Stormwater Quantity Management Plan-2003

a

SUPPLEMENTAL STORMWATER
QUANTITY MANAGEMENT PLAN
TOWN OF CALABASH
ANNEXATION
Calabash, North Carolina
May 5, 2003
The preparation of this report was financed in part through a grant provided by the North Carolina
Coastal Management Act of 1972, as amended, which is administered by the office of Ocean and
Coastal Resource Management, National Oceanic and Atmospheric Administration.
Prepared by:
URS Corporation — North Carolina
1600 Perimeter Park Drive
Morrisville, North Carolina 27560
[phone] .
Fax: [phone]

TOWN OF CALABASH ANNEXATION
TABLE OF CONTENTS SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT 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...........................................................:.....................................................1-3
1.5
Public Involvement.......................................................................................................1-3
Chapter 2 Regulations, Ordinances, and Policies
2.1 Regulations, Ordinances, and Policies..........................................................................2-1
Chapter 3 — Annexed Area Overview
3.1 Setting...........................................................................................................................3-1
3.2 Hydrography.................................................................................................................3-1
3.3 Hydrologic and Hydraulic Characteristics....................................................................3-1
3.3:1 Waterbodies.........................................................................................................3-1
3.3.2 Soils......................................................................................................................34
3.4 Land Use.......................................................................................................................3-3
3.5 Effects on Water Quantity............................................................................................3-3
Chapter 4 — Drainage Problem Area Recommendations
4.1 Selection Criteria..........................................................................................................4-1
4.2 Evaluation and Recommendations ............................. ................................................... 4-2
4.3 Operation and Maintenance..........................................................................................4-9
Chapter 5 - Stormwater Management Program
r5.1 Recommendations Summary ........................................................................................5-1
■ 5.2 Project Selection Criteria..............................................................................................5-1
5.3 Capital Improvement Program......................................................................................5-4
5.4 Operation and Maintenance Program...........................................................................
5-4
5.5 Funding.........................................................................................................................5-4
IChapter 6 References
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TOWN OF CALABASH ANNEXATION
TABLE OF CONTENTS SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
LIST OF APPENDICES
Appendix A Stormwater Focus Area Pictures
Appendix B Public Hearing Material
LIST OF TABLES
Table 3-1
Soils Data
Table 4-1
Recommendations
Table 5-1
Project Selection Criteria and Rankings
Table 5-2
Capital Improvement Program
LIST OF FIGURES
Figure 3-1
Soil Map
Figure 4-1
Drainage Focus Areas
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TOWN OF CALABASH ANNEXATION
EXECUTIVE SUMMARY SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
The Calabash Supplemental Stormwater Quantity Management Plan provides direction for
stormwater quantity management for the annexed portion of the Town of Calabash. The general
information in the original Stormwater Quantity Management Plan dated February 27, 2002
applies to the annexed area and is considered part of this Supplemental Plan. The starting point
for this Plan begins with the purpose, goals, and objectives described in this summary.
The purpose of the Calabash Supplemental Stormwater Quantity Management Plan is to
provide a comprehensive and unified framework for stormwater management, which follows
the Management Plan, complies with all regulations, and includes a Capital Improvement
Program that will benefit the entire Town.
e following goals provide the direction in meeting the purpose of improving hydrological
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functions:
1) Evaluate the water quantity problems in the annexed area of Calabash 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 The Stormwater Quantity Management Plan
dated February 27, 2002. The water quantity problems in the annexed portion of the Town are
described and action items for these problems are provided in Chapters Four and Five. The
policy, maintenance, and capital improvement action items described in the Stormwater Quantity
Management Plan for the Town of Calabash should be considered the first steps in working to
achieve sound stormwater quantity management. Further information such as detailed tasks for
each action item should be addressed in future tasks.
The recommendations for each area of concern were evaluated based upon the safety and water
quantity benefits provided by the recommended solution. The area determined to be the highest
priority was Highpoint Avenue. Flooding due to blocked channels and culverts, along with
improper and/or non-existent roadside swales causes flooding along Highpoint Avenue and
residential properties along the ditch to the east. 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 quantity management
plan proceeds. Public education and public involvement is critical to successful stormwater
quantity management.
r
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CHAPTER ONE TOWN OF CALABASH ANNEXATION
PURPOSE AND GOALS SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
The Calabash Supplemental Stormwater Quantity Management Plan (Plan) outlines an approach
to stormwater management for the Town of Calabash' s newly annexed area (Annex). The
general information regarding regulations, ordinances, and policies in the original Calabash
Stormwater Quantity Management Plan dated February 27, 2002 applies to the annexed area and
is considered partof this Supplemental. Plan. This Plan begins by detailing the purpose, goals,
and objectives described in this chapter.
For a stormwater quantity management plan to be successful, it must have a clear purpose, plus
attainable goals and action items. In order to develop a clear purpose and goals, it is necessary to
identify the problems or potential problems within the watershed. Within the annexed area,
flooding and water quantity issues have been identified as major problems. The purpose and
goals described below provide direction for the future stormwater management effort to improve
these problems.
1.1 PURPOSE
Stormwater Quantity Management Plan is to
The purpose of the Calabash Supplemental Q ty g
provide a comprehensive and unified framework for stormwater quantity management that
complies with all regulations and includes a Capital Improvement Program that will benefit
the entire Anne -
The purpose of the Plan is to provide a framework for stormwater quantity management that will
restore hydrological functions within the annexed area of the Town. The framework for
stormwater quantity management 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 Plan will identify the components of stormwater quantity management and outline the action
items for implementation. The recommended action items that will help to meet the goals for the
program are described in the next section (Section 1.2).
1.2 GOALS OF THE PLAN
The following goals provide the direction in meeting the purpose of improving hydrological
functions:
1) Evaluate the water quantity problems in the annexed area and recommend actions to
mitigate these problems.
2) Provide a capital improvement program and outline maintenance actions that incorporate
recommendations from the plan.
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CHAPTER ONE TOWN OF CALABASH ANNEXATION
PURPOSE AND GOALS SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT 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 focus area are summarized in Chapter Five.
L Evaluate the water quantity problems in the annexed area and recommend actions to
mitigate these problem
This management plan will evaluate the water quantity problems in the annexed area 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 quantity management 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 — Regulations, Ordinances, and Policies
Refer to the original Stormwater Quantity Management Plan dated February 27, 2002 for
information regarding Regulations (Chapter 2), Ordinances (Chapter 2), and Policies (Chapter 3).
Chapter Three - Annexed Portion 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.
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CHAPTER ONE TOWN OF CALABASH ANNEXATION
PURPOSE AND GOALS SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
Chapter Four— Drainaize Problem Area Recommendations
The characteristics of the Town, along with the water quantity 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
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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 have been
obtained from Town of Calabash personnel, local citizens, and site investigations.
' Where appropriate, the draina a area to the problem area has been identified based on two -foot
g
contours provided by SBWSA. These drainage areas are approximate and are based on
' professional judgment due to the size of the contour interval in this area. These drainage. areas
were then used to determine the 25-year flow rate using the Rational Method.. This flow rate was
then used to size reinforced concrete pipe culverts based on culvert capacity charts with a
maximum headwater (feet) divided by pipe diameter (feet) ratio of 1.2. This is a preliminary
method and will need to be refined through a drainage system analysis With stormwater routing
identified and improved topographic mapping.
1.5 PUBLIC EWOLVEMENT
A Public Hearing was held on April 24t', 2003 at 7:00 pm in the Calabash Town Hall. The
Hearing was included with a sgecial meeting of the Town Commissioners. The Public Hearing
' was advertised in the April 17 and April 24 h issues of the "Brunswick Beacon", the area's local
newspaper. Copies of these notices are included in Appendix B of this report:.
In addition to the Commission Members, one citizen attended the Hearing. Comment sheets were
made available, also included in Appendix B of this report. No specific comments were made at
' the Hearing; however, there were approximately forty-five minutes of discussion about the
Towns stormwater issues before the meeting adjourned at 7:50 pm.
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CHAPTER TWO
REGUL.ATIONS, ORDINANCES, TOWN OF CALABASH ANNEXATION '
AND POLICY SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
2.1 REGULATIONS, ORDINANCES, AND POLICIES.
'
It is assumed for the purposes of this plan, that the Regulations and Ordinances (Chapter 2) and
the Policy (Chapter 3) reviewed in the - original Stormwater. Quantity Management Plan dated
'
February 27, 2002 have not been modified.
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' CHAPTER THREE TOWN OF CALABASH ANNEXATION
ANNEX OVERVIEW SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
r 3.1 SETTING
The Annexed Area lies east of the original Calabash Town limits, located in southwestern
Brunswick County, North Carolina. The annexed portion is primarily a mix of residential
communities, mixed forests, and wetlands. The primary areas of concern lie within the
residential communities of Calabash Acres and Pine Bur Acres.
3.2 HYDROGRAPHY
The annexed area is located in the southeastern portion of the Lumber River Basin that flows
' from the Northwest to Southeast direction. This river basin is comprised of smaller watersheds
or hydrological units (HUs). The primary water feature in this community is Calabash River.
The annexed area lies within the United States Geological Survey (USGS) Carolina Coastal
watershed and the Waccamaw River watershed. These watersheds have 8-digit hydrological unit
code (HUC) of 03040207 (Carolina Coastal) and 03040206 (Waccamaw River). Within this
watershed, the United States Department of Agriculture Natural Resources Conservation Service .
(MRCS) has delineated subwatershed areas with 14-digit HUC for the purpose of natural
resource planning. The Town of Calabash lies within the NRCS HUC 03040207020110 and
030,40206090020. The beginning of the 14-digit code uses the 8-digit designation of the USGS
HUC.
URS subdivided these hydrologic units into drainage basins, using the most recent topographic
mapping provided by SBWSA. See Figure 4-1 for the drainage basins within the annexed area
and surrounding areas.
3.3 HYDROLOGIC AND HYDRAULIC CHARACTERISTICS
3.3.1 Waterbodies
The Calabash River is the main water body in the Town of Calabash. Several small tributaries
feed the Calabash River in and around the Town of Calabash. According to NCDENR Division
of Water Quality, the Calabash River, from its source to the Intracoastal Waterway is considered
SA waters. Any direct tributaries are also considered SA waters. The SA classification denotes
surface waters, which are suitable for commercial shellfishing and all other tidal saltwater uses.
Several perennial ponds and reservoirs are scattered throughout the annexed region are in
addition to a small number of low-lying wet spots.
3.3.2 Soils
The soils found in the annexed area are comprised of a variety of sandy soils (Figure 3-1 and
Table 3-1). The portion north of Highway 179 is mostly Baymeade fine sand and Leon fine
sand. Baymeade fine sand consists of a well -drained sandy soil with slow runoff and rapid
permeability mostly suited for woodland, cropland, and urban areas. Leon fine sand is a poorly
drained soil suited for woodland areas and not usually for residential areas.
East of Highway 179 primarily consists of Baymeade fine sand, Leon fine sand, Mandarine fine
sand, Wando fine sand, and a small portion of Murville Mucky fine sand. Mandarine fine sand is
somewhat a poorly drained soil with slow runoff and a permeability of moderate to rapid. This
soil is mostly comprised of woodlands and is poorly suited for residential development. Wando
fine sand is an excessively drained soil on mterstream areas with slow runoff and high
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CHAPTER THREE TOWN OF CALABASH ANNEXATION
ANNEX OVERVIEW SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
permeability. The soil consists of mostly woodland areas and is suited for urban areas, however
poorly suited for sanitary and recreational facilities due to its sandy conditions.
The area Southwest of Highway 179 consists of Blanton fine sand, Kureb fine sand, Boticket
silty clay loam, Leon fine sand, Wando fine sand, and Murville Mucky fine sand. Blanton fine
sand is a moderately well drained soil with high permeability. It is well suited for residential and
woodland areas. Kureb fine sand is an excessively drained soil with slow runoff and rapid
permeability. It is suitable for woodland and urban areas. Boticket silty clay loam is a poorly
drained soil with slow runoff and slow permeability. This soil lies along areas surrounding
Calabash River.
The sandy construct of these soils is not an ideal soil for detention ponds or embankments, but
does introduce the potential of pervious concrete as a method to control stormwater runoff. The
majority of these soils are not considered suitable linings for detention ponds due to their sandy
compositions. They are not considered suitable for embankments or drainage ways because the
soils are typically hard to pack and experience piping and caving along waterways. Due to the
composition and variety of soils present in the Calabash annexed area, it is recommended that
soil borings be completed as part of the design for any .stormwater Best. Management Practice
(BMP) (i.e. retention basin, etc.).
Table 3-1 describes the soil types found in the annexed area (USDA, 1986).
TABLE 3-1
ANNEXED AREA
SOILS DATA
Soil Type
Soil Name
Limitations for
Sanitary
High Water
Hydric
Symbol
Pond Reservoir
Facilities Rating
Table Depth
Condition
Areas
(feet)
BaB
Baymeade
Severe: seepage.
Severe: poor filter.
4.0 — 5.0
No
fine sand
BnB
Blanton fine
Severe: seepage.
Moderate: wetness.
5.0 - 6.0
No
sand
BO
Bohicket
Slight. Slow
Severe: flooding,
+ 3.0-0.0
Yes
silty clayey
permeability.
ponding, peres
loam
slowly.
KrB
Kureb fine
Severe: seepage.
Severe: poor filter.
> 6.0
No
sand
Lo
Leon fine
Severe: seepage.
Severe: wetness,
0.0 - 1.0
Yes
sand
poor filter.
Ma
Mandarin
Severe: seepage.
Severe: wetness.
1.5 - 3.5
No
fine sand
Mu
Murville
Severe: seepage.
Severe: ponding,
0.0 - 1.0
Yes
mucky fine
poor filter.
sand
WaB
Wando fine
Severe: seepage.
Severe: poor filter.
4.0 - 6.0
No
sand
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CHAPTER THREE TOWN OF CALABASH ANNEXATION
ANNEX OVERVIEW SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
3.4 LAND USE
Land use within the annexed area primarily consists of residential development. Residential
properties are predominantly comprised of impervious surfaces as a result of paved areas (e.g.,
roads, streets, driveways, etc.) and structures (e.g., houses, barns, carports, etc.). Vegetation, if
present, varies and includes wooded areas, maintained lawns, maintained scrub areas along
utility easements, and landscaped areas.
3.5 EFFECTS ON WATER QUANTITY
The drainage system of the annexed area presently consists of a network of ditches and swales
with several catch basins and piped outfalls to the Calabash River. Stormwater runoff quantity
problems occur in various locations across the annexed Calabash area. 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
canresult in environmental hazards. Increased impervious surfaces reduce the opportunity for
stormwater runoff to be naturally retained and filtered by vegetation, wetlands, and . estuaries.
Pipe culverts located under roads allow a. ditch or channel to flow under the road. Culverts
located under driveways allow ditches to flow under the driveway.
Major flooding problems observed in the annexed area, further discussed in Chapter Four, are a
direct result of the inadequate size,. number, grade and/or location of stormwater inlets and
detention devices, plus a lack of vegetated ditches to accommodate the increased stormwater
runoff from the development of impervious surfaces. Stormwater management will allow the
Town to effectively design, implement, construct, and manage stormwater controls to prevent
problems associated with the increased stormwater quantity.
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CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN of CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
4.1 SELECTION CRITERIA
During the development of recommendations for each area of concern, several criteria were
evaluated to determine the most appropriate Best Management Practice (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
• Commitment to longevity
Cost to implement and maintain
The cost to implement and maintain each BMP was evaluated and compared. Specific costs for
each BMP were not determined, but relative costs of each BMP type were compared to
determine the most cost effective solutions.
Regulatory Requirements
Each BMP was evaluated to determine if any special regulatory requirements would have to be
met for implementation..
Effectiveness at solving the problem
Each BMP was evaluated to determine the effectiveness at solving the flooding problem(s). The
recommended BMP may only alleviate the problem, not. completely solve it, but the other criteria
indicated that this BMP was the most appropriate.
Acceptability to the 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.
Implementability
Some structural BMPs cannot be constructed in certain areas due to 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.
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CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN OF CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
Commitment to Lon evi
For this criterion, the amount of maintenance required was evaluated to assess whether a
commitment will and/or can be made in regards to long-term maintenance and. upkeep of the
BMP.
4.2 EVALUATIONS AND RECOMMENDATIONS
Flooding is the primary stormwater problem in the annexed area of the _Town of Calabash.
Below is an explanation of the flooding, areas of concern, and recommendations for
improvements. Deficiencies and recommendations are summarized in Table 4-1.
General Recommendations
A survey of the complete drainage system in this annexed area is necessary to determine if the
channels need to be re -graded to allow the stormwater to flow through the system. To ensure
sufficient channel and pipe size, a detailed survey, which includes channel bottom, pipe inverts,
and! related information, is necessary. In addition, improved topographic mapping will be
necessary to determine accurate flow paths. This data would then be used to complete some
simple modeling and calculations to confirm the initial assumptions.
URS also recommends that the Town attempt to obtain a drainage easement that allows the
Town to have maintenance access to the channels and culverts to help maintain stormwater
flows. If SBWSA improves part of the system for water quality purposes, the drainage easement
could be obtained by SBWSA, thus easing the burden on the Town.
Any drainage improvements, which are recommended within the right-of-way of an NCDOT
roadway, must be coordinated with NCDOT. All plans and designs must be approved by
NCDOT prior to implementation. It may be possible to obtain assistance from NCDOT on the
construction of the system. URS recommends that the Town have a meeting with NCDOT to
discuss the drainage issues and how the NCDOT and the Town can work together to alleviate the
flooding problems.
To reduce the amount of stormwater runoff which reaches the street and the annexed area's
storm drain system, URS recommends that the Town encourage its residents to reduce the
1 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.
As SBWSA further evaluates their stormwater fee structure, it will be looking to set a utility
credit program for residents that go beyond the stormwater ordinance requirements to try to
reduce and/or eliminate stormwater runoff from their lots.
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CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN OF CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
Calabash Acres
Lamb Street and Charlotte Avenue Intersection
Flooding is the main concern in this area, which begins at the intersection of Lamb Street and
Charlotte Avenue (See pictures 1-6, Appendix A). The water accumulates in this area and flows
toward the eastern direction into a channel that runs into an area across SR 1165. At the Lamb
Street and Charlotte Avenue intersection, an 18-inch corrugated metal pipe culvert extends under
Charlotte Avenue and outfalls at the corner of a residential property. On this particular property,
water tends to build up during rainfall events. The pipe under Charlotte Avenue is slightly
crushed. Large tree branches, plants, and saplings block the surrounding swales that do exist,
including one that runs parallel to Lamb Street on the southwestern corner of the intersection and
the ditch that runs parallel to Charlotte Avenue on the northwestern corner.
Just north of the intersection, a 15-inch concrete culvert runs underneath a gravel drive that
appears to be slightly undersized (See picture 5, Appendix A). A portion of the water that flows
here contributes to the flooding (See picture 6, Appendix A).
Possible recommendations to alleviate flooding in this area include cleaning debris from existing
swales, re -grading existing swales, and introducing grass -lined swales where non-existent.
Grass -lined swales should be placed along both sides of Charlotte Avenue extending from' SR
1165 to the intersection of Lamb and Charlotte. On the east side of Charlotte Avenue, the swales
should then be directed east and run parallel to the driveway until it connects with the ditch. This
will create a drainage path for water flow and keep excess water from flooding into the
residential property. The existing pipe under Charlotte Avenue may be undersized. Due to the
coarseness of the contours and uncertainties about the drainage system, the exact size is not
known at this time. However, according to the information used for this report the culvert should
be no greater than a 30-inch RCP.
A survey of the complete drainage system in this area is necessary to determine if the swales
need to be re -graded to allow the stormwater to flow through the system. To ensure sufficient
channel and pipe size, a detailed survey, which includes channel bottom, pipe inverts, and related
information, is necessary. Further studies and evaluation downstream of this drainage area need
to be investigated to understand the flooding of this area. This information would be taken and
used to perform simple modeling calculations to confirm initial assumptions.
Highpoint Avenue -General Overview
Flooding along Highpoint Avenue appears to be due to overgrown and ineffective drainage
devices, blocked pipes, as well as blocked and/or eroding swales. Rainfall in this area appears to
collect from impervious surface areas and lawns along Highpoint and Charlotte Avenue (See
pictures 7-27, Appendix A). Some flooding problems occur on the uphill portion on Highpoint
Avenue immediately south of the intersection with Mears Road (See pictures 7-14, Appendix A).
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CHAPTER FOUR
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RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
A ditch runs perpendicular to the roadway and is connected by a culvert and pipe system that
runs alongside a residential property and drains into a ditch that runs behind homes on the east
side of Highpoint Avenue. Flooding problems exist where the ditch continues and runs along the
backside of these homes. Further along Highpoint Avenue, at the intersection of Charlotte
Avenue, a large portion of water accumulates on the impervious surface areas, which in turn
creates a sheet flow of water across the intersection directly towards the Dixon residential
property. The water then flows towards the pond behind the home, which causes localized
flooding (See pictures .17-22, Appendix A). The remaining water continues to flow along
Highpoint Avenue and into a storm drain that directs flow into a Calabash River inlet (See
pictures 23-27, Appendix A).
Highpoint Avenue South of Mears Road Intersection
Flooding occurs along a small ditch that exists behind the homes of residents located along the
eastern side of Highpoint Avenue, eventually draining into Calabash River. The residential
properties on this side appear to be on a ridgeline meaning that the water flow makes a
directional split along these properties. Aportion of the water flows down into the ditch behind
the homes, while the rest contributes to the flow along Highpoint Avenue.
Near the top of the hill on Highpoint Avenue, swales are filled with debris and are nonexistent in
some areas. On the west side, immediately south of the Mears Road intersection, a 1.5-foot
concrete structure appears to block drainage along the existing Swale (See picture 9, Appendix
A). The function of this structure is unknown and may need further investigation. A deteriorating
corrugated metal pipe culvert sits next to this structure and extends into a ditch perpendicular to
the roadway swale (See pictures 7-8, Appendix A). On the east side of the road, where a new
home is under construction, it appears that filter fabric and rip -rap has been placed around the
inlet and outlet of a newly installed culvert to provide protection. This may inhibit the flow in
this area. (See picture 10-13, Appendix A). The property owner has also installed a new 20-inch
plastic culvert pipe underneath his driveway that drains into another 24-inch plastic pipe that
runs perpendicular to this one. This pipe runs along the side of the home and outfalls into a pipe
that leads to the ditch, which runs parallel to Highpoint Avenue. Behind the owner's home where
the 24-inch pipe outfalls, erosion from the construction site has caused accumulation of sediment
along the bottom of the pipes (See picture 14, Appendix A). The ditch that runs alongside of
these homes, and abuts Hidden Valley, is a main concern for flooding backyards in this area. It is
a possibility that the ditch is blocked downstream before entering the marsh.
One recommendation is to remove the debris along the existing swales along Highpoint Avenue
and extend them the full length of the roadway. Removal of this debris may help prevent water
flow onto the roadway as well as direct flow off of flood prone properties. Another
recommendation is to resize the culvert and re -grade the ditches under and along Highpoint
Avenue, south of Mears Road intersection. Another recommendation concerning erosion near the
residential property where new pipes were installed can be alleviated by lining the swales and
ditch with grass. Further erosion of the sandy site can lead to clogging .of pipes near and along
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CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN OF CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
the ditch, which can lead to increase in flood elevations during rainfall events. To remedy flood
problems along properties along the ditch, the ditch would need to be re -graded to allow a more
efficient flowing system.
A survey of the complete drainage system in this area is necessary for further evaluation of the
downstream area. To ensure sufficient channel and pipe size, a detailed survey, which includes
channel bottom, pipe inverts, and related information, is necessary along Highpoint Avenue. 1
This information. would be taken and used to perform simple modeling calculations and confirm
initial assumptions.
Intersection o�point and Charlotte Avenue
At the intersection of Highpoint Avenue and Charlotte Avenue, the water accumulates and sheet
flows through the property of the Dixon residents directly into a pond. On the opposite corner
from the flood -prone property, an inefficient. 15-inch corrugated metal pipe extends under
Charlotte Avenue towards the Dixon property and joins the drainage system at a concrete
covered junction box, located at the edge of the sandy grass drive (See pictures 15-22, Appendix
A). The junction box connects another pipe that drains under the Dixon property into the pond.
Within the pond is a riser/barrel that directs excess water into a Calabash River inlet.
To relieve flooding along the Dixon property, the first step would be to re -grade existing swales
including roadway along Highpoint Avenue and the east side of Charlotte Avenue. The swales
should be extended in order to accommodate and direct the water flow off of the road to allow
natural infiltration and pollutant removal. Concerning the area where water accumulates, a
possible solution would be to install a steel grate in place of the concrete junction box along the
edge of the gravel drive and direct the water to flow along roadway ditches rather than through
and underneath the Dixon property. The property needs to be avoided of any drainage system on
the property due to an existing septic tank system. The existing pipe under the Dixon property
draining into the pond needs further evaluation to determine whether it should stay in place or be
removed. It cannot, however be enlarged since the flow is discharged into SA waters.
Further down Highpoint Avenue where the road curves along the Dixon property, existing
swales are eroding extensively. Upon the curving of the road, the concrete culvert under the
Dixon's driveway is breaking and caving in (See pictures 23-24, Appendix A). The property
owner has attempted to line the swales with gravel, rocks, and even asphalt in attempt to hinder
the erosion. However, the materials used were not sufficient enough to stabilize the sandy soil '
during periods of heavy flow. Another indication of erosion on the inner curve of the roadway is
the asphalt breakage. The end of the swale leads to an 187inch corrugated metal pipe extending
approximately 40 feet that runs under the roadway of Highpoint Avenue. This pipe bends in the
middle of the roadway and leads to a stormwater drain on the opposite side. This drain contains
an outlet pipe that drains into an inlet of the Calabash River (See pictures 25-27, Appendix A).
05/05/03
4-5

CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN OF CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
In order to address the erosion problems along the inner part of the curve on Highpoint Avenue,
one recommendation is to re -grade the swales with a grass lining. Grass lined swales will allow
more infiltration into the ground. Resizing pipes along this road to accommodate more
stormwater will reroute water away from the road and residential property. On the inner curve of
the road, where erosion is severe, the concrete pipe underneath the Dixon driveway may need to
be enlarged in order to accommodate the stormwater flow. The stormwater swales may need to
be lined with rock depending on the slope of the system.
This area is a major concern and will need a more detailed study including a complete survey of
the drainage area. To ensure sufficient channel and pipe size, a detailed survey, which includes
channel bottom, pipe inverts, and related information, is necessary. This information would be
taken and used to perform simple modeling calculations.
Pine Bur Acres
Flooding is a main concern for the Pine Bur Acres residential community. This particular area
contains inadequate drainage. areas due to non-existent swales, blockage of existing swales,
inadequate pipe systems, and/or pipe elevation problems.
Pine Burr Acres Community Overall Recommendation
The general recommendation for this community is to obtain a comprehensive study that would
further investigate the current drainage patterns and systems at a more detailed level. This means
major easements will be required for the entire area. Though minor problems can be addressed
by replacing culverts and re -grading swales, flooding in this area may be remedied with an on -
site bioretention or a regional stormwater retention basin if there is property available. However,
further investigations need to be performed in order to find suitable locations for the placement
of the BMP's.
N Wren Drive Carlyle Street and Pine Bur Circle Intersection
This primary concern for this intersection is flooding. Drainage systems do not exist, causing
water to build along residential properties. A 10-inch plastic culvert pipe can be seen under a
residential drive on the east side of the intersection (See pictures 28-29, Appendix A). However,
lack of continuous swales along the roadside hinders adequate drainage from nearby properties.
The same problem exists on the south side of the intersection (See picture 30, Appendix A).
Where flooding problems occur at the corner of this intersection, a home is currently under
construction. The lot under construction has been flooded due to the low elevation relative to the
golf course drainage that it feeds into. The drainage could be piped from the property to the
stream that flows south of the Ruth Street and Carlyle Street.
A recommendation is to provide grass -lined swales along the properties in this area that can be
directed to the east or into the stream that begins south of the Carlyle -Ruth Street intersection as
05/05/03 4-6

CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN OF CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
needed. In addition, a bioretention area could be installed on a portion of the newly constructed
lot to provide treatment prior to entering into the stream along the golf course.
Pine Bur Circle
A ditch running perpendicular to Pine Bur Circle flows in a southeastern direction away from the
residential area towards a golf course that eventually drains into the Calabash River (See pictures
31-34, Appendix A). The ditch between the properties of two residents on the western side of
Pine Bur Circle is filled with excess vegetation. An 18-inch corrugated metal pipe extends under
the roadway to the eastern side where the outfall is located. It appears attempts were made to
prevent erosion by pouring concrete around the pipe and on a portion of the ditch entrance.
The 18-inch pipe culvert may be undersized. According to preliminary calculations, the pipe
may need to be increased to as much as a 36-inch RCP. The two -foot contours do not provide
detailed enough information to accurately determine the drainage area; therefore, further studies
and modeling will need to be performed before final pipe size is chosen.
Melvin Drive
Upstream from this location on Melvin Road, drainage system concerns exist. On the western
side of Melvin Drive, three pipes meet at a circular hole in the ground, where mucky water is at a
standstill (See pictures 35-36, Appendix A). The ditch on the eastern side of the road is also
filled with debris including trees and small plants (See pictures 37-38, Appendix A).
Removal of this debris and excess vegetation will help prevent standing water on the western
side of Melvin Road. It appears that the pipe elevations need to be re -graded in order for proper
water drainage. No swales exist in this area and may not need to be installed, however, lowering
the pipes to a more effective elevation, may solve water backup in this location. The current
mapping does not provide detailed enough information to accurately determine the drainage area.
Therefore further studies and modeling will need to be performed before final pipe size is
chosen.
Wren Drive
Between the properties of.Wren Drive and Melvin Drive, a low-lying wet area exists causing
water to backup into adjacent properties during rainfall events. Site investigations and current
SBWSA topographic maps revealed that water flows away from this area. From the swampy
location, a pipe extends under a residential property and connects to a stormwater catch basin
that exists on the east side of Wren Drive (See picture 40, Appendix A). Three pipes converge
here which includes two inlet pipes one in which the source is unknown, and one outlet pipe
whose destination is off of Ruth. One of the inlet pipes extends from the swampy area that exists
between properties located on Melvin and Wren Drive. The flow in this pipe appears to be
directed from Melvin towards Wren Drive. The outlet pipe that comes into the catch basin at an
05/05/03 4-7

CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN OF CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
angle appears to flow under the Wren Drive. The source of this flow of water is unknown and
may need further investigation. The third pipe extends under and perpendicular to Wren Drive
extending to Ruth Drive.
Another concern on Wren Drive is that roadside drainage swales do not exist. In addition, a
concrete culvert that exists under a driveway appeared to be nonfunctioning and in need of repair
(See pictures 39-40, Appendix A).
A possible solution to improve drainage along this road is to install grass -lined swales along
Wren Drive that can control the water flow into the nearby catch basin. Since pipes in the catch
basin could not be measured, a more detailed survey would need to be completed to verify any
concerns, to ensure a proper functioning system. Another possible solution is to convert the wet
area into an infiltration area with proper grading and soil properties.
Ruth Drive
The main problem along Ruth Drive is flooding due to blockages of pipe systems (See pictures
41-44, Appendix A). The pipe extending from Melvin Drive contains an outlet on the eastern
side; of Ruth Drive between two residential properties. This pipe outfalls into a small ditch full of
excess vegetation. A culvert then extends under Ruth Drive that outfalls into a ditch that flows in
a southwestern direction. This ditch continues and merges with another ditch along.Highway
179.
Where the drainage ditch continues across Ruth, evidence shows that this area needs to be
cleaned of its excess vegetation. The ditch on this side of Ruth needs to be cleared of debris and
saplings to prevent restriction of flow. It appears that there may be a vacant lot that can provide
a retention pond or a bioretention area between Ruth and Highway 179. The two -foot contours
do not provide detailed enough information to accurately determine the drainage area. Therefore
further studies and modeling will need to be performed before final pipe size location for a
retention pond is chosen.
Wren Drive and Petty Drive Intersection
A stream channel exists near the intersection of Wren and Petty Drive that flows south along
rWren Drive (See pictures 45-47, Appendix A). The channel is lined with overgrown plants and
excess vegetation. The main concern is an undersized pipe that needs to be replaced and re-
graded as well as to clean out the ditch to ensure adequate drainage.
Cavrl le Street and Ruth Drive Intersection
Alongside Carlyle Street a stream channel flows west and bends south at the intersection with
Ruth Drive (See pictures 48-50, Appendix A). This channel eventually connects with a stream
that extends from Jericho Road, which flows into Calabash River. The channel near this
' 05/05/03 4-8

CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN OF CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
intersection is blocked with large tree branches and other debris. The banks of this channel
indicated severe erosion and undercutting.
A recommendation would be to remove any debris interrupting flow and to consider improving
the channel using natural channel design techniques. As previously stated, the two -foot contours
do not provide detailed enough information to accurately determine the drainage area. Therefore
further studies and modeling will need to be performed before final recommendations are made.
4.3 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. Most of the inlets and pipe systems are
in need of maintenance and some are in need of excavation to remove sediment buildup.
Calabash should work with SBWSA when developing a maintenance program for the storm
drain system so as to not overlap duties and to ensure effective and efficient operation and
maintenance of the system. 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.
Once developed, use of SBWSA's inventory system for future maintenance tracking will be very
useful. Regular monitoring and maintenance of all components of the storm drain system is
recommended to prevent problems.
Roadside swales should be periodically cleaned of debris and mowed. Vegetation is critical for
infiltration and pollutant removal, but excess vegetation will block flow.
05/05/03 4-9

CHAPTER FOUR
DRAINAGE PROBLEM AREA TOWN OF CALABASH ANNEXATION
RECOMMENDATIONS SUPPLEMENTALSTORMWATER QUANTITY MANAGEMENT PLAN
Table 4-1
Recommendations
Annexed Area of Calabash
Location/Site Number*
Problem Description
Recommended Action
Remove debris in swales, re -grade
existing swales, install grass lined
Charlotte Avenue and Lamb Street
Crushed culvert, blocked swales,
swales where non-existent, resize
Intersection
non-existent swales, poor drainage
culvert under Charlotte Avenue,
Site # 1
further study of drainage area
downstream
Remove debris in swales, re -grade
Degraded/nonexistent roadside
existing swales, install grass lined
Highpoint Avenue
swales, blocked swales and pipes,
swales where non-existent, resize
Site # 2
improper culvert placement/size,
culverts along and under Highpoint
erosion, flooding along ditch
Ave, re -grade ditch on east side,
further study of ditch downstream
Overgrown/degraded/non-existent
Re -grade swales with grass lining,
Highpoint Avenue and Charlotte
roadside swales,
replace culverts, steel grate in place
Avenue Intersection
ineffective/damaged culverts,
of junction box, further study of
Site # 3
excess erosion
'unction box
Carlyle Street, Wren Drive and Pine
Ineffective/nonexistent drainage
Improve roadside swales and
channels possible location of
p
Bur Circle Intersection
Site # 4
system
s
'
retention pond downstream
Drainage ditch needs to be cleared of
Pine Bur Circle
Excess vegetation in drainage ditch,
excess vegetation, replace/resize
Site # S
resize culvert
culvert
Ditch full of trash and debris,
Remove debris and excess vegetation
Melvin Drive
inappropriately placed/sized pipes,
blocking ditch, resize/re-elevate
Site # 6
crushed pipe ends
culverts
Wren Drive.
Nonexistent swales, flooding
Install grass -lined swales, more
detailed study of catch basin pipe
Site # 7
between Wren and Melvin
system
Remove excess vegetation, install
Ruth Drive
Debris filled ditch
bioretention or infiltration swales,
Site # 8
possible location of retention pond in
adjacent property
Wren Drive and Petty Drive
Remove debris and excess
Intersection
Debris filled ditch
vegetation, replace culvert
Site # 9
Carlyle Street and Ruth Drive
Stream has excess erosion and
Natural channel improvements,
Intersection
undercutting of banks, overgrown,
remove debris and excess vegetation
Site # 10
debris -filled areas
* Number corresponds to location depicted in rigure 4-i
05/05/03 4-10

CHAPTER FIVE
STORMWATER MANAGEMENT TOWN OF CALABASHANNExATION
PROGRAM SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT 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
The project rankings are shown in Table 5-1. Costs for the recommendations (design and
construction) were estimated (order of magnitude) and are shown in Table 5-2. It should be
noted that these are only estimates. Surveying and Hydraulic & Hydrologic modeling are
necessary to determine more precise estimates on sizes of facilities, length of pipe, etc. The
costs of obtaining drainage easements and whether the Town can obtain land needed for several
of the projects is also a factor (drainage easement cost and other land costs are not included in
the estimates). 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�prcject 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
Safe
This criterion is for projects that maintain safe travel ways during rainstorms and protect against
property damage from flooding. The safety benefits are apparent from the nature of the project.
Quantity Bene its
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
Though these projects are mainly water quantity control projects, water quality in the receiving
waterbodies cannot be degraded due to the stormwater discharge. 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, shell fishing, and other recreation due to
05/05/03 5-1

' CHAPTER FIVE
STORMWATER MANAGEMENT TOWN OF CALABASHANNEXATION
PROGRAM SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
pollutants. Projects, which improve the quality of stormwater runoff, will help protect and
improve the quality of water in the Calabash River.
r
05/05/03 5-2

CHAPTER FIVE
STORMWATER MANAGEMENT TOWN OF CALABASHANNEXATION
PROGRAM SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
Table 5-1
Project Selection Criteria and Ranking
Annexed Area of Calabash
Evaluation Criteria
Overall
Problem
Quantity-
Quality
Project
Recommended
Location/
Description
Safety
Benefits
Benefits
Ranking
Action
Site Number*
Remove debris in swales, re -grade
Charlotte Ave and
existing swales, install grass lined
Lamb Street
swales where non-existent, resize
Site # 1
Flooding
2
3
7
3
culvert under Charlotte Avenue,
further study of drainage area
downstream
Remove debris in swales, re -grade
existing swales, install grass lined
Highpoint Avenue
swales where non-existent, resize
Site # 2
Flooding
6
4
6
5
culverts along and under Highpoint
Avenue, re -grade ditch on east side,
further study of ditch downstream
Highpoint and
Re -grade swales with grass lining,
Charlotte, Avenue
Flooding
1
1
1
1
replace/resize culverts, further study
'unction
Site # 3
of box
Carlyle St, Wren
Improve roadside swales and
Drive, and Pine
channels, possible location of
Bur Circle
Flooding
3
2
4
2
retention pond downstream
Site # 4
Pine Bur Circle
Drainage ditch needs to be cleared of
Site # S
Debris filled
8
5
g
8
excess vegetation, replace/resize
culvert
Melvin Drive
Remove debris and excess vegetation
Site # 6
Flooding
4
6
9
6
blocking ditch, resize/re-elevate
culverts
Wren Drive
Install grass -lined swales, more
Site # 7
Flooding
5
7
3
4
detailed study of catch basin pipe
system
Remove excess vegetation, install
Ruth Drive
bioretention or infiltration swales,
Site # 8
Flooding
7
8
5
7
possible location of retention pond in
adjacent property
Wren and Petty
Debris filled
Remove debris and excess
Drive
ditch
9
9
10
10
vegetation, replace culvert
Site # 9
Carlyle St Ditch
Erosion and
Natural channel improvements,
near Ruth Drive
undercutting
10
10
2
9
remove debris and excess vegetation
Site # 10
of bank
Ranking: 1=highest; 10=lowest.
* Number corresponds to location depicted in Figure 4-1
05/05/03 5-3

' CHAPTER FIVE .
STORMWATER MANAGEMENT TOWN OF CALABASHANNEXATION
PROGRAM SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
5.3 CAPITAL IMPROVEMENT PROGRAM
' Inadequate system capacity is the biggest 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 sub -
drainage areas. Simpler models are available to use for specific design calculations such as
culverts, drop inlets, site drainage systems, etc.
I
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 jointly
with SBWSA. A work order process and form should be developed to track work progress and
to record maintenance work for overall program success.
Maintenance costs will be dependent on the length of pipe, length of roadside swales, number of
drop inlets, and size of infiltration facilities. A few estimates for maintenance costs are
approximately $1.00 per linear foot for cleaning ditches and pipes (assuming Town personnel
and equipment), approximately $40475 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). 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. This
action 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.
05/05/03 5-4

CHAPTER FIVE
STORMWATER MANAGEMENT TOWN OF CALABASHANNEXATION
PROGRAM SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
Taxes
The Town could raise property taxes to fund part or the entire 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.
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.
05/05/03 5-5

CHAPTER FIVE
STQRMWATER MANAGEMENT TOWN OF CALABASHANNEXATION
PROGRAM SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT PLAN
Table 5-2
Capital Improvement Program
Annexed Area of Calabash
Location/ Site Number*
Recommended Action
Relative Cost**
Remove debris in swales, re -grade
Charlotte Avenue and
existing swales, install grass lined swales
Lamb Street Intersection
where non-existent, resize culvert under
$40,000
Site # 1
Charlotte Avenue, further study of
drainage area downstream
Remove debris in swales, re -grade
existing swales, install grass lined swales
Highpoint Avenue
where non-existent, resize culverts along
$50,000
Site # 2
and under Highpoint Avenue, re -grade
ditch on east side, further study of ditch
downstream
Highpoint Avenue and
Re -grade swales with grass lining, replace
Charlotte Avenue
culverts, steel grate in place of junction
$60,000
Intersection
box, further study of junction box
Site # 3
Carlyle Street, Wren Drive
Improve roadside swales and channels,
and Pine Bur Circle
possible location of retention pond
$100,000
Intersection
downstream
Site # 4
Pine Bur Circle
Drainage ditch needs to be cleared of
$40,000
Site # 5
excess vegetation, replace/resize culvert
Melvin Drive
Remove debris and excess vegetation
$40,000
Site # 6
blocking ditch, resize/re-elevate culverts
Wren Drive
Install grass -lined swales, more detailed
$40,000
Site # 7
study of catch basin pipe system
Remove excess vegetation, install
Ruth Drive
bioretention or infiltration swales,
$150,000
Site # 8
possible location of retention pond in
adjacent property
Wren Drive and Petty
Remove debris and excess vegetation,
$30,000
Drive Intersection.
replace culvert
Site # 9
Carlyle Street and Ruth
Natural channel improvements, remove
$75,000
Drive Intersection
debris and excess vegetation
Site # 10
* Number corresponds to locations depicted on Figure 4-1
' ** These cost estimates are based on similar information in the original Stormwater Quantity Management Plan
and should not be taken as the final cost. Further investigation of the drainage system will need to be performed
to determine the length, size, and type of swales, culverts, and BMP's to be installed.
1
05/05/03 5-6

CHAPTER SIX TOWN OF CALABASHANNEXATION
REFERENCES SUPPLEMENTAL STORMWATER QUANTITY MANAGEMENT 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 Calabash. 1994. 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.
1
05/05/03 6-1

FIGURES

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ANNEXED AREA SUPPLEMENTALSTORMWATER QUANTIT
TOWN LIMITS MANAGEMENT PLAN
BaB Baymeade fine sand Ma Mandarin fine sand SOIL MAP
BnB Blanton fine sand Mk Muckalee loam
BO Bohicket silty clay loam Mu Murville mucky fine sand FIGURE 3-1
Fo Foreston loamy fine sand Pn Pantego mucky loam
GoA Goldsboro fine sandy loam Ra Rains fine sandy loam URS
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APPENDIX A
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1
APPENDIX A
STORMWATER FOCUS AREA PICTURES

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Photo 1
Description
View of pipe culvert under
Charlotte Avenue at the
intersection with Lamb Street
on southwest comer.
Drainage Concern
Pipe is slightly crunched and
adjacent swales filled with
debris. This pipe extends under
Charlotte Avenue and runs
beside residential home.
Photo 2
Description
Alternate view of southwest
corner where you can see that
the swale barely exists and is
completely blocked.
Drainage Concern
Drainage swales are filled with
debris.
Photo 3
Description
Outfall of pipe on East side of
Charlotte Avenue where the
ditch runs alongside a resident's
home.
Drainage Concern
Water drains alongside home
into drainage area downstream.
During rainfall events water
builds up next to this property.
Photo 4
Description
Alternate view where pipe
outfalls on east side of
Charlotte Avenue.
Drainage Concern
Water drains alongside home
into drainage area downstream.
During rainfall events water
builds up next to this property.

Photo 1
Description
View of pipe culvert under
Charlotte Avenue at the
intersection with Lamb Street
on southwest comer.
Drainage Concern
Pipe is slightly crunched and
adjacent swales filled with
debris. This pipe extends und: i
Charlotte Avenue and runs
beside residential home.
Photo 2
Description
Alternate view of southwest
corner where you can see that
the swale barely exists and is
completely blocked.
Drainage Concern
Drainage swales are filled with
debris.
Photo 3
Description
Outfall of pipe on East side of
Charlotte Avenue where the
ditch runs alongside a resident's
home.
Drainage Concern
Water drains alongside home
into drainage area downstream.
During rainfall events water
builds up next to this property.
Photo a
Description
.Alternate view where pipe
outfalls on east side of
Charlotte Avenue.
Drainage Concern
Water drains alongside home
into drainage area downstream.
During rainfall events water
builds up next to this property.

Photo-5
Description
View of concrete pipe under
gravel driveway north of
intersection of Lamb Street and
Charlotte Avenue that
contributes to the Flow of area
in photo 6.
Drainage Concern
Pipe is partially blocked and
needs to be resized/replaced
Photo 6
Description
View of left side of driveway
next to property of concern.
Drainage Concern
Water drains alongside home
into drainage area downstream.
During rainfall events water
builds up next to this property.
Swales are practically non-
existent.
Photo 7
Description
Ditch that lies perpendicular to
Highpoint Avenue near the top
of the hill near Mears Road
intersection.
Drainage Concern
Water does not drain
adequately in this area due to
blocked and improperly placed
culvertpipe.
Photo 8
Description
Alternative view of ditch that
lies perpendicular to Highpoint
Avenue near top of the hill
near Mears Road intersection.
Drainage Concern
Pipe is completely blocked
from debris, excessive plant,
and saplings.

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Photo 9
Description
West side of Highpoint Avenue
next to ditch and entrance to
culvert under roadway.
Drainage Concern
Structure needs further
investigation of its purpose to
ensure proper flow in adjacent
ditch and swales.
Photo 10
Description
Opposite side of Highpoint
Avenue where pipe is outfall is
covered at new construction
site.
Drainage Concern
Pipe has excess sediment build
up.
Photo 11
Description
View ofswale that contributes
to sediment buildup on East
side of Highpoint Avenue.
Drainage Concern
Swale has been graded by
owner. This shows where
swales become either non-
existent or filled with debris
further uphill.
Photo IZ
Description
East side of Highpoint Avenue
where property owner has
placed his own pipe and graded
swale along property.
Drainage Concern
Erosion from site has caused
pipes to fill with sediment.

Photo 13
Description
Southeast side of driveway on
Highpoint Avenue where pipe
inlet from photo 9 leads.
Drainage Concern
Erosion from site has caused
pipes to fill with sediment.
Photo 14
Description
Behind construction site of nets
home otiof Highpoint Avenue.
Drainage Concern
Drains into a pipe that extends
into ditch behind residents
homes. Erosion from site has
caused pipe to fill with
sediment.
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Photo 15
Description
View of crushed pipe culvert
under Charlotte Avenue at the
intersection with Highpoint
Avenue on norhem comer.
Drainage Concern
Crashed pipe culvert in comer
ditch where water is not
collecting and instead flowing
directly over the road. Pipe
may need to be enlarged as
well as re -graded.
Photo 16
Description
Closer view of crushed pipe
culvert under Charlotte Avenue
at the intersection with
Highpoint Avenue on northern
comer.
Drainage Concern
Crushed pipe culvert in corner
ditch where water is not
collecting and instead flowing
directly over the road. Pipe
may need to be enlarged as
well as swale system installed.

Photo 17
Description
Alternate view of Charlotte and
Highpoint Avenue.
Drainage Concern
Water is not collecting in this
pipe and rather flowing directly
over the road. Pipe may need to
be enlarged as well as Swale
system installed.
Photo 18
Description
Alternate view of Charlotte and
Highpoint Avenue.
Drainage Concern I
Area where water accumulate,
sheet flows over roadway inn.
residents yard and into pond.
Photo 19
Description
Alternate view of Charlotte and
Highpoint Avenue standing in
yard of the Dixon residence
where water sheet flows over
road and into yard.
Drainage Concern
The water coming off the road
floods the yard of this property.
Photo 20
Description
Alternate view of Charlotte and
Highpoint Avenue where the
Dixon residence resides.
Corner where house is and
where flow of water off the
road floods back into pond.
Drainage Concern
The water coming off the road
floods the yard of this property.

Photo 21
Description
View of culvert under driveway
where water flows into yard.
Drainage Concern
Culverts may need to be resized
to handle stonmwater flow.
Photo 22
Description
View ofCharlone Avenue that
shows system of culverts under
driveways that contribute to
flooding.
Drainage Concern
Culverts may need to be
resized to handle stormwater
flow.
Photo 23
Description
Further along Highpoint
Avenue next to Mr. Dixon's
driveway.
Drainage Concern
Inadequate sizing of pipe,
erosion, and sediment buildup.
Photo 24
Description
Section of Highpoint Avenue
that runs perpendicular to an
inlet that flows into Calabash
Creek.
Drainage Concern
Inner curve of road is eroding
along with the swale.

Photo 25
Description
View ofstorm drain in
reference to Highpoint Avenue.
Drainage Concern
Catch basin and pipes may
need to be resized.
Photo 26
Description
Inlet area to Calabash Creek
otiof Highpoint Avenue.
Drainage Concern
Catch basin and pipes may
need to be resized.
Photo 27
Description
View of location where an
outlet pipe exists that connects
to the pond as well as outfall
pipe from the storm drain
which all flows into the inlet o f
Calabash Creek.
Photo 28
Description
Intersection of Carlyle, Wren.
and Pine Bur Circle.
Drainage Concern
No swales exist in this area.

Photo 29
Description
Intersection of Carlyle, Wren,
and Pine Bur Circle.
Drainage Concern
No swales exist in this area
Photo 30
Description
Intersection of Wren Drive
poking south and Carlyle
Sweet where flooding is prone.
Drainage Concern
Rater floods in this area due to
nonexistent drainage system.
Photo 31
Description
Ditch running perpendicular to
Pine Bur Circle that heads
toward golf course.
Drainage Concern
Culvert pipe is undersized.
Photo 32
Description
Alternate view of Pine Bur
Circle on the East side of the
road where outfall flows
wwards golf course.
Drainage Concern
Culvert pipe is undersized.
y'

Photo 33
Description
West side of Pine Bur Circle.
Drainage Concern
( ulvert pipe is undersized.
Photo 34
Description
.4ltemate view of ditch on west
side of Pine Bur Circle that
extends from Melvin Road and
Mows under Pine Bur Circle
owards golf course.
Drainage Concern
Culvert pipe is undersized and
ditch further upstream needs to
be cleared of excess vegetation,
Photo 35
Description
Outlet pipe off of Melvin Drive
on west side coming from
storm basin on Wren Rd.
Drainage Concern
Water is at a standstill filled
with trash and other debris.
Concrete culvert needs to be
resized and/or replaced at
proper elevation.
Photo 36
Description
Another view of pipe system
under Melvin Drive on west
side.
Drainage Concern
Water is at a standstill filled
with trash and other debris.
Concrete culvert needs to be
resized and/or replaced at
proper elevation.

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Photo 37
Description
Melvin drive outfall into ditch
filled with trash and debris.
Drainage Concern
Drainage path is filled with
wash and other debris.
Photo 38
Description
Alternative view of Melvin Dr.
where ditch curves around to
Pine Bur Circle.
Drainage Concern
Excess vegetation lined in
ditch. Needs to be cleaned out
and maintained.
Photo 39
Description
� „ncrete pipe culvert under
driveway along Wren Drive.
Drainage Concern
No swale exists to direct the
water flow. Water accumulates
and builds.
Photo 40
Description
Storm water drain off of Wren
Drive that connects pipes from
swampy area, an unknown
source, and an outlet pipe
connecting to east side of Ruth
Drive. (Arrows show pipe flow
direction)
Drainage Concern
Property adjacent to the east
between Melvin and Wren
accumulates water and floods
during rainfall events due to
inadequate functioning of
drainage basin.

Photo 41
Description
Dual pipe system on east side
u( Ruth Drive.
Drainage Concern
Plants consume the drainapr
area and need to be cleared
in order to prevent water
backup.
Photo 42
Description
Dual pipe system on east side
of Ruth Drive.
Drainage Concern
Plants consume the drainage
area and need to be cleared out
in order to prevent water
backup. Further west to this
area exists a possible location
for a retention pond.
Photo 43
Description
View of outlet pipe off of the
west side of Ruth Drive.
Drainage Concern
Ditch is filled with overgrown,
excessive vegetation.
Photo 44
Description
Alternate view of outlet pipe
off of the west side of Ruth
Drive.
Drainage Concern
Ditch is filled with excessive
vegetation.

Photo 45
Description
View of ditch on northwestern
corner of W ren and Petty
Drive.
Drainage Concern
Overgrown vegetation within
ditch.
Photo 46
Description
View of ditch on northeastern
corner of W ren and Petty
Drive.
Drainage Concern
Ditch and inlet pipe arc
covered with overgrown.
excessive vegetation.
Photo 47
Description
Alternate view of ditch on
northeastern corner of Wren
and Petty Drive.
Drainage Concern
Ditch and inlet pipe are
covered with overgrown,
excessive vegetation.
Photo 48
Description
Channel that runs northwest,
parallel to Carlyle Street and
turns west at intersection of
Ruth Drive.
Drainage Concern
Channel showing major signs
of erosion and undercutting of
banks.

Photo 49
Description
( Ihannel that tuns west
perpendicular to Carlyle Street
Drainage Concern
('hannel showing major signs
4 erosion and undercutting of
banks.
Photo 50
Description
Channel that runs west
perpendicular to Carlyle Street.
Drainage Concern
Channel is filled with large tree
branches and other debris.

APPENDIX B

APPENDIX B
= r m m s m m = = = = i= m m r = m m

APPENDIX B
PUBLIC HEARING MATERIAL

TOWN OF CALABASH
T � K NOTICE OF PUBLIC HEARING
APRIL 24, 2003
The Town of Calabash will conduct a public hearing
on Thursday, April 24th, 2003 at 7:00 p.m. in the Town
Hall located at Persimmons Road in Calabash, NC.
The purpose of this public meeting is to receive com-
ments on a proposed stormwater management plan for
the Calabash annexed area.
The basis for the stormwater management plan is to
improve stormwater runoff from both quantity and qual-
ity perspectives. The town encourages the public to
participate in the planning process that will lead to the
development and implementation of a storm water pro-
gram.
Copies of the draft stormwater management plan for
the annexed portion of Calabash are available at the
Town Hall. Copies can be reviewed between the hours
of 8:30 a.m. and 4:30 p.m. beginning April 16th.
Oral and written comments are welcome, written
comments should be directed to:
Calabash Town Hall • PO Box 4967
Calabash NC 28467
Anthony Clemmons
Town Commissioner

COMMENT SHEET
PUBLIC HEARING - April 24, 2003
' PLEASE PRINT:
NAME
ADDRESS:
' CITY/TOWN: STATE:
PHONE NUMBER: E-MAIL:
ZIP CODE:
❑ Please add my name to the mailing list. ❑ Please remove my name from the mailing list.
' I wish to comment or inquire about the following aspects of this project:
■

Town Administrator
Town of Calabash
'
P.O. Box 4967
882 Persimmon Road
Calabash, North Carolina 28467
'
910-579-6747
(Fold Here to Mail)
'
'
Please
Place
Stamp
'
Here
Town Administrator
Town of Calabash
P.O. Box 4967
882 Persimmon Road
Calabash, North Carolina 28467