/Waves/Salvo
Rodan
BnD
Beaches-Newhan complex
0 to 25 percent
Not rated.
Not available.
Not available.
No
CeA
Carteret sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 6.0
+3.0 -1.0
Yes
CoB
Corolla fine sand
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
CrB
Corolla-Duckston complex
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
DtA
Duckston fine sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 20
0 - 1.0
No
NeC
Newhan fine sand
0 to 10 percent
Severe: poor filter.
0 - 80
> 20
> 6.0
NhC
Newhan-Corolla complex
0 to 10 percent
Severe: poor filter.
0 - 80
>20
> 6.0
No
Avon
BnD
Beaches-Newhan complex
0 to 25 percent
Not rated.
Not available.
Not available.
No
CeA
Carteret sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 6.0
+3.0 -1.0
Yes
CoB
Corolla fine sand
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
CrB
Corolla-Duckston complex
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
DtA
Duckston fine sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 20
0 - 1.0
No

= = = M
Appendix E
Soil Characteristics
Dare County, North Carolina
Soil Type
Symbol
Soil Name Slope
Sanitary Facility Rating
Permeability High Water Table Depth
Depth (In) Inches/Hour (Feet)
Hydric
Condition
Avon (continued)
NeC
Newhan fine sand
0 to 10 percent
Severe: poor filter.
0 - 80
>20
> 6.0
No
NhC
Newhan-Corolla complex
0 to 10 percent
Severe: poor filter.
0 - 80
>20
> 6.0
No
PsB
Psamments
0 to 6 percent
Not rated.
---
---
----
No
Buxton/Frisco
BnD
Beaches-Newhan complex
0 to 25 percent
Not rated.
Not available.
Not available.
No
CnA
Conaby muck
0 to 2 percent
Severe: wetness.
0 -14
14-60
0.2 - 2.0
2.0-6.0
0 - 1.5
Yes
CeA
Carteret sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 6.0
+3.0 -1.0
Yes
CoB
Corolla fine sand
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
CrB
Corolla-Duckston complex
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
CuA
Currituck mucky peat
0 to 1 percent
Severe: flooding, wetness,
poor filter.
0 - 40
40 - 65
0.6 - 6.0
6.0-20.0
+1 - 1.0
Yes
DtA
Duckston fine sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 20
0 -1.0
No
DwE
Dune land-Newhan complex
2 to 40 percent
Severe: poor filter, slope.
0 - 60
> 20
> 6.0
No
FrD
Fripp fine sand
2 to 30 percent
Severe: poor filter, slope.
0 - 80
6.0-20
> 6.0
No
NeC
Newhan fine sand
0 to 10 percent
Severe: poor filter.
0 - 80
>20
> 6.0
No
NhC
Newhan-Corolla complex
0 to 10 percent
Severe: poor filter.
0 - 80
>20
> 6.0
No
OsA
Osier fine sand
0 to 2 percent
Severe: wetness, poor filter.
0-3
3 - 80
6.0-20
>20
0 -1.0
Yes
OuB
Ousley fine sand
0 to 5 percent
Severe: flooding, wetness,
poor filter.
0 - 80
6.0-20
1.5 - 3.0
No
PsB
Psamments
0 to 6 percent I
Not rated.
----
----
----
No
Hatteras -
BnD
Beaches-Newhan complex
0 to 25 percent
Not rated.
Not available.
Not available.
No
CeA
Carteret sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 6.0
+3.0 -1.0
Yes
CoB
Corolla fine sand
0 to 6 percent
Severe: wetness, poor filter.
0 - 75
> 20.0
1.5 - 3.0
No
DtA
Duckston fine sand
0 to 2 percent
Severe: flooding, wetness,
poor filter.
0 - 80
> 20
0 - 1.0
No
NhC
Newhan-Corolla complex
0 to 10 percent
I Severe: poor filter.
0 - 80
>20
> 6.0
No

Appendix E
Soil Characteristics
Dare County, North Carolina
Soil Type
Symbol
Soil Name Slope
Sanitary Facility Rating
Permeability
High Water Table Depth
(Feet)
Hydric
Condition
Depth (In)
Inches/Hour
Hatteras (continued)
OuB
Ousley fine sand
0 to 5 percent
Severe: flooding, wetness,
0 - 80
6.0 - 20
1.5 - 3.0
No
poor filter. .
PsB
Psamments
0 to 6 percent
Not rated.
----
----
----
No
Manns Harbor
BaC
Baymeade fine sand
1 to 10 percent
Severe: poor filter.
0 - 32
6.0 - 20
4.0 - 5.0
No
32-46
2.0-6.0
46-80
6.0-20
BvA
Belhaven muck
0 to 2 percent
Severe: wetness, peres
0 - 38
0.2 - 6.0
0 -1.5
Yes
slowly.
38 - 47
2.0 - 6.0
47-72
0.2-0.6
CuA
Currituck mucky peat
0 to 1 percent
Severe: flooding, wetness,
0 - 40
0.6 - 6.0
+1 -1.0
Yes
poor filter.
40 - 65
6.0 - 20.0
HoA
Hobonny muck
0 to 1 percent
Severe: flooding, wetness.
0 -16
0.6 - 6.0
+1 - 0
Yes
16-72
0.6-2.0
IcA
Icaria loamy fine sand
0 to 2 percent
Severe: wetness.
0 -12
0.6 - 6.0
0 -1.0
Yes
12-33
0.6-2.0
33-72
2.0-6.0
JoA
Johns loamy sand
0 to 2 percent
Severe: wetness, poor filter.
0 -13
2.0 - 6.0
1.5 - 3.0
No
13-26
0.6-2.0
26-72
6.0-20.0
LeA
Leon fine sand
0 to 2 percent
Severe: wetness, poor filter,
0 -15
6.0 - 20.0
0 -1.0
flooding.
15 - 23
6.0 - 20.0
23-72
0.6-6.0
PsB
Psamments
0 to 6 percent
Not rated.
----
---
----
No
RpA
Roper muck
O to 2 percent
Severe: wetness, peres
0 -13
0.2 - 6.0
0 -1.0
Yes
slowly.
13 - 34
0.2 - 0.6
34 - 72
----

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
APPENDIX F
Charlotte -Mecklenburg Stormwater Services
Credit Application
Instruction Manual

CITY OF CHARLOTTE
STORM WATER SERVICES
=i
CREDIT APPLICATION
INSTRUCTION MAN -UAL
Charloffe-Mecklenburg
END, STOR-q
WATER.
Services
URS PA r, INC,
J

May 16, 1994 '
A note to recipients of the Charlotte-Mwklenburg Storm Water Services Credit Application '
Manual:
This is the first revision of the City of Charlotte Storm Water Services Credit Application that '
contains the basis, procedures, and technical support for a professional to understand and
complete a credit application. As with the first version of the Credit Application Manual, this '
manual is not intended to be all inclusive and should be used as a general guide. With the need
to make editorial changes due to the recent consolidation of the City and County Storm Water
Programs, technical changes were made based on approximately one year of it's application in '
the Citv of Charlotte. Other engineering references, previous engineering experience and sound
engineering judgement must complement this manual to allow the applicant to properly fulfill
the requirements of the application procedure.
The Charlotte -Mecklenburg Storm Water Services staff looks forward to working with the '
County's design professionals in preparing and approving your future credit applications.
Sincerely, ,
James W. Schumacher, P.E. W. Dave Canaan
Charlotte Storm Water Manager Associate Director of Engineering '
L

I
CHARLOTTE-MIECKLEN13URG
STORM WATER SERVICES
CREDIT APPLICATION
INSTRUCTION MANUAL
I

CHARLOTTE -ME C KLENB UR G
STORM WATER SERVICES
CREDIT APPLICATION
INSTRUCTION MANUAL
'
Prepared For
City of Charlotte Storm Water Services
'
Prepared By
Ogden Environmental and Engineering Services, Inc.
Charlotte, NC
,
December 14,1992
Revised 05/16/94
'

SECTION 1: E IMODUCTORY MATERLAL
Charlotte -Mecklenburg Storm Water Services has elected to provide a credit toward reducing
a ratepayer's storm water user fee. This manual provides information, instructions and an
application form for applying for the credit.
It is organized as:
Section 1: Introductory Material
Section 2: Definitions
Section 3: Policies and Procedures
Section 4: Technical Procedures
Section 5: Example Credit Computations
Section 6: Forms and Checklist
When it rains a certain portion of the rainwater runs off from all proper -des into the channels,
pipes, and streams of Mecklenburg County. Property development increases the por•Lion of
runoff and creates a negative impact on the drainage system. This increase in runoff (and thus
the negative impact) is generally proportional to the amount of impervious area the developed
property has.
The storm water fee a property
owner pays is also proportional to
the amount of impervious area on
a given property. Therefore the
credit is 'also developed to be
proportional to the effective
reduction in impervious area.
Storm water runoff primarily
impacts a drainage system
through:
• increases in peak floe';
• increases in the total volume of runoff; and
• increases in pollution runoff.
Therefore the crediting system allows for credit to be Gained for reductions in each of these tnre_-
areas. In order to keep the credit system more simple than it otherwise could be with a more
"exact" methodology, these thre: impacts have been reduced to three easy -to -understand criteria
standards which still gua ranter real reductions in impact because they have a basis in technical
fact. The runoff peal:, volume or pollution load calculated is the total from the whole site and
f the location of controls. Care should be t :en to determ;ne
r,ot simply the total at the point 01,7
the physical location or reference point at the site outlet(s) where calculations will be made.

SECTION 2: DEFIINZTIONS
Best management practices (BMPs):
Biochemical oxygen demand (BOD):
CMSWS:
Design storm:
Detention:
Detention time:
Directly Connected impervious Area:
Extended Detention Basin:
Forebay:
Freeboard:
Structural controls and/or non-structural controls
that temporarily store or treat urban storm water
runoff to reduce flooding, remove pollutants, and
provide other amenities.
The quantity of oxygen consumed during the
biochemical oxidation of matter over a specified
period of time.
Charlotte -Mecklenburg Storm Water Services.
A rainfall event of specified size and return
frequency that is used to calculate the runoff
volume (e.g., a storm that occurs on the average
once every 2 years) and peak discharge rate (e.g.,
a storm that occurs on the average once every 10
years) to a BMP.
The temporary storage of storm runoff in a BMP,
which is used to control the peak discharge rates,
and which provides gravity settling of pollutants.
The amount of time water actually is present in a
BMP. Theoretical detention time for a runoff event
is the average time water resides in the basin over
the period of release from the BMP.
The impermeable area within the watershed which
enters the drainage system without traveling across
permeable surfaces, i.e. roof surfaces which drain
through roof drains directly into the storm sewer
system.
A structural BMP which holds storm water for a
lengthened period of time in order to reduce peak
discharge and enhance water quality by allowing
particulates to settle out.
An extra storage area provided near an inlet of a
BMP to trap incoming sediments before they
accumulate in a pond BMP.
The space from the top of an embankment to the
highest water elevation expected for the lamest

.a
:I.' design storm stored. The space is required as a
safety margin in a pond or basin.
� C-1 A computer program, developed by the li.S..�.-rsny
Corps of Engineers which allows the user to
generate hydrographs by simulating the watersheds
' response to precipitation.
Hydrograph: A °raph showing variation in the water depth or
discharge in a stream or channel, over time, at a
specified point o^ interest.
.� Impervious area (imperviousness): Impermeable surfaces, such ' as pavement or
rooftops, (but not gravel driveways) which prevent
the infiltration of water into the soil.
Initial losses: The amount of rainfall not transformed into runoff
-;� due to interception, ' depression storage, and
a
infiltration.
Lag time:
The increment of time from the center of mass of
rainfall to the peak- of the hydrograph (may be
assumed to be 0.6 * time of concentration).
-
Low flow channel:
A paved channel from inlet to outlet in a dry basin
which is designed to carry low runoff flows and/or
baseflow, directly to the outlet without detention.
IN, PDES:
National Pollutant Discharge Elimination System
regulations for storm water discharges as described
in the Federal Register 40 CFR Parts 122, 123, and
124.
Peak discharge:
The maximum instantaneous rate of flow during a
storm, usually in reference to a specific design
storm event.
Pilot channel:
A riprap or paved channel that routes runoff
through a BMP to prevent erosion of the surface.
Retention:
The holding of runoff in a basin without release
except by means of evaporation, infiltration, or
emergency bypass.
r __:rout:
To install a new BMP or improve an existing BNMP
'
in a previously developed area.
Return frequency:
A statistical tern: for the average time of expected

interval that an event of some kind will equal or '
exceed given conditions (e.g., a storm water flow
that occurs on the average every 2 years).
Riprap: A combination of large stones, cobbles, and '
boulders used to line channels, stabilize banks,
reduce runoff velocities, or filter out sediment. '
Riser: A vertical pipe extending from the bottom of a pond
BMP that is used to control discharge rate from a ,
BMP for a specified design storm.
Runoff coefficient: Ratio of runoff to precipitation. '
SCS: Soil Conservation Service.
Soil group, hydrologic: A classification of soils by the Soil Conservation
Service into four runoff potential groups. The
groups range from A soils, which are very '
permeable and produce little runoff, to D soils,
which are not very permeable and produce much '
more runoff.
Spillway: A depression in the embankment of a pond or basin '
which is used to pass peak discharge greater than
the maximum design storm controlled by the pond.
Structural control: A constructed device that temporarily stores or '
P Y
treats urban storm water runoff to reduce flooding
and/or remove pollutants. '
Time of concentration: The time required for surface runoff from the most '
remote part of a drainage basin to reach the basin
outlet.
Wemond: A structural BMP which retains storm water runoff t
in a permanent pool for water quality enhancement
by settling pollutants.
R

SECTION 3: POLICIES AND PROCEDURES
It is ClviSWS's intent to encourage sound technical design practices which reduce the negative
impact of development on the drainage system through a simple but effective crediting system.
Credits will be granted for any combination of peak, volume and/or pollution reduction. Cn
policies have been developed to help maintain this balance between simplicity and effectiveness.
Further questions on these brief policy statements should be directed to CMSWS.
Single Family Residences L Credit will be allowed for all properties except
individual single-family residential Properties. Credits
can be granted in extraordinary situations for single-
farnily residences through the appeals process. Credit
' will not be allowed for any properties which do not
pay a storm water fee.
Maintenance Requirements 2. Credit will only be allowed for properties which
maintain their structural controls in fully functional
condition and according to maintenance criteria and
BMP standards issued by CMSWS.
a ZZistin, Structure Credits
3. Credit will be allowed for previously constl-ucmd
_
controls. The amount or credit -ranted will be
determined by the methods of design as outlined within
the body of this document.
-;, Industrial NPDES Permits
4. The full pollution portion of the credit will be granted
,_and Credits
to those industries which must obtain and do mainntain
an NPDES permit for storm water runoff from the
A
State.
watershed Protection Wet
5. Each customer maintaining an approved Best
Ponds and Credits
Management Practice (BMP- wet pond) in accordance
with local watershed regulations for any developed
land will receive full credit for the water quality
portion of the charge.
Property Location
6. Credit will not be granted solely on the basis of
location of a given property in relation to a major
stream, river or within a watershed.
_Joluntary Controls 7. For new developments, credit will be granted where
C."iSWS requires controls to be consLructed andror
maintained. Other voluntary controls or upgrades of
existing systems through retrofitting will be granted
credits on a case -by -case basis, as determined by
,'MrApplicapon Inc-

CMSWS, considering the impact of the controls on the
drainage system. '
Percent Credits 8. A maximum of 100 percent of the user fee can be
granted in credit with a maximum of: '
• 50 percent of the fee for peal: reduction;
• 25 percent of the fee for volume reduction; and '
• 25 percent of the fee for pollution reduction.
Types of Structural BMPs 9. Pollution credit will be granted for extended detention ,
basins and wet ponds. Credit may be granted for other
control devices on a case -by -case basis providing
sufficient technical justification is available to make '
such determinations.
Regional Basins 10. Credit will not be granted to properties draining into a
regional basin maintained by CMSWS. Credit will be
granted for privately owned and maintained regional
'
controls and will be apportioned among owners on a
prearranged basis.
'
A eals 11. An appeal must be initially filed in writing with the
PP PP Y b
Charlotte Storm Water Manager for those customers
within the City. An appeal must be initially filed in
'
writing with the Mecklenburg County Storm Water
Manager for those customers outside the City. Should
satisfaction not be achieved, an appeal may be lodged
'
with the Charlotte -Mecklenburg Storm Water Citizens
Advisory Committee.
'
Timing of ADalications 12. It is the intent of CMSWS that all applications will be
reviewed and credits determined within thirty days
'
after submittal of a complete and correct application
package. The credit will be effective on the 1st billing
cycle for the property following completion of
'
construction. However, applications for locations
outside of the City limits submitted to the Mecklenburg
County Storm Water Manager by 12/31/94 will receive
'
credit retroactively to the first billing of service
charges.
'
L
Credit Application Inst.-uetion %janual Hare - 6

PROCEDURES FOR STJBINUTTAL
' New Developments
,�I Submitt...l of credit calculations for
new developments will occur as
par of the normal development
and subdivision procedures' in
' two steps as indicated in the box
at the right.
&-isring Controls
Existing controls should be
r�
maintained to the standard in
existence at the time they were
constructed. Coordination with
the En&ineering Departments
should be done if there are any
- questions concerning the
applicable standards.
Retrofit of Fxisring Controls
Retrofit of existin- stl--uctures is a
two-step process similar to that of
new developments.
A
r,
" i
F
Sec the Charlonc-MccUcnbu a Dc�cloper Handbook available from the City or the Couruv,
Vpp6cariuo Iz_f ructioC

SECTION 4: TECHNICAL PROCEDURE
Technical Criteria The credit is based on: peak, volume, and pollution runoff. I
Credit Distribution
"Effective" Imperviousness
• The 10-year, 6-hour storm is used for peak
runoff (in cubic feet per second).
• The total accumulated runoff volume for the 2-
year 6-hour storm is measured at the 12th hour
to determine the volume credit.
• Annual pollutant loadings (in pounds per year)
for BOD5, Total Phosphorous and Lead (one-
third credit for each) are the standards for
pollutant reduction.
The distribution of the credit is:
• Fifty (50) percent for peak reduction credit;
• Twenty-five (25) percent for volume reduction
credit;
• Twenty-five (25) percent for pollution reduction
credit.
of
vZ
zo
rvt
Q3
O
U
_o
OU
PEAK FLOW,
> t
L:
v
VOLUME
t
OP. Q2
t
POLLUTANT
LOAD
t I
1 I
Q1
I
I � 1
------+-------1
I1
1 I
112 1
I3
PERCENT IMPERVIOUS
The figure above illustrates the credit calculation concept in
which:
• Il is the impervious area without development
(always assumed to be zero).
• Q1 is the pre -development peak, volume or
pollution runoff.
• I3 and Q3 are the post -development peaks,
volumes or pollutant loadings without any
H
n
C
Credit Application l=tructioo ,,i=u-d page -

' controls in place.
• I2 is the "effective imperviousness" which
results from controls reducing peak, volume or
' pollution runoff from Q3 to some lesser value
Q2.
• The property owner will pay a fee based on the
"effective" impervious area I2 rather than the
actual impervious area I3.
Uedir Calcularion Eouarions The goal is to find I2, the effective impervious area which
matches Q2. This procedure assumes that each of tine credit
factors (peak, volume and pollutant load) can be approximated
as varying linearly with the percent impervious. Equating
triangfes and solving for I2 yields an effective impervious
value and a credit percentage:
' I2 = (Q2-Q1)(13)/(Q3-Ql) (1)
_{ Credit Percent = 100 * (1-I2/I3) (2)
This calculation is done for peek, volume, and pollution if
7
credit is sought for all three factors. Credit may be applied
in only one or two of these areas as appropriate. Examples in
a later section illustrate this procedure.
To obtain the actual credit for any of the three impacts the
Credit Percent is multiplied by the available credit. Since
T fifty percent of the total monthly fee is available for the peak
credit the Credit Percent for peak flow would be multiplied by
0.50. For both volume and pollution reduction the Credit
Percent would be multiplied by the maximum credit available
a which is twenty-five percent of the monthly fee or 0.25.
4 ree Conditions: To obtain storm water user fee creditsit will be necessary to
Undeveloped develop and submit certain supporting documentation as listed
Fully Developed on the credit application checklist (Section 7).
Wirhour Controls
Fully Developed With Calculation of credit is based on impact reduction in three
Controls. areas: peak, volume and pollution.. Credit may be earned in
any or all of these three areas. Analysis are necessary for
each area to develop data and information for three conditions
to find I2: (1) undeveloped conditions (Q1, I1); (2) fully
developed conditions without controls (Q3, I3); and (3) fully
developed conditions with controls (Q2). The next swtions
detail the necessary procedures.
II7. L,': "U❑ L- ruCGOa Ntan,;:.; p.Ve - 9 -

PEAK CREDIT CALCULATION
STEP 1: Calculate the 10-year, 6-hour storm runoff peak -for undeveloped conditions.
This should be done using an approved method from chapters 3.0 (Hydrology)
and 7.0 (Storage and Detention). This gives Q1. Remember that the runoff
calculated is the total runoff from the site, not simply the runoff at the point of
the controls.
A "balanced storm approach" as described in the HEC-1 model documentation is
recommended for these calculations. Other methods described in this manual will also
be accepted. The following inputs into the HEC-1 model and the resulting rainfall
distribution for the 10-year, 6-hour storm as given below should be used if the designer
chooses the model HEC-1 for the hydrologic calculations. The distribution of rainfall is
similar to the Soil Conservation Service's distribution of rainfall shown in chapter 3.0
(Hydrology). The total depth is 3.72 inches.
10-YEAR, 6-HOTJR BALANCED STORM RAINFALL DISTRIBUTION
Time Interval
5 min
15 min I . 1 hour I 2 hour
3 hour
6 hour
Rainfall depth (in)
0.59
1.26 I 2.36 I 2.90
3.21
3.72
STEP. 2: Calculate the 10-year, 6-hour storm total runoff for fully developed conditions
without any controls in place and measure the total impervious area.
This should be done using the same storm information but with appropriately
adjusted runoff coefficients and lag or travel times. This gives Q3 and I3.
STEP 3: Inserr designed controls for the fully developed condition and route the I0-year, 6-
hour storm through the controls. Calculate the controlled runoffpeak.
Remember that to be eligible for credits any controls must meet both the policy criteria
given above and design criteria detailed elsewhere in this manual. This gives Q2.
STEP 4: Calculate the credir j5-om eguarions 1 and 2.
Remember that the peak credit can be up to 50 percent of the monthly drainage
fee.
H
E
H
C
Credit Application Instruction Manual page - 10 -

!I
VOLUME CREDIT CAI,CUTLAMN
When a site is developed the total volume of runoff from the site increases. The basis of
the volume credit is to hold on -site for 12 hours the additional volume of runoff c: used
by development. For example (see figure below), assume the total volume of runoff over
a 12 hour period for an undeveloped site was 10 acre-feet. If after development the total
volume of runoff after 12 hours was 15 acre-feet it would indicate that an additional 5
acre-feet of runoff was generated because of site development. In order to receive 100 co
volume credit, the 5 acre-feet of runoff generated by development must still be held on
site after 12 hours. This is accomplished by designing a basin with sufficient volume and
low discharge rate such that with continual discharge from the start of runoff the basin
still holds 5 acre-feet of waster after 12 hours.
PCs, Development w/o Controls
r Vol= "5QC-F .
to
L .
vPre Development
3
l= 10 nC-Ft
0 Post Developnen; w/ Controls
_j /—Vol= 10 CC -Ft
L
12 hrs volume cFter 12 hours measured
TIME (min) — From la test star-, of runoFF.
11 STEP 1: Calculate the hydrooraph for the 2-year, 6-hour storm for undeveloped corkrions.
Acc.: nula1e the total volume of runof.15-om the stare of the storm for a period of I
Twelve hours of runofr.
Make sure that you calculate the runoff for a period of twelve (12) hours from
the start of runoff from the 2-year, 6-hour storm. This may require a calculation
period longer than 12 hours to allow for initial losses. This gives Ql in the
volume calculation.
Either acre-feet or inches of runoff is a convenient unit of measure. The total can be
obtained by summing the ordinates of the hydrograph and applying a suitable conversion
factor.
• Volume, ac-ft = (flow at each time step, cfs)(60 sec/l min)(1 acre/43,560
ft=)(time step, min)
'L"' ^PPCCUoa 1tLZllcdoa \mull -.

Depth, in = r(flow at each time step, cfs)(60 sec/1 min)(12 in/1 ft)(1
acre/43,560 ft=)(1/area, acres)(6me step, min)
A "balanced storm approach" as described in the HEC-1 model documentation is
recommended for these calculations. Other methods described in this manual will also
be accepted. The following inputs into the HEC-1 model and the resulting rainfall
distribution for the 2-year, 6-hour storm, as given below, should be used if the designer
chooses the model HEC-1 for the hydrologic calculations. The total depth is 2.28 inches.
It is similar to the SCS storm distribution.
2-YEAR, 6-HOL-R BALANCED STORM R4L-N7'ALL DISTRIBUTION
Time Interval 5 min '15 min I 1 hour I 2 hour 3 hour 6 hour
Rainfall depth (in) I 0.42 I 0.83 1.45 I 1.76 I 1.95 2.28
=EP 2: Calculate the hydro0 ph for the 2-year, 6-hour storm for fully developed conditions
without controls. Accumulare the total volume of runofffrom the srarr of the storm
for a period of twelve hours of runot, and measure the impervious area.
All three of the hydrographs must have the same time basis... the 12-hour period must
start at the same time from the latest beginning of runoff. This will generally be the
undeveloped hydrograph since runoff starts later than for developed conditions. This step
gives Q3 and I3.
STEP 3: Calculate the 2-year, 6-hour hydrograph for fully developed conditions with controls.
Accumulare the total volume of runoffrom the start of the storm for a period of
twelve hours of 2nofr.
J
This is the total runoff hydrograph at the outlet.of the site. It includes the runoff from ,
the controls as well as runoff which may not flow through the controls. This is Q2.
STFP Y . Calculate the credit from equations 1 and 2.
Remember that the volume credit can be up to 25 percent of the monthly drainage fee.
Credit AppGca000 Instructioa `tanual page - 12 -

'
POLLUTION CREDIT CALCULATION
' Introduction
The calculation ' of pollution reduction depends on the
;�.
estimation of annual loads and reduction in those loads based
on standard designs for certain best management
(BMPs). Although, without actual measured data, :his
calculation may not have high accuracy in predicting actual
'
pollution runoff per storm, it is considered sufficiently
accurate and consistent for the calculation of credits.
The T-nree Consriruenrs
Three constituents have been chosen for pollution reduction
credits because of their different origins, impacts on the
aquatic ecosystem, and the numerous different struc-mral
controls that can be used to reduce their concentrations:
;,r
• Lead - a common measure of toxic once metal
production;
• BODS - a measure of the easily available bio-
chemical oxygen demand of such things as
leaves and debris; and
• Total Phosphorous - a measure of nuuient
loading and normally the limiting nutrient in
lake eutrophication.
Merhodology
The method (termed the Simple Method) and much of the
information is derived from several sources most notably
Schuelerl and The EDGe Group'-. The annual loadings in
Charlotte to be used for credit calculations based on overall
,.
percent imperviousness are given in the attached table. The
"undeveloped" value is to be used for all undeveloped
calculations. Exceptions to these standard values can be made
on a case -by -case basis.
,1
1
1
edit AppL'rspoa La LrWtion Al tzl page- L:

ANN JAL PER ACRE LOADINGS FOR CHARLOTTE' -
Land Type
Approximate
Percent
Pollutant Loading, (lbs/ acre per
Zoning
Impervious
year)
CIassifications
Pb
BOD5
TP
Undeveloped
No
< 6
0.004
1
0.07
Classification
Rural Residential
No
6
0.017
5
0.23
Classification
Low Density
R-1 -
12
0.025
7
0.36
Residential
Medium Density
R-4
30
0.050
14
0.73
Residential
High Density
R-22MF
60
0.093
26
1.34
Residential
Medium Density
0-3
75
0.114
32
1.65
Non -Residential
Hicrh Density I-1, I-2 90 0.142 40 2.06
Non -Residential
STEP 1: Calculate the pollutant loading for each of the three constituents for on -site
undeveloped conditions. Calculate any off -site loadings based on existing conditions.
This is done simply by multiplying the total on -site area in acres by the
"Undeveloped" value taken from the table. Additionally, multiply any off -site
area in acres by the pollutant loading corresponding to the existing oft" -site percent
impervious. Add both products to determine QI for each of the three -
constituents.
E
I STEP 2. Calculate the on -sire fully developed poliu:ant load without controls for each of the II
three constituents.
This is done by multiplying the annual unit load values taken or interpolated from
the table for the percent imperviousness (I3) by the total on -site area in acres.
A weighted percent impervious is warranted unless there are parts of the
development which have a distinctly different character, in which case it is
Credit Appl;=tjoo Instruction M=uzl page - 14 - '
n.. .....ti... I, 1"0

i
appropriate to make two calculations and add the two together. Also add any off -
site loadings calculated in step one. This is Q3 and I3.
S �P 3: Calculate the total pollutant load for the fully developed condition with the controls
in Place.
From the plan for implementation of controls determine the part of the flow Qoing,
throu-h each control and its corresponding percent imperviousness. Determine
the loadin- coin- to that control. Determine its percent effectiveness for each
constituent (see next section) and reduce the toil load coming, out of it on an
annual basis by that amount. Add all the loads coming to the outlet(s) of the site.
This is Q2 for each of the three constituents.
fI STEP 4: Calculate the credit from equations 1 and 2.
Remember that the total credit can be 25 percent of the total monthly user fee
_L proportioned 1/3 for each constituent).
' STCP S: Develop description of BMP, documentation and maintenance requirements.
For all non-standard BMPs (including modifications on standard BMPs) full
documentation and back -round must be supplied upon which you relied for
r determination of pollutant reductions. Maintenance planning must be supplied
and (if retluested)' a monitoring plan. In all cases, plans and specifications must
be supplied according to CMSWS guidance for ;radina and dr4ina;e plans and
normal detention.
E
c AppLi-tion page - 14

POLLUTION REDUCTION CA.LCU7LATTONS '
Inrroducrion The development of types of Best Management Practices
(BIv1P) and information on the effectiveness of BMPs in ,
removing pollutants is in a state of constant change. CMSWS
is concerned with maintaining the flexibility for designers to
develop and use new innovative BMPs and modifications to '
old systems.
Standard Designs: Initially credits will be granted automatically only for wet
We! Ponds (retention) ponds and extended detention ponds which meet the
• Exrended Derenrion criteria in the attached Standard Specifications for BMPs. The '
Ponds indicated credit will be automatically granted for BMPs
meeting these standard criteria and falling among the volume
criteria given. In order to obtain additional credit the designer '
must provide CMSWS evidence that controls contain features
which further remove pollution or evidence, through sampling
and monitoring, that a standard design has exceptional '
capabilities.
BMP EFFECTIVENESS AT RENIOVING MENT=D POLLUTANTS
Percent Removal
BMP
Design Criteria
TP BOD Pb
1. Wet Pond
Pool volume = 0.5 inch storage per impervious acre,
50 30 30
Vff (see below).
2. Wet Pond
Pool volume = 2.5 * volume of runoff from mean
50 30 70
storm event, Vm (see below).
3: Wet Pond
Pool volume = 4.0 * volume of runoff from mean
70 50 70
storm event, Vm (see below).
4. Extended Detention
Runoff volume from a half inch storm released after
30 30 50
12 hours, Vh (see below).
5. Extended Detention
Runoff volume from a one inch storm released after
50 50 70
24 hours, V 1 (see below).
6. Extended Detention
Runoff volume from a one inch storm released after
70 50 70
24 hours with bottom marsh (minimum drainage area
of 10 acres), V 1 (see below).
7. Watershed
Pool volume = 4.0 - volume of runoff from mean
100 90 pollution
Protection
storm event, Vm (see below). Additionally, the
credit - no
discharge rate following a 1.0 inch storm shall be
pollutant loading
such that the basin volume does not draw down to the
calculations
permanent pool level in less than 2 days and does not
required.
exceed a maximum vertical distance of 2 feet.
0
71
7
u
DesiZn 1. The "impervious acreage" is all impervious area draining to the control. '
The volume Vff is the "first -flush" volume from this acreage and can be
calculated as:
Cr-i;t APPLI-ation lascruction Manual page - 16 - ,

'
Vff = (A.,Pj(0.12 in)
where:
'
A.P,u = area of impervious (acres)
The remainin- storm volumes (Designs 2, 3, 4, 5 and 6) can be estimated, for the
purposes of credit calculations, based on the SCS runoff curve number method as
described in National Engineering Handbook, Section 4.0. Hydrology' or from the runoff
procedures outline in Controlling Urban Runoff' '.
SCS Formula:
'
For pervious area and unconnected P _ impervious (i.e., a paved parlan- lot that
r-
drains by sheet flow to' a grassed area)
Q = (P - Ij2 /[(P - Ij S] P > 0.2S
which reduces to:
Q = (P - 0.2S)2/(P : 0.8S)
where:
runoff (in)
P = rainfall (in)
:.
S = potential maximum retention after runoff begins (in),
_ (1000/CI) - 10
I, = initial abstraction (in),
'
= 0.2S for pervious area and unconnected impervious area
Other research has found that the discharges are underestimated for connected impervious
area in small urban watersheds by the SCS method. The losses for connected impervious
area are typically in the range of 0.1 inch instead of the 0.2S as used in the previous
formula. Therefore, for all connected impervious area calculations, in accordance to the
losses described in Applied Hydrology and Sedimenrology for Disturbed Areas`, the
following formula should be applied:
For connected impervious area
Q = (P - 0.1)
where:
Q = runoff (in)
P = rainfall (in)
.� Controlling Urban Runo 2formula:
R, = 0.05 _ 0.009(I)
ApDi+:aoon tasL-u. iou `11n�i1

where: '
Rr = storm runoff (in) / storm rainfall (in)
I = percent of watershed imperviousness (ro)
vn The mean storm in Charlotte based on National Weather Service '
Desi _ s ,
2. 3. & 7. information is 0.64 inches. The volume from the mean storm event can ,
be calculated with SCS methodologies as:
Vm = {[(0.64 - 0.2Sper)2]A➢,J(0.64 + 0.8S;,r) '
[(0.64 - 0.1)]A:,=�}(0.0833) 0)
0.2SPCr < 0.64 '
where:
Sp<r = (1000/CNPI-r) - 10 (Note: when the vailue of CNp,r is low '
the initial abstraction/maximum retention (0.2SP,r) may be greater
than the storm event and therefore there will be no runoff. In such
cases the first term of equations 3, 4, and 5 will be zero.) ,
Aj., = area of directly connected impervious (acres)
Apar = area of watershed without the directly connected impervious
(acres) '
CNper = curve number of the watershed without the directly
connected impervious in acres. This will include the impervious ,
area which is not directly connected to the system.
Similarly, the volume of the mean storm event can be calculated with the I
Rr method as:
Vm = (0.64)[0.05 + 0.009(I)](A)(1 ft/ 12 in)
where:
I = percent of watershed imperviousness
-A = total watershed area (acres)
The volumes for designs 2 and 3 are 2.5 and 4.0 times the mean storm '
volume.
Design 4. The volume for the half -inch storm event can be calculated as: '.
Vh = {[(0.50 - 0.2Sper)2]A;,.r/(0.50 - 0.8Sper) ,
+ [(0.50 - 0.1)] k:=Pl (0.0833) (4)
0.2SNr < 0.50 '
Similarly, the volume of the one-half inch storm event can be calculated
with the Rr method as: '
Vh = (0.50)[0.05 . 0.009(I)](A)(1 ft/ 12 in) '
Cre6t App"- lion Instruction 1Lwuaj page - 18 -

s
7
1
where:
I = percent of watershed imperviousness (io)
A = total watershed area (acres)
DesiL,ns The volume for the one -inch storm event can be calculated as:
5 & 6.
VI = {[(1.00 - MSPCr)']A,(1.00 0.8Sper)
[(1.00 - 0.1)1Ap}(0.0833) (5)
0.2S,Cr < 1.00
Similarly, the volume of the one inch storm event can be calculated with
the Rr method as:
Vh = (1.00)[0.05 0.009 j)](A)(1 ft/ 12 in)
where:
I = percent of watershed imperviousness (io)
A = total watershed area (acres)
The volume required in design 4 must be stored for 12 hours prior to being released.
The volume required in designs 5 and 6 must be stored for 24 hours prior to being
released.
Vff = Half inch of runoff from the impervious area. (acre-feet)
Vm = Volume of runoff from the mean storm (acre-feet)
Vh = Volume of runoff from the half inch storm (acre-feet)
V1 = Volume of runoff from the one inch storm (acre-feet)
■

Credit APPUc-3 ioo lnsL-uctioa :Manual R1C 20

I
Po, i .... Credit' 6n
-f4 -n CCCCrv- n =,A • r\^
-Summary
Peak- credit = 100%
Volume credit = 0%
Pollution credit = 057o
Total credit = (1005'o)(0.50) (0%)(0.25) + (05ro)(0.25) = 50%
APP6-600 burruction \I.irmn' fl.1

Example n2
Basic Information. Example design considerinza peak control and pollution control required for
the watershed protection regulations '
• Site area - 124.6 acres
• Pre -developed land use - woods
• Developed land use - commercial (percent impervious - 65 ro)
rl
I -
Creti';c Application laswctioa Manual 11 1

......... . .
Pollution
ution '6r.ed-lt-CaI6,61ation
Crei!k Ap,,,L�catjor. In, —inn v -

Summary
'
Peal: credit = 99.7 %
'
Volume credit = 26.47o
Pollution credit = 52.2 7c
'
Total credit = (99.7 %)(0.50) - (26.4 %)(0.25) (52.2 %)(0.25) = 69.517o
'
Cred;t
Applic-rion Insuvcdon NI -La l
page .d -

' Example r3
Basic Information. Example design attempting to maximize available credit.
• Site area - 16.0 acres
• Pre -developed land use - woods and open area
' • Developed land use - institutional (percent impervious - 38 io)
1
1
l
i
1
1
1
.....:,
1 Woo o;' the fatal at allable
Application _: ,:.

Credit AppGcatioo page 26 - '

Summary
Peak- credit = 100%
Volume credit = 10OFo
Pollution credit = 60.9%
Total credit = (10OFo)(0.50) (1005,'c)(0.25) (60.9%)(0.25) = 90.2%
75-,I,t Ap;:i; jocj IL,—Uctitlll -1 e - -

SECTION 7: FORMS .4-ND CHECKLIST
The next three pages contain forms and checklists to assist in applying for the credit.
• Credit Application Form - basic information summary about the project.
• Credit Application Instructions - to accompany the form.
• Credit Application Checklist - used by the reviewer to check the application packet.
The application packet should consist of the application form on top followed by pertinent
drawinEs and calculations sufficient io fully evaluate both the site and the proposed controls.
Maintenance provisions, schedule, and responsible parses must be specified for each control
proposed.
Cniu AppGration I_c---action \1.1n1:::1
pure -

Aoolicant Information (Financially Responsible
Name•
CHARLOTTE-i• IE C KL.EINB LR G
STORM WATER SERVICES
CREDIT APPLICATION FOP.,
Person): (Please print or tune)
-. �.
Aidr:ss:
City:
State:
t
Zip Code:
Telephone:( )
Owner's Reoresentative (Enginezr/Landscane Architect):
'
Name•
Address:
City:
Zip Code:
State:
Telephone:( )
Registration Number (PE or RLA):
Proiect Information:
y'
Name of Project:
Address'
Tax Number:
'
Property Size (acres):
Brief Description of Storm Water Structures Responsible for Effective Impervious Reduction:
>
lImpervious.Percentage:
+ruhxlopod: ` p-t:
Q/pu1 vi co ugl.:
``�
vp.�,de slope!• VpW:
`y
vyou _/ aaoue•
Load p� �;O , : Load,,,.
Load,,,
LoadsoD;,,;tee: Loada0Dpo.1
Loadsonpo., .
-'
LoadTP-,-.�1w,,: Loads:
=.u�6:
Load? r
Requested Credit Percentage:
,,
r
1
The above information is true and correct to the best of ray knowledge and belief. . �s form must be signed by
the rinaricially responsible person if an individual, or if not an individual by an officer, director, parmer, or
registered agent with authority to execute instruments for the financially responsible person). I agree to provide
corrected information should there be any change in the information provided herein.
Type or print name Title or Authority
Signature
Date
a Notary Public of the Countv of ,State of North Carolina,
hereby certify that appeared personally before me this day and being sworn
acknowledged that the above form was executed by hire.
Witness my hand and notarial seal, this day o
, 19_
Notary
My commission expires
Designer's Certification:
Existing conditions are W reasonably close conformance to the conditions refl��.ted in the calculations.
Si_c-yr:ature and Seal of P.E. or R.L.A.
:i; Application

CREDIT APPLICATION CHECKLIST I
General Plan Reouirements '
Seal and signature of designer (PE or RLA). '
Property boundaries.
Scale (minimum 1"=100').
Vicinity Map. '
North arrow.
Site Drainage Features
Adjoining lakes, streams, or other major drainage ways. ,
Existing and proposed contours, interval less than A.01
.
SCS soil types. '
Impervious delineations and labels (buildings, driveways, etc.).
Drainage area map, including off -site areas draining through the site.
Delineation of floodway fringe and encroachment areas, where applicable.
Size and location of all storm water structures.
Hvdrologic Hvdraulic and Pollution Calculations
Hydrologic calculations for undeveloped and developed land uses for the 2-year, 6 hour and '
10-year, 6-hour storm event.
Hydraulic calculations showing stage -discharge relationships of structural controls.
Pollutant loading computations for undeveloped and developed land use. '
Pollution reduction calculations.
Structural control routings
Credit computations.
Construction Details '
As -built details of existing structures. ,
Construction drawing and details of proposed controls.
Maintenance
Maintenance schedule of all operations that affect the efficiency of the structural conr'ols '
including mowing, sediment removal, etc.
page - 32•

Scbueler, T. R., "Controlling urban Runoff.' Metropolitan Wasbi.ngtou Council of Govern.rnents, 1576
Eve St., N.W.. Suite 200, Washington, D.C., 20006. (202-962-3200), July 1957.
2. The EDGe Group (Ogden Environmental &'Engineering Services, Inc.), "Mountain Island Lake Best
Management Practices Feasibility Srudv,' 1989.
3 United States Department of Agriculture, Soil Conservation Service, 'National Engineering Handbook,'
Section 4.0, Hydrology.
4 Barfield, B.J.; Warner, R. C.; and Haas, C. T., -Applied Hydrology and Sedimentology for Disturbed
Areas, ' OUaboma Tecbnical Press, 815 Hillcrest, Stillwater, Oklahoma, 19081.
1
1

STANDARD SPECIFICATIONS FOR BMPs
I
11
14

STA..NDARD SPECIFICATIONS FOR B�IPs
CMSWS desires that all water quality BMPs be designed and constructed to allow for
ease of maintenance, effectiveness of operation and aesthetic appearance. Minimum
standards for such design are given below. Optional ideas for further increasing the
pollution removal capability or improving the appPtuance or effectiveness of the BMP
are also given. Deviations from the specifications are permitted on a case -by -case basis.
-t
i
F
STA2NDARD SPBCIrICATIONS FOR EXTENDED DETENTION BASINS
REQUIRED SPECIFICATIONS
•
Pilot channel of paved or concrete material
•
Side slopes shall be no greater than 3:1 if mowed.
•
Inlet and outlet located to maximize flow length.
•
Design for full development upstream of control.
•
Rip -rap protection (or other suitable erosion control means) for the outlet and all
inlet structures into the pond.
•
One-half foot minimum freeboard above peak stage for top of embankment for
design storm.
•
Emergency spillway designed to pass the 50-year storm event (must be paved in fill
areas).
•
Maintenance access (< 15 ro slope - 10 feet wide).
• •
Trash racks, filters or other debris protection on control.
•
Anti -vortex plates.
•
Benchmark for sediment removal.
RECOMINIENDED SPECIFICATIONS
•
Two stave design (top stage - dry during the mean storm, bottom stage - inundated
during storms less than the mean storm event.)
•
Top stage shall have slopes between 2 % and 5 S.
•
Bottom stage maintained as shallow wetland or pool (6' to 12").
•
Manage buffer and pond as meadow.
•
Minimum 25-foot wide buffer around pool.
•
On -site disposal areas for two sediment removal cycles.
•
Anti -seep collars on barrel of principal spillway.
•
Imper .-ions soil boundary.
The r,gure on the next page presents a typical extended detention pond built in two
' st?ges.

SCHEMATIC OF TYPICAL EXTENDED DETENTION POND -
TQP VIEW
rror7o
burrtn
`
]S• uul.
(w,oSC ( ./tar uurntwu,tt
,.r.
(VO477KuU71
1CRI iSCS.S11RUBS. MID TREES)
i —
oonac suGc
i
?KI VnJ. SlOr•C —
TOP STAG(
(aoRUACIr oar �
r
I11
PILOT c7wurarcnn[ DR rArlo)
1�So llWEtwro
on vooL
SIADIU2E0
t uur , S •E
a1SER _
1
u1LEEs
U1
S )ABA L I ZU.
(nIF'R/U)
•`outrA
- - -
4-IF
/
I- `--" � -
��t Sim nor[S —
Bonou SIAGE
3:1 MAX
10:1 Ur,.
StvuOW maxsIt FOR OCSIGII #I (Ir-W DE(P)
EWWOKN[rR SIWl IkK At LUST
RKCA ./ 0.5 f601 OE PAIR D0AR0 AOOvE
OESIGII STORM WATER SURFACE ELCVATIOU 17oo0 - EuERG(IICY SPILLWAY
Rrt IOW - - - - r�airlw .W ulu.luallul�alulvaY.1) - - - - - - CCXLS [S
IAA,NTAIIIEO CRASS —/ 171 OR GREATER SLOPE FOR OR/d,WGE
DOtfou A SUE SLOPES
ACCEPT R7R Ita r�WLVuE kt/
Slit
SIDE VIEW Or uwl SIORu [1RjCjSEDT KD GRAKL AICKCT (TIP.)
COtnROWIIC URDAII RVIOrT 1 HOT 10 SCALE
r r r r r r r rr r r rr rr rr r� r rr r rr rr

ST�-NDAP.D SPECIFICATIONS FOR WET PONDS
REQUIRED SPECIFICATIONS
'
•
Minimum length to width ratio of 2:1 (preferably wedge shaped).
•
Inlet and outlet located to inaximize flow length.
',
•
•
Minimum depth of permanent pool 2.0 feet, maximum depth of 10.0 feet.
Design for null development upstream of control.
•
Side slopes shall be no greater than 3:1 if mowed.
.a
•
Rip -rap protection (or otbtr suitable erosion control means) for the outlet and all
'
inlet structures into the pond.
•
Minimum drainage area of 10 acres.
•
Anti -seep collars on barrel of principal spillway.
-'
•
One-half foot minimum freeboard above peal; stage for top of embankment.
•
Emergency drain; i.e. sluice gate, drawdown pipe; capable of draining structure
within 24 hours.
•
Emergency spillway designed to pass the SO -year storm event (must be paved in fill
areas).
'
•
Trash racks, filters, hoods or other -debris control on riser.
•
Maintenance access (< 15 S slope and 10 feet wide).
•
Benchmark for sediment removal.
•
Paved or concrete channel.
RECOMIN4ENDED SPECIFICATIONS
'
•
•
Multi -objective use such as amenities or flood control.
Landscaping management of buffer as meadow.
•
Design for multi -function as flood control and extended detention.
•
Minimum length to width ratio of 3:1 to 4:1 (preferably wedge shaped).
•
Use reinforced concrete instead of corrugated metal.
•
Sediment forebay (often designed for 10-20% of total volume). Forebay should have
separate drain for de -watering.
•
Provision shall be made for vehicle access at a 4:1 slope.
•
Impervious soil boundary to prevent draw -down.
•
Shallow marsh are-, around fringe (including aquatic vegetation).
•
Safety bench at toeof slope (minimum 10 feet wide).
•
Minimum 25 foot wide buffer around pool.
•
Mow embankment and side slopes at least twice a year.
•
Emergency drain to allow draw --down within 24 hours.
•
On -site disposal areas for r-o sediment removal cycles prote„^ted from rtnoff.
•
An oil and greease skimmer for sites with high production of such pollutants.
The figure
on the next page presents a typical wet pond design.
n

SCHEMATIC OF TYPICAL WET POND
TOP VIEW
ItAlr E SIIRVDS H+0 IRCCS
PWII[D rOR •A'4DUIE CMA
AROVIIO IVLr Or Po11O's PERIUE1ER +^L`14 � 9-A
�j1 cRAsscoWy
2� t TALL rtSCUC
stoutswEtr 110401 ; C� tsY;U<<�4
n1'pOR'wEUI t:l Atto[ or SLOPE ♦ s fi A. 4 1 .r3
?�it•
>.t�i�;. � A � '+1¢141111u1Ra 10 �,`\�. t i �••i;
V.
/:S'F1 110 MISS OH
YILET }T .?1; w�•{'a�• r pTL'A .. t.�� S _ •` 1 kisr1'p!�•1+
>, +1y OVICALL PROTECh011
. •SCO Ilff URGE RMRM
Tor+caAr y DArn[ {!1
�•h1`'" -hj :•a .\: �. . •lRsRISER
194k1 .. /I1000-�
� •+ '►o` ! " 1 Y. Gp,4C'$ i ROCK otn[cTons
•:. • AS NCO'D
�`✓,1�) ,`p pu 3s root m0C �•j ! . r i p l )
i�A/(/h11f.•�uLtz>�1�:��•
rh fi• r!r\t , r _ �i' txw11
Eutr+cu+cr
--•"�i• �•_ _.aAi �lA�`fl 1�,1� . /! tiV .Mi 7, SPILLWAY
RESERVE off -SITE:
DISPOSAL AREA to"
(t MIMED SCOIM".
1RAS11 11000
_ - _ _ - - --- S10- - - - - - _ _ - - - - _ - - S10R4W
C 4OA/IKUEHI
SCdup11 fORCOAY ' . • COUAm -MS sttP
(PW11[0 AS 11RSIQ :•1 '
CLAY OR C[OTEXTILL t1+CR
(Ir E%ISTVIG SOILS ARE
PCR4VDLC)
SIDE VI W
BEEIRENCE: commul+0 uRami Rur+orr t

C
STANDARD SPECIFICATIONS FOR WATERSHED PROTECTION BASIC`S
(A) -Ul storm water control structures shall be designed by either a North Carolina Registered Professional
Engineer or Landscape Architect, to the extent that the General Statutes, Chapter 89A, allow.
(B) All scorn water controls shall use wet detention ponds as a primary treatment system. Specific
requirements for these systems shall be in accordance with the follow desi_u criteria:
{1) Volume of the permanent pool shall be a minimum of four (4) times the volume of runoff
generated by the mean storm over the contributing watershed. In addition, the discharge rate from
these ponds following a one (1) inch rainfall design storm shall be such that the runoff does not
draw down to the permanent pool level in less than two (2) days and have a maximum vertical
distance of two (2) feet.
'
(2)
The permanent pool surface area shall be a minimum of one percent (1 90) of the drainage area.
(3)
The mean depth of the permanent pool shall be a minimum of three (3) feet.
(4)
The maximum depth of the permanent pool depth shall be ten (10) feet.
-`�
(5)
The pond shall have a minimum length to width ratio of 4:1 (preferably an irregular pond shape).
-.t
(6)
The inlet and outlet shall be located to maximize flow length.
(7)
Tne design shall assume full development (maximum allowed in accordance to current zoning
regulations) in the contributing drainage area.
'
(S)
At the elevation of permanent pool, a minimum ten (10) feet wide, one (1) foot deep shelf (littoral
shelf) shall be provided around the perimeter of the permanent pool, or a littoral shelf equivalent
in area to 35 o of the surface area of the pond at maximum elevation of water quality sto.age
'
pool, whichever is greater.
(9)
The littoral shelf shall be planted with aquatic vegetation shown in Attachment A, or equavalent,
that is suitable for planting in this area.
(10)
The design must include a sediment forebay with a design volume equivalent to 20% of the
permanent pool volume. The forebay shall also include a separate drain for dewatering. Tne
forebay volume cannot be included as part of the permanent pool volume requirement. See
schematic drawing for further details.
(11)
Side slopes of the pond shall be no greater than 4:1.
(12)
Rip -rap protection (or other suitable erosion control means) shall be provided for all outlet and
inlet structures.
(13)
All risersfbarrels must be reinforced concrete ra her than corrugated metal. In addition, all risers
'
must be cbecked for floatation.
(1 �)
Anti -seep collars shall be provided on the barrel of the principal spillway.
1
`

(15) A minimum one-half foot freeboard shall be provided above peal: stage to the top of the '
embankment.
(16) The pond shall be equipped with an emergency drain (i.e. sluice gate, drawn dDwm pipe) capable ,
of draining the structure within twenty-four (24) hours.
(17) The pond shall have an emergency spillway designed to pass the 50-year storm event. The
difference between the one (1) inch rainfall design storm and the 50-year storm (water quantity '
volume) should be released downstream in 12 hours or less.
(18) The inlet structure to the forebav shall be designed to minimize turbulence using baffles or other '
appropriate design features.
(19)
Vegetative filters shall be constructed for the overflow and discharge of all storm water wet
detention ponds and shall be at least thirty (30) Meet in length. The slope and width of the
'
vegetative filter shall be determined so as to provide a non -erosive velocity of flow -through the
filter for a 10-year 24-hour storm with a slope of five percent or less. Vegetation in the filter
shall be natural vegetation, grasses or artificially planted wetland vegetation appropriate for the
'
site characteristics.
(20)
The riser shall be located within or on the face of the embankment rather than out in the middle
'
of the pool.
(21)
Hoods or trash racks shall be installed on both the low flow and design storm orifices to prevent
clogging. The low flow orifice pipe shall be negatively sloped so that it draws water at ]east one
'
foot below the surface of the permanent pool.
(22)
Maintenance access shall be provided to the pond at a required minimum width of 12 feet and
'
shall be constructed of grass (0-3.5 So), gravel (3.5-10.5 90) or paved (10.5-205o), to allow access
during wet weather conditions.
(23)
A benchmark shall be provided in both the forebay and permanent pond to indicate the maximum
sediment level allowed.
for
'
(24)
A minimum ten (10) feet wide safety bench shall be provided outside the permanent pool area
the purpose of manuerving landscaping equipment. It is recommended that this safety bench bA
located at the top of sloping banks..
'
5)
A minimum ten (10) feet wide buffer shall be provided around the storm water management
facility. The ten (10) feet wide safety bench mentioned above can be located within the buffer as
long a other design criteria is adherted to.
'
(26)
A clay or geotextile liner may be required if the existing pond soils are permeable.
'
(27)
An oil and grease skimmer ..,a} be required for commercial or industrial use sites with a high
production of such pollutants.
filed
'
(28)
A description of the area containing the stor;n water control structure shall be prepared and
as a separate deed with the County Register of Deers along with any easements necessary for
general access to the storm water control structure. The deeded area shall include the detention
pond, vegetative filters, all pipes and water control structures, berms, dikes, etc., and sufficient
,
area to perform inspections, maintenance, repairs, and reconstruction.
(29)
Dams 15 feet or higher (measured at the downs -ream side of the dam) with an impoundment
'

capacity of 10-ac-feet or greater at the top of the dam must obtaL--t a Dam Safety perlit from
North Carolina Department of Natural Resources, Land Quality.
See wet pond Figure for typical design.
1
1
J
1
l
1
1
i1

I .-UNTEN —DICE STANDARDS FOR EXTENDED DETENTIONN .-%ND WET PONDS
• Sediment to be removed when 50 c of forebay volume is filled and/or when 20 Fo of
the per-manem pool volume is filled (design storage volume must account for volume
lost to sediment storage).
• Sediment traps shall be cleaned out when filled.
• No woody vegetation shall be allowed to ;row on the embankment without special
design provisions.
• Other vegetation shall be cut when it exceeds 18 inches in height unless part of
planned landscaping.
• Debris shall be removed from blocking inlet and outlet structures and from areas of
potential clogging.
• The control shall be kept structurally sound, free from erosion, and functioning as
designed.
• Periodic removal of dead vegetation shall be accomplished.
• No standing water is allowed within extended detention pond unless Design n6 is
selected.
• An annual inspection is required, reports to be kept by owner.
• The site should be inspected and debris removed after every major storm.
• All special consideration maintenance responsibilities will be listed in the credit
application.

r
ACCEPT-A3LE PLAIN7 SPECIES FOR LITTORAL SHELF PLANTING
�fECKLE`BURG COli1,-TY ,tiORTH CAROLf`.A
Developed by David D. Patrick, Jr., HDR Engineering, Inc,
Common Name
Scientiric Name
1 •
Fragrant water lily
Nvmphaea odors a
2•
Arrow -head
Sasittar' z latifolia var pubesceus S Ion�irost a
3•
Bacopa
;14ecardonia acuminata
4•
Hedge hyssop
Gratiola virsinians
�•
False-pimpemel
Lindemia dubia
6.
Sort rush
Juncu�msus
7•
BuIrush
Scirpus validus: S. atrovirens: S.
cvperinus
S.
Spikerush
Eleocharis obtusa. among others
9.1
Day flower
Commelina communis
10.
Blue -flab Iris
Iris v�ni_a
11 •
Lizard's tail
Sauru us cernuus
12•
Maidencane
Panicum sop.
13•
Pickerelwe:d
AontA deria cordata
1�
Meadow -bury
Rhezia mariana, R. virsinica
15.
Marsh seedbox
Ludw'isia D2il!clriS
16.
Cutsrass
L"rsia v o;
ir_.r.ica. L. on•zoides
17.
Hatpins
�riocaulon decans -- ulare
30� buttons
Lac tnocaulon a�ceps
Hv
Resime
3
2
1
1
1
1
1
1
1
1
1,2
1
1
1

Common Name
A.
Swamp Rose
B.
Buttonbush
C.
Willow
D.
Virginia willow
E.
Alder
F.
Maleberry
G.
retterbush
H.
Swamp Dogwood
SHRUBS
Scientific Nam,-
RosaalUStr75
CeDhalanffius occidentalis
Salix nigra
ltea v_ irgin=ca
Alnus -Ierlulata
Leonia ligust ina
Leugothoe racemosa
Corpus amomum
Hvdric Regime
1 = less than 1 ft. of water (extended inundation)
2= 1 ft. - 2 ft. of water
3 = more than 2 ft. of water
Hvdric
Regime
1
1
1
1
1
1
1
1

Common Name Scientific Namt!
Hvdric
Regime
19.
Buttercup
Ranunculus Dusillus.-R. carolinianus
1
20.
Easter Lily
Zephvranthes atarnasco
1
21.
Arrow Arum
Peltandra vireinica
1,2
22.
Cattail
Tvt)ha latifolia
2,3
23.
Sedee
'Ca re- x - su pp.
I
A
Flat sedge
Cvverus spp.
1
25.
Bedstraw
Galium tinctorium
I

MOREHEAD CITY I
OFFICE!COPY