HomeMy WebLinkAboutStormwater Master Plan-20001
i
1
1
1
1
1
1
1
1
1
1
1
1
y--Y
Ili
Y
DCM COPY DCM COPY
lease do not remove!!!!!
Division of Coastal Management
STORMWATER
MASTER PLAN
TOWN OF OCEAN ISLE BEACH
OCEAN ISLE BEACH, NORTH CAROLINA
DUNE 295 2000
Prepared By:
URS GREINER WOODWARD CLYDE
Raleigh, North Carolina
The preparation of this report was financed in part through a grant
provided by the North Carolina Coastal Management Program,
through funds provided by the Coastal Zone Management Act of
1972, as amended, which is administered by the office of Ocean
and Coastal Resource Management, National Oceanic and
Atmospheric Administration.
1
LI
1
1
1
1
1
1
1
1
1
1
1
1
1
1
STORMWATER MASTER PLAN
TOWN OF OCEAN ISLE BEACH
Ocean Isle Beach, North Carolina
June 29, 2000
Prepared by:
URS Greiner Woodward Clyde
3109 Poplarwood Court, Suite 301
Raleigh, North Carolina 27604
(919) 850-9511
Fax: (919) 790-0217
TABLE OF CONTENTS
OCEAN ISLE BEACH
STORMWATER MASTER PLAN
'
Section
Page
ExecutiveSummary
.........................................................................................................................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 ....................................... ......................................................................................
1-2
Chapter 2 - Policy
'
2.1
Responsibilities........................................................................................................................2-1
2.2
Ordinances and Regulations.....................................................................................................2-1
2.2.1 Federal Regulations
'
.........................................................................................................2-1
2.2.2 State Regulations .2-5
2.2.2.1 Division of Coastal Management......................................................................2-5
2.2.2.2 Division of Land Resources...............................................................................2-6
2.2.2.3 Division of Water Quality.................................................................................2-6
2.2.2.4 North Carolina Division of Highways...............................................................2-8
2.2.2.5 NCDOT Subdivision Roads..............................................................................2-13
2.2.2.6 NCDOT Policy on Street and Driveway Access to Highways ..........................2-14
2.2.3 Local Ordinances............................................................................................................2-15
2.3
Drainage System Design, Operation, and Maintenance...........................................................2-18
'
2.4
Best Management Practices......................................................................................................2-18
2.5
Floodplain Development..........................................................................................................2-19
2.6
Stormwater Management Ordinance........................................................................................2-19
2.7
Increased Runoff Due to Development....................................................................................2-19
'
2.8
Pollution Prevention.................................................................................................................2-19
2.9
Public Education/Public Involvement......................................................................................2-20
Chapter 3 - Island Overview
3.1
3.2
Setting.......................................................................................................................................3-1
Hydrography.............................................................................................................................3-1
3.3
Land Use......................................................................................:............................................3-1
'
3.4
3.5
Effects on Water Quantity........................................................................................................3-1
Effects on Water Quality..........................................................................................................3-2
3.6
Storm Drain System Inventory and Mapping...........................................................................3-2
' Chapter 4 - Watershed Characteristics
4.1 Watershed Characteristics........................................................................................................4-1
' 4.1.1 Hydrologic and Hydraulic Characteristics..................................................................4-1
4.1.2 Water Quality Characteristics......................................................................................4-1
4.2 Future Development.................................................................................................................4-2
4.3 Evaluation and Recommendations...........................................................................................4-2
1
06/29/00 1
1
11
TABLE OF CONTENTS
Section
OCEAN ISLE BEACH
STORMWATER MASTER PLAN
Page
4.3.1 Water Quantity ............................................................................................................4-3
4.3.2 Water Quality ..............................................................................................................4-14
4.3.3 Operation and Maintenance.........................................................................................4-15
Chapter 5 - Stormwater Management Program
5.1 Recommendation Summary .....................................................................................................5-1
5.2 Project Selection Criteria..........................................................................................................5-1
5.3 Capital Improvement Program.................................................................................................5-3
5.4 Operation and Maintenance Program.......................................................................................5-3
5.5 Funding.....................................................................................................................................5-4
Chapter 6 - References
' LIST OF APPENDICES
' Appendix A Proposed Stormwater Management Ordinance
Appendix B Public Information Flyers
Appendix C Charlotte -Mecklenburg Stormwater Services Credit Application Instruction Manual
' LIST OF TABLES
Page
Table 3-1
Stormwater Pollutants..............................................................................................3-3
Table4-1
Soils Data.................................................................................................................4-1
Table 4-2
Table 5-1
Recommendations....................................................................................................4-15
Project Selection Criteria and Rankings
...................................................................5-2
Table 5-2 .
Capital Improvement Program......................
........................................................... 5-5
I F FIGURES LIST O
Page
Figure3-1
Location Map...........................................................................................................3-4
'
Figure 3-2
Figure 4-1
Hydrologic Unit Map...............................................................................................3-5
Existing Storm Drain System...................................................................................4-16
Figure 4-2
Stormwater Areas of Concern ..................................................................................4-17
lJ
1
06/29/00 11
OCEAN ISLE BEACH
EXECUTIVE SUMMARY STORMWATER MASTER PLAN
The Ocean Isle Beach Stormwater Master Plan provides an outline of the stormwater management
policies and actions for the entire island of Ocean Isle Beach. This document provides direction for
stormwater management for the Town OF Ocean Isle Beach. The starting point for this Plan begins with
the purpose, goals, and objectives described in this chapter.
The purpose of the Ocean Isle Beach 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 Town.
' The following goals provide the direction in meeting the purpose of improving hydrological functions and
protecting and improving water quality:
' 1) Evaluate the water quantity and quality problems on the island 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.
' Policy regarding responsibilities, ordinances, system operation and maintenance, easement acquisition,
and public involvement is described in Chapter Two. The water quantity and water quality problems on
the island are described and action items for these problems are provided in Chapter Four. The policy,
' maintenance, and capital improvement action items described in Chapter Five 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.
11
1
The recommendations for each area of concern were evaluated based upon the safety, water quantity, and
water quality benefits provided by the recommended solution. The area determined to be the highest
priority was First Street on the east end of the island. Severe flooding occurs in this area, and water often
covers both travel lanes causing potential safety hazards. The remaining areas of concern and
recommended solutions are described in Chapter Four. The evaluation criteria are presented in Chapter
Five.
Preliminary, order of magnitude cost estimates are provided in Chapter Five. 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.
06/29/00 E-1
L�
CHAPTER ONE OCEAN ISLE BEACH
PURPOSE AND GOALS STORMWATER MASTER PLAN
The Ocean Isle Beach Stormwater Master Plan (Plan) is a document that outlines an approach to
stormwater management for the entire island of Ocean Isle Beach. This document provides direction for
stormwater management for the Town of Ocean Isle Beach (Town). 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. Flooding and water quality within the Town 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 Ocean Isle Beach 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 Town.
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 Town. This
framework for the Stormwater Management Program will incorporate the policies and procedures already
established by the Town, 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 Master 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 following goals provide the direction in meeting the purpose of improving hydrological functions and
protecting and improving water quality:
' 1) Evaluate the water quantity and water quality problems on the island 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 5.
1. Evaluate the water quantity and water quality problems on the island and recommend actions to
mitigate these problems.
06/29/00 1-1
7
CHAPTER ONE OCEAN ISLE BEACH
PURPOSE AND GOALS STORMWATER MASTER PLAN
This master plan will evaluate the water quality and water 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
regard 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 to ensure 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 - 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 Three — Island 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 water quality.
Chapter Four — Watershed Characteristics
The characteristics of the island, along with the quantity and water quality problems, are described and
action items recommended.
Chapter Five - 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 Town of Ocean Isle Beach personnel, citizens, and water quality
06/29/00 1-2
1
1
1
1
1
CHAPTER ONE OCEAN ISLE BEACH
PURPOSE AND GOALS STORMWATER MASTER PLAN
monitoring data. Public input to the Stormwater Management Plan has been obtained during a public
workshop.
06/29/00 1-3
fl
1
1
J
CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
Decisions the Town makes now regarding stormwater issues have an effect on future water quality, storm
drain system performance, and system condition. This chapter outlines the existing Town policies
regarding stormwater management and evaluates what policies need changes for effective management in
the future. Current responsibilities of the Town are explained in this chapter.
2.1 RESPONSIBILITIES
Stormwater management in the Town of Ocean Isle Beach is currently the responsibility of the State of
North Carolina. The Town of Ocean Isle Beach will be responsible for stormwater management when the
Town implements a Stormwater Management Program.
Currently the Town has the following responsibilities regarding stormwater management:
• Inspection and maintenance of the Town's existing stormwater collection system.
• Approval of site plans with respect to setbacks from the mean high water mark.
Approval of erosion and sediment control plans.
Inspection of sites for erosion and sediment control compliance in accordance with the Town's
Soil Erosion and Sedimentation Ordinance.
• Inspection of sites for compliance with the Town's Flood Ordinance.
2.2 ORDINANCES AND REGULATIONS
2.2.1 Federal Regulations
This section provides a summary of federal regulations that presently define or in the future may affect
stormwater management requirements for the Town. The goal of this review is to identify and summarize
the regulatory and technical issues that must be incorporated into the Town's stormwater management
and development policies. The summarized requirements presented in this section will subsequently be
compared to existing Town stormwater management policies with recommended modifications provided
as necessary.
The Clean Water Act
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 a 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 stormwater 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 H Storm Water Regulations).
06/29/00 2-1
�7_i
CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
Phase I NPDES Stormwater Re elation
In 1987, Congress amended the CWA to require implementation of a comprehensive national program for
addressing stormwater 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
stormwater 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 the Town of Ocean Isle Beach
As of the year 2000, the Town is not required to obtain a NPDES stormwater discharge permit
under the Phase I regulations because of its small population and lack of industrial activity.
Phase II 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:
• 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 stormwater. States with NPDES permitting authority (North Carolina
has permitting authority) can extend NPDES requirements to smaller towns 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 Sewer 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 Practices (BMPs) at small construction sites will also reduce pollutants in urban stormwater.
' 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/Public 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
06/29/00 2-2
CHAPTER TWO OCEAN ISLE BEACH
' POLICY STORMWATER MASTER PLAN
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 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/Public Participation
As part of the Phase H Public Involvement/Public 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.
Illicit Discharge Detection and Elimination
Under the Phase H 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 through ordinance, or other regulatory mechanism, illicit discharges into the
separate storm sewer system, and implement appropriate enforcement procedures and actions as
needed, 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.
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.
rConstruction 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.
06/29/00 2-3
CHAPTER TWO OCEAN ISLE BEACH
I
POLICY STORMWATER MASTER PLAN
• 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 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 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.
06/29/00 2-4
1
CHAPTER Two OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
Applicability to the Town of Ocean Isle Beach
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 June 2000, the Town of Ocean: Isle Beach was not included on any of these lists, although
Brunswick County is included and will be required to obtain a Phase II permit. In this situation,
the Town may be required to obtain a permit jointly with the County, or the Town may be able to
obtain a separate permit, if desired. The State is encouraging cooperation between entities which
may be the most effective way to implement a program which complies with permit conditions.
URSGWC recommends that the Town contact both the County and the State to determine its status
regarding a Phase II NPDES permit.
URSGWC also recommends that the Town implement applicable Phase II management measures
as part of its long-term storm water management policies. These management measures are good
standard practice for water quality protection, and their implementation would put the Town on the
track toward implementation of Phase II requirements if a permit becomes necessary in the future.
2.2.2 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 and Natural
Resource (NCDENR); 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 Town
ordinances. The NCDENR, 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 (NCDOT) has
drainage standards for subdivision highways.
2.2.2.1 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, V, & 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
06/29/00 2-5
CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
• 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 exempt
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
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 percent
• 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
• 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
2.2.2.2 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 413 & 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. The Town has
adopted a Sediment and Erosion Control Ordinance, which contains similar requirements to the Division
of Land Resources requirements. Sediment and erosion control responsibilities lie with the Town, unless
the project is funded by State money.
Designs must provide protection from peak runoff resulting from a 10-year storm event and increased
stormwater runoff will not allow impact of receiving waters.
2.2.2.3 Division of Water Quality
rThe 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 the Ocean Isle Beach area include
the ocean and the Intracoastal Waterway.
06/29/00 2-6
CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
The following letter system is used to define the "best usage classifications" for waters in the Ocean Isle
Beach 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 for primary recreation, aquatic life propagation/protection and
secondary recreation.
HQW (High Quality Waters) Indicates a supplemental classification for waters protected by an
Antidegradation Policy enforced through the NCDENR. 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.
The SA primary classification denotes surface waters, such as the Atlantic Intracoastal Waterway
(AIWW), which are suitable for commercial shellfishing and all other tidal saltwater uses. Supplemental
classifications such as HQW (high quality water) provide added protection for waterbodies.
rThe 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
NCAC211.1000. 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
3.2 of this report) or a Sedimentation/Erosion Control Plan (see Section 3.3 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).
Ocean Isle Beach is included in the 20 coastal counties (Brunswick County) and is subject to permitting
requirements as specified in 15A NCAC 211.1005. Permitting requirements as specified in 15A NCAC
2H.1005 are described in the following paragraph.
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.
1
06/z9/00 2-7
i
CHAPTER Two OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
Ocean Isle Beach is predominantly surrounded by water (Atlantic Intracoastal Waterway), therefore
permitting requirements are as specified by category 2.
Ocean Isle Beach Permitting Requirements (SA Waters)
Permitting requirements for the Town'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.
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 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 211.0126.
2. Stormwater control systems must be infiltration systems designed in accordance with 15A
NCAC 2H.1008.
3. Stormwater control systems must be designed to control runoff from all surfaces generated by
one and one-half (1.5) inches of rainfall.
4. Runoff in excess of the design volume must flow overland through a vegetative filter with a
minimum length of 50 feet.
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 percent removal for total suspended solids
(TSS).
1 A stormwater BMP design manual was published by NCDENR in April 1999. 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.
2.2.2.4 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 Town stormwater management policies since a portion of NC 904 is
located on the island portion of Ocean Isle Beach.
06/29/00 2-8
1
CHAPTER Two OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
L
n
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 to allow a landowner reasonable use of his
property evolved.
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 modern 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 upstream and downstream properties and to
include provisions 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.
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, insofar as is practicable from good engineering practice.
06/29/00
W
CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
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 borne by the requester, and that appropriate consideration and
measures have been taken to indemnify and hold harmless the Division of Highways from potential
downstream damage claims. It is Division of Highways policy not to grant 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.
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 borne 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 culverts should have
approval from the State Hydraulics Engineer.
When new private drives are constructed entering the highway, the property owner can furnish, 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.
06/29/00 2-10
CHAPTER Two OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
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.
In general, outlet ditches will be maintained for a sufficient distance below the road to provide adequate
drainage. 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.
i 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 their 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.
1
ot'z9io0 2-11
1
CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
Subdivision Streets
When roads 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.
HydroloQy
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 Federal Emergency Management Act (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.
Method for Calculating 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.
Hiehway Desi-an 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 Desiyn 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.
rStorm 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
1 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.
1 06/29/00 2-12
' CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
1
Design Frequency
Roadway inlet location, capacities and gutter spread is to be analyzed using a standard rainfall intensity of
four 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 percent 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.
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.
2.2.2.5 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. Drainage design and construction requirements for state -maintained subdivision roads are
summarized for review purposes in the following paragraphs.
Requirements for Addition of Subdivision Roads to the State S s
• 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 System.
1 06/19/00 2-13
' CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
• 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.
' 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.
Storm sewer collector — 10 years
' 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.
2.2.2.6 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. 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
' 06/29/00 2-14
' CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
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.
' (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 carry 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 (surface 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 or wingwalls 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 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.
2.2.3 Local Ordinances and Policies
' 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 following provides a summary of some of the zoning and subdivision
ordinances for the Town of Ocean Isle Beach.
' The Town of Ocean Isle Beach has the following ordinances in place to control development:
1 06/29/00 2-15
' CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
1
j
l
• minimum lot size of 5,000 square feet for single family in zones R-1, R-2, R-3, C-1, C-2 and C-3.
• minimum lot size requirement of 7,500 square feet for two-family homes in zones R-2, R-3, C-1,
C-2, and C-3.
• minimum lot size of 10,000 square feet for multi -family in zones R-2, R-3, C-1, C-2 and C-3.
• minimum lot size of 5,000 square feet for mobile homes in zones R-3. and C-3.
• minimum lot size of 10,000 square feet for commercial accommodations in zones R-1, C-1, C-2
and C-3.
• minimum lot size of 5,000 square feet for commercial business in zones C-2 and C-3.
• minimum lot size of 5,000 square feet for commercial highway in zone C-3.
• 36-foot building height restrictions for zone R-1.
• 55-foot building height restriction for zones C-1, C-2 and C-3.
• The structure's "footprint" shall not exceed thirty-six (36) percent of the lot area, not to include
driveways and walkways.
The Town of Ocean Isle Beach adopted ordinances as they relate to flood damage prevention and soil
erosion and sedimentation.
Flood Dam a�-e Prevention Ordinance
This ordinance was established under the authority of the North Carolina General Statutes, Chapter 160A-
17(4). The intent of the ordinance is to promote the public health, safety and general welfare and to
minimize public and private losses due to flood conditions in specific areas by restricting or prohibiting
uses in certain areas, require that uses vulnerable to floods be protected against flood damage, controlling
the alteration of natural flood plains and protective barriers, controlling filling, grading, dredging and
other development which may increase erosion or flood damage, and by preventing or regulating the
construction of devices which will naturally divert flood water or increase flood hazard to other lands.
Soil Erosion and Sedimentation Ordinance
The purpose of the ordinance is to regulate certain land -disturbing activities to control accelerated erosion
and sedimentation in order to prevent the pollution of water and other damage to watercourses and other
public and private property by sedimentation. This ordinance also establishes procedures through which
these purposes can be fulfilled.
CAMA Land Use Plan
Statements of local policy on land use issues which affect the Town of Ocean Isle Beach are grouped in
five general categories including:
• Resource Protection Issues
• Resource Management Issues
• Economic and Community Development Issues
• Citizen Participation Issues
• Natural Hazards
Policies from each of these categories that affect stormwater management are discussed in the following
paragraphs.
06/29/00 2-16
7
CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
' Areas of Environmental Concern (AECs)
According to the policy statement regarding AECs, the Town of Ocean Isle Beach 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 Town's Zoning Ordinance, Subdivision Regulations, Dune Maintenance and Protection Plan,
' Extraterritorial Jurisdiction Ordinance, and jet ski regulations will continue to protect these resources.
Stormwater management measures will be implemented so as to comply with the Town's policies
regarding AECs.
' Stormwater Runoff
The Town recognizes the value of water quality maintenance with regard 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 Town to reduce stormwater
pollution to the waterways and enhance the water quality in the area.
' Surface Water Quality Problems
The Town 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 Town to reduce stormwater
pollution to the waterways and enhance the water quality in the area.
' Residential Commercial, and Industrial Land Development Impacts on Any Resources
The Town's policy is to allow residential and related commercial development to occur as long as
resource degradation does not occur. The Stormwater Management Program will be a tool the Town
can implement to help ensure there is no degradation of resources due to stormwater runoff from
these developed areas.
Types of Urban Growth Patterns Desired
The Town would like to maintain its image of a quiet, relaxing family beach community.
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 encourage the desired growth patterns.
Redevelopment of Developed Areas, Includiniz the Relocation of Threatened Structures
' The Town supports redevelopment of previously developed areas. It is Town policy that density
allowances for redevelopment areas conform to existing Town building and zoning regulations. The
proposed stormwater ordinance does impose requirements for reducing stormwater runoff from the
' property after redevelopment, but it does not restrict redevelopment.
Continuing Public Participation
' Town policy is to assure that all residents have a full and adequate opportunity to be informed of and
participate in the Town's planning decision -making process. The Stormwater Management Program
also includes public education and public participation.
' 06/29/00 2-17
' CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
0
r_
2.3 DRAINAGE SYSTEM DESIGN, OPERATION AND MAINTENANCE
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 2.2.2.5 -
2.2.2.6. These design criteria, along with NCDENR stormwater design criteria are excellent references
and should be followed by the Town during design and construction of additional stormwater
management measures. The Town may also want to develop their own Stormwater Drainage Design
Manual.
It is important that the Town has an easement for its storm drain systems so maintenance and repairs can
be performed when necessary. For Town -owned storm drain systems carrying runoff from public right-
of-way, the Town may want to obtain an easement for any pipe, inlet, manhole, and outfall. Storm drain
systems which only carry runoff from private property are considered private systems and the Town is not
responsible for their maintenance. For existing inlets and pipes that carry runoff from Town streets, the
Town should try to obtain easements for the pipes and inlets.
The operation and maintenance of the drainage system in the service area will be the responsibility of the
Town. In order for the Town to effectively maintain the stormwater drainage system, the Town 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.
2.4 BEST MANAGEMENT PRACTICES (BMPs)
BMPs are methods or practices that can effectively reduce stormwater pollution. Some BMPs, such as
street sweeping, prevent pollutants from reaching stormwater and other BMPs, such as an infiltration
trench, reduce the amount of pollutants already in the runoff. Structural control BMPs described in the
North Carolina Department of Environment and Natural Resources Stormwater Management Guidance
Manual include:
• infiltration trenchesibasins
• dry detention basins
• wet retention basins
• grassed swales
• filter strips
06/29/00 2-18
F
' CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
' 2.5 FLOODPLAIN MANAGEMENT
The Town of Ocean Isle Beach has an ordinance that regulates development in the floodplain and they
' participate 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 Town.
Any drainage system improvements proposed in the floodplain will have to comply with the existing
requirements.
' 2.6 STORMWATER MANAGEMENT ORDINANCE
The Town currently has a Sediment and Erosion Control Ordinance in place, which affects stormwater
' management. The Town does not currently have a Stormwater Ordinance, though. 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. A recommended
' Stormwater Management Ordinance is included in Appendix A.
2.7 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.
2.8 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 Town can implement 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 Town 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 with stormwater fee bills at 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.
1 06/29/00 2-19
' CHAPTER TWO OCEAN ISLE BEACH
POLICY STORMWATER MASTER PLAN
2.9 PUBLIC EDUCATION/PUBLIC INVOLVEMENT
This Stormwater Master Plan provides a way for the Town 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 workshop, and in the Town Hall. Copies of
these handouts are included in Appendix B. Additional information could be supplied to the public as
inserts included in sewer bills or handouts provided at Town Hall or real estate offices.
The Town has also provided for public involvement as part of the development of the Stormwater
' Management Program. A public workshop was 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.
-1
7
LJ
06/29/00 2-20
CHAPTER THREE OCEAN ISLE BEACH
SERVICE AREA OVERVIEW STORMWATER MASTER PLAN
' This overview describes the physical features on the island of Ocean Isle Beach and how they affect
stormwater quality and quantity.
3.1 SETTING
The Town of Ocean Isle Beach is located in southwestern Brunswick County, North Carolina. Figure 3-1
shows the location of Ocean Isle Beach. The island of Ocean Isle Beach is mostly residential development
with some commercial businesses. The Town of Ocean Isle Beach has year-round residents and an
' increase in the visiting population during the summer months because of seasonal tourism. Figure 3-2
shows the town limits of Ocean Isle Beach.
11
11
II
I
3.2 HYDROGRAPHY
The Town is located in the eastern portion of the Lumber River Basin that flows from North Carolina to
South Carolina. This river basin is comprised of smaller watersheds or hydrological units (HUs). The
primary water features include the Atlantic Intracoastal Waterway (AIWW), Tubbs Inlet and Shallotte
Inlet marsh systems, and the Atlantic Ocean.
Within the service area, the United States Geological Survey (USGS) classifies one smaller watershed
within the Lumber River Basin. The Carolina Coastal watershed (03040207) has an 8-digit hydrologic
unit code (HUC). Within this watershed, the United States Department of Agriculture Natural Resources
Conservation Service (MRCS) has delineated two 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. These two subwatersheds are the 'AIWW, Atlantic Ocean (03040207020120) and the 2AIWW
(03040207020080). Figure 3-2 shows the boundaries of these two subwatershed hydrological units.
3.3 LAND USE
Land use on the island primarily consists of residential and commercial. Residential and commercial
properties consist predominantly 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, barns,
etc.). Vegetation, if present, varies and includes maintained lawns, maintained scrub areas along utility
easements, and landscaped areas.
3.4 EFFECTS ON WATER QUANTITY
Stormwater runoff quantity problems occur in various locations across the island. These problems
include:
• flooding
• soil erosion
• freshwater flow increase to estuaries/shellfish harvest areas
• 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
06/29/00 3-1
r
' CHAPTER THREE OCEAN ISLE BEACH
SERVICE AREA OVERVIEW STORMWATER MASTER PLAN
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.
Major flooding problems observed on the island, discussed in Chapter Four, 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 of impervious surfaces. Stormwater management will
allow the Town to effectively design, implement, construct, and manage stormwater controls to prevent
environmental problems associated with the increasing amount of stormwater quantity.
3.5 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 island drainage system consists of several catch basins with piped
' outfalls to the canals and the AIWW. There are also several swales along roads which collect stormwater
runoff .
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.
r 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 3-1 shows the land use activities associated with pollutants.
Stormwater management includes control practices and preventive measures which will improve water
quality. Chapter Four discusses the water quality problems on the island and provides recommended
' mitigation measures.
3.6 STORM DRAIN SYSTEM INVENTORY AND MAPPING
rThe storm drain system map was drawn using AutoCAD version 14 and the Town base map was obtained
from Boney and Associates, Inc. Some of the system components (drop inlets) may have been buried
r under sand/vegetation and thus were not included in this inventory. Based upon the preliminary
inventory of the Town's storm drain system it was determined that there are approximately 59 storm drain
inlets, 16 pipe outfalls, and 8,000 linear feet of ditches on the island of Ocean Isle Beach. The length of
stormwater pipe on the island is unknown. The size of the storm drain pipe appeared to range from 2-inch
to approximately 18-inch, although pipe sizes were not measured. No Town -owned stormwater
management facilities (retention basins, etc.) are located on the island.
06/29/00 3-2
1
1
1
1
1
1
1
CHAPTER THREE OCEAN ISLE BEACH
SERVICE AREA OVERVIEW STORMWATER MASTER PLAN
Table 3-1
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 crops
Fecal colifonn .
• 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
06/29/00 3-3
m m m m m m m m m m m w m m m m m m m
Ji.
N
HYDROLOGIC UNIT
000 500 0 1000 2000 BOUNDARIES
SCALE 1' = 2000'
1
H
�I
1
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
4.1 . WATERSHED CHARACTERISTICS
4.1.1 Hydrologic and Hydraulic Characteristics
The AIWW is the main water body in the area of Ocean Isle Beach which discharges into Tubbs Inlet
(separates Sunset Beach island and Ocean Isle Beach) and Shallotte Inlet (separates Ocean Isle Beach and
Holden Beach). The AIWW is classified as a shellfishing harvest area (SA). The AIWW and the
surrounding estuarine waters have been designated as a primary nursery area (PNA) which means they
are considered a highly productive habitat for juvenile marine species.
Salt marshes occur between the open water of the AIWW and the upland areas of the barrier islands. The
majority of the island of Ocean Isle Beach is located within the 100-year flood plain (Ocean Isle Beach,
1997). Table 4-1 describes the soil types found in this watershed (USDA, 1986).
Table 4-1
Soils Data
Ocean Isle Beach
Soil Type
Symbol "';:
Soil Name
Sanitary Facility Rating',
High Water Table
Deptli�(feet)
Hydric
Condition . "
BO
Bohicket
Severe: flooding, ponding,
peres slowly
+3.0-0.0
Yes
CA
Carteret
Severe: flooding, ponding,
poor filter
+3.0-1.0
No
Co
Corolla
Severe: wetness, poor filter
1.5-3.0
No
NeE
Newhan
Severe: poor filter, slope
>6.0
No
NhE
Newhan, dredged
Severe: poor filter, slope
>6.0
No
The island has little to no relief, which creates ponding problems in various areas. These will be
discussed in Section 4.3.1. The existing drainage system on Ocean Isle Beach consists of shallow swales,
inlet structures and pipes. There are 16 pipe outfall locations. These locations are shown on Figure 4-1.
4.1.2 Water Quality Characteristics
Some SA shellfishing areas around Ocean Isle Beach have been closed for many years due to poor water
quality, specifically high fecal coliform bacteria levels, according to the NC Department of Health,
Shellfish Sanitation Section. The portion of AIWW and the canals on the island of Ocean Isle Beach are
closed to shellfishing. Unlike many of the other barrier islands, though, Ocean Isle Beach has a municipal
sewer system instead of septic tanks. Many of the barrier islands with septic tank systems have very high
fecal coliform counts in the surrounding estuarine waters. Benthic macroinvertebrate sampling has been
conducted at the junction of the main canals on the east end of Ocean Isle Beach by the Division of Water
Quality since 1983. A moderate impact bioclassification has been given to this location. This
classification indicates that most nonpoint source problems are confined to the canals and not spreading to
surrounding waters.
06/29/00 4-1
' CHAPTER FOUR - OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
The Division of Water Quality also has an ambient water quality sampling site located in the.A1WW near
the Ocean Isle Beach bridge. The most recent data from the Division of Water Quality indicates that
approximately 25 percent of the samples collected had concentrations of fecal coliform bacteria above the
criterion for SA waters. Approximately 15percent of the samples collected at this location had dissolved
oxygen concentration less that the state standard for aquatic life. Additionally, there were a few minor
exceedances of the saltwater action level for copper (DENR, 1998).
Additionally, the entire Lumber River Basin has fish advisories for largemouth bass and bowfin, due to
high levels of mercury in the waters. These elevated mercury levels are predominately due to airborne
contaminants (DENR, 1998).
4.2 FUTURE DEVELOPMENT
As outlined in the 1997 CAMA Land Use Plan for Ocean Isle Beach, the year-round population of the
Town was 832 in 1997, and is projected to be 1,121 by2007. Future development on the island portion
of Ocean Isle Beach will be primarily comprised of residential units, with limited additional commercial
development. By 2007, it is estimated that an additional 97.6 acres will be developed for residential, 1.2
acres for commercial, 2 acres for government/utilities, and 5.5 acres for roads. The anticipated future
development will increase overall imperviousness on the island.
4.3 EVALUATION AND RECOMMENDATIONS
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 Town and the public
• Reliability
• Implementability
• Environmental Impact
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.
' Regaulatoa Requirements
Each BMP was evaluated to determine if any special regulatory requirements would have to be met for
implementation.
Effectiveness at solving 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.
06/29/00 4-2
I
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
1 Acceptability to the Town and the public
Each BMP was evaluated as to whether it would be an acceptable solution to the Town and to the public.
Education is an important aspect to acceptability of a BMP.
Reliability
The reliability over time of each BMP was evaluated. Some BMPs retain their effectiveness longer than
others with a limited amount of maintenance.
Im lementabili
Some structural BMPs can not be constructed in certain areas dueto regulatory and/or physical
constraints.
Environmental Impact
Each BMP was evaluated to determine if any positive or negative environmental impacts would occur due
to implementation of the BMP.
4.3.1 Water Quantity
Flooding is the primary stormwater problem on the island of Ocean Isle Beach. Below is an explanation
of the flooding areas of concern, and recommendations for improvements. Deficiencies and
recommendations are summarized in Table 4-2.
' First Street (east end)
There is significant flooding that occurs on First Street between Laurinburg Street and Greensboro Street.
The flooding appears to be the worst between Chapel Hill Street and LaGrange Street, and near
Goldsboro Street. Flooding is several -inches deep and extends across the entire road on many occasions.
These flooding conditions cause a safety hazard for pedestrians and motorists, along with the potential for
property damage to cars from hidden obstructions under the water.
The only storm drain inlets identified in the area were near Chapel Hill Street, Raeford Street, Oak Ridge
Street, and Greensboro Street. Only the Greensboro Street inlet is connected to an outfall (ocean
discharge). It does not appear that any of the other inlets are connected to an outfall, and they are
insufficient to capture the flow from the area.
In order to solve the flooding problem in this area it is recommended that underground infiltration
trenches be used. The island has very permeable soils, and although the water table is high, it should be
possible to design an infiltration system which will have a sufficient separation distance from the bottom
of the infiltration facility and the water table. With the high permeability of the soils and a correct design,
stormwater runoff will infiltrate very quickly, thus eliminating the standing water on the roadway. If
possible, the stormwater outfall at Greensboro Street will be removed, so as to minimize polluted
stormwater from entering the ocean.
Since First Street 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. URSGWC recommends that the Town have a meeting with
NCDOT to discuss the issues along First Street and how the NCDOT and the Town can work together to
alleviate the flooding problems.
06/29/00 4-3
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
URSGWC understands that there are utility easements on either side of First Street. This will have to be
taken into account during design of an infiltration system. The Town may want to consider obtaining an
easement (from property owners) for an infiltration system outside the right of way. Another option
would be to pipe the stormwater to underground infiltration basins/trenches which could be located at the
CAMA beach accesses (Monroe Street, Concord Street, Newport Street, Raeford Street, Leland Street,
Goldsboro Street, Chadbourne Street, Winnabow Street, and/or Greensboro Street). Coordination with
DCM would be required for these facilities. URSGWC understands that DCM has, in the past, stated that
they would be willing to work with the Town in the use of the CAMA accesses for use as stormwater
facilities also.
In designing an underground infiltration system, it is recommended that some type of oil/grit chamber or
trap be constructed to pretreat the runoff before it enters the trench/basin. There are various types of
oil/grit chambers, from small devices that fit into standard inlet structures to larger three -chamber
facilities. The size of the oil/grit chamber will be dependent on the size of the area draining to the inlet.
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 of the
area is also necessary prior to completion of the modeling efforts.
To reduce the amount of stormwater runoff which reaches the street and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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).
11
1
Through evaluation of various BMPs, underground infiltration 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, and possibly DCM, this is an implementable BMP. As long as
the infiltration 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 Town).
First Street at Private Drive
There is significant flooding that occurs on First Street near Private Drive. The Private Drive area is a
private subdivision, thus the streets are not Town -owned or maintained. It is the understanding of
URSGWC that the subdivision had obtained a stormwater permit from the State prior to construction.
The roadside swales that were constructed in the subdivision have not been maintained and are virtually
non-existent. Most of the stormwater runoff from this subdivision flows down onto First Street, causing
flooding on the south side of First Street. The lots on the south side of First Street are also graded so that
the stormwater flows directly to the street. These flooding conditions cause a safety hazard for
pedestrians and motorists, along with the potential for property damage to cars from hidden obstructions
under the water.
06/29/00 4-4
' CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
There are no storm drain inlets identified in the area of First Street and Private Drive. 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. ,
iThe first step in solving this problem is to work with the Division of Water Quality Stormwater Section,
the developer, and the homeowners in the private subdivision to reinstall the roadside drainage swales. A
maintenance agreement is required by the State if a stormwater permit was issued for a high density
development. It is the State's responsibility to enforce the maintenance of stormwater systems
constructed under a State stormwater permit. Reinstalling the swales in the subdivision will not eliminate
the flooding problem on First Street, but it will alleviate the problem. URSGWC recommends design and
construction of underground infiltration trenches along the south side of First Street. As stated
previously, with the high permeability of the soils and a correct design, stormwater runoff will infiltrate
very quickly, thus eliminating the standing water on the roadway.
As with the previously described area, First Street is a NCDOT roadway and 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. URSGWC recommends
that the Town have a meeting with NCDOT to discuss the issues along First Street and how the NCDOT
and the Town can work together to alleviate the flooding problems.
URSGWC understands that there are utility easements on either side of First Street. This will have to be
taken into account during design of an infiltration system. The Town may want to consider obtaining an
easement (from property owners) for an infiltration system outside the right of way. Another option
would be to pipe the stormwater to underground infiltration basins/trenches which could be located at the
nearest CAMA beach accesses (at Duneside Drive). On the west side of the island, the CAMA access
points are only walkways, therefore space is limited. Modeling will indicate if there is enough space for
an infiltration trench/basin in the CAMA access. Coordination with DCM would be required for these
facilities. URSGWC understands that DCM has, in the past, stated that they would be willing to work
with the Town in the use of the CAMA accesses for use as stormwater facilities also.
In designing an underground infiltration system, it is recommended that some type of oil/grit chamber or
trap be constructed to pretreat the runoff before it enters the trench/basin. There are various types of
oil/grit chambers, from small devices that fit into standard inlet structures to larger three -chamber
facilities. The size of the oil/grit chamber will be dependent on the size of the area draining to the inlet.
1 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 of the
area is also necessary prior to completion of the modeling efforts.
To reduce the amount of stormwater runoff which reaches the street and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lot, and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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).
06/29/00 4-5
1
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
k
Through evaluation of various BMPs, underground infiltration 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, and possibly DCM, this is an implementable BMP. As long as
the infiltration 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 Town).
First Street between Shelby Street and Troy Street
There is significant flooding that occurs on the south side of First Street between Shelby Street and Troy
Street. Flooding is several inches deep and extends into the travel lanes on many occasions. These
flooding 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 no storm drain inlets identified in this area of First Street. 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 flooding problem in this area it is recommended that underground infiltration
trenches/basins be used. Since First Street 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. URSGWC recommends
that the Town have a meeting with NCDOT to discuss the issues along First Street and how the NCDOT
and the Town can work together to alleviate the flooding problems.
URSGWC understands that there are utility easements on either side of First Street. This will have to be
taken into account during design of an infiltration system. The Town may want to consider obtaining an
easement (from property owners) for an infiltration system outside the right of way. Another option
would be to investigate the purchase of a tract of the undeveloped land on the north side of First Street in
this area. The stormwater could be piped to underground infiltration basins/trenches which could be
located in this area. The north side of the street is currently at a higher elevation, therefore some
regrading of the land on the north side would be required. Underground infiltration in this area would
allow the land to still be developed for a variety of uses (parking lot, park, etc.).
In designing an underground infiltration system, it is recommended that some type of oil/grit chamber or
trap be constructed to pretreat the runoff before it enters the trench/basin. There are various types of
oil/grit chambers, from small devices that fit into standard inlet structures to larger three -chamber
facilities. The size of the oil/grit chamber will be dependent on the size of the area draining to the inlet.
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 of the
area is also necessary prior to completion of the modeling efforts.
To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
06/29/00 4-6
IJ
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
Town's Stormwater Management Program (Section 5.5), the Town 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, underground infiltration 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, and possibly DCM, this is an implementable BMP. As long as
the infiltration 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 Town).
First Street from Driftwood Drive to the west Town limit
' There is some minor flooding that occurs on First Street from Driftwood Drive to the western Town limit.
Flooding is several inches deep and extends into the travel lane on many occasions. These flooding
conditions cause a safety hazard for pedestrians and motorists.
1 The only storm drain inlets identified in the area were west of Starboard Street. It does not appear that
either of the inlets are connected to an outfall, and they are cannot capture the flow from the area due to
the lack of topographic relief.
In order to solve the flooding problem in this area it is recommended that either additional inlets be
installed as subsurface retention basins with perforated pipe to infiltrate the retained stormwater or
roadside swales be installed on the south side of the road. Since First Street 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.
URSGWC recommends that the Town have a meeting with NCDOT to discuss the issues along First
Street and how the NCDOT and the Town can work together to alleviate the flooding problems.
URSGWC understands that there are utility easements on either side of First Street. This 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. Since there are inlets already located in the area, it is assumed that
there would be sufficient space to install additional inlets as necessary. Utility maps will have to be
obtained prior to design.
It is recommended that some type of oil/grit trap be installed in the inlet to pretreat the runoff before it
enters the infiltration pipe.
The location, number, and size of storm drain inlets, or the size of the swale will have to be determined
' through hydraulic and hydrologic (H & H) modeling of the area. A detailed survey of the area is also
necessary prior to completion of the modeling efforts.
To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town may want to offer fee/tax credits for
06/29/00 4-7
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
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, subsurface retention 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 storm drain inlets are
periodically cleaned and maintained, it is a reliable stormwater BMP. There are no negative
' environmental impacts associated with this type of 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 Town).
Second Street at Scotland Street
There is minor flooding that occurs on Second Street at Scotland Street and on the east side of Scotland
Street, just north of Second Street. These flooding conditions cause a safety hazard for pedestrians and
motorists, especially if the water enters the travel lane.
1 There are no storm drain inlets identified in this area of Second Street. 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 flooding problem in this area it is recommended that either additional inlets be
installed as subsurface retention basins with perforated pipe to infiltrate the retained stormwater, or
roadside swales be installed.
' 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.
It is recommended that some type of oil/grit trap be installed in the inlets to pretreat the runoff before it
enters the infiltration pipe.
The location, number, and size of storm drain inlets, or the size of the roadside swale will have to be
' determined through hydraulic and hydrologic (H & H) modeling of the area. A detailed survey of the
area is also necessary prior to completion of the modeling efforts.
To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
' will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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, subsurface retention with a stormwater ordinance was determined
to be the most cost effective, applicable, implementable and effective at solving the flooding problems in
the area. As long as the storm drain inlets are periodically cleaned and maintained, it is a reliable
stormwater BMP. There are no negative environmental impacts associated with this type of system in
06/19/00 4-8
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
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 Town).
Second Street between Lee Street and Goldsboro Street
There is minor flooding that occurs on Second Street between Lee Street and Goldsboro Street. These
flooding conditions cause a safety hazard for pedestrians and motorists, especially if the water enters the
travel lane.
There are no storm drain inlets identified in this area of Second Street. 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 flooding problem in this area it is recommended that additional storm drain inlets be
installed as subsurface retention basins with perforated pipe to infiltrate the retained stormwater
The presence of utility easements will have to be taken into account during design. Utility maps will have
' to be obtained prior to design.
It is recommended that some type of oil/grit trap be installed in the inlets to pretreat the runoff before it
enters the infiltration pipe.
The location, number, and size of storm drain inlets 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.
To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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, subsurface retention 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 storm drain inlets are periodically cleaned and 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 Town).
Second Street at Sanford Street
There is significant flooding that occurs on Second Street at Sanford Street. Flooding is several inches
deep and extends across Sanford Street on many occasions. These flooding conditions cause a safety
hazard for pedestrians and motorists, along with the potential for property damage to cars from hidden
obstructions under the water.
06/29/00 4-9
r
11
11
1
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
There are no storm drain inlets identified in this area of Second Street. 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 flooding problem in this area it is recommended that underground infiltration
trenches/basins be used.
The presence of utility easements will have to be taken into account during design. Utility maps will have
to be obtained prior to design. The recommended option would be to investigate the purchase of a tract of
the undeveloped land on the north side of Second Street, in this area. The stormwater could be piped to
underground infiltration basins/trenches which could be located in this area. Regrading of the land on the
north side would be required during construction. Underground infiltration in this area would allow the
land to still be developed for a variety of uses (parking lot, park, etc.).
In designing an underground infiltration system, it is recommended that some type of oil/grit chamber or
' trap be constructed to pretreat the runoff before it enters the trenchibasin. There are various types of
oil/grit chambers, from small devices that fit into standard inlet structures to larger three -chamber
facilities. The size of the oil/grit chamber will be dependent on the size of the area draining to the inlet.
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 of the
area is also necessary prior to completion of the modeling efforts.
To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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, underground infiltration 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 public, this is an implementable BMP. As long as the infiltration 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 Town).
Second Street between Charlotte Street and Shallotte Boulevard
There is minor flooding that occurs on Second Street between Charlotte Street and Shallotte Boulevard, at
the entrance to the Sand Dwellers Condos. These flooding conditions cause a safety hazard for
pedestrians and motorists, along with the potential for property damage to cars from hidden obstructions
under the water.
1 06/29/00 4-10
I
CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
There are no storm drain inlets identified in this area of Second Street. 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 flooding problem in this area it is recommended that additional storm drain inlets be
installed as subsurface retention basins with perforated pipe to infiltrate the retained stormwater.
' The presence of utility easements will have to be taken into account during design. Utility maps will have
to be obtained prior to design.
It is recommended that some type of oil/grit trap be installed in the inlets to pretreat the runoff before it
enters the infiltration pipe.
' The location, number, and size of storm drain inlets will have to be determined through hydraulic and
hydrologic (H & H) modeling of the area. A detailed survey of the area is also necessary prior to
completion of the modeling efforts.
7
11
ri
To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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). It is recommended that the
Town work with the Sand Dwellers Condos to encourage them to reduce the amount of stormwater runoff
that leaves their property. The reduction in the amount of stormwater would reduce the flooding in both
the roadway and the entrance to the Sand Dwellers parking lot.
Through evaluation of various BMPs, subsurface retention 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 storm drain inlets are periodically cleaned and maintained, it is a reliable stormwater BMP.
There are no negative environmental impacts associated with this type of 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 Town).
Third Street at Columbia Street
There is significant flooding that occurs at Third Street and Columbia Street. Flooding is several inches
deep (or more) and extends across the entire intersection on many occasions. These flooding 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 no storm drain inlets identified in this area. 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.
06/29/00 4-11
' CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
' In order to solve the flooding problem in this area it is recommended that an aboveground infiltration
basin be used. This area is in a less developed area, therefore an aboveground infiltration basin would be
more cost effective.
The presence of utility easements will have to be taken into account during design. Utility maps will have
to be obtained prior to design. The recommended option would be to investigate the purchase of a tract of
the undeveloped land in the immediate area. Roadside drainage swales could be used to convey the
' runoff to the infiltration basin area. If purchase of land in this area is determined not to be an option,
underground infiltration trenches would be recommended.
' Although it is not as critical in aboveground construction, it is recommended that some type of oil/grit
trap be constructed to pretreat the runoff before it enters the basin. The size of the oil/grit chamber will
be dependent on the size of the area draining to the inlet.
' The size of infiltration facility will have to be determined through hydraulic and hydrologic (H & H)
modeling -of the area. A detailed survey of the area is also necessary prior to completion of the modeling
' efforts.
To reduce the amount of stormwater runoff which reaches the street, and the Town's storm dram system,
' URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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, infiltration 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 public, this is an implementable BMP. As long as the infiltration 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 Town).
' Craven Street
There is minor flooding that occurs along Craven Street. This flooding condition causes a safety hazard
for pedestrians and motorists, especially if the water extends into the travel lanes.
' There are a few storm drain inlets, although it appears that many of them may be outside the right of way
and on private property. Many of these do not appear to be effective due to the grading of the surface.
' In order to solve the flooding problem in this area it is recommended roadside swales be constructed. The
presence of utility easements will have to be taken into account during design. Utility maps will have to
be obtained prior to design.
06/29/00 4-12
CHAPTER FOUR OCEAN ISLE BEACH
' WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
' The size of the roadside swales will have to be determined through hydraulic and hydrologic (H & H)
modeling of the area. A detailed survey of the area is also necessary prior to completion of the modeling
efforts.
' To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town may want to offer fee/tax credits for
I
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, roadside swales with a stormwater ordinance were determined to be
the most cost effective, applicable, implementable 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 roadside swales 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 Town).
' Leland Street
There is minor flooding that occurs along Leland Street. This flooding condition cause a safety hazard for
pedestrians and motorists, especially if the water extends into the travel lanes.
There are a few storm drain inlets, although they are insufficient for the area. Many of these do not
appear to be effective due to the grading of the surface.
In order to solve the flooding problem in this area it is recommended roadside swales be constructed. The
presence of utility easements will have to be taken into account during design. Utility maps will have to
' be obtained prior to design.
The size of the roadside swales will have to be determined through hydraulic and hydrologic (H & H)
' modeling of the area. A detailed survey of the area is also necessary prior to completion of the modeling
efforts.
To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
' URSGWC recommends that the Town 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. A recommended stormwater ordinance that
' will assist in accomplishing this is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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, roadside swales with a stormwater ordinance were determined to be
the most cost effective, applicable, implementable 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 roadside swales in this area. Public education will be necessary to
06/29/00 4-13
CHAPTER FOUR OCEAN ISLE BEACH
' WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
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 Town).
Concord Street Wilmington Street Fairmont Street, Monroe Street, and Lattrinburz Street
' There is minor flooding that occurs along Concord Street, Wilmington Street, Fairmont Street, Mon roe
Street, and Laurinburg Street. These flooding conditions cause a safety hazard for pedestrians and
motorists, especially if the water extends into the travel lanes.
' There are a few storm drain inlets and some roadside swales, although there are not a sufficient number of
storm drain inlets. Many of the roadside swales do not appear to be effective due to the grading of the
surface around them, and several residents have built wooden "boxes" around many of the swales,
' presumably for landscaping purposes. This is preventing any runoff from entering the swales.
In order to solve the flooding problem in this area it is recommended the roadside swales be reconstructed
and improved. In many areas these swales have become deep "ditches". Also, many of the driveway
culvert pipes are blocked and/or destroyed.
The presence of utility easements will have to be taken into account during design. Utility maps will have
to be obtained prior to design.
The size of the roadside swales will have to be determined through hydraulic and hydrologic (H & H)
' modeling of the area. A detailed survey of the area is also necessary prior to completion of the modeling
efforts.
' To reduce the amount of stormwater runoff which reaches the street, and the Town's storm drain system,
URSGWC recommends that the Town encourage its residents to reduce the amount of impervious surface
on their lots and direct stormwater runoff (from rooftops and other impervious surfaces) to vegetated
' areas, instead of directly off their property and into the street. A recommended stormwater ordinance that
will assist in accomplishing this, is included in Appendix A. Depending on the method of funding of the
Town's Stormwater Management Program (Section 5.5), the Town 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, roadside swales with a stormwater ordinance were determined to be
' the most cost effective, applicable, implementable 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 a roadside 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 Town).
4.3.2 Water Quality
Although water quality in the Ocean Isle Beach 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.
06/29/00 4-14
' CHAPTER FOUR OCEAN ISLE BEACH
WATERSHED CHARACTERISTICS STORMWATER MASTER PLAN
4.3.3 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 particular, on several of the canal streets, wood has been
placed around several of the swales (for landscaping or similar reason), which blocks 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 Town 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 4-2
Recommendations
Ocean Isle Beach
W Location .
Problem Descri tion
Recommended Action
First Street east end
Flooding
Underground Infiltration
First Street at Private Drive
Flooding
Underground Infiltration
First Street between Shelby Street and Troy
Street
Flooding
Underground Infiltration
First Street from Driftwood Drive to the west
Town limit
Flooding
Subsurface Retention or
Roadside Swales
Second Street at Scotland Street
Flooding
Subsurface Retention or
Roadside Swales
Second Street between Lee Street and Goldsboro
Street
Flooding
Subsurface Retention
Second Street at Sanford Street
Flooding
Underground Infiltration
Second Street between Charlotte Street and
Shallotte Blvd.
Flooding
Subsurface Retention
Third Street at Columbia Street
Flooding
Aboveground Infiltration
Basin
Craven Street
Flooding
Roadside Swales
Leland Street
Flooding
Roadside Swales
Concord Street, Wilmington Street, Fairmont
Street, Monroe Street, and Laurinburg Street
Flooding
Roadside Swales
06/29/00 4-15
A7C-0+� z
J
ABBL r OAL C H I
E•ISt yL1.. PEA V
pro q li A l / 7R. '1
I
/ N I R A C D a S T 4 l r A
l E R r A r
• � ^—� ... `--._ ... - .. I — — � — — -- IOW L lYl 75
� � f
1. BAYBERRY ORIVE JJ. INDIGO COURT 1 ��'•, •'�� "I I�
1• BARNACLE COURT JUNIPER CQwI
3. SA/YER COURT 15. OLEANDER LANE
4. HERON COURT /6. CHANNEL ORIVf
UR'� -�~'' U .•.0 ;
5. OOLPION COT 77. OLOE COURT
S. SCHOONER ORIrE 18. COOU/NA COURT /1
7. PfLICAN COURT 19. ATLANTIC rAr __ / I �•-- /•
8. SANDPIPER COURT ?0. WINDY COURT
9. EGRET COURT ?r. SPINARER COURT ??. TEAL CLWT70. EACOURT ?SWLi CDURT/I \
1J. SEABROOtt ROAD
I?. YrRTLf COURT ?I. WARBLER COURT
\ •,•� / - - _ _ / 1 f
\/I i
E4 \•'•
Eq
19• PP' H T FOURTH STREET _ r A L
/ 10. _ ...
9. t8• ----... mM'S /w bNL
t/AMMtl N nl Y Y y Oa[S/Of rNLAS
sfsT n+lao s r
1. 6 1. ?J. ' g
��
J. 4. 5• 1 '�' ?�. WSr SECOND STRf[T
? ff=E N .Esr FI sr r m
75. 76.11 IAr
C C Im Ap7L
fAVD v LL• C5� 0.0 ]Clop .- tu0 r"," Sr.0 r [AS
w MIS Wp tIK LASRL Sup VILLAS
Sf 1 - II FLAK • SAG 1-II
I• ... ... ... ...
500 0 500 1000 1500
GRAPHIC SCALE
LEGEND
Irm EXISTING STORM DRAIN
-=-- EXISTING STORMWATER
CHANNEL W/ OUTFALL
- - - - - - TOWN LIMITS
c CAMA BEACH ACCESS
T I C
IAAm QW
FIGURE 4-1
Lit
YC/A(NSl.QQ . I � eP�• Ct. W �u ! ! � flOfrATfR y
PD�pt
✓...---�_...� 1 aT N
I � I/MI CWSIu
ORIVf / a
7r157 0
\ \ AC 'T4rb C ff
C,p�rfA, C/
r A 7 E R V A Y fOW L lul 7S
_
CRAYfq SlRffl
IIA I
I I
�N I
Li
r r
Qz fAsr slxrH
N Asr 0
A ?� Sr � /h
�--r�
SJREfr
... ... ... .. .. --
0 C E A N
500 0 500 1000 1500
GRAPHIC SCALE
TOWN OF OCEAN ISLE BEACH
STORMWATER
MASTER PLAN
EXISTING STORM
DRAINAGE SYSTEM
FIGURE 4-1
URS Greiner Woodward Clyde
J � � A`2''�E
V 0�
A Y DAL E �+ I
E4 , �`PL A -'
q14 ti R If JR. 1
• I N r R A C 0 A S r A L WA r E R WA Y
I NI rs
I
r. BAYBERRY DRIVE 1J. INDIGO COURT �'•, ��
a. BARNACLE COURT 11. JUNIPER COURT
J. 591)"R CO7R! /s. O[EANOER LANE 1y'
1. HERON COA41 76. CHAA►L DIVE •� •��•' r/ ;
s. DOLPHIN COURT 17. DONE COURT� I •\. 1/
6. SCfIWWR DRIVE f8. COQUINA COURT
7. PELICAN COURT 19• ATLANTIC MAY __•/ I �• J
8. SANDPIPER COURT a0. r/NOY COURT I\ <
9. ECRET COURT 11. SPIWER COURT \ --/� _ I •—.�--- � •-
lo. FERN COURT ??. TEAL COURT \\\ •\ :
11. SEABROOK ROAD ?J. 51sEtt COURT
12. MYRTLE COURT 2 rARBL ER COUPI J - - - / \'•,
E A
jO `�.. CN A 1,
yW�
)9. ??. 1—` 1 (DURUM 51` N E L
/ to.
iB.
is
�...�— ..
9• srWuson rr sr ti A.rs/a vnru IEsT THIRD SrRU�s■.oNr
?A. rts! SECDvO 57REFT / ^ V+ ST SEC STR£Er
LIO
s!a Lasnr
500 0 500 1000 1500
GRAPHIC SCALE
R.C[ • K� 1-I I
LEGEND
® EXISTING STORM DRAIN
EXISTING STORMWATER
CHANNEL W/OUTFALL
%t FLOODING PROBLEM AREAS
- - - - - - TOWN LIMITS
c CAMA BEACH ACCESS
N SI FI SiREE! m
N C Ir 41Nt
010 ""o DaM, fW VAAAS rib r /Af
WO riu.s QQ
58
A T L A N T
FIGURE 4-2
Lit
LJ
LYC/A LH. SI. D
e Q
h
TWIVArfR
Mor : W
7
DRIVECDASrAt
DR
Os, 0, � C
C't'E'FA• CrR � W
A C 0 A
A( I
Of
��'.• �_• ��, L, _ . �_ \ ` ` \ vAnE ROAD
------
/
J \ ���,,�
CRAVE" SWEI 'LTs_ _ _�" •`._... .��
J "'
IA I I I I� I I!W I I� I I� I I� I� i I� I � I I� I� I I� I" I` •/ �\�� Vr Q
r
W
z
J
U
Q
m
C E A N
500 0 500 1000 1500
GRAPHIC SCALE
MEN
`a
a r r
�U
ASr r EAST S/XTH J
F/vrH sr
$T r / vl
If��_-���I,1 �������ii�"'' � �, Lear" 5T fr �' J� �-•�
�Q A
SEC SrH/ SrRffr
v0 •
rgL•fl t� ... °tttc •� ::.sic; �
... ...
TOWN OF OCEAN ISLE BEACH
STORMWATER
MASTER PLAN
STORMWATER
AREAS OF CONCERN
FIGURE 4-2
URS Greiner Woodward Clyde
7
' CHAPTER FIVE
STORMWATER OCEAN ISLE BEACH
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
The recommendations presented in Chapter Four 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 5.2. Recommendations for minor repair and
maintenance should be made part of the Town's operating budget. Recommended policy changes may or
may not have budget implications.
5.1 RECOMMENDATION SUMMARY
Costs for the recommendations were estimated (order of magnitude) and are shown in Table 5-1. The
' total estimated cost for all CIP projects is approximately $1,055,000 (plus potential land costs for some
items). It should be noted that these are only estimates. Surveying and H & H modeling is necessary to
determine more precise estimates on sizes of facilities, length of pipe, etc. Whether the Town can obtain
' land needed for several of the projects is also a factor. Therefore, these costs should only be looked at as
order of magnitude given the recommendations presented in Chapter Four.
5.2 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 were used:
• Safety
• Quantity Benefits
• Quality Benefits
Safety
' This criterion is for projects that maintain safe travelways during rain storms and protect against property
damage from flooding. 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 AIWW.
Table 5-1 lists the project selection criteria as well as the rankings of each proposed project.
06/19/00 5-1
1
I
ll
1
CHAPTER FIVE
STORMWATER OCEAN ISLE BEACH
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
Table 5-1
Project Selection Criteria and Ranking
Ocean Isle Beach
Evaluation Criteria , ... "
Overall.,
"''Problem,.,.
Project.
,Recommend e
", '
Quantity
'Quality
Location
Descri tion
SafeBenefits
Benefits
Rankin .
Action ,
First Street (east
Flooding
1
1
2
1
Underground
end)
Infiltration
First Street at
Underground
Private Drive
Flooding
2
2
8
2
Infiltration
First Street
Underground
between Shelby
Flooding
3
5
10
7
Infiltration
Street and Troy
Street
First Street from
Subsurface
Driftwood Drive
Flooding
9
8
11
11
Retention or
to the western
Roadside Swales
Town limit
Second Street at
Subsurface
Scotland Street
Flooding
6
10
5
8
Retention or
Roadside Swales
Second Street
between Lee
Flooding
7
11
6
9
Subsurface
Street and
Retention
Goldsboro Street
Second Street at
Underground
Sanford Street
Flooding
4
7
7
5
Infiltration
Second Street
between
Flooding
8
12
12
12
Subsurface
Charlotte Street
Retention
and Shallotte
Blvd.
Third Street at
Aboveground
Columbia Street
Flooding
5
3
9
4
Infiltration Basin
Craven Street
Flooding
10
6
3
6
Roadside Swales
Leland Street
Flooding
11
9
4
10
Roadside Swales
Concord Street,
Wilmington
Flooding
12
4
1
3
Roadside Swales
Street, Fairmont
Street, Monroe
Street, and
Laurinburg Street
Ranking: 1=highest; 12=1owest.
06/21/00 5-2
CHAPTER FIVE
' STORMWATER OCEAN ISLE BEACH
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
5.3 CAPITAL IMPROVEMENT PROGRAM
Inadequate system capacity is the biggest water quality and water quantity problem requiring capital
improvements. Table 5-1 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 5.2.
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 flooding areas. Stormwater modeling is briefly
described below.
' 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 for 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 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 scheduling of
these action items is dependent upon the Town's financing needs and methods. Funding options are
' described in Section 5.5.
5.4 OPERATION AND MAINTENANCE PROGRAM
' 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.
I
1 06/19/00 5-3
C
1
CHAPTER FIVE
STORMWATER OCEAN ISLE BEACH
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
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 Town 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 Town purchase
a vacuum truck for cleaning pipes and infiltration facilities. The Town 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. Other beach towns have used this sediment for beach renourishment. Both these actions
would require permitting.
5.5 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 Town 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 Town could depend on a certain amount year
to year being committed to a planned program of operation and maintenance (O & M) and replacement
and improvements.
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 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 City
of Charlotte is provided in Appendix C.
' The implementation of a BMP or buffer used to receive credit will reduce some of the cost to the Town
for construction of a similar facility for a water quantity/quality benefit. However, some portion of the
06/29/00 5-4
CHAPTER FIVE
STORMWATER OCEAN ISLE BEACH
MANAGEMENT PROGRAM STORMWATER MASTER PLAN
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 Town can apply to for grants and low interest loans. Due to the
location of the Town, and its sensitive environment, the Town 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 Town to establish policy on
additional funding methods.
Table 5-2
Capital Improvement Program
Ocean Isle Beach
Location
Action Description
Estimated Cost
First Street (east end)
Underground Infiltration
$400,000+ land if needed
First Street at Private Drive
Underground Infiltration
$50,000+ land if needed
First Street between Shelby Street
Underground Infiltration
$75,000+ land
and Troy Street
First Street from Driftwood Drive
Subsurface Retention or
$40,000
to the western Town limit
Roadside Swales
Second Street at Scotland Street
Subsurface Retention or
$30,000
Roadside Swales
Second Street between Lee Street
Subsurface Retention
$50,000
and Goldsboro Street
Second Street at Sanford Street
Underground Infiltration
$50,000+ land
Second Street between Charlotte
Subsurface Retention
$50,000
Street and Shallotte Blvd.
Third Street at Columbia Street
Aboveground Infiltration
$130,000+ land
Basin
Craven Street
Roadside Swales
$40,000
Leland Street
Roadside Swales
$30,000
Concord Street, Wilmington
Roadside Swales
$40,000 each street
Street, Fairmont Street, Monroe
Street, and Laurinburg Street
1 06/29/00 5-5
1
n
1
J
CHAPTER SIX OCEAN ISLE BEACH
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.
1998. Basinwide Assessment Report — Lumber River Basin. Environmental Sciences Branch.
1999. Lumber River Basinwide Water Quality Plan. Raleigh, NC: Division of Environmental
Management.
A Guide to Protecting Coastal Resources Through the CAMA Permit Program. Raleigh, NC:
Division of Coastal Management.
Town of Ocean Isle Beach. 1997. CAMA Land Use Plan Update.
Ogden Environmental and Engineering Services, Inc. 1994. City of Charlotte Storm Water Services
Credit Application Instruction Manual. Charlotte, NC: City of Charlotte Stormwater Services.
US Department of Agriculture. 1986. Soil Survey of Brunswick County, North Carolina. Soil
Conservation Service.
06/19/00 6-1
APPENDIX A
Draft Stormwater Management Ordinance
C1
DRAFT
1 Section 1.
STORMWATER MANAGEMENT ORDINANCE
Title
Ratification Number: XXXXXXX
This document may be cited as the Town of Ocean Isle Beach's Stormwater Management
Ordinance for implementation within Town limits.
Section 2. Goals and Purposes
The central environmental goal of the Town of Ocean Isle Beach is to preserve water
quality and the natural ecological functions of the surface water located within the Town
limits. In order to meet this important goal, the Town of Ocean Isle Beach Stormwater
Ordinance will be adopted for the following purposes:
a) To regulate existing developments, new developments, and construction activities
consistent with State of North Carolina requirements and the Town of Ocean Isle
Beach's requirements.
b) To establish the authority of the Town of Ocean Isle Beach to administer and enforce
stormwater quantity and quality regulations including limiting impervious surface,
improvements on redevelopment and landscaping requirements.
c) To create public education programs so the citizens of the Town will have knowledge
of how to reduce and prevent pollution of all nature from their land, homes, and
businesses.
Section 3. Definitions and Abbreviations Used Within This Ordinance
For the purposes of this ordinance, the following listed terms and phrases shall have these
definitions:
Alphabetical Listing
a) Agricultural Land Management Practices shall mean those methods and procedures
used in cultivation of land in order to further crop and livestock production and
conservation of related soil and water resources.
b) Area of Environmental Concern shall mean an area identified by the State of North
Carolina Coastal Resources Commission as environmentally fragile and
economically important where uncontrolled or incompatible development could
result in irreversible damage.
c) Built -Upon Area shall mean that portion of an individual development project that
is covered by impervious or partially impervious cover including buildings,
Town of Ocean Isle Beach 1
Draft Stormwater Management Ordinance
' DRAFT
' pavement, recreation facilities, roads and parking areas, etc. Wood slatted decks
and the water area of a swimming pool are not considered to be built -upon area.
d) BMP shall mean Best Management Practices as adopted by the Town of Ocean Isle
Beach.
te) CAMA shall mean Coastal Area Management Act, which was adopted by North
Carolina in 1974. The Act established a comprehensive regional resource
management program for the state's 20-county coastal area. The management
program that has evolved since 1974 in North Carolina has land use planning,
regulatory, land acquisition, and policy development components.
f) CAMA Major Development Permit shall mean the permit required by the Coastal
Resources Commission for developments that infringe on Areas of Environmental
Concern.
g) Coastal Wetland shall mean any salt marsh or other marsh subject to regular or
occasional flooding by tides, including wind tides (whether or not the tide waters
reach the marshland areas through natural or artificial watercourses), provided this
shall not include hurricane or tropical storm tides. Coastal wetlands contain some,
but not necessarily all, of ten indigenous wetland plant species. Included in this
definition of coastal wetlands is "such contiguous land as the Secretary of the North
Carolina Department of Environment and Natural Resources (NCDENR)
reasonably deems necessary to affect any such order in carrying out the purposes
[of the regulations]." (G.S. 113-230(a)).
h) Customer shall mean the person or firm to which a bill for stormwater management
services is sent.
i)
Development shall mean any land disturbing activity that increases the amount of
built -upon area or that otherwise decreases the infiltration of precipitation into the
soil.
j)
Erosion shall mean the wearing away of land surface by the action of wind, water,
gravity or any combination thereof.
'
k)
Erosion and Sediment Control Plan shall mean a written plan including drawings or
other graphic representations for the control of soil erosion and sedimentation
resulting from a land disturbing activity.
1)
Estuarine Shoreline shall mean a non -ocean shoreline connected to the estuarine
waters that are especially vulnerable to erosion, flooding, and other adverse effects
of wind and water. Estuarine shorelines extend from the mean high water level (in
areas of tidal influence) or normal water level (in areas without tidal influence)
along the estuaries, sounds, bays, and brackish waters for a distance of 75 feet
landward unless otherwise set by the Coastal Resources Commission.
1
Town of Ocean Isle Beach 2
Draft Stormwater Management Ordinance
' FT
DRA
m) Estuarine Waters shall mean all the water of the Atlantic Ocean within the
boundary of North Carolina and all the waters of the bays, sounds, rivers, and
tributaries thereto seaward of the dividing line between coastal fishing waters, as
set forth in the most recent official published agreement adopted by the Wildlife
Resources Commission and NCDENR.
n) Existing Development shall mean any land that has been utilized for a land -
disturbing activity as of the effective date of this ordinance.
o) Health Department shall mean the Brunswick County Health Department or the
North Carolina State Board of Health depending on jurisdiction.
p) Illegal Discharge shall mean any direct or indirect non-stormwater discharge to the
storm drain system except as defined in Section 9.1.
q) Illicit Connections shall mean either of the following:
(1) Any drain or conveyance, whether surface or subsurface, which allows an
illegal discharge to enter the storm drain system including but not limited to
and conveyances which allow any non-stormwater discharge including
sewage, process wastewater, and wash water to enter the storm drain system
and any connections to the storm drain system from indoor drains and sinks,
regardless of whether said drain or connection had been previously allowed,
permitted, or approved by a government agency; or
(2) Any drain or conveyance connected from a commercial or industrial land use
to the storm drain system which has not been documented in plans, maps, or
equivalent records and approved by the Town
r) Impervious Surfaces shall mean those areas within the land of the Town which
prevent or significantly impede the infiltration of water into the soil. Common
impervious surfaces include, but are not limited to, roof tops, sidewalks, walkways,
patio areas, driveways, parking lots, storage areas, brick or concrete pavers and
other surfaces that prevent or significantly impede the natural infiltration of water
into the soil.
s) Improved Lands for the purposes of this Ordinance shall mean any lands that have
had land disturbing activities that altered or changed the natural cover or
topography of said land.
t) Infiltration System shall mean a stormwater treatment system designed to allow
runoff to pass or move (infiltrate) into the soil.
u) Land Disturbing Activity shall mean any use of the land by any person in
residential, industrial, educational, institutional or commercial development,
highway and road construction and maintenance that results in a change in the
natural cover or topography and that may cause or contribute to sedimentation.
i
Town of Ocean Isle Beach 3
Draft Stormwater Management Ordinance
DRAFT
v) New Development shall mean any land that is utilized for a land -disturbing activity
after the effective date of this Ordinance.
iw) NCAC shall mean the North Carolina Administrative Code.
' x) North Carolina Coastal Resources Commission shall mean the state policy -making
organization with responsibility for the coastal region.
y)
NPDES shall mean the National Pollutant Discharge Elimination System
permitting process of the Environmental Protection Agency (EPA).
z)
Ocean Hazard Area shall mean an area where there exists a substantial possibility
of excessive erosion and shoreline fluctuation. The seaward limit of this boundary
is the mean low water line.
aa)
Town shall mean that area within the Ocean Isle Beach Town limits.
bb)
Redevelopment shall mean any rebuilding activity that exceeds 50% of the tax
value of the structure, and that has no net increase in built -upon area or that
provides equal or greater stormwater controls than the previous development.
cc)
SA Waters shall mean tidal saltwater of the highest quality that are suitable for
commercial shell fishing, swimming, and all other tidal saltwater uses. The
chloride concentration of SA waters must be at least 500 parts per million.
dd
Sedimentation shall mean the deposition of solid material both mineral and
organic, that has been transported from its site of origin by air or water.
ee)
Sedimentation/Erosion Control Plan shall mean a plan required by the Division of
Land Resources in which developers must describe the sedimentation and erosion
control devices they will use for land disturbing activities that are one acre or
greater.
ff) Sewerage or Septage shall mean the liquid and solid human body waste and liquid
waste generated by water -using fixtures and appliances including those associated
with food handling.
Stormwater shall mean the flow of water that results from reci itation and that
gg) p P
occurs immediately following rainfall or a snowmelt.
hh Stormwater Collection System shall mean an conduit, pipe channel, curb or gutter
y Y Pp
utilized for the primary purpose of transporting (not treating) runoff.
' ii SWMP is the Stormwater Management Plan for the Town of Ocean Isle Beach.
J) State Certification shall mean one or more of the following documents: a CAMA
permit application and accompanying CAMA permit from the Division of Coastal
Management, a Stormwater certification or permit, as required, from the Division
Town of Ocean Isle Beach 4
Draft Stormwater Management Ordinance
'
DRAFT
'
of Environmental Management, and/or a Sedimentation and Erosion Control Plan
that has been approved by the Division of Land Quality.
tkk)
Surface Waters shall mean rivers, streams, creeks, channels, lakes, reservoirs,
ponds, drainage systems, springs, wetlands, wells, the Atlantic Ocean, and other
bodies of surface or subsurface water, natural or artificial, lying within or forming
part of the boundaries of the Town. This term excludes privately owned ponds that
have no entry or exit of water to or from waters of public domain.
11)
Unimproved Land for the purposes of this Ordinance shall mean any land that has
not had land disturbing activities as described herein.
min)
10-Year, 24-Hour Storm shall mean the storm of the largest intensity expected to
occur on the average once every 10 years and of a 24-hour duration.
nn)
2-Year. 24-Hour Storm shall mean the storm of the largest intensity expected to
occur on the average once every 2 years and of a 24-hour duration.
oo)
Vegetative Filter shall mean an area of natural or planted vegetation through which
stormwater flows in a diffuse manner so that runoff does not become channeled and
that provides for control of stormwater runoff through infiltration or filtering of
pollutants. The defined length of the filter shall be provided for the direction of
stormwater flow.
pp)
Wet Detention Pond shall mean a structure that provides for storage and treatment
of runoff and includes a permanent pool of water under normal circumstances.
Section 4. Jurisdiction
The regulations contained herein shall govern all real property and each and every
' stormwater quantity and quality management device within the approved Town Limits of
Ocean Isle Beach. Whenever conflicts exist among federal, state, or local laws and this
ordinance, the more restrictive provision shall apply.
Section 5. Findings
1 a) The Town of Ocean Isle Beach finds evidence that the development and
implementation of a reliable SWMP to best serve the citizens of the Town will
require that all sources of pollution that are carried with stormwater runoff be
identified, quantified and analyzed to implement an effective SWMP pollution
control and abatement plan to protect the surface and groundwater's within the Town;
and
1 b) The Town of Ocean Isle Beach needs to affirm its responsibility and enhance its
capability to maintain existing water quantity and quality management facilities of all
natures in the Town and establish future water quantity and quality management
facilities and measures that will ensure that as growth occurs and the population
density increases, the Town's sensitive environment and ecosystems are protected for
future generations.
Town of Ocean Isle Beach 5
Draft Stormwater Management Ordinance
I DRAFT
ISection 6. Scope of the Ordinance
This Ordinance shall apply to all real property within the jurisdiction of the Town of
Ocean Isle Beach.
a) All property owners and managers should give specific attention to the
recommendations set forth in the General Water Quality Protection
Recommendations (Section 7) of this Ordinance.
b) All property owners, regardless of their previous practices, shall be subject to the
regulations listed under Section 8, Landscaping/Buffer Requirements.
c) All property owners, regardless of their previous practices, shall be subject to the
regulations listed under Section 9, Discharge Prohibition.
d) All property owners, regardless of their previous practices, shall be subject to the
regulations listed under Section 10, Mandatory Standards for Existing Development.
e) All new developments, regardless of its size, shall be subject to the regulations listed
under Section 11, Mandatory Standards for New Developments.
f) All redevelopment activities shall be subject to the regulations listed under Section
12, Mandatory Standards for Redevelopment.
g) All construction activities, whether for new development or improvements on
existing development, shall be subject to the regulations set forth under Section 13,
Mandatory Standards for Construction Activities.
Section 7. General Water Ouality Protection Recommendations
a) All visitors, residents, business owners, developers, and others who utilize the
resources within the Town of Ocean Isle Beach shall take all reasonable measures to
protect surface waters from damage resulting from their activities.
Section 8. Landscapin2/Buffer Requirements
Buffer zones shall be established in accordance with the Coastal Resources Commission
Shoreline Buffer Rules. The Town of Ocean Isle Beach has established additional
guidelines for the management of these buffers. Failure to comply with these
requirements will be subject to fines in accordance with Section 17 of this Ordinance for
each incident and day of violation.
a) The vegetation within a buffer zone must be either retained in a natural, undisturbed
condition, or properly managed in accordance with the standards contained in this
section. In cases where native flora (vegetation) does not exist within a buffer zone,
the Town may require restoration efforts which include, but are not limited to,
replanting the buffer zone with native plant species.
b) Buffer zones shall remain covered with native flora and in an undisturbed state in
order to promote the Town's goal of preserving, protecting, and restoring ecological
systems. However, the Town may permit minor alterations to buffer zones that
facilitate the continued enjoyment of the area's coastal resources. All alterations to
Town of Ocean Isle Beach 6
Draft Stormwater Management Ordinance
I DRAFT
buffer zones or alterations to the natural vegetation (e.g.: areas not presently
maintained in a landscaped condition) within the Town shall be conducted in
accordance with the standards contained in this section, as well as all other applicable
policies and standards of the Town.
b) In order to promote the Town's goal to preserve, protect and, where possible, restore
ecological systems, buffer zones shall be vegetated with native flora and retained in a
natural, undisturbed condition, or shall be properly managed in accordance with the
following:
(1) Shoreline Access Paths: Pathways which provide access to the shoreline are
normally considered permissible provided they are less than or equal to 6 feet
wide and follow a path that minimizes erosion and gullying within the buffer zone
(e.g., a winding, but direct path). Pathways should avoid, or may be prohibited in,
sensitive habitat areas, including, but not limited to, coastal wetlands. Pathways
may be vegetated with grasses and mowed or may be surfaced with crushed stone
or mulch.
(2) View Corridors: Selective tree removal and pruning and thinning of natural
vegetation may be allowed within a defined corridor in order to promote a view of
the shoreline. Only the minimal alteration of vegetation necessary to obtain a
view shall be acceptable to the Town. Shoreline access paths shall be located
within view corridors to the maximum extent practicable in order to minimize
disturbance of buffer zones. View corridors shall be prohibited in sensitive or
critical habitat areas.
(A) Selective Tree Removal - In cases where the applicant wishes to remove a
few select trees, trees proposed to be cut must be specifically identified for
Town staff review. In most cases, photographs of the buffer area may be
sufficient provided the affected trees are clearly shown in relation to the
surrounding buffer and shoreline. Trees may also be marked on -site to
allow inspection by Town staff. In order to minimize disturbance and
allow monitoring by Town staff, tree stumps of fallen trees shall not be
removed. Town staff may make a follow-up inspection to verify that only
marked trees were cut based upon stump counts. Should the applicant wish
to remove a fallen tree from the buffer zone, this must be performed in a
manner which does not disturb remaining vegetation. Selective tree
removal is often a preferred technique for the establishment of a view
corridor.
(B) Selective Pruning - Pruning as defined for Town purposes involves cutting
branches from trees, tree saplings and shrubs. For certain buffer zone
management options, pruning the tops of shrubs and forest undergrowth
(topping) may be appropriate to discourage growth in height. On level
' ground, shrubs and forest undergrowth should be pruned to a height of not
less than 4-5 feet. In areas where the ground surface descends toward the
shoreline, topping should only be performed to a height that allows a view
of the water. Property owners proposing pruning must describe in detail
the work proposed, provide photographs and a site plan, and/or mark those
portions of the buffer zone where vegetation to be pruned should be
Town of Ocean Isle Beach 7
1 Draft Stormwater Management Ordinance
I DRAFT
identified since some species of vegetation cannot tolerate excessive
pruning or topping. Selective pruning is often a preferred technique for
' the establishment of a view corridor.
(C) Selective Thinning - Thinning as defined for Town purposes involves the
selective removal of tree saplings, shrubs and vines occurring in brush
' areas and in the undergrowth of forested buffer zones. Applicants
proposing thinning must describe in detail the work proposed, provide
photographs and a site plan, and/or mark areas to be thinned on -site. The
species of vegetation to be removed from a buffer zone management area
must be differentiated from those species which are to be retained and
encouraged. Selective thinning is often a preferred technique in areas
where habitat management will be performed.
(D) Mowing - In most cases, mowing of vegetation within a buffer zone shall
be prohibited unless associated with the establishment and maintenance of
I shoreline access path or approved shoreline recreation area. However, for
certain habitat management options, annual or biannual mowing may be
allowed to maintain field vegetation where such vegetation is considered
valuable to wildlife and other natural values. In such cases, mowing shall
be confined to 25% of the buffer zone area, or less.
(E) Clearin - Clearing or clear -cutting of vegetation within a buffer zone shall
only be allowed for the establishment of shoreline access paths, shoreline
recreation areas and in certain cases, habitat management options, which
are designed to maintain a field of native grasses and herbaceous plants.
Clearing shall not affect more than 25% of the buffer zone area. Clearing
for habitat management shall not be allowed in Buffer zones of less than
one acre.
(F) Filling rg ading - Minor filling (10 cubic yards or less) and grading
shall only be allowed in buffer zone areas for the establishment of
shoreline access paths and shoreline recreation areas. Certain, minor
' cutting and filling activities may also be allowed on a case -by -case basis
to promote these uses. Filling and grading shall not be allowed for habitat
management options.
(3) Habitat Management: Management of natural vegetation within a buffer zone to
enhance wildlife habitat and control nuisance and non-native species of vegetation
may be allowed. Homeowner control of pest species of vegetation such as
European bittersweet and nuisance species such as poison ivy is normally
considered acceptable. However, the indiscriminate use of herbicides or the
clear -cutting of vegetation shall be prohibited. The use of fertilizers is generally
prohibited within the buffer zone except when used to enhance the replanting of
native vegetation (e.g., hydro -seeding) approved by the Town. However, the
clearing or outright elimination of natural vegetation for such purposes as
controlling ticks or pollen shall not be permitted.
(A) Restorative Planting - For purposes of buffer zone management,
restorative planting shall be strictly defined as the planting or replanting of
natural vegetation native to the North Carolina shoreline. However,
naturalized species may be allowed, as determined by Town staff. The
i
Town of Ocean Isle Beach 8
1 Draft Stormwater Management Ordinance
' DRAFT
rplanting of non-native, landscape and exotic species, in most cases, shall
not be considered appropriate in buffer zones.
1 (4) Safety and Welfare: Selective tree removal, pruning and thinning of natural
vegetation within a buffer zone may be allowed by the Town on a case -by -case
basis for proven safety and welfare concerns (e.g., removal of a damaged tree in
close proximity to a dwelling). In order to promote child safety and manage pets
in areas harboring ticks, fences along the inland edge of a buffer zone and along
shoreline access pathways may be permitted.
Section 9. DischarEe Prohibitions
ISection 9.1 Prohibition of Illegal Discharges
No person shall discharge or cause to be discharged into the municipal storm drain
system or watercourses any materials, including but not limited to pollutants or waters
containing any pollutants that cause or contribute to a violation of applicable water
quality standards, other than stormwater.
' The following direct discharges resulting from the improper disposal of such materials
into surface waters are unlawful. Violators will be subject to fines in accordance with
tSection 17 of this Ordinance for each incident and day of violation as well as any and all
costs of removal, cleanup and remediation.
a) Sewage or biosolids.
b) Polluted household wastewater, including but not limited to laundry wash
water and dishwater.
c) Leaking sanitary sewers and connections, which have remained uncorrected
for three days or more after seven days notice.
d) Leaking water lines with flows sufficient to cause soil erosion that have
remained uncorrected for three days or more after seven days notice.
e) Commercial, industrial, or public vehicle, vessel, or equipment wash
discharge.
f) Solid, chemical, or sanitary waste.
g) Dead terrestrial animals or animal fecal waste.
h) Petroleum products or derivatives thereof.
i) Wrecked or discarded vehicles or equipment.
j) Trash, refuse, or garbage.
The commencement, conduct or continuance of any illegal discharge to the storm drain
system is prohibited except as follows:
a) Discharges from the following activities will not be considered a source of pollutants
to the storm drain system and to waters of the U.S. when properly managed to ensure
that no potential pollutants are present, and therefore they shall not be considered
' illegal discharges unless determined to cause a violation of the provisions of the
Clean Water Act or this ordinance: potable water line flushing; uncontaminated
pumped groundwater and other discharges from potable water sources; landscape
Town of Ocean Isle Beach 9
I
Draft Stormwater Management Ordinance
DRAFT
11
1
1
irrigation and lawn watering; diverted stream flows; rising groundwater; groundwater
infiltration to the storm drain system; uncontaminated foundation and footing drains;
uncontaminated water from crawl space pumps; air conditioning condensation;
uncontaminated non -industrial roof drains; springs; individual residential and
occasional non-commercial car washing; flows from riparian habitats and wetlands;
dechlorinated swimming pool discharges; street wash waters; and flows from fire
fighting.
b) The prohibition shall not apply to any non-stormwater discharge permitted under a
NPDES permit, waiver, or waste discharge order issued to the discharger and
administered by the State of North Carolina under the authority of the Federal
Environmental Protection Agency, provided that the discharger is in full compliance
with all requirements of the permit, waiver, or order and other applicable laws and
regulations, and provided that written approval has been granted by the Town of
Ocean Isle Beach for any discharge to the storm drain system.
Section 9.2 Prohibition of Illicit Connections
a) The construction, use, maintenance or continued existence of illicit connections to the
storm drain system is prohibited.
b) This prohibition expressly includes, without limitation, illicit connections made in the
past, regardless of whether the connection was permissible under law or practices
applicable or prevailing at the time of connection.
Section 9.3 Waste Disposal Prohibitions
a) No person shall throw, deposit, leave, maintain, keep, or permit to be ,thrown,
deposited, left, or maintained, in or upon any public or private property, driveway,
parking area, street, alley, sidewalk, component of the storm drain system, or water of
the U.S., any refuse, rubbish, garbage, litter, or other discarded or abandoned objects,
articles, and accumulations, so that the same may cause or contribute to pollution.
Wastes deposited in streets in proper waste receptacles for the purposes of collection
are exempt from this prohibition.
b) Yard wastes, including dredge spoil, leaves, and yard trimmings may not be deposited
into surface waters. Acceptable management practices for yard wastes include
composting and landfilling. Persons who deposit yard wastes into surface waters are
subject to fines in accordance with Section 17 of this Ordinance for each incident of
violation as well as any and all costs of removal, cleanup and remediation.
Section 10. Mandatory Standards for Existing Development
a) No landscaping using impervious materials such as solid waste and vinyl will be
permitted. Property owners must remove any such materials installed after the
effective date of this Ordinance. Failure to comply within 30 days of notification is
' subject to a fine of $50 for each incident and day of violation as well as any and all
costs of removal.
Town of Ocean Isle Beach 10
' Draft Stormwater Management Ordinance
DRAFT
7
I
(1) Exemptions: Use of plastic covering for agricultural land management
practices shall be permitted.
b) All label directions must be followed so that fertilizers and pesticides are mixed and
applied correctly and at the proper time. The label is a legal document. Persons who
incorrectly mix or apply chemicals are subject to fines in accordance with Section 17
of this Ordinance for each incident of violation as well as any and all costs of
removal, cleanup and remediation.
c) Chemicals on both commercial and residential property must be stored in properly
built and maintained storage facilities, which are located above the 100-year flood
elevation. Persons who do not store chemicals safely will be given seven calendar
days to correct such conditions. Failure to comply following this seven-day period
will be subject to fines in accordance with Section 17 of this Ordinance for each
incident and day of violation as well as any and all costs of removal, cleanup and
remediation.
d) No person shall intentionally or unintentionally create a nuisance or harmful
stormwater problem on a neighboring property. Persons who do create such a
problem, as determined by the Town, along with the Town's designated professional
engineer, will be given seven calendar days to correct such conditions. Failure to
comply following this seven-day period will be subject to fines in accordance with
Section 17 of this Ordinance for each incident and day of violation.
Section 11. Mandatory Standards for New Developments
Section 11.1 Coverage and Application Process
a) Site plan approval is required for all development activities within the Town.
Approvals and permits may also be required by the State of North Carolina. Copies
of all State certifications and permits must be submitted to the Town prior to the start
of construction activities. The requirements of this section are consistent with the
15A NCAC 2H.1000 Stormwater Management Rules for application and issuance of
permits for stormwater management systems.
b) Other Projects: Development may also be permitted on a case -by -case basis if the
proj ect:
(1) controls runoff through an off -site stormwater system meeting the provisions of
this Section;
(2) is redevelopment which meets the requirements of this Section to the maximum
extent practicable.
c) Approval of new development stormwater management shall be made through the
Town. A processing fee must be submitted with the plans and specifications.
d) For every submittal of a new site plan, a nonrefundable processing fee shall be
submitted at the time of submittal. The processing fee shall be $50.
e) The applicant shall submit all necessary information to describe the site, development
and stormwater management practices proposed. The following documents and
information shall be submitted:
(1) two sets of detailed plans and specifications for the project;
Town of Ocean Isle Beach 11
' Draft Stormwater Management Ordinance
DRAFT
(2) plans and specifications must be dated and sealed as outlined in Section 11.3 and
show the revision number and date;
(3) general location map showing orientation of the project with relation to at least
two references (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 patterns;
(5) delineation of relevant boundaries including drainage areas, seasonal high water
table, wetlands, property/project boundaries and drainage easements;
(6) existing and proposed built -upon area including drainage 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, runoff coefficients, runoff volume,
runoff depth, flow routing, inlet and outlet configuration (where applicable), other
'
applicable information as specified;
(8) operation and maintenance plan and maintenance agreement signed by
responsible party;
1
(9) recorded deed restriction and protected covenants. As an alternative proposed
deed restriction and protected covenants, a signed agreement to provide final
recorded articles shall be accepted when final documents are not available at the
time of submittal.
(f) As -built drawings of the site shall be submitted to the Town within 30 days of
completion of project construction.
1
Section 11.2 Stormwater Requirements
a) All development activities within the Town shall manage stormwater as follows:
(1) runoff from all new development, regardless of size, shall approximate the rate of
flow and timing of runoff that would have occurred following the same rainfall
under predevelopment conditions for the 24-hour two (2) year and ten (10) year
frequency rainfall events.
t11.3
(2) control systems must be infiltration systems designed in accordance with Section
to control the runoff from all surfaces generated by the first one and one-half
inches of rainfall along with the requirements from paragraph (1) above.
Alternatives as described in Section 11.3 may also be approved if they do not
discharge to surface waters in response to the design storm;
(A) Development shall be approved if the following conditions are met:
(i) no direct outlet channels or pipes to SA waters unless permitted in
accordance with 15A NCAC 2H .0126;
(ii) control systems must be infiltration systems designed in accordance with
Section 11.3 to control the runoff from all surfaces generated by the two
(2) and (10) year frequency rainfall event. Alternatives as described in
Section 11.3 may also be approved if they do not discharge to surface
1
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 Section 11.3, with a
Town of Ocean Isle Beach 12
IDraft
Stormwater Management Ordinance
DRAFT
1
I
J
minimum length of 50 feet measured from mean high water of SA
waters.
Section 11.3 Design of Stormwater Management Systems
a) Structural Stormwater Control Options. Stormwater Control Measures which may be
approved include:
(1) Stormwater infiltration systems including infiltration basins/ponds, swales, dry
wells and vegetative filters;
(2) Wet detention ponds; and
(3) Devices meeting alternative design criteria.
b) Innovative measures for controlling stormwater which are not met will be established
through actual experience and may be approved on a demonstration basis under the
following conditions:
(1) There is a reasonable expectation that the control measures will be successful;
(2) The projects are not adjacent to or near High Quality Waters (HQW);
(3) Monitoring requirements are included to verify the performance of the control
measures; and,
(4) Alternatives are available if the control measures fail and when the Town has
determined that the system has failed.
c) Vegetation in the filter may be natural vegetation, grasses, or artificially planted
wetland vegetation appropriate for site characteristics.
d) General engineering design criteria, specific stormwater management system design
criteria and alternatives design criteria shall be as described in 15A NCAC 2H.1008
Design of Stormwater Management Measures.
e) Stormwater systems must be designed by an individual who meets the North Carolina
professional engineer 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 approved by the Town and
complies with the requirements of this Section prior to issuance of the certificate of
occupancy.
Section 11.4 Operation and Maintenance
a) Prior to site plan approval by the Town, 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 for restoring a
stormwater system to design specifications if a failure occurs and must include an
acknowledgment by the responsible party. Development must be maintained
consistent with the requirements in the operation and maintenance plan and the
original plans and any modifications to these plans must be approved by the Town.
b) A maintenance agreement between the responsible party and the Town shall be
signed by the responsible party in which the responsible party agrees to the continued
Town of Ocean Isle Beach 13
' Draft Stormwater Management Ordinance
DRAFT
11
performance of the maintenance obligations. This agreement shall be assigned to the
successors in the title upon transference of the property.
Section 11.5 Staff Review
a) The Town shall conduct a review of the plans, specifications and other project data to
determine if all required information has been submitted and shall acknowledge
receipt of a complete set of information. The Town shall notify the applicant if the
information is incomplete and advise the applicant on how to make the application
package complete.
b) The Town shall take final action on all applications no later than 30 days following
receipt of a complete application with all the required information.
c) If site plan approval is denied, the letter shall state the reason(s) for denial and any
reasonable measures which the applicant may take or make to receive site plan
approval.
Section 12. Mandatory Standards for Redevelopments
a) For all redevelopment activities, the property owner must:
(1) reduce the impervious surface on the lot by 20% from the original built upon
amount; or
(2) construct an on -site stormwater system which is designed to reduce the quantity
of stormwater leaving the site by 75% from the original built -upon lot.
(A) In order to achieve these requirements, the property owner may employ any
control measure specified in Section 11.3.
(B) Site plan approval is required for all redevelopment activities (as per Section
11.1). -
(C) Stormwater system designs must be completed in accordance with Section
11.3.
(D)An operation and maintenance agreement as required per Section 11.4.
Section 13. Mandatory Standards for Construction Activities
' Persons who fail to comply with these regulations after they have received notice from
the Town of Ocean Isle Beach will be subject to fines for each violation and other actions
or penalties as may be authorized by the Town of Ocean Isle Beach.
' a) The Town of Ocean Isle Beach will require developers and individuals to furnish
copies of all necessary State certifications involved with the land disturbance activity.
' b) Any person conducting a land -disturbing activity within the Town for the purpose of
creating permanent impervious surface exceeding 500 square feet must notify the
Town of Ocean Isle Beach if a soil erosion and sedimentation control device is
necessary.
c) For construction activities that are one acre or larger, the Town will require a
Sedimentation and Erosion Control Plan per the Town's Erosion and Sedimentation
' Control Ordinance.
Town of Ocean Isle Beach 14
' Draft Stormwater Management Ordinance
DRAFT
11
d) The Town of Ocean Isle Beach's designated official has the authority to monitor
construction activities to ensure that developers comply with the Sedimentation and
Erosion Control Plan.
e) A 50-foot vegetated buffer strip must be retained or established adjacent to any
surface water bordering a land -disturbing activity where feasible. If the land -
disturbing activity is water -dependent (e.g., bulkheads, piers, marinas, and bridges)
and thus is not feasible, then the activity may be permitted with the appropriate
approvals from either the State of North Carolina or the local permitting officer.
f j Construction activities that are under one acre and infringe upon a State of North
Carolina defined Area of Environmental Concern will require a CAMA minor permit
from the local CAMA permit official.
g) All debris and trash must be contained on -site during construction. All garbage
receptacles must have high sides or covers to prevent the airborne transport of debris
such as plastic and paper. In addition, hazardous materials used during the
construction process must be stored and disposed of properly to ensure that they do
not enter surface waters.
h) During construction, the person or firm responsible for the site development is
responsible for maintenance of erosion and sedimentation control devices.
Section 14. Exemptions
No public or private property shall be exempt from the general enforcement requirements
as set forth within this Ordinance relating to stormwater quantity and quality management
unless granted through the appeal process set forth herein. No exemption shall be
granted based on the age, tax or economic status, race, religion of the customer, or other
conditions unrelated to the enforcement of the general requirements of this Ordinance.
Section 15. Inspection and Notifications
a) The Town of Ocean Isle Beach's representatives shall have the power and authority
to conduct inspections as may be reasonably necessary to carry out its duties
hereunder and to enforce the terms of this Ordinance. When necessary to carry out
the Town of Ocean Isle Beach's duties hereunder or to enforce the terms of this
Ordinance, the designated representatives of the Town of Ocean Isle Beach may enter
at reasonable times upon public or private property for the purpose of inspection.
b) All persons, firms, or corporations owning real estate within the Town shall allow the
designated representative of the Town of Ocean Isle Beach to inspect such real estate
to determine compliance with the terms and provisions of this Ordinance.
c) No person shall refuse access to the designated representative of the Town of Ocean
Isle Beach nor shall any person interfere with any such representative while in the
process of carrying out his or her duties for the Town of Ocean Isle Beach at
reasonable times. Any person, firm, or corporation that obtains a building permit,
zoning permit, approval of a land use plan, subdivision approval or other
development approval or permit, or that discharges into the Town of Ocean Isle
Beach's stormwater system or surface waters, hereby consents to and gives
Town of Ocean Isle Beach 15
Draft Stormwater Management Ordinance
DRAFT
permission to the designated representatives of the Town of Ocean Isle Beach to
inspect its premises for compliance with the terms of this Ordinance.
d) If it is determined that a person has failed to comply with this Ordinance, a notice of
violation shall be served upon that person by registered or certified mail or other
reasonable means to give actual notice. The notice shall set forth the measures
necessary to achieve compliance with the plan and specify a reasonable time period
within which such measures must be completed. The notice will warn that failure to
correct the violation within the time period will result in the assessment of a civil
penalty or other enforcement action. If the person in violation of this Ordinance fails
to comply within the time specified, enforcement action will be initiated.
Section 16. Appeals
a) Any person who is found in violation of the requirements set forth under this
Ordinance, or has a site plan denied, may appeal by submitting a written explanation
of the appeal to the designated Town official within thirty (30) days of the date of the
notification of the violation.
b) The designated Town official shall render a Recommended Decision on the appeal in
writing within thirty (30) days after the receipt of the written appeal to the Board of
Commissioners of the Town of Ocean Isle Beach.
c) The Town of Ocean Isle Beach's Board of Commissioners shall accept, reject or
modify the Recommended Decision.
d) Appeals from the Town of Ocean Isle Beach's action will be made through the
General Court of Justice of Brunswick County, North Carolina.
Section 17. Penalties
Violation of this Ordinance shall subject the offender to a civil penalty of not less than
two hundred dollars ($200) or more than one thousand dollars ($1,000) per violation to
be recovered by the Town of Ocean Isle Beach in a civil action in the nature of debt if the
offender does not pay the penalty within a prescribed period of time after he has been
cited for violation of this Ordinance. Each day of continuing violation thereof shall
constitute and be a separate and distinct offense.
This Ordinance shall be enforced by any appropriate equitable remedy issuing from a
' court of competent jurisdiction. In such cases, the General Court of Justice shall have
jurisdiction and authority to issue such orders as may be appropriate to enforce the
Ordinance of the Town of Ocean Isle Beach, and it shall not be a defense to application
' made by the Town of Ocean Isle Beach therefore that there is an adequate remedy at law.
Section 18. Iniunctive Relief
This Ordinance may also be enforced b appropriate a uitable remedy issuing from a
Y Yq
court of competent jurisdiction. The General Court of Justice shall have jurisdiction to
rissue such orders as may be appropriate to enforce the terms of this Ordinance. The
institution of an action for injunctive relief under this section shall not relieve any party
from any civil or criminal penalty prescribed for violations of this Ordinance.
Town of Ocean Isle Beach 16
' Draft Stormwater Management Ordinance
DRAFT
Section 19. Severability
It is the declared intent of the Town of Ocean Isle Beach that the sections, subsections,
paragraphs, sentences, clauses, phrases and provisions of this Ordinance are severable;
and should any sections be declared unconstitutional, illegal or in conflict with any State
of North Carolina or federal law or otherwise be invalid or unenforceable by a court of
competent jurisdiction, the validity or enforceability of any remaining portions of this
Ordinance shall not be affected thereby, and it is the intent of the Town of Ocean Isle
Beach that all unaffected provisions shall continue in full force and affect.
Section 20. Effective Date
This Ordinance shall be in effect on
RATIFIED THIS OF 12000
TOWN OF OCEAN ISLE BEACH
Town of Ocean Isle Beach 17
Draft Stormwater Management Ordinance
APPENDIX B
Public Information Flyers
1
TOWN OF OCEAN ISLE BEACH
STORMWATER MANAGEMENT PROGRAM
WffX11-1yy1 ER 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:
• Sediment • Bacteria from Leaking Septic Tanks
• Pesticides and Fertilizers • Bacteria from Animal Wastes
• Oil and Grease • Waste from Boats
• Solvents and Cleaners
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 and storm drains 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 the Town
of Ocean Isle Beach, please contact Jason Walker at the Town Hall at (910) 576-2166.
TOVVN OF OCEAN ISLE BEACH
9
jjjq� In
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, 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.
'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 the Town of Ocean Isle Beach. If you have
any questions or comments about the Stormwater Management Program for the Town of Ocean Isle
Beach, please contact Jason Walker at the Town Hall at (910) 576-2166.
APPENDIX C
City of Charlotte Stormwater Services Credit Application
Instruction Manual
CITY OF CHARLOTTE
STORM WATER SERVICES
CREDIT APPLICATION
INSTRUCTION MANUAL
Charloffe-Mecklenburg
STORM
WATER
Services
JUL
May 16, 1994
A note to recipients of the Charlotte -Mecklenburg 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 City 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
CHARLOTTE-MECKLENBURG
STORM WATER SERVICES
CREDIT APPLICATION
INSTRUCTION MANUAL
i
i
}
CHARLOTTE-MECKLENBURG
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 OS116194
SECTION 1: INTRODUCTORY MATERIAL
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 properties into the channels,
pipes, and streams of Mecklenburg County. Property development increases the portion 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.
l The storm water fee a property
owner pays is also proportional to
the amount of impervious area on
a given property. Therefore the
j, credit is also developed to be
proportional to the effective
reduction in impervious area.
S Corm water runoff primarily
impacts a drainage system
through:
• increases in peak flow;
• 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 three
areas. In order to keep the credit system more simple than it otherwise could be with a more
"exact" methodology, these three impacts have been reduced to three easy -to -understand criteria
standards which still guarantee real reductions in impact because they have a basis in technical
fact. The runoff peak, volume or pollution load calculated is the total from the whole site and
not simply the total at the point of the location of controls. Care should be taken to determine
` the physical location or reference point at the site outlet(s) where calculations will be made.
rrclic Application Instruction Manual page.- 1
SECTION 2: DEFINITIONS
Best management practices (BMPs): 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.
Biochemical oxygen demand (BOD): The quantity of oxygen consumed during the
biochemical oxidation of matter over a specified
period of time.
CMSWS: Charlotte -Mecklenburg Storm Water Services.
Design storm: 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.
Detention: 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.
Detention time: 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.
Directly Connected Impervious Area: 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.
Extended Detention Basin:
Forebay:
Freeboard:
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 largest
Credit Application lnstuvctioa Manual
page - 2
design storm stored. The space is required as a
safety margin in a pond or basin.
HEC-1 A computer program developed by the U.S. Army
Corps of Engineers which allows the user to
generate hydrographs by simulating the watersheds
' response to precipitation.
Hydrograph: A graph showing variation in the water depth or
discharge in a stream or channel, over time, at a
specified point of 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
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.
NPDES: 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.
To install a new v an existing, BMP
Retrofit: e BMP or improve
t in a previously developed area.
■
Return frequency: A statistical term for the average time of expected
t
"Credit Apolication [actnution Manual mace- 3 -
Riprap:
Riser:
Runoff coefficient:
SCS:
Soil group, hydrologic:
Spillway:
Structural control:
Time of concentration:
Wetpond:
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).
A combination of large stones, cobbles, and
boulders used to line channels, stabilize banks,
reduce runoff velocities, or filter out sediment.
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.
Ratio of runoff to precipitation.
Soil Conservation Service.
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.
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.
A constructed device that temporarily stores or
treats urban storm water runoff to reduce flooding
and/or remove pollutants.
The time required for surface runoff from the most
remote part of a drainage basin to reach the basin
outlet.
A structural BMP which retains storm water runoff
in a permanent pool for water quality enhancement
by settling pollutants.
1
Credit Application Iastnuction Manual page - 4 -
1
' SECTION 3: POLICIES AND PROCEDURES
It is CMSWS'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. Certain
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 1. Credit will be allowed for all properties except
individual single-family residential properties. Credits
can be granted in extraordinary situations for single-
family 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.
Existing Structure Credits 3. Credit will be allowed for previously constructed
controls. The amount of credit granted will be
M 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 maintain
an NPDES permit for storm water runoff from the
State.
.0 Watershed Protection Wet 5. Fach customer
s omer 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.
Properry 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.
Voluntary Controls 7. For new developments, credit will be granted where
CMSWS requires controls to b-- constructed and/or
e
maintained. Other voluntary controls or upgrades of
' existing systems through retrofitting will be granted
A credits on a case -by -case basis, as determined by
■
"'"re(EE AppGcatioa Instruction Manual page - 5 -
HY
Tld.o.nhor.1l...1992 - -
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 peak reduction;
• 25 percent of the fee for volume reduction; and
0 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.
Appeals 11. An appeal must be initially filed in writing with the
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 Applications 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 Ist 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.
Credit Application Instruction Manua) page - 6 -
December 14. 1992
PROCEDURES FOR SUBMITTAL
New Developments
Submittal of credit calculations for
new developments will occur as
part of the normal development
and subdivision procedures! in
two steps as indicated in the box
at the ri?ht.
Existing Controls
Existing controls should be
maintained to the standard in
existence at the time they were
constructed. Coordination with
the Engineering Departments
should be done if there are any
questions concerning the
applicable standards.
Retrofit of Existing Controls
Retrofit of existing structures is a
two-step process similar to that of
new developments.
' See the Charlotte-Mecklcnbu a Developer Handbook available from the City or the County.
'Credit Applicadoo laswction Manual page - 7 -
SECTION 4: TECBNICA.L PROCEDURE
Technical Criteria The credit is based on: peak, volume, and pollution runoff.
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.
The figure above illustrates the credit calculation concept in
which:
• I1 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
Credit Application Instruction Manual Page _ 8 -
n..-... to 1.4 1001
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.
Credit Calculation Equations The goal is to find 12, the effective impervious area which
matches Q2. This procedure assumes that each of the credit
factors (peak, volume and pollutant load) can be approximated
as varying linearly with the percent impervious. Equating
triangles and solving for I2 yields an effective impervious
value and a credit percentage:
12 = (Q2-Ql)(I3)/(Q3-Ql) (1)
Credit Percent = 100 * (142/I3) (2)
This calculation is done for peak, volume, and pollution if
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
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
which is twenty-five percent of the monthly fee or 0.25.
Three Conditions: To obtain storm water user fee credits it will be necessary to
• Undeveloped develop and submit certain supporting documentation as listed
• Fully Developed on the credit application checklist (Section 7).
Without 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 sections
detail the necessary procedures.
Application Instruction Manual
page- 9 -
11 1002
1
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-HOUR BALANCED STORM RAINFALL DISTRIBUTION
Time Interval
5 min
15 min
1 hour
2 hour
3 hour
6 hour
Rainfall depth (in)
0.59
1.26
2.36
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: Insert designed controls for the fully developed condition and route the 10-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 credit from equations 1 and 2.
Remember that the peak credit can be up to 50 percent of the monthly drainage
fee.
II
Credit Application Instruction ,Manual page - 10 -
,00,
VOLUME CR-EDTT CALCYJLAnON
1
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 caused
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 %
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 water after 12 hours.
Post Development w/o Controls
Vol= 15ac-f t
LA
U
Pre Development
Vol= 10 ac-Ft
Post Development w/ Controls
—Vol= 10 ac-f t
J
Ls.;
.....:::
12 hrs
Volume after 12 hours measured
TIME
(min) from latest start of runoFF.
STEP 1: Calculate the hydrograph for the 2-year, 6-hour storm for undeveloped conditions.
Accumulate the total volume of runoff from the Stan of the storm for a period of
twelve hours of runo .
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 Q1 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 = E(flow at each time step, cfs)(60 sec/1 min)(1 acre/43,560
ft-)(time step, min)
"A.
Application Instruction Manual
page - 11 -
ne, 14. 1992
• Depth, in = E(flow at each time step, cfs)(60 sec/1 min)(12 in/1 ft)(1
acre/43,560 ft2)(1/area, acres)(time 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-HOUR BALANCED STORM RAINFALL DISTRIBUTION
Time Interval
5 min
15 min
1 hour
2 hour
3 hour
6 hour
Rainfall depth (in)
0.42
0.83
1.45
1.76
1.95
2.28
STEP 2: Calculate the hydrograph for the 2-year, 6-hour storm for fully developed conditions
without controls. Accumulate the total volume of runoff from the start of the storm
for a period of twelve hours of runoff 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 13.
STEP 3: Calculate the 2-year, 6-hour hydrograph for fully developed conditions with controls.
Accumulate the total volume of runo from the start of the storm for a period of
twelve hours of runo .
fl
1
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. ,
STEP 4: 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 Application Instruction Manual page _ 12 -
ild wnhvr 14. 1992
' 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 practices
(BMPs). Although, without actual measured data, this
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 Three Constituents Three constituents have been chosen for pollution reduction
credits because of their different origins, impacts on the
aquatic ecosystem, and the numerous different structural ,
controls that can be used to reduce their concentrations:
• Lead - a common measure of toxic trace metal
production;
• BOD5 - a measure of the easily available bio-
chemical oxygen demand of such things as
leaves and debris; and
• Total Phosphorous - a measure of nutrient
loading and normally the limiting nutrient in
lake eutrophication.
Methodology
The method (termed the Simple Method) and much of the
information is derived from several sources most notably
Schueler' 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
frediL Application Instruction Manual page - 13 -
December 14, 1992
ANNUAL PER ACRE LOADINGS FOR CHARLOTTE' -
Land Type
Approximate
Percent
Pollutant Loading (lbs/ acre per
Zoning
Impervious
year)
Classifications
Pb
BODS
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
High 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 off -site percent
impervious. Add both, products to determine Q1 for each of the three
constituents.
STEP 2: Calculate the on -site fully developed pollutant load without controls for each of the
three constituents.
P-1
L�
This is done by multiplying the annual unit load values taken or interpolated from
the table for the percent imperviousness J3) 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 Application Instruction :Manual
page - 14 -
December 14.19,92
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.
STEP 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 going
through each control and its corresponding percent imperviousness. Determine
the loading going to that control. Determine its percent effectiveness for each
constituent (see next section) and reduce the total 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.
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
(proportioned 1/3 for each constituent).
STEP S: Develop description of BMP, documentation and maintenance requirements.
For all non-standard BMPs (including modifications on standard BMPs) full
documentation and background must be supplied upon which you relied for
determination of pollutant reductions. Maintenance planning must be supplied
and (if requested) a monitoring plan. In all cases, plans and specifications must
be supplied according to CMSWS guidance for grading and drainage plans and
normal detention.
. � Credit Application insuvction Manua] page �-
POLLUTION REDUCTION CALCULATIONS
Introduction The development of types of Best Management Practices
(BMP) 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
• Wet Ponds (retention) ponds and extended detention ponds which meet the
• Extended Detention 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 REMOVING IDENTIFIED 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.
Design 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:
Credit Application Instruction Manual page - 16 -
n.....,.. 1— Id 1041
IVff = (A,,,PJ(0.5 in)(1 ft / 12 in)
where:
area of impervious (acres)
The remaining 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 impervious (i.e., a paved parldng lot that
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:
Q = runoff (in)
P = rainfall (in)
S = potential maximum retention after runoff begins (in),
_ (1000/Cl) - 10
I, = initial abstraction (in),
= 0.2S for pervious area and unconnected impervious area
y 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 0.25 as used in the previous
formula. Therefore, for all connected impervious area calculations, in accordance to the
losses described in Applied Hydrology and Sedimentology for Disturbed Areas4, the
following formula should be applied:
For connected impervious area
Q = (P 0.1)
4.1 ■
where:
Q = runoff (in)
i P = rainfall (in)
Controlling Urban Runoff' 2 formula:
' R� = 0.05 + 0.009(l)
■
-relit Application Imtruction Manual page - 17 -
where: '
Rr = storm runoff (in) / storm rainfall (in)
I = percent of watershed imperviousness (%)
Designs The mean storm in Charlotte, based on National Weather Service
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 - 0.2SNL)21Aper/(0.64 + 0.8SpeC) ,
+ [(0.64 - 0.1)]Ai .p)(0.0833) (3)
0.2Sper < 0.64
where:
Sper = (1000/CNpef) - 10 (Note: when the value of CNN is low
the initial abstraction/maximum retention (0.2Spe) 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.)
A;mp = area of directly connected impervious (acres)
Aper = area of watershed without the directly connected impervious
(acres)
CNN, = 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
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]Aper/(0.50 + 0.8SN ,
+ [(0.50 - 0.1)1A;mp)(0.0833) (4)
0.2Spet < 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)
Credit Application Instruction Manual page -
tb..e- v_r 14. 1992
where:
I = percent of watershed imperviousness (%)
' A = total watershed area (acres)
Desizns The volume for the one -inch storm event can be calculated as:
5&6.
V1 = {[(1.00 - 0.2Sp<j)Z]Ap��(1.00 + 0.8SpC7)
+ [(1.00 - 0.1)]Ap}(0.0833) (5)
< 1.0
0.2Sp« 0
Similarly, the volume of the one inch storm event can be calculated with
the Rr method as:
Vh = (1.00)[0.05 + 0.009(I)](A)(1 ft/ 12 in)
where:
I = percent of watershed imperviousness (%)
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)
r.�
■
„Iredit Application Instruction Manual page - 19 -
SECTION 6: EXAMPLE CREDIT COMPUTATIONS I
Example #1
Basic Information. Example design with consideration for peal- and volume control only
• Site area - 15.7 acres
• Pre -developed land use woods
• Developed land use - high density residential (percent impervious - 61 %) '
Credit Application lastruction ,Manual Page - 20 - ,
1
1
1
Pollution credit = 0 %
Total credit = (100%)(0.50) + (0%)(0.25) + (0%)(0.25) = 50%
edit Application Instruction Manual page - 21 -
Example #2 '
Basic Information. Example design considering 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 %)
Credit Application Instruction Manual
I
I
I
I
I
u
1
I
1
1
1
1
1
1
Credit AppUcatioa Instruction Manual page - 23 -
Summary
'
Peak credit = 99.7 %
'
Volume credit = 26.4 %
'
Pollution credit = 52.2 %
Total credit = (99.7 %)(0.50) + (26.4 %)(0.25) + (52.2 %)(0.25) = 69.5 %
'
Credit Application
Lwuvction Nlanual
page - 24 -
.. .... • no,
Example n3
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 %)
A
„`Credit Application Instruction Manual page"2$"
Credit Application Lxvruction Manual page - 26 - '
..._._ti..� 14 1001
ISummary
U
1
1
1
1
1
1
1
1
Peak credit = 100%
Volume credit = 100%
Pollution credit = 60.9 %
Total credit = (100%)(0.50) + (100%)(0.25) + (60.9%)(0.25) = 90.2%
Credit Application Instruction :Manual page - 27 -
'
SECTION 7: FORMS AND 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.
r
• 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
drawings and calculations sufficient to fully evaluate both the site and the proposed controls.
'
Maintenance provisions, schedule, and responsible parties must be specified for each control
proposed.
'
Credit Application Instruction Manual page - 28 -
CHARLOTTE -IN EEC K,LENBURG
STORM WATER SERVICES
1 CREDIT APPLICATION FORINI
Applicant Information (Financially Responsible Person): (Please print or tvpe)
Name: -
1 Address:
City: State:
Zip Code: Telephone:( )
' Owner's Representative (Eneineer/Landscape Architect):
Name:
Address:
1 City: State:
Zip Code: Telephone:( 1
Registration Number (PE or RLA):
1 Proiect Information:
Name of Project:
' Address:
Tax Number:
Property Size (acres):
Brief Description of Storm Water Structures Responsible for Effective Impervious Reduction:
1
Impervious Percentage:
1 Qp-d—lop,a: Qpw: Qpo.t v/ =W"U:
V• Vpo.t' Vpo.t v/ conual.
Loadpb,-d- -k,W: Loads,,,: Loads,, WOw"6:
LoadBpD� �k,.d: LoadBoD,.t: LoadBODpo., �/ ooauob
1 LoadTpV--k—,,p,,: Loads,,: I..oadTpp.„ L.:
Requested Credit Percentage:
1 The above information is true and correct to the best of my knowledge and belief. (This form must be signed by
the financially responsible person if an individual, or if not an individual by an officer, director, partner, or
registered agent with authority to execute instruments for the financially responsible person). I agree to provide
1 corrected information should there be any change in the information provided herein.
' Type or print name Title or Authority
1 Signature Date
I, , a Notary Public of the County of State of North Carolina,
hereby certify that appeared personally before me this day and being sworn
1 acknowledged that the above form was executed by him.
Witness my hand and notarial seal, this day of 19_
Notary
My commission expires
1 Designer's Certification:
Existing conditions are in reasonably close conformance to the conditions reflected in the calculations.
Signature and Seal of P.E. or R.L.A.
t
.Credit Application instruction NUnual page -29-
CREDIT APPLICATION CHECKLIST
General Plan Requirements
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 4.0'.
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.
HvdroloF_ic Hydraulic 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 controls
including mowing, sediment removal, etc.
Credit Application lasuuction Manual page - 32
December 14, 1992
1. Schueler, T. R., "Controlling urban Runoff, Metropolitan Washington Council of Governments, 1S75
' Eye St., N.W., Suite 200, Washington, D.C., 20006. (202-962-3200), July 1987. 2. The EDGe Group (Ogden Environmental &: Engineering Services, Inc.), "Mountain Island Lake Best
Management Practices Feasibility Study," 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 Haan, C. T., "Applied Hydrology and Sedimentology for Disturbed
Areas, " Oklahoma Technical Press, 815 Hillcrest, Stillwater, Oklahoma, 1981.
1
1
1
1
Ij
•. Y;
Credit Appl;cation Instruction Manual !fie - 33 -
STANDARD SPECIFICATIONS FOR BMPs t
11
11
.1
G
i
STANDARD SPECIFICATIONS FOR BMPs
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 appearance or effectiveness of the BMP
are also Given. Deviations from the specifications are permitted on a case -by -case basis.
STANDARD SPECIFICATIONS 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 (< 15576 slope - 10 feet wide).
•
Trash racks, filters or other debris protection on control.
•
Anti -vortex plates.
•
Benchmark for sediment removal.
RECOMMENDED SPECIFICATIONS
•
Two stage 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 27, and 5 %.
•
Bottom stale 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.
•
Impervious soil boundary.
The figure on the next page presents a typical extended detention pond built in two
staves.
SCHEMATIC OF TYPICAL EXTENDED DETENTION POND
T
TOP VIEW
POND
BU//ER
♦
2Y uON.
\
i
(LANDSCAPE rILOW u.INIVIANCE
[uBANKUENt
1CRASSES.SNRUDS. ANO 1RCES)
BOnou siAGE
1
K LOU$. SLOPE TOP SIACE
1
I I
ILY
1
PILOT CItvNN(t(CONCRCIC OR PAyEO)
kNDRU DRY
AS YCIOQw) /
SNLaUOW M[11A1N0
OR POOL
STABILIZED
2 ININ
1Op E'er—
RISER —
)
INLEI
(f21PRAP)
$i
l
—
�,f1' srlbluzCo
\
�
♦
RIPRAP
♦APRON
- �bYW OuifAu
— — —
a�,v
/
� \ \
W it
/
SIDE SLOPES
DOnOu sI
3:1 ";
20A URN.
swaaw u4Rs11 FOR aslcN fi (r-12' DCCP)
(MOMKY(fR SIIAI.l, IuVE AT LFASi
R16SER r 0.5 r001 Of ERE(DOAD ADM
— - — — —� D[SICN srOR4 WATER SURFACE CILVAlION �— — — — — — — N000 / CuERC[NCY SPILLWAY
Tbfr ST)ci riTsALP NfAr — -
IN/lOw .ivatai+ru ►r.N.A. — — — — — — ANTI -SEC
_ CavA+s
uHNTARNCO CRASS 2X OR GREATER SLoPC FOR DRANuOC
00n0u A SIDE SLOPES
BOTTOM STA4C 42ro 10
SIDE VIEW o/`uEM STORu `O11" E PCR/ORAICD RISER
UKJSED IN GRAVEL .VCKEi (rYP.)
REFERENCE: CONTROWNG URBAN Rlxrorr 1 NOT 10 SCALE
STANDARD SPECIFICATIONS FOR WET PONDS
REQUIRED SPECIFICATIONS
•
Minimum length to width ratio of 2:1 (preferably wedge shaped).
•
Inlet and outlet located to maximize flow length.
•
Minimum depth of permanent pool 2.0 feet, maximum depth of 10.0 feet.
•
Design for full development upstream of control.
•
Side slopes shall be no greater than 3:1 if mowed.
•
Rip -rap protection (or other 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 peak 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 50-year storm event (must be paved in fill
areas).
•
Trash racks, filters, hoods or other debris control on riser.
•
Maintenance access (< 15 9c slope and 10 feet wide).
•
Benchmark for sediment removal.
•
Paved or concrete channel.
RECOMMENDED 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 5r of total volume). Forebay should have
separate drain for de -watering.
•
Provision shall be made for vehicle access at a 4:1 slope.
0
Impervious soil boundary to prevent draw -down.
•
Shallow marsh area around fringe (including aquatic vegetation).
•
Safety bench at toe of 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 two sediment removal cycles protected from runoff.
•
An oil and grease skimmer for sites with high production of such pollutants.
The figure on the next pace presents a typical wet pond design.
TOP VI W
SCHEMATIC OF TYPICAL WET POND
ILATNE SIRUOS A14D TREES
PLMr1O FOR WILOUrE- COVER
ARWND KqF OF POND'S PERIMETER
IOE SLOPES �� _ SF/[ry BENCH
FESCUE
NOvcl TREES OH
J ~
YIIIf �.7�11"�'fi"r "��. — `- •�: •1
' '
•RISER
tTYSt',z
OV1rAEE PROTCC110f1
URGE RIPRAP
.'i
.•. .t .1 ...�
i ' • SEOIMEMY B VrpEE .
1 .
.�,+.' fORCOAY ;♦'\,, (AS. REO'D)
on
,�
•
Vt
�.(`.I �{ tq .. � �,��Piytrr ;; ., ..' •...
ER
p ROCK DErucroas
uIN vu ooWIDE \ .: ' "''.: '. /.....
1.)y/ Y �/"y !: r
S rt
••�_.
t
�'I a ' e p (AS REO'O)
•_i::. `•-' '• ' •.h
�`%: s£y�� d �. {,h ���I�.`Jv.
;•s CLACROEtcy
Kx
':11 �'L�L>S\ LL•�.'� t\�)uT `Lt} Cy�/�'%T"1 CNCRCCNCY
�' ��� � SPILLWAY
�+rf•t�
l RESERVE ON-SEC•=�1'a:u'
OISPOSAL AREA rOR
(l DREDGEO SEDNtfli
Twit HOW
_—_—_--_— STORUwAIER STORAGE -----_
WEIR—
Eu6WKUENT
n rcRUAwilrt :voo
' Ai. SEEP
SEDIUENT FOREBAY
•''.�•
COLtlJIS
(P,.EO AS MARSN) .. ..
//�r
CLAY OR GCOIEXRLE LINER
(IF EKISTYtG SOILS ARE
P(RUEABLE)
SIDE VIEW
RFFFRFNCF: CONTROLuNO uRB.W RUNOrr I
u
G
A
1
1
1
1
1
i
1
STANDARD SPECIFICATIONS FOR WATERSHED PROTECTION BASINS
(A) All 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 storm water controls shall use wet detention ponds as a primary treatment system. Specific
requirements for these systems shall be in accordance with the follow design 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 (I %) 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).
(6) The inlet and outlet shall be located to maximize flow length.
(7) The design shall assume full development (maximum allowed in accordance to current zoning
regulations) in the contributing drainage area.
(8) 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 % of the surface area of the pond at maximum elevation of water quality storage
pool, whichever is greater.
(9) The littoral shelf shall be planted with aquatic vegetation shown in Attachment A, or equivalent,
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. The
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 risers/barrels must be reinforced concrete rather than corrugated metal. In addition, all risers
must be checked for floatation.
(14) Anti -seep collars shall be provided on the barrel of the principal spillway.
(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 sate, drawn down 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 forebay 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) feet 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 least 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 (0-3.59o), gravel (3.5-10.57oo) or paved (10.5-205ro), 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.
(24) A minimum ten (10) feet wide safety bench shall be provided outside the permanent pool area for
the purpose of manuerving landscaping equipment. It is recommended that this safety bench be
located at the top of sloping banks.
(25) 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 may be required for commercial or industrial use sites with a high
production of such pollutants.
(28) A description of the area containing the storm water control structure shall be prepared and filed
as a separate deed with the County Register of Deeds 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 downstream side of the dam) with an impoundment I
' capacity of 10-ac-feet or greater at the top of the dam must obtain a Dam Safety permit from
North Carolina Department of Natural Resources, Land Quality.
See wet pond f aure for typical design.
MAINTENANCE STANDARDS FOR EXTENDED DETENTION AND WET PONDS
Sediment to be removed when 50% of forebay volume is filled and/or when 20% of
the permanent 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 grow 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.
ACCEPTABLE PLAINT SPECIES FOR LITTORAL SHELF PLANTING
MECKLENBURG COUNTY NORTH CAROLINA
Developed by David D. Patrick, Jr., HDR Engineering, Inc.
Common Name
Scientific Name
1 •
Fragrant water lily
Nvmohaea odorata
2•
Arrow -head
Saoittaria latifolia var pubeseeus. S lonoirostra
3.
Bacopa
Mecardonia acuminata
4•
Hedge hyssop
Gratiola virgimans .
5•
False -pimpernel
Lindernia dubia
6.
Soft rush
Juncus effusus
7.
Bulrush
Scirous validus: S. atrovirene. S. cv erinus
S•
Spikerush.
Eleocharis obtusa. among others
9-
Day flower
Commelina communis
10.
Blue -flag Iris
Iris viroinica
11.
Lizard's tail
Saururus cemuus
12•
Maidencane
Panicum spp.
13.
Pickerelweed
Pontederia cordata
14.
Meadow-buary
Rhexia mariana. R. virsinica
15.
Marsh seedbox
Ludwigia oalustris
16.
Cutgrass
Leersia viroinica. L. orvzoides
17.
Hatpins
Eriocaulon decangrulare
is.
Bog buttons
Lachnocaulon ances
Hvdric
Resime
3
2
• 1
1
I
1
7
1
1
1
1,2
1,2
2
1
1,2
1
1
1
Common Name
A.
Swamp Rose
B.
Buttonbush
C.
Willow
D.
Virginia willow
E.
Alder
F.
Maleberry
G.
Fetterbush
H.
Swamp Dogwood
SHRUBS
Scientific Name
Rosa_ palustns
Ceohalanthus occidentalis
Sal ix nigh
Itealtea v_ irginica
Alnus serrulata
Lvonia ligustrina
Leucothoe racemosa
Cornus amomum
Hvdric Regime
1 = less than 1 ft. of water (extended inundation)
2 = 1 ft. - 2 ft. of water
3 = more thatn 2 ft. of water
Hvdric
Regime
1
i
1
1
1
1
1
1
1
Common Name
Scientific Name
rx
19.
Buttercup
Ranunculus pusillus. R. carolinianus
'
20.
Easter Lily
Zephvranthes atamasco
21.
Arrow Arum
Peltandra virginica
'
22.
Cattail
Tvpha latifolia
23.
Sedge
Carex supp.
24.
Flat sedge
Cvperus spp.
?5.
Bedstraw
Galium tinctorium
As!
.s
Hvdric
Regime
1
i
1,2
2,3
1
1
1