Stormwater Master Plan-1999

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I DCM COPY
DCM COPY
Please do not remove!!!!!
1 R Division of Coastal
Copy Village of Bald Head
Island, North Carolina
Stormwater
Master Plan
May 1999
MacConnell & Associates, P.C.
Post Office Boa 30%
Cary, North Carolina 27519
9638 Chapel Hill Road
Cary, North Carolina 27513
Telephone: [phone]
Far. [phone]

Village of Bald Head Island, North Carolina
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The preparation of this Stormwater Management Plan 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.
MacConnell & Associates, P.C.

Village of Bald Head Island, North Carolina
Table of Contents
Executive Summary ...................................... 1-1
Project Summary ....................................... 2-1
A. Introduction ....................................... 2-1
B. Existing Situation ................................ 2-2
1. Climate ................................................ 2-6
2. Soils & Vegetation ....................................... 2-8
3. Impervious Area .................................. 2-10
C. The Need For the Project ............................. 2-12
Stormwater Management Issues ............................ 3-1
A. Overview of Drainage Patterns .......................... 3-1
1. Planned Development I ....................................
3-3
2. Planned Development H & HC................................3-5
3. Planned Development III (Marina) ............................
3-5
4. Planned Development IV (Middle Island) .......................
3-5
B. CAMA Land Use Plan ................................
3-6
C. Stormwater Regulations ..............................
3-7
D. Water Quality/Quantity Issues ..........................
3-7
1. Recreation ..............................................
3-7
2. Wildlife ................................................
3-8
a. Land Environment ..................................
3-9
b. Riparian Environment ...............................
3-9
c. Estuarine Environment ...............................
3-9
d. Ocean Environment .................................
3-10
3. Human Consumption ......................................
3-10
E.
Stormwater Best Management Practices ..................
3-11
1. Pollutant Prevention Techniques .............................
3-12
a. Sediment .........................................
3-12
b. Sanitary Sewers .....................................
3-13
2. Landscaping and Lawn Maintenance Control Measures ............
3-13
3. Lagoon Cleaning.........................................3-14
4. Nutrient Removal.........................................3-15
5. Comprehensive Site Planning for Future Development .............
3-16
Stormwater Management Alternatives Analysis ................
4-1
A.
Subsurface Drainage System ...........................
4-1
B.
Surface Swales and Ditches ............................
4-3
C.
Surface Runoff Collection System ........................
4-5
1. Stormwater Sewer with Outfall Discharge .......................4-5
2. Stormwater Sewer with an Infiltration Basin .....................
4-7

Village of Bald Head Island, North Carolina
3. Stormwater Sewer with Detention/Retention System. ..............
4-9
D. Do Nothing Alternative ...............................
4-12
Recommendations.......................................5-1
A. General Recommendations
5-1
............................
B. Future Development ..................................
5-4
C. Site Specific Recommendations .........................
5-5
Area 1. Snowy Egret Trail/Black Skimmer Trail ...................
5-5
Area 2. Dogwood Trail/Dowitcher Trail .........................
5-5
Area 3. Sabal Palm Trail .....................................
5-7
Area 4. Edward Teach Road and Surrounding Roads ................
5-9
Area 5. North Bald Head Wynd ...............................
5-9
Area 6. Stede Bonnet Wynd...................................
5-9
Area7. Cape Fear Trail.......................................5-9
Area8. Green Teal Trail. .....................................
5-9
Area 9. Middle Island .......................................
5-9
Area 10. Cape Fear Station ...................................
5-10
Area 11. Marina.......................................5-10
Area 12. Bald Head Creek .....................................
5-10
D. Environmental Concerns ..............................
5-11
Cost Analysis and Responsibilities ..........................
6-1
A. Cost of Implementation ..............................
6-1
B. Responsibilities .....................................
6-4
1. Responsibility of the Village of Bald Head Island .................
6-4
2. Responsibility of the Bald Head Island Utilities, Inc ...............
6-5
3. Responsibility of the Bald Head Island Conservancy ..............
6-5
4. Responsibility of the Property Owner's Association ...............
6-5
5. Responsibility of the Bald Head Island Club ....................
6-5
6. Responsibility of the Bald Head Island Limited .................
6-5
7. Responsibility of the Property Owners .........................
6-6
Conclusions ............................................
7-1

Village of Bald Head Island, North Carolina
I List of Tables
Table 2-1:
Significant Storm Events in the Past 5 Years .................
2-6
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Table 2-2:
Typical 24-Hour Storm Events ...........................
2-7
Table 2-3:
High / Low Precipitation Data ...........................
2-7
' Table 24:
High / Low Temperature Data ...........................
2-7
Table 2-5:
Impervious Area Calculations ...........................
2-11
' Table 3-1:
Best Management Practice Efficiencies ....................
3-16
Table 4-1:
Advantages and Disadvantages of a Subsurface Drainage System.
4-2
Table 4-2:
Ranges of Typical Installed Costs that may be Incurred
During Construction of a Subsurface Drainage System.........
4-2
Table 4-3:
Advantages and Disadvantages of a Surface Swales and Ditches .
4-4
Table 4-4:
Estimated Costs that may be Incurred During Construction
of a System of Swales and Ditches ........................
4-4
Table 4-5:
Advantages and Disadvantages of a Storm Sewer with an Outfall
Discharge..........................................
4-6
Table 4-6:
Estimated Costs that may be Incurred During Construction
'
of a Stormwater Sewer with an Outfall Discharge .............
4-6
Table 4-7:
Advantages and Disadvantages of a Storm Sewer with an
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Infiltration Basin .....................................
4-7
Table 4-8:
Estimated Costs that may be Incurred During Construction
of a Stormwater Sewer with an Infiltration Basin .............
4-8
' Table 4-9:
Advantages and Disadvantages of a Storm Sewer with a
Detention System ....................................
4-10
' Table 4-1O:Estimated Costs that may be Incurred During Construction
of a Stormwater Sewer with an Outfall Discharge..........- ..
4-11
Table 6-1:
Cost Estimate for Stormwater Management Facilities.........
6-2
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List of Figures
Figure 2-1:
Development Zones of Bald Head Island ..................
2-4
Figure 2-2:
Soil Types of Bald Head Island .........................
2-9
Figure 2-3:
Vegetation Zones of Bald Head Island ....................
2-10
Figure 2-4:
Typical Island Aquifer Layout ..........................
2-13
Figure 3-1:
Drainage Patterns of Bald Head Island ...................
3-2
Figure 4-1:
Typical Subsurface Drainage System with Outfall Discharge ...
4-3
Figure 4-2:
Typical Grass Swale with a Check Dam for Velocity Control...
4-4
Figure 4-3:
Typical Storm Sewer with Outfall Discharge ...............
4-7
Figure 4-4:
Typical Infiltration Basin ..............................
4-9
Figure 4-5:
Typical Wet Detention Pond ............................
4-11
Figure 4-6:
Typical Dry Detention Pond ............................
4-12
Figure 5-1:
Trash Rack ........................................
5-3
Figure 5-2:
Trailer Pump .......................................
5-3

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Village of Bald Head
Island, North Carolina
Chapter I
Executive Summary

Village of Bald Head Island, North Carolina
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1. Executive Summary
A. Summary
This document provides an island wide plan for managing the stormwater on Bald Head Island
and provides recommendations for minimizing the potential for flooding in specific problem areas
on the island. The scope of this document is to provide a planning level study of the island and A
stormwater ordinance which can be utilized as a basis for future detailed design and construction
activities. Due to current conditions, flooding occurs in various areas on the island during
significant rainfall events. This creates many nuisance and hazardous conditions; resulting in
homeowners, visitors, and emergency personnel not being able to reach certain portions of the
island during these flood events. This stormwater management plan is based on: accepted
engineering practice, discussions with individuals familiar with the island, review of existing
(although limited) technical information, projected costs, maintenance requirements, land
requirements, and public health and safety issues.
' Bald Head Island is an island of approximately 3 square miles of developable land. A portion of
the island has already been developed as a vacation resort. Much of the areas around the
developable portions consists of wetlands and marshes that can not be developed. The island is
' located in the southeast corner of Brunswick County, approximately 30 miles south of
Wilmington, N.C. and 50 miles east of North Myrtle Beach, S.C. Access to Bald Head Island is
generally by a private ferry, which travels between Indigo Plantation in Southport, N.C. and the
' Bald Head Island Marina. The Bald Head Island Marina lies on the eastern side of the mouth of
the Cape Fear River, across from Caswell Beach on Oak Island.
The development of the island, including the preservation of natural areas, has generally occurred
in blocks or zones of land as a result of the zoning requirements on the island. Figure 2-1
presents the Island's zoning map which gives the names and locations of each planned
development. To date, there has been development on a portion of the island creating an
impervious area of approximately 10 percent of the zoned land area or 200 acres. Because
development within each zone is often quite different, it is important to address storm water
issues from the following perspectives: island wide basis, by drainage patterns (basins), and by
zones. The Island includes the following zones: Beach/Foredune, Shrub, Forest, and Marsh. A
summary of the various zones is presented below and are illustrated in Figure 2-2.
The Beach/Foredune zone contains the primary and secondary dunes and the entire beach area.
This area provides protection from the ocean for the inner portions of the island and contains
primarily sea oats and beachgrass as vegetation. The Shrub zone is' found in the lower, flat
portions of the island. Much of this area has been developed into residential areas and the golf
course. Primary vegetation consists of yaupon, salt meadow cordgrass, wax myrtle and live oak.
The Forest zone is primarily found in the higher elevations. The majority of the developable
portion of the island is contained in the Forest zone. Typical vegetation found in the Forest zone
is live oak, loblolly pine, laurel oak, American holly, cabbage palm, and eastern redcedar. The
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Village of Bald Head Island, North Carolina
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Marsh zone is found on the inland side of the island where it adjoins the Cape Fear River, Bald
Head Creek, Lighthouse Creek or some other body of water other than the ocean Much of the
Marsh zone is undevelopable because they are primarily considered wetlands. Typical vegetation
of the Marsh zone is smooth cordgrass, black needlerush and saltwort.
' The major area of concern is the development section referred to as Planned Development 1
(PD-1) because it does not have a stormwater permit and is experiencing the most significant
' flooding problems. This area includes the golf course and surrounding areas which represent the
first major areas developed on the island. PD-1 is also significantly developed with planned built
upon areas nearing 15% or approximately 125 acres.
' Planned Development 2 D-2 apparently does not resent a stormwater problem on the island.
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A detailed survey of PD-2 was previously conducted and a stormwater management plan for this
' section has been approved. The lack of stonnwater problems in this area may be attributed to
several things; since the area is undeveloped, the lack of impervious areas may allow for complete
infiltration of the stormwater into the soils; natural drainage patterns that have the capacity to
transport the stormwater to disposal areas on or around the island may still exist; or because the
area is not developed, no one is adversely impacted by possible flooding in the area to
communicate the flooding problems to proper authorities. Compliance with the zoning
' regulations and the stormwater ordinance as the rate of development increases in this area should
insure that no stormwater problems arise. PD-2 is also planned to have significant development
' with planned built upon areas nearing 7% or approximately 50 acres.
The development section referred to as Planned Development 3 (PD-3, marina area) is nearing
' built -out capacity with a planned built upon area of approximately 33% or approximately 26
acres. This area also has an approved stormwater management plan and currently presents no
stormwater flooding problems. The stormwater runoff from PD-3 is collected and transported in
' underground piping systems and uses a combination of surface water discharge and infiltration for
disposal of the runoff generated in this area.
' Planned Development 4 (PD-4) is the area known as Middle Island. This area is beginning to
undergo development and currently does not experience any stormwater flooding problems.
Middle Island enjoys gently sloping terrain which allows stormwater to be channeled away from
development. Managed growth in this area, following zoning regulations and the stormwater
ordinance, should be very effective in minimizing the potential for stormwater flooding problems
' in the future. .
Site specific recommendations are presented indetail in "Chapter 5, Recommendations" of this
' report for the areas of Bald Head Island which are experiencing problems with frequent flooding.
The site specific recommendations have been made based upon visual observations, discussions
with individuals familiar with the Island, and other documents. Aerial surveys of the island are not
' possible due to the vegetative canopy covering large portions of the island and a field survey of
the entire island is not practical for a planning document such as this. The recommendations
outlined in this document include: the construction of ditches, swales, culverts, road
modifications, and other similar structures which will enhance conveyance of stormwater.
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Village of Bald Head Island, North Carolina
Because there is a general lack of good topographic information of the island, many of the
' recommended alternatives are general or qualitative in nature, and lack quantitative information
such as the size of culverts. Approximate values are often presented but they must be confirmed
once reliable field information is available. Once reliable topographic information is available, the
' actual detailed design can be performed, and site specific solutions can be implemented.
Projected costs for the technical recommendations presented in this document and
' recommendations for funding of these recommendations are presented in detail in "Chapter 6,
Cost Analysis and Responsibilities" of this report. Implementation of all the technical
recommendations presented is estimated to cost between $450,000 and $500,000, but could
change when more quantitative information (surveys) is available and final designs are complete.
Recommended funding options include: the Village of Bald Head Island, combinations of
' individuals and/or entities, and specific individuals or entities. Funding recommendations are
based on the cause and extent of flooding. Funding of the recommendations is a complex issue
which has been addressed to be "fair" to all concerned parties.
' Approximately six months to one year should be budgeted to implement the recommendations
contained in this document. This time frame allows for the completion of: regulatory
' requirements, surveys, design and construction activities and is based on previous experience with
similar projects. However, the time for completion of these tasks may vary significantly from the
time frames projected, depending on resolution of regulatory issues and other unforeseen
' circumstances which take time to resolve.
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' Village of Bald Head
� Island, North Carolina
� Chapter 2
� Project Summary
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Village of Bald Head Island, North Carolina
2. Project Summary
' A. Introduction
The purpose of this stormwater management plan for Bald Head Island is to provide a document
' which serves as guidance in the management of stormwater on the island. When much of the
island was developed stormwater management was not regulated; thus much of the island was
developed with little or no attention given to stormwater. For this reason, when significant storm
' events occur on the island there is significant flooding in isolated areas which cause both a
nuisance and safety hazard for those living on Bald Head Island. This plan addresses the
problems associated with stormwater and provides qualitative recommendations for reducing or
' eliminating the problems.
The primary goal of this study is to develop a plan for mane the island's stormwater. This
' includes identifying existing drainage basins, assessing drainage trends, identifying outfalls of the
island, calculating the watershed areas using the limited topographic information available,
' determining the percentage of pervious and impervious areas on the island, and reviewing existing
geologic and hydrogeologic data that is available. This scope also includes evaluating the need
for site specific stormwater control alternatives which include: storm sewers, detention basins,
' and other runoff control measures. A baseline "best management practice," a monitoring and
inspection program, and a Stormwater Management Ordinance that may be used by the Village
Council for implementing a Stormwater Management Plan were also included in the scope of
' services. The Stormwater Master Plan is designed to complement the CAMA Land Use Plan so
the same basic principles of the CAMA Land Use Plan will be maintained through the
implementation of the Stormwater Master Plan.
' The scope of services also extends to site -specific "problem" areas that experience flooding during
significant storm events. The goal is to formulate ideas and present specific solutions to route the
' stormwater out of the flooded areas and into drainage ditches, golf course lagoons, or other
outfalls to mitigate flooding. In some cases it may not be practical nor cost effective to mitigate
ponded stormwater, and these cases will be presented. Analyses are provided with estimated
' costs for correcting the existing problems.
Bald Head Island was evaluated with respect to its existing soils, climate, topography and other
' factors that directly affect the island's stormwater management alternatives. However, because of
the severe lack of reliable topographic information certain quantitative analysis such as sizing
' culverts and drainage areas are limited to estimated values and must be confirmed when adequate
field data (most notably a topographic survey) is collected. Even though some areas of the island
are practically impossible to survey with the significant amount of plant growth (i.e. live oaks,
wax myrtles, American hollies), site -specific information is vital for the proper sizing of storm
drainage structures.
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Village of Bald Head Island, North Carolina
B. Existing Situation
' Bald Head Island is a resort comet that is characterized b having approximately 180
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' permanent residents and a fluctuating visitor population of 700 to 5,000, depending on the season.
It is a quiet, secluded community in which motor vehicles are not allowed, with the exception of
emergency, construction, utility and arrival/departure vehicles. Bald Head Island is a delicate
' ecosystem which reties heavily on its water resources. These water resources provide the benefits
of a potable water source, a source of irrigation water, aesthetic value, and habitat for its diverse
flora and fauna.
' Because of its isolation, Bald Head Island's surface waters and shallow aquifer must be
replenished by stormwater or precipitation. The source of potable water for the island is this
' shallow fresh water aquifer which lies beneath the ground surface of the island at a depth of about
55 to 65 feet mean sea level, as determined by Kenneth Kirkman. The golf course lagoons
provide an irrigation source for the golf course. Recharge of the aquifer is a function of the direct
' percolation of precipitation through the soil and the infiltration of water from surface sources to
the aquifer. Because surface waters and the aquifer are dependent on stormwater for recharge,
protection of the Island's water resources with respect to both quality and quantity are extremely
important to the welfare of the residents and visitors of Bald Head Island.
The Island's fresh water aquifer and its surface waters are also very sensitive in that they must be
' protected from the saltwater that surrounds the island. Intrusion into these water sources by the
surrounding saltwater could cause significant problems with respect to both potable and irrigation
' water. Contamination of the fresh water aquifer would impact the Island's source of potable
water. If the surface waters become saline either by salt water intrusion or ocean overwash from
storms, the saline irrigation water could actually damage some of the plants and grasses which are
' to be irrigated. Thus, there is a delicate balance among the island's water resources which must be
maintained for the benefit of everyone.
' Although stormwater is a valuable and necessary resource for the island, it can also create
problems when it occurs in excessive amounts. The Village of Bald Head Island has experienced
a great deal of problems during significant storm events. It is during these events that many of the
low lying areas experience a great deal of flooding. Excessive flooding can impede emergency
vehicle access, damage homes, and cut vacations short. Efforts in isolated areas to remove the
stormwater with temporary pumping measures have met little success. Thus many of Bald Head
Island's residents and the entities on Bald Head Island have reached out for help to solve these
flooding problems.
' Water is used extensively throughout the island for many things, such as cooking, bathing,
washing, irrigation, etc. Approximately 400 gallons of water per day is needed for a typical
3-bedroom home, based on standard values provided by the North Carolina Department of Health
' 15A NCAC 18C.0409. According to the current Zoning Map, there are over 1,400 recorded
housing units planned for the island. At build out of the island, it is estimated that approximately
560,000 gallons of water per day will be required for domestic uses during the peak tourist
' seasons.
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Village of Bald Head Island, North Carolina
' The Island's water resources provide a rich environment for the island's diverse wildlife and plants.
These resources are enjoyed by both residents and visitors throughout the year. The island
contains several creeks that are great for kayaking and canoeing, as well as bird watching. Many
' people also enjoy nature walks and bicycling through the Maritime Forest to see the many
different species of birds, turtles and the occasional alligator which inhabit the island. According
to the Division of Coastal Management (DCM), most of the island north of North Bald Head
' Wynd is a wetland which provides a perfect environment for the unique wildlife that inhabits the
island.
' The beauty and unique resources which the island provides also attract people who wish to visit
or live on the island. Because the area is desirable to people as a home or vacation area, there is
ongoing construction which is expected to continue until build out of the entire island. This
construction leads to the continual process of decreasing the pervious area of the island, which in
turn affects the infiltrative capacity of the soil. Construction of new homes also requires the
' construction of roads which also decreases the permeable surface on the island. Decreasing the
permeable surface increases stormwater runoff which must be managed so that the chance of
flooding in any given area is not increased. Without careful planning and design, the construction
' of new roads could act as small dikes which will not allow stormwater to flow naturally therefore
potentially creating flooding in certain areas. The drainage of stormwater must be addressed by
providing culverts, or some other drainage feature, beneath these roads. The planning and design
' of these facilities should be in accordance with the Zoning Ordinance and the proposed
Stormwater Ordinance. Also, the Bald Head Association will assure compliance with these
ordinances during their architectural reviews.
' The golf course and surrounding areas are known as Planned Development-1, or PD-1 (Figure
2-1) according to the Zoning Ordinance. Much of this area was developed before the current
' stormwater regulations were in place. Therefore, little consideration was given to stormwater
management and stormwater management plans were not developed. As a result of this lack of
attention to stormwater, PD-1 has the most problems on the island with respect to stormwater
' management and flooding. More stringent environmental regulations for stormwater management
and erosion and sedimentation control have resulted in the proper management of stormwater in
' the newer developments. For instance, Middle Island and the developments east of Muscadine
Wynd will have an approved stormwater management plan prior to construction to ensure that
these developments will not have the same flooding problems as the areas of PD-1.
During large storm events, pooling occurs along Black Skimmer Trail, Snowy Egret Trail,
Towhee Court, Sabal Palm Trail, Stede Bonnet Wynd, Dogwood Trail and the areas north and
' south of Edward Teach Wynd. Other streets, such as Dogwood grail and Dowitcher Trail
experience a flow of water along the properties and streets during significant storm events.
Following three large storm events in early 1998, severe flooding in the area of Black Skimmer
' Trail and Snowy Egret Trail prevented access to several homes. Normal access by foot or cart
was limited because of the standing water. This condition did not subside until approximately one
month after the last storm. Ms. Jayne Howard, who is a resident of Snowy Egret Trail, had
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Village of Bald Head Island, North Carolina
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Figure 2-1: Development Zones of Bald Head Island
Information obtained by the Zoning Map of Bald Head Island, North Carolina
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Village of Bald Head Island, North Carolina
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invited her mother who was in questionable health to visit during this time. Because access to her
' home was restricted, Ms. Howard's mother was forced to cut her vacation short. Ms. Howard
and her husband Mr. Rick Howard were unable to go to work and their son was unable to attend
school without wading through 100 feet of standing water to get to their golf cart, which was
' parked on higher ground. The only means of transportation at the time was by a small boat or
canoe. Fire trucks and other emergency vehicles were unable to reach their destination because of
flooded roads. A former resident, Ms. Barbara McQuaide, decided to move because living at
' Bald Head Island with these stormwater problems was unacceptable due to the nuisances and
safety hazards.
' The topography of the island is relatively flat with a dune ridge that extends as high as 40 feet
above mean sea level in isolated spots, according to the Cape Fear, N.C. USGS topograohic map
' dated 1970. In addition to the dune ridge, there are coastal dunes along much of the perimeter of
the island where there are beaches. The coastal dunes range in height from 5 to 29 feet above
mean sea level. The areas between the dune ridge and the coastal dunes do have various
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topographic changes; however, the island as a whole has relatively flat topography.
The roads are used mainly by golf carts and bicycles, as the only internal combustion vehicles
t allowed on the island are utility, construction, emergency services, and arrival/departure vehicles.
Most of the roads are built above the existing grade with no or minimal consideration for
stormwater drainage. For example ditches to divert stormwater runoff, culverts to allow runoff to
' flow underneath the roads, and crowns to help the runoff flow off of the roads are limited or
non-existant. Because of these construction deficiencies, many of these roads appear to act as
dikes which prevent stormwater from flowing to Bald Head Creek or the Atlantic Ocean,
' depending on which side of the dune ridge the water falls.
There is only one stormwater outfall that is currently active on the island. It is located in the
' northwest corner of the developed portion of the island and allows the golf course lagoons to
drain when their levels rise during and after storm events. This outfall allows water to flow into
Lighthouse Creek from the lagoon system and prevents salt water backflow into the lagoon
' system with the use of a flap valve. The outf dl maintains variable lagoon levels by using a
flashboard riser outlet structure. This flashboard riser allows the level of the lagoons to be
maintained at different levels depending upon the time of the year and what the lagoons are being
' used for at that time. For example, during the summer season, the flashboards would typically be
installed to the maximum level to store as much water as possible for irrigation of the golf course.
' During winter months, the flashboards may be removed, lowering the lagoon levels and providing
more storage capacity for large storm events.
' Visual observation of the riser indicates the lack of a functioning trash rack. According to some
on Bald Head Island, the riser/barrel system was clogged with trash (branches, leaves, etc.) prior
to the storm events of 1998 during which tremendous flooding occurred. Since then, the outfall
' has been evaluated to assure that the lagoons have an unobstructed path into Lighthouse Creek.
Measures to assure that this riser/barrel system does not become clogged need to be taken. The
design of a trash rack for the riser will minimize the potential for clogging the riser/barrel system
' and allow for drainage of the lagoons as necessary during large storm events. Drainage of the
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Village of Bald Head Island, North Carolina
lagoons is critical during large storm events so that adequate storage capacity will be provided
' around the island for stormwater runoff storage.
1. Climate
' a Islan 's weather is similar to eastern North Carolina except that its high and low
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' temperatures are somewhat buffered by the Atlantic Ocean. The island gets rainfall about seven
days per month with an average of five total inches of rainfall per month. Since Bald Head Island
is in the coastal region, it typically receives more precipitation during the hurricane season, which
' is between June 1 st and November 25th. Monthly precipitation data was taken from the United
States Geological Survey's (USGS) Southport Station and is presented in Table 2-1. The data
presented ranges from 1993 to 1998. The Southport Station is located approximately 3 miles
across the Cape Fear River from Bald Head Island.
From the monthly data, it is difficult to determine how often a 10-year, 25-year, or 100-year
' storm has hit Bald Head Island in the past few years. Daily precipitation amounts were obtained
from the USGS's Wilmington Station, which allows us to determine what types of storms have
occurred within the last 5 years and the significant storm events of January 1998 and February
' 1998. From the data received by the National Data Climatic Data Center, dates and precipitation
amounts over 4 inches on a given day were recorded as well as other significant precipitation
events in 1998. This data was taken from a graph and exact amounts and dates are estimated
from the scale of the graphs. Also, several of the storms have lasted longer than a 24-hour
period. These recordings are listed in Table 2-1 below. Since the size of a storm event is
dependent on its duration and intensity, it is possible that the precipitation events in Table 2-1
' were larger storms. For example, if the storm event that occurred on September 20, 1994 lasted
6 hours instead of the assumed 24 hours, it would be classified as a 10 year, 6-hour storm
' Table 2-1: Significant Storm Events in the Past 5 Years
d
Date
Precipitation
Amount (in)
Storm Size
(24-hour)
September 201994
4.58
between 2. 5 year
October 1Z 1994
6.8
25 year
September 5 1996
4.45
between 2 - 5 year
February 3 1998
1 3.37
12 year
Februa 16, 1998*
1 4.84
lbetween 2 - 5 ear
- - . _..... . ------ - - -
• This sthrmevent lasted for nmre than a 24hour period and 27 inches on
........ - ...... .. .
February 16 w as recorded fromthe local new spa per.
Data obtained from National Climatic Data Center, from 1994 to 1998.
' To determine the theoretical return period (Le. 10-year, 25-year, 100-year) of a storm,
incremental precipitation data for each storm event is required. This data would be used to
' determine the intensity and the duration of a given storm event and correlate it with one of the
theoretical storm events. Table 2-2 below was calculated using the intensity -duration -frequency
MacConnell & Associates, P.C. 2-6

Village of Bald Head Island, North Carolina
1
1
F
curves for Wilmington found in North Carolina's "Erosion and Sedimentation Control Planning
and Design Manual."
Table 2-2: Typical 24-Hour Storm Events
Type of Storm
Amount of Precipitation
100 year, 24•hour storm
9.2 inches
5 year, 24-hour storm
7.4 inches
10 year, 24-hour storm
6.3inches
Data was calculated from the Wilmington intensity curves from the North Carolina Erosion and Sedimentation Control Planning Manual
High /Low Data
January
February
March
April
May
June
July
August_
Se*mber
October
November
December
Table 2-3: High / Low Precipitation Data
High Average
8.84
6.06
10.46
3 94
6.93
4.90
8.6
3.35
4.93
3.11
12.29
5.33
16.1
6.83
13.7
7.35
18.73
7.01
11.98
6.67
6.91
3.13
6.S6
4.41
Low
4.07
1.24
2.81
0.39
1.67
1.28
1.52
2.86
3.53
1.82
1.12
1.85
High / Low Data
20
15
., High
10 Average
■ Low
b
0 ULL
2 a �' e
z
Data obtained from National Climatic Data Center, from 1993 to 1998.
The average daily temperature ranged from 15 degrees Fahrenheit to a high of 90 degrees
' Fahrenheit, during the years 1993 to 1998. The daily average maximum and minimum
temperatures by month are presented in Table 2-2, for this same period. This data was also
collected from the USGS's Wilmington Station.
' Table 2-4: High / Low Temperature Data
1
--
High i Low Data
January
February
March
'
April
May
June
..._........_.... ..... . .
July
August
September
'
October
November_
December
Avg. Daily Avg. Daily
High
Low
74
21
76
22
83
26
86
38
92
46
96
55
96
64
95
63
92
54
88
41
82
32
75
23
High / Low Data
120
m
100
m
so
High
m
Go
Low
io
m
40
20
0
c
2
'
U.
S
z°
Data obtained from National Climatic Data Center, from 1993 to August 1998.
MlacConnell & Associates, P.C. 2-7

Village of Bald Head Island, North Carolina
2. Soils & Vegetation
The major soils found on Bald Head Island are of the Corolla and Newhan series, although there
are other soil types. These soils are sands which have either a clayey or mucky subsoil. The
Corolla fine sand range from being poorly drained to moderately well drained. The surface runoff
for this soil is slow because of its high permeability. Because of the soirs high seepage rate, the
available water capacity (ability of the soil to store water) of the soil is low. The Newhan fine
' sand has similar characteristics as the Corolla fine sand except that it is excessively drained.
Figure 2-2 shows where the various soils are located on the island, and these soils, in addition to
the vegetation zones are described below.
The island is comprised of four vegetation zones: the marsh zone, forest zone, shrub
mP Pri�'3' g
zone, and beach/dune zone. Each of these zones varies in the type of vegetation they support and
the soils contained within them. The types of soil present dictate the rates of permeability,
seepage, and the amount of available water capacity within the zones. Figure 2-3 shows the
typical island configuration illustrating the locations of the zones and the types of vegetation and
soils found in each.
The vegetation within the marsh zone is primarily smooth cordgrass, black needlerush, saltwort,
and other common wetland species. This zone is found between the forest zone and the sound.
Representative areas of Bald Head Island which are located in the marsh zone can be found north
' of North Bald Head Wynd and Federal Road. The soils commonly found in this zone are of the
Bohicket and Duckston series. Both of these are very poorly drained soils and experience daily
flooding with the rise and fall of the tide.
The forest zone contains live oaks, dogwoods, yaupon, wax myrtles, cabbage palms, and
American holly trees. This zone is typically found on the higher grounds and sandy ridges.
Representative areas of the forest zone on Bald Head Island are the Maritime Forest and most of
the area contained within North Bald Head Wynd, Muscadyne Wynd, South Bald Head Wynd,
and West Bald Head Wynd. This zone contains soils of the Newhan, Duckston, and Corolla
' series. These soils have high infiltration and seepage rates creating an area with a low available
water capacity.
' The shrub zone contains vegetation such as yaupon, saltmeadow cordgrass, wax myrtle, and
liveoaks. This zone is found in the lower lying areas of the island within North Bald Head Wynd,
' Muscadyne Wynd, South Bald Head Wynd, and West Bald Head Wynd. This zone consists
typically of the Newhan, Duckston, and Corolla soils which have high infiltration rates and high
seepage rates creating an area with a low available water capacity. The forest zone and the shrub
I
zone make up most of the area which is currently developed or planned for development.
MacConnell & Associates, P.C. 2-8

Village of Bald Head Island, North Carolina
L
LEGEND
BO BOHICKET SILTY CLAY LOAM
NeE NEWHAN FINE SAND
Du DUCKSTON FINE SAND
Co COROLLA FINE SAND
Figure 2-2: Soil Types of Bald Head Island
Information obtained by the Soil Survey of Brunswick County, North Carolina
MacConnell & Associates, P.C. 2-9

Village of Bald Head Island, North Carolina
The beach/dune zone is located between the shrub zone and the ocean. Areas representative of
the beach/dune zone are located on the oceanside of South Bald Head Wynd and the riverside of
West Bald Head Wynd. This zone contains primarily sea oats and American beachgrass and is
made up of Newhan soils. The Newhan soils have very high seepage rates and permeabilities
creating an area with very low available water capacities.
The type of soils present greatly influences the island's natural ability to manage stormwater.
Since much of the land area is flat, drainage is sometimes limited to the infiltration rates and the
available water capacity of the soil. Some of the soils are poorly drained, which leads to low
available water capacities. The soils in these areas are not suitable for residential and recreational
developments, according to the Soil Survey of Brunswick County, and when precipitation occurs
the runoff pools in low spots until it infiltrates into the soil or flows into the golf course lagoons,
Lighthouse Creek, Bald Head Creek or the Atlantic Ocean.
INTRACOSTAL
WATERWAY
MARSH ZONE
LIVE OAK
LAUREL OAK
LOBLOLLY PINE
SMOOTH CORDGRASS
BLACK NEEDLEBRUSH
SALTWORT fl'i
FOREST ZONE
SHRUB Zvi!=
WAX MYRTLE
CABBAGE PALM
AMERICAN HOLLY
YAUPON
LIVE OAK
BOHICKET COROLLA, DUCKSTON, OR COROLLA, DUCKSTON, OR
SOILS NEWHAN SOILS NEWHAN SOILS
Figure 2-3: Vegetation Zones of Bald Head Island
Information obtained by the Soil Survey of Brunswick County, North Carolina
3. Impervious Area
BEACH ZONE
SEA -OATS
AMERICAN BEACHGRASS
OCEAN
NEWHAN SOILS
Impervious areas are the areas in which water is prevented from directly percolating into the
ground. Examples of impervious areas include buildings, roads, and parking lots. All or 100% of
the precipitation that falls on them is used for calculating stormwater runoff. These impervious
areas provide will no storage for stormwater which makes runoff from them almost instantaneous.
Only about 10% of the entire island will become impervious at build out, based on the calculations
presented in Table 2-3. The data used in these calculations was obtained from existing maps of
MacConnell & Associates, P.C. 2-10

Village of Bald Head Island, North Carolina
Table 2-5: Impervious Area Calculations
Assumptions:
Calculation is based on future development when all of the lots are purchased.
Roads are 30 feet wide, houses (including driveways) are 2000 square feet.
PL)-1
Parameter
Number
Lin. Feet
Area
(Sq. Ft.
Area
Acres
Roads
78 780
Z363,400
54
Lots
1088
2176 000
50
Condos, Parldrig Lots & Miscellaneous Buildings
711,900
16
Total Impervious Area
5,253,3DO
I121
otaI Area
36 360
831
Percent Impervious Area(Future)
PD-2
Parameter
Number
Lin. Feet
Area
S . Ft.
Area
Acres
Roads
22 380
671400
15
Lots
185
370,000
8
Condos, Parking Lots & Miscellaneous Buildings
954,800
22
Total Impervious Area
200
46
Total Area
130,492,000
700
Percent Impervious Area(Future)
- . .......
PDT
Parameter
Number
Lin. Feet
Area
S . Ft.
Area
Acres
Roads
4 700
141000
3
Lots
84
168,000
4
Condos, Parking Lots & Miscellaneous Buildings
797,850
18
Total Impervious Area
850
1 25
ota I Area
3,397,680
78
Percent Impervious Area(Future)
Parameter
Number
Lin. Feet
Area
S . Ft.
Area
Acres
Roads
14 380
431400
10
Lots
62
124,000
3
Condos Parking Lots & Miscellaneous Buildings
0
0
Total Impervious Area
1 50,400
1 13
ota I Area
1 V,483,288
287
Percent Impervious Area(Future)
Total Impervious Area on 4Developments
205
acres
Total Area on 4 Developments
2,896
acres
Percent Impervious Area(Future),
n
Data was calculated by using the zoning map and drawings that were sent by the Village.
MacConnell & Associates, P.C.
2-11

E
Village of Bald Head Island, North Carolina
1
the island. Since development is a ongoing process, there is no way of calculating the current
impervious area of planned developments.
As development continues, more impervious will be created. The increased impervious area will
decrease currently available stormwater storage and increase both the volume and speed of the
runoff. This will cause a continued increase in the magnitude of stormwater flooding which
occurs on the island, if stormwater management practices are not implemented.
C. The Need For the Project
In early 1998, there was extreme flooding all over the island. Acording to the local news, January
and February received a combined record -breaking total of 16.66 inches of rain in Wilmington.
During periods of such large amounts of rainfall, the groundwater levels rise and the soils become
saturated so the infiltration rates become very slow. Homes along Snowy Egret Trail and Black
Skimmer Trail were surrounded by water for weeks. The residents of some of these homes (the
Howard's, the Pardue's, the Flanagan's, the McQuaide's, and the Mauney's) have all written letters
regarding the flooding problems in the area. This is only one of the problem areas on the island
and only a portion of the letters that have been written on the subject by residents throughout the
island. Electric golf carts are the mode of transportation for the residents and visitors of the
island and they can not function when the electrical components get wet with flooding.
Flooding creates not only an annoyance for the residents and visitors of these areas, but also
creates a hazardous situation. Flooding of the roads limits access to these areas which can keep
emergency vehicles and assistance out of the reach of the flood victims. Previous attempts by the
utilities department to pump the stormwater out of these areas were unsuccessful. Not only were
the pumps undersized for flooding to this extent, but there was limited personnel available to tend
to the pumps (assure adequate gasoline and oil supplies, etc.). The continued flooding problem
prompted many of Bald Head Island's residents to write letters requesting assistance with this
problem
The purpose of this project is to formulate a plan to manage both the quantity and quality of
1 rainwater. The quantity is the amount of rainfall the island receives during a storm event and the
quality is the concentration of nutrients and contaminants contained in the water. This plan is not
intended to route all of the stormwater to nearby drainage basins or bodies of water since some of
the stormwater should be allowed to infiltrate into the soil. This plan takes into consideration the
need for some of the stormwater to percolate into the soil to increase the groundwater supply.
The rainwater is fairly pure until it reaches the ground surface where it 'picks up many types of
' contaminants before it infiltrates into the soil or reaches a surface water body (i.e. lagoon, creek,
river or ocean). Runoff also picks up fine organics and sediment which can be deposited into
surface waters where it blocks sunlight from vegetation, covers food for many of the inhabitants
' of these bodies of water, and reduces the overall volume of the water body. The runoff can also
pick up chemical contaminants that are found in pesticides and fertilizers which can cause algae
' blooms or kill the vegetation within a surface water depending upon the contaminant. Runoff can
also contain pathogens from the waste of subsurface systems, household pets and native wildlife.
MacConnell & Associates, P.C. 2-12

Village of Bald Head Island, North Carolina
Another potential problem with groundwater quality is saltwater intrusion. Saltwater intrusion is
the migration of saltwater into the freshwater aquifer that lies beneath Bald Head Island. As the
levels of the freshwater aquifer under the island drop, a hydraulic gradient is created, which gives
the saltwater aquifer more energy than the freshwater aquifer. This difference in energy allows
the saltwater to move further underneath the island, shrinking the cone of the freshwater aquifer
perhaps to the point where it contaminates the freshwater supply used as potable water on Bald
Head Island (See Figure 2-4.). According to "Water Supply and Pollution Control, Fifth Edition,"
Viessman and Hammer, "Under equilibrium conditions, a drawdown of 1 foot in the freshwater
table will result in a rise by the saltwater of approximately 40 feet." Contamination of the
freshwater aquifer may require that the existing water treatment system be upgraded to treat
brackish or salt water.
GROUNDWATER
SURFACE
DUNE POND OR
OCEAN WATER BODY
H —
-- � E
\ FRESHWATER AQUIFER /
SALTWATER AQUIFER \ /
AQUIFER INTERFACE \
SOUND
SALTWATER AQUIFER
AS HE DECREASES: FRESHWATER AQUIFER
CONE DECREASES ALSO.
' Figure 24: Typical Island Aquifer Layout
information obtained by the Soil Survey of Brunswick County, North Carolina
HE is the hydrostatic pressure which keeps the saltwater from intruding on the
freshwater aquifer. As the pressure (HE) decreases, the aquifer interface will
intrude towards the freshwater aquifer from the ocean side and sound side.
' Bald Head Island is, in fact, a beach community and land owners should realize that when a large
storm event occurs, there will be standing water which may cause an inconvenience for a few
' days. However, several weeks of inconvenience, as described by the residents of Black Skimmer
Trail and Snowy Egret Trail, should be considered unacceptable. This duration of flooding
creates hazardous conditions and potential public health concerns.
MacConnell & Associates, P.C. 2-13

H
H
0
0
C
C
Village of Bald Head
Island, North Carolina
Chapter 3
Stormwater Management Issues

Village of Bald Head Island, North Carolina
0
3. Stormwater Management Issues
A. Overview of Drainage Patterns
Comprehensive, detailed and accurate topographic information for Bald Head Island is not
currently available. For example, the only topographic information available for the entire island
is from the Cape Fear USGS 7 1/2 minute series quad map dated 1970. This map is somewhat
out of date since it is 29 years old. Some of the buildings and roads are difficult to see from this
flown survey map, due to the large tree canopy covering much of the island. Some topographic
information which has been compiled by Brunswick Surveying is available for localized areas but
it provides little help in determining the lay of the land for the entire island. Since no other
detailed topographic surveys have been performed, site visits, visual observations, and discussion
with employees and residents of the island were the primary methods used for data collection,
regarding problem areas and general drainage characteristics. Detailed technical analysis cannot
be made until a topographic survey is completed for the entire island, or at least in the problem
areas where solutions are being proposed for design and construction.
' Because of the varying terrain of the island, the problem areas of the island have site specific
issues that need to be addressed individually. For example, the marina represents the most
impervious area on the island and thus requires that more stormwater management practices be
' implemented than the Maritime Forest which has been left at its natural state. However, the
marina area has an approved stormwater management plan and stormwater is not as big a conern
as other areas which do not have acceptable stormwater management. The areas that are
experiencing the most problems are the low lying areas that have a small separation between them
and the groundwater table. These areas have little storage capacity within the soils and therefore
' tend to flood faster and more often than areas in higher ground. In addition, runoff tends to flow
to these areas and collect, which increases the problem.
' One of the first things necessary to perform a stormwater management plan is to determine the
drainage basins on the island. Figure 3-1 shows the drainage patterns that are present on the
developed portion of the island. These basins were determined by visual observation, discussions
with several people familiar with the island, and review of the limited topographic data that is
available. The accuracy of these sources cannot be determined until detailed topographic
information is available. From the available topographic data, it was determined that a dune ridge
' presently separates the island into two large drainage basins. The dune ridge runs through the
southern portion of the island separating the West and South Beaches from the Maritime Forest
Reserve and East Beach. From the USGS map, this dune ridge approaches 40 feet above mean
' sea level in elevation, at its highest point. Smaller ridges run parallel to the main dune ridge,
creating smaller drainage basins. The basins north and south of the main dune ridge are
interconnected by way of the golf course lagoon system. However, without verifying the
existence of and physically evaluating the condition of the submerged pipes which connect these
areas, the stormwater drainage between the two basins cannot be fully evaluated.
MacConnell & Associates, P.C. 3-1

Village of Bald Head Island, North Carolina
MIDDLE ISL ANID
ATLANTIC OCEAN
ATLANTIC
OCEAN
LEGEND
' -�— DIRECTION OF FLOW
STANDING WATER
Figure 3-1. Drainage Patterns of Bald Head Island
(Drainage information obtained from Wade Horne, Kent Mitchell, Bill Bruce, and Andy Sayre)
MacConnell & Associates, P.C. 3-2

Village of Bald Head Island, North Carolina
Only one drainage outlet is currently operational on the entire island. It is located under North
Bald Head Wynd near it's intersection with Lighthouse Wynd. Based on conversations with
residents of the island, it is believed that level and size of the riser contributed to the severity of
the flooding which eliminated the only path for stormwater to flow off the island and into
Lighthouse Creek. This culvert, which runs underneath the road, has a flap valve on the outlet
end to keep the saltwater from flowing back into the freshwater lagoons. The flashboard riser on
the entrance of the barrel or culvert can be used to control the level of the lagoons.
Roads surround and run throughout the developed portion of the island and in some cases appear
to act as dikes. For example, Bald Head Wynd (North, South, and West) and Muscadine Wynd
' appear to be at or above the level of the areas surrounding them. These dikes appear to keep
stormwater from flowing along their natural drainage paths and off the island. A small row of
primary dunes surrounds the beach portions of the island, separating the beach from the roads and
' preventing stormwater from draining towards the Atlantic Ocean. To complicate the issue, some
lagoons may actually have a higher level of water in them during flood conditions than flooded
areas, according to Mr Wade Horne, Village Manager. These situations help contribute to the
stormwater problems that have occurred on the island.
Because of the variation in the topography of Bald Head Island, the planned development of the
' island, and the different stormwater problems associated with the various areas, stormwater
management issues are discussed by zone. The areas are broken down according to the different
development stages that are listed in the Village's Zoning Ordinance.
1. Planned Development I (PD-1)
' Planned Development I, or Stage I as it was previously called represents most of the originally
developed area of the island. Planned Development I includes the area from the intersection of
' North Bald Head Wynd and West Bald Head Wynd to Muscadine Wynd, which separates it from
Planned Development II (PD-II), or Stage II. Stage I experiences the most severe stormwater
flooding problems on the island. Planned Development I was primarily developed before
' regulations governing stormwater were in place.
The southern portion of the island along South Bald Head Wynd experiences major flooding.
According to residents in this area (Martha Flanagan and Bob Mauney) some of the flooding has
been caused by ocean overwash when large storms wash away the primary dunes separating the
beach from the residential portions of the island. Also, part of South Bald Head Wynd has been
' developed, preventing the natural flow of stormwater. The area inside Snowy Egret Trail and
South Bald Head Wynd is in a low spot that collects water when a large storm hits. To further
enhance the accumulation of stormwater, each of the roads in this area appear to act as a dike,
preventing excessive amounts of stormwater from flowing towards the lagoons. During
significant storms, this area fills with water, which results in the flooding in and around Morning
Warbler Trail. If a storm event is large enough and the areas around Snowy Egret Trail, Black
Skimmer Trail and Mourning Warbler Trail are already flooded, the accumulated water eventually
reaches levels high enough to flow over the roads towards the lagoons by the Bald Head Island
Villas. This area becomes a large pond until the water is able to infiltrate into the groundwater.
' This area remained flooded for more than one month during the storm event of 1998.
MacComell & Associates, P.C. 3-3

Village of Bald Head Island, North Carolina
Stede Bonnet Wynd is a road that connects North and South Bald Head Wynds, divides portions
' of the golf course, and roughly bisects the Stage I development. This road has a crown that
allows the stormwater to flow away from the road. However, according to Bill Bruce, the
Building Inspector, the section of the Stede Bonnet just north of the No. 17 tee is in a bowl and
collects some of the stormwater. Most of the stormwater that enters this area cannot flow across
Stede Bonnet because the road is higher than the surrounding grounds and has no culverts or
other subsurface drainage mechanisms. Stormwater which collects in this area flows into the golf
' course lagoons or ponds in low areas until it infiltrates into the groundwater.
Sabal Palm Trail is a road that connects to Stede Bonnet and runs east, towards the lagoon at hole
' #13 of the golf course. The natural drainage pattern of the stormwater before the road was built
flowed west towards the lagoon at hole #6, and to the outlet at Lighthouse Creek. According to
Mr. Bruce, there is an area along this road that collects much of the stormwater. This appears to
' be a low spot along the road, and water that collects in this area eventually percolates into the
ground, since it cannot flow across Stede Bonnet and towards the lagoon by hole #6 of the golf
' course.
Dowitcher Trail experiences a great deal of flooding during storm events, with the greatest
' flooding at the loop at the end of the road. According to Mr. Mitchell and Mr. Bruce, the natural
stormwater drainage pattern prior to development was across Stede Bonnet, through Dowitcher
Trail, and into the lagoon at hole #6 of the golf course. We believe the development in this area
' has disturbed the former natural drainage path. Stede Bonnet and Dowitcher Trail both appear to
be elevated above the existing ground and have no culvert or other subsurface drainage
mechanisms. This causes a ponding effect in the low lying areas surrounding these two roads.
' The stormwater ponds in this area until it eventually infiltrates into the ground.
Edward Teach Wynd is also constructed on fill which creates a ridge that stormwater can not flow
over and because there is no drainage mechanism to allow .the water to flow underneath it,
' stormwater collects in this area. The majority of the lots on this road are currently undeveloped.
The roads on the north side of Edward Teach Road (i.e. Spanish Needles Court, Partridge Berry
' Court) decrease in elevation as you go away from Edward Teach Wynd. These roads and the
surrounding lots appear to be constructed in "bowls," naturally occurring low spots with no
channels for water to flow out. Without some sort of man made structures, stormwater has no
other alternative than to collect as it infiltrates into the groundwater at these points, creating long
lasting, flooded conditions. According to Mr. Mitchell, these bowl areas encompass a large area
and stretch from Spanish Needles Court to Muscadine Wynd.
North Bald Head Wynd separates Bald Head Creek and Lighthouse Creek from PD-1. It turns
into Federal Road at it's intersection with Muscadine Wynd. The only large culvert connecting
' the island's lagoon system to surface waters off the island crosses underneath North Bald Head
Wynd near it's intersection with Lighthouse Wynd. There are other former drainage outlets,
according to Mr. Mitchell, that routed stormwater to Bald Head Creek (one of which was at lot
' #829 and in front of Timbercreek #s 14-17 and the other was before lot #828). However, when
North Bald Head Wynd was constructed, these outlets were taken oui of service. The activation
of these former outf al locations may be beneficial in providing a disposal area for the stormwater
that is currently flooding portions of the island in these areas.
MacConnell & Associates, P.C. 3-4

Village of Bald Head Island, North Carolina
According to Andy Sayre, Superintendant of Construction at Bald Head Island Management, the
' area between Laurel Cherry Court, Towee Court and Muscadine Wynd is in a low spot that
collects water. This water is blocked from entering Bald Head Creek through an original outlet
because of North Bald Head Wynd, which acts as a dike.
' 2. Planned Development II & IIC
' The development just south of Federal Road and north of the Utilities Office has experienced
some standing water after storm events, according to Mr. Mitchell and Mr. Sayre. This area
appears to be in a low spot and does not have an outlet.
' Much of the area east of Muscadine Wynd has not been developed and because of this, there is no
known, detailed survey information of this area. The absence of topographic information in this
area has prevented a more detailed explanation of the drainage patterns that exist in these areas.
The Maritime Forest is a preserved area so that it maintains its natural drainage patterns. This is
' also true for the remainder of Federal Road and into the Cape Fear section of Bald Head Island,
which has not been developed. The lack of development in this area is presumably the main
reason there have been no complaints of stormwater ponding. Much of this area appears to be
natural wetlands with low lying areas which provide some natural treatment of surface runoff
prior to its infiltration into the groundwater. The maritime forest plays a large role in the recharge
' of the islands aquifer.
3. Planned Development III (Marina)
' The Marina area, which is also known as Planned Development III (PD-III), represents the most
impervious area of the island, with approximately 54 percent impervious area. Stormwater is
' collected by drop inlet type structures and flows through an underground network of pipes into a
retention basin. Once the retention basin is full, the water discharges through overflow pipes into
the bay at the marina This basin appears to have adequate capacity to prevent flooding when a
' storm event occurs. Also, the area appears to be nearing built out capacity with only a small
amount of future development possible. The marina has previously applied for stormwater
permits that are currently under review by the State.
4. Planned Development IV (Middle Island)
' Middle Island, which is also known as Planned Development IV (PD-IV), is a stretch of land with
a maximum elevation of about 15 feet above mean sea level, according to the Cape Fear, N.C.
USGS Quadrangle Map dated 1971. This stretch of land is flanked with marshlands on both
' sides. It is approximately 2 miles long and approximately 500 feet wide. This stretch of land is
currently under development with 16 lots being recently approved by the Village Council.
Because of the larger lot sizes found on Middle Island which results in a lower percentage of
' impervious area to be created, stormwater management will not be as difficult as in Planned
Developments I, II, and III of Bald Head Island. The smaller amount of impervious area
maintains more natural land area allowing for more land into which infiltration into the
groundwater is possible.
MacConnell & Associates, P.C. 3-5

Village of Bald Head Island, North Carolina
' Middle Island which was purchased in 1978 by Young Realty Co., Inc., has no known stonnwater
problems. Because of the varying topography of this small stretch of land and the regulations
governing it's development, stormwater problems are not anticipated in this area. Minimum
setbacks of all structures are 15 feet from the sidelines and 25 feet from the marshes. The 25-foot
buffer from the marshes will provide a fairly large stormwater storage capacity that would have to
be filled before the water levels ever reached the structures on the properties in this area.
' Bald Head Creek is located between Bald Head Island and Middle Island and lies in a south-east
' to north-west direction. Previously this stream was used for shellfishing but has been closed since
November 17, 1992 due to the high fecal coliform counts which exceeded the National Shellfish
Sanitation Program Requirements, according to Dave Clawson of the North Carolina. Department
' of Environment and Natural Resources' Shellfish Sanitation Section. The closing applies from the
mouth of Bald Head Creek upstream to it's headwaters including all of it's tributaries.
' B. CAMA Land Use Plan
The Coastal Area Management Act of 1974 requires local governments to develop land use plans
and update them every five years. Each plans' main function is to anticipate and plan for the
growth of the study area. They provide a goal for desirable development patterns to protect the
quality'of life of residents while protecting the area's natural resources. The plans are also used
for guidance and once adopted become the foundation for future decisions on budgets, ordinances
and development.
' Bald Head Island does not have its own land use plan; Bald Head Island is part of the overall
County Land Use Plan that has been adopted by Brunswick County. In this plan, some
' stormwater measures are presented to give guidance for any future decisions on matters dealing
with growth.
' The Brunswick County Land Use Plan's stormwater management guidelines discourage piping
and dumping runoff to a receiving stream because this method may cause downstream flooding,
increase the amount of toxins which reach the receiving waters, and create a rapid decrease in the
' salinity of the estuarine waters. According to the Plan, pipes often become undersized as more
development occurs. The guidelines recommend the more natural approach that involves grassed
swales and retention of rainwater until it percolates into the groundwater. The guidelines also
' recommend using low lying areas as natural drainage basins as opposed to graded, cement -lined
drainage basins. The Plan also indicated that natural drainage patterns are often not practical
since ponding will occur during a large storm event which is unsightly and unacceptable for
' residents.
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Village of Bald Head Island, North Carolina
C. Stormwater Regulations
The Clean Water Act of 1972 prohibits the discharge of stormwater into receiving streams from a
P g g
' particular point, or point source. From this Act, stormwater is regulated by both the state and
Federal government through the National Pollutant Discharge Elimination System (NPEPES)
permit program. Any stormwater that discharges into receiving streams via pipes will be required
to obtain a NPDES permit. Permits will require stormwater pollution prevention plans and
pollution reduction plans of the area. Individual permits are required by the federal government
for new businesses and facilities, and general permits are used for a large number of sites with
' similar stormwater discharges.
The State of North Carolina requires discharge permits for new developments and other
' construction that occurs within one mile of waters designated as High Quality Waters. Bald Head
Creek has a primary classification of SA waters, which is defined by the North Carolina
Department of Environment and Natural Resources (DENR) as "suitable for commercial
shellfishing and all other tidal saltwater uses." Bald Head Island Marina has a primary
classification of SC waters, which is defined by DENR as "saltwaters protected for secondary
recreation, fishing, aquatic life including propagation and survival, and wildlife." SA (shellfishing)
' waters have a secondary classification of High Quality Waters. According to Linda Lewis from
the Wilmington Regional Office of DENR, a stormwater permit for the existing discharge point
will not be required. Also, installing stormwater drainage systems under roads is allowed as long
' as all piping stops at least 50 feet from the creeks.
' D. Water Quality
In this age of environmental awareness and concern, one cannot overlook the importance of water
' quality. This becomes even more critical when discussing such large volumes of stormwater that
fall on Bald Head Island during storm events, because Bald Head Island is so dependent on its
water resources. For example, the majority of the developed portion of the island, PD-1, which is
' approximately 800 acres, will collect approximately 22 million gallons of water during a 1-inch
rainfall event. This volume of stormwater presents many management problems on such a flat
piece of land at or near sea level. The stormwater flows overland and into the surface or
groundwater systems on the island, potentially picking up many pollutants, nutrients, and/or
sediment. Other sections of this document contain information on reducing the levels of these
contaminants. However, all of these contaminants cannot be removed prior to the stormwater
' entering into the receiving waters on and around the island. Therefore, it's impact on the
ecosystems and uses of the island must be addressed.
' 1. Recreation
' Bald Head Island offers many recreational opportunities. These activities include golf, swimming,
tennis, croquet, bicycling, boating, fishing, bird watching, hiking on nature trails and typical beach
activities. At least one facet of each of these activities can contribute to the pollution of
' stormwater runoff. The stormwater runoff may pick up sediment, residual pesticides and
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Village of Bald Head Island, North Carolina
fertilizers, animal waste, and many other pollutants as it is transported to the surface water or
ground water systems by overland flow and infiltration.
Although our discussions with the residents of Bald Head Island have indicated that none of these
' recreational activities have adversely impacted its water resources through contamination of
stormwater, this is not necessarily correct as we have seen algal blooms in some of the lagoons
and shellfish waters have been closed, as previously discussed. These activities are likely to be
' large contributors of contaminants to the stormwater, especially nutrients. Flows over the grassy
areas making up the golf course and croquet greensward will likely pick up many nutrients and
also some pollutants in the form of pesticides and herbicides. These areas are generally high
' maintenance from a lawn care standpoint and have many chemicals applied to them on a routine
basis. Since the lagoon system is almost entirely within the limits of the golf course, there is not
much chance for nutrient or pollutant removal prior to the flow of stormwater into this system.
The only way to reduce the impact of the concentrations of pollutants in the stormwater coming
' from these areas is to limit the amounts of fertilizers, herbicides and pesticides applied to the
vegetated areas. The Bald Head Island Club should carefully monitor horticultural chemical
applications. The timing and over -application of pesticides and fertilizers plays a key role in
determining the amounts that will eventually make its way into the surface and ground water
systems. Over -application of fertilizers and pesticides leaves a residual material on the vegetation.
This residual is then washed off the vegetation's surface during storm events and transported into
' the surface or ground water systems. The timing of the application can also influence the
concentrations of these pollutants as the stormwater runoff reaches the surface and ground water
systems. By researching weather forecasts prior to the scheduling of an application of these water
' pollutants, they can be applied during times of expected dry weather. This will allow the
vegetation to take up the majority of the nutrients for their use instead of being washed away
prior to absorption into the vegetation. Proper chemical application is also desired based on pure
economics.
2. Wildlife
Because of the work of the Bald Head Island Conservancy and other individuals, much of the
' island's natural resources and wildlife habitats are preserved. This contributes to the abundance
of wildlife present on the island. Even with development of the island, much of the wildlife
habitat remains and humans and nature have learned to live together in harmony. Because of the
' dependence on water for their homes, food or drinking water, the water quality of Bald Head
Island is critical to the survival of the wildlife indigenous to the area. It is certain that without a
reliable source of fresh water, the animals of Bald Head Island would migrate away from or perish
' on the island.
The presence of certain contaminants in stormwater runoff can change the water quality enough
' that there may be concerns for the wildlife. For instance, consider the shellfishing ban on Bald
Head Creek due to the high fecal content of the waters within the creek. Drinking water for the
wildlife may be contaminated with fecal matter or chemicals and salt water aquatic life may be
' threatened by the reduction in salinity of the receiving waters near stormwater discharge points.
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Village of Bald Head Island, North Carolina
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Source reduction of any pollutants is the easiest and most cost effective measure of ensuring the
water quality of Bald Head Island. However, other methods are available for reduction of these
contaminants. Discussion on the various environments which are present on the island are
presented below.
' a. Land Environment
' There are many species of fauna and flora that live on the land and rely on a good freshwater
source of water for survival. All plants require water to grow. Contamination of the stormwater
with nutrients, and especially pesticides and herbicides, can lead to the degradation of the plant
' species. If the concentrations of pesticides become high enough in the stormwater runoff; that
alone could kill the plant species. Birds, rabbits, squirrels, etc. all rely on a good freshwater
source for drinking water. The pollution of the fresh water source for these animals would
primarily affect their drinking water supply. An overload of nutrients or other pollutants could
contaminate the water source so that it is no longer safe for consumption by these animals.
' b. Riparian Environment
' The riparian environment consists of the plants and animals that live in close proximity to or on
the banks of a water source. The plants in these areas can be affected by the same types of
stormwater contamination discussed above. The animals that reside here are muskrats, snakes,
' mollusks, frogs, turtles, etc. These animals all rely on fresh water for a source of drinking water,
protection and for food. Pollution of the fresh water source can lead to the lack of a- water source
for drinking, lack of food and/or lack of protection from their predators.
' c. Estuarine Environment
The estuarine environment is made up of the plants and animals that actually live in an estuary of a
main river or an arm of the sea. This consists primarily of plants, fish and shellfish. Plants require
the dissolved oxygen in fresh or brackish water to complete their photosynthetic cycle. This
environment is critical for early stages of many fish and invertebrate species. Fish and shellfish
require fresh and brackish water for survival mainly in that it provides them with a home,
protection, food and water. Contamination of the fresh water available to them can lead to them
' extirpated on the island.
An overload of nutrients into the system can also cause algal blooms which not only shades the
' bottoms of the bodies of water, it reduces the oxygen levels available for the fish and shellfish.
The dissolved oxygen in the water is a key ingredient within the process of photosynthesis.
Without dissolved oxygen, the plants can not complete photosynthesis and will perish. The killing
' off of the plant life creates a vicious cycle in that the decaying matter of the plants will also
consume more of the available dissolved oxygen. This creates anoxic environment in which the
' fish and shellfish can no longer survive. These species also depend on the dissolved oxygen for
their respiratory process. A lack of oxygen will suffocate the fish and shellfish. The decomposing
bodies of these animals will also tend to use up more of the dissolved oxygen in the water
' continuing the cycle. Also, if a fresh water source becomes anaerobic (no dissolved oxygen),
objectionable odors can be created.
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Village of Bald Head Island, North Carolina
1
An overload of other pollutants can also make survival of these species more difficult. Deposits
of sediment can fill in spawning beds limiting reproduction of the existing species. Contaminants
such as herbicides and pesticides can make the water generally unsuitable for sustaining life.
These and other contaminants can contribute to the killing off of the vegetation within an estuary
starting the vicious cycle described above.
d. Ocean Environment
The ocean environment consists of several species of plants, fish and shellfish which make up a
separate ecosystem altogether. As described above, plants require dissolved oxygen to carry out
the photosynthetic process. The lack of oxygen could lead to the death of many plant species.
The fish and shellfish require dissolved oxygen for their respiratory process. Without the
dissolved oxygen, they too will die off. Sediment deposits are also a major factor in the ocean
environment. Even with the constant currents within an ocean environment, deposits can settle to
the bottom of the ocean floor filling in fish spawning beds, limiting reproduction. Another factor
to consider in the ocean environment is salinity. The rapid introduction of large volumes of fresh
water could decrease the salinity enough to kill off plant and shellfish species within the localized
area. The fish species would most likely be able to move quickly enough to areas of higher
salinity that they would not be affected by this dilution with fresh water.
The ocean environment is much more able to cope with larger amounts of nutrients and pollutants
' than the other environments discussed. The ocean is so large that dilution of these contaminants
will occur at such a rapid rate, and the effects of these contaminants would be minimal on a large
scale. However, there can be localized effects as described above. These localized effects would
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occur at specific discharge points from the island. This would be at the main outfall near the
intersection of Lighthouse Wynd and North Bald Head Wynd and any other proposed major
outfalls.
There are means of reducing the levels of these contaminants prior to their introduction into a
receiving body of water. These methods are documented in detail in Section 3D, Best
Management Practices, of this report. There is a concise list of stormwater management
practices, developed by engineerss, universities and state and federal organizations, which have
been determined to be very good practices for managing stormwater. The section on best
management practices will describe various stormwater management practices and how they can
reduce different levels of contaminants physically and biologically.
3. Human Consumption
The potable water source for the island is the freshwater aquifer present underneath the ground
surface. There are wellheads within this aquifer which pump water to the water treatment plant
where it is treated prior to distribution around the island. Maintaining this aquifer is critical to the
drinking water needs of the Island.
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Village of Bald Head Island, North Carolina
The fresh water aquifer is maintained by the presence of hydrostatic pressure on top of the
' aquifer. This pressure maintains a state of equilibrium between the salt water aquifer present on
all sides of the island and the fresh water aquifer. This state of equilibrium assures that the salt
water aquifer does not intrude on the fresh water aquifer.
' Bald Head Island Utilities uses a state of the art reverse osmosis water treatment plant for
purifying the fresh water from the shallow aquifer on the island. This type of system uses a
' membrane technology which filters out smaller and smaller contaminants as the water passes
through each membrane. This type of technology also removes salt by the use of a
semi -permeable membrane. These systems are designed based upon the quality of the water that
' they will be treating. Therefore, any big changes in the quality of the raw water could lead to
changes in the quality of the treated water, even leading to possible failure of the osmosis system
altogether.
E. Stormwater Best Management Practices
' Point source pollution is pollution that enters streams from a specific point, most commonly a
pipe, whether it is from a business, wastewater treatment plant, or other facility. On the contrary,
' non -point source pollution is essentially pollutants and contaminants that enter rivers and streams
in various ways such as overland flow or through groundwater. This type of pollution comes
from fertilizers, animal wastes, petroleum products, decaying leaves, and other contaminanats.
' Regulations which require municipalities and facilities to obtain discharge and/or stormwater
permits is an attempt to reduce non -point source pollution. The Federal stormwater regulatory
program views stormwater to be point source pollution because current stormwater management
' practices typically use pipes to collect and discharge stormwater runoff into rivers, streams and
other bodies of water at a specific point.
' The North Carolina Department of Environment and Natural Resources (DENR) along with the
North Carolina Cooperative Extension Service and NCSU's Water Quality Group have developed
' "Best Management Practices," or BMPs for stormwater management. BMPs are engineered
solutions which have been documented to reduce pollutants by treating and disposing of
stormwater. BMPs provide design guidance for the various methods..
In 1995, the Division of Water Quality of DENR issued a detailed report of Best Management
Practices in hopes of managing nonpoint source pollution. Most of the coastal counties contain
' waters that are classified as "High Quality Waters" and/or "Outstanding Resource Waters." In
Bald Head Island's case, the waters are considered "SA" and "High Quality Waters." Stormwater
from the developing areas is a major source of pollution that enters these nutrient sensitive waters.
' Listed below are some of the practices that Bald Head Island can implement to enhance the
quality of its water resources.
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Village of Bald Head Island, North Carolina
1. Pollutant Prevention Techniques
It is much easier to prevent pollutants from entering the water than to remove the pollutant once
the stormwater is contaminated. Source reduction and preventative measures can be used to
reduce the exposure of materials to stormwater. Municipalities are in a great position to
formulate and enforce ideas and procedures to help reduce the amount of pollutants that enter
stormwater. For example, development guidelines can be drafted in the form of a stormwater
ordinance. The ordinance can provide procedures that must be followed for not only new
developments, but for the use, care and handling of certain equipment and materials. The
ordinance can also contain enforcement provisions when those procedures are not followed.
Municipalities can also educate the public in stormwater management guidelines through routine
distribution of information on water conservation, fertilizer and pesticide use, proper care of
electric golf carts, proper use and care of their subsurface wastewater treatment and disposal
system, etc.
1 a. Sediment
The pollutant that is transported in the greatest quantity in stormwater runoff is sediment,
according to the Department of Environment, Health and Natural Resources. Sediment is made
up of fine soil particles that are picked up by stormwater flowing at high velocities and carried
into receiving streams. Sediment comes from unstabilized soils that are present in construction
sites or eroded areas. Sediment can also be carried by the wind. Sediment is a pollutant itself and
a transport mechanism for other pollutants, such as toxic metals, pesticides, fertilizers and other
organic pollutants. Once these pollutants reach a body of water, they settle out to the bottom and
become concentrated. At this point, concentration can become high enough that they are a threat
to both the water quality and aquatic life. Not only can sediment smother plants and animals as
they settle to the bottom, the pollutants they carry will begin to break down and pollute the water,
and volumes of water will be reduced. Very fine sediment that does not settle in the water is
known as total suspended solids, or TSS. This type of sediment will be discussed later in this
chapter.
Since most sediment found in receiving streams is caused by erosion of soil, some preventative
measures can be taken to reduce the amount of pollutants in the stormwater. Minimizing erosion
can be accomplished using the following procedures:
• Identifying bare areas that are vulnerable to erosion and provide vegetation or ground
cover.
• Limiting the amount of disturbed area during construction or other land disturbing
activities.
• Limiting the amount of time that bare land or disturbed land is exposed, and providing
vegetation as soon as practical.
• In construction activities, minimize the flow and velocity of runoff by either rninimizing
the slope over which the stormwater will travel or by increasing the width of the channel
provided for the stormwater.
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Village of Bald Head Island, North Carolina
b. Sanitary Sewers
Another pollution prevention practice that can be implemented is to connect residences that
' currently use subsurface wastewater treatment and disposal systems to the centralized wastewater
treatment system Currently, part of Bald Head Island uses subsurface treatment and disposal
systems (i.e. septic systems, mound systems), and some of these areas occasionally experience
' flooding. Some of the subsurface systems on Bald Head Island have failed and homeowners have
been required to connect to the wastewater collection system. Also, according to Dave Clawson
from the Shellfish Sanitation Section of the Department of Environmental Health, Bald Head
' Creek has had a high fecal content and has been closed for shellfishing since November 17, 1992
due in part to this problem Migratory birds have used the creek area as a rookery and their waste
' has also contributed to the this problem The remaining mound systems on the island are fir from
Bald Head Creek and they are not likely to cause a significant impact on the water quality of the
creek. Bald Head Creek also does not receive enough surface water runoff to get flushed out
' very often. Therefore, any waste materials that enter Bald Head Creek will likely remain there for
some time.
' The major cause of subsurface system failure is that they are installed in soils that have high water
tables. Although leaks in subsurface systems have not been reported, there is a potential for
malfunctioning subsurface systems to leach into stormwater and groundwater causing
' contamination. By connecting to an existing wastewater collection system the potential for failure
of the subsurface systems is reduced along with potential of pollutants entering nearby water
bodies. Before hooking on to an existing system, a wastewater calculation should be made to
' ensure that the extra flow does not exceed the current treatment capacity of the plant, which is
200,000 gallons per day. If the additional flow exceeds the limit, flooding of the treatment system
may occur which will prevent the flow from receiving adequate treatment before being pumped to
' the irrigation pump station at the golf course. In future development, subsurface systems should
not be installed in areas that contain impervious soil layers or a high groundwater table per
regulations, which is the case for much of the island.
2. Landscaping and Lawn Maintenance Control Measures
' Pesticides, herbicides and fertilizers that are used for lawn maintenance contribute greatly to
stormwater pollution. Particular attention should be paid to the golf course and other areas of
high -intensity landscaping. Fertilizers, herbicides and pesticides should not be used near streams
or other water bodies. However, in the case of Bald Head Island's golf course, this idea is not
practical since the water bodies surround the golf course. As mentioned earlier, weather forecasts
' should be studied prior to the application of fertilizers, herbicides and pesticides to avoid high
concentrations from entering stormwater during rainfall soon after application.
' The Village currently has a Zoning Ordinance that preserves special plants, such as live oaks,
dogwoods, sea oats, and other plants that are native to the area. Also, -the Ordinance requires any
plants or soils that are removed to be to revegetated or restored within 60 days. Revegetation
limits the amount of erosion that can take place during a storm event. Limiting the types of
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Village of Bald Head Island, North Carolina
vegetation allowed on individual lots and the amount of chemicals that homeowners use to
' fertilize these areas reduces pollution. For instance, if a homeowner tries to grow nonnative
grasses, the soils may not accept them Therefore, the homeowner may apply more fertilizers and
chemicals to promote this species' growth, thus causing more chemicals to enter stormwater. Any
landscaping should be done in accordance with the Village Ordinance.
It is possible to plant and maintain an aesthetically pleasing area in individual lots as long as
' erosion control measures are undertaken. Low maintenance plants and shrubs can be used for
landscaping in sloped areas to reduce runoff and pollutants present therein.
' 3. Lagoon Cleaning
Another preventative measure that can be implemented is to remove collected sediment from the
' golf course lagoons. The golf course lagoons have not been cleaned out for years, and Mr. Paul
Corder, the golf course greenskeeper does not recall a time that accumulated material has been
' removed. According to Mr. Kent Mitchell, President of Bald Head Limited, pipes were originally
installed during the construction of the golf course to connect the lagoons. These connection
pipes are submerged and therefore cannot be verified without further investigation. Dye studies
' would not be a practical method of testing the connectivity since the lagoons contain stagnant
water and do not appear to flow in either direction. Cofferdamming each end of a suspected
connection pipe and pumping out of the water from within these co$erdammed areas will likely
be the only means of confirming connection of these lagoons. The connecting pipes are likely
blocked by silt, sediment, or vegetation since the surfaces of the lagoons appear to be at different
levels. The lagoons appear to have accumulated much sediment, algae, organic matter, nutrients
and miscellaneous debris from stormwater runoff The depth of the lagoons is also unknown due
to the change over of staff of the Bald Head Island Club and the lack of maintenance of these
lagoons. However, the depth is an important factor in evaluating the potential for the lagoons to
become detention/retention ponds.
Plant nutrients are found in fertilizers and animal waste and are required for the growth of algae.
' These nutrients, which are mostly nitrogen and phosphorus, can also cause unsightly algal blooms
and overgrowth of bacteria and plants in the water. It is evident that this is occurring in most, if
not all of the lagoons. These plant nutrients accumulate in the water body and cause a greater
' growth of plants and algae. This deplinishes the amount of oxygen in the water available for
aquatic life.
The golf course, which is intensely landscaped, likely causes high concentrations of these plant
nutrients to runoff into these lagoons. Although eliminating the use of fertilizer is not an option
for the Club, by applying the fertilizer at recommended rates, during dry periods, and during the
growing season, the amount of these fertilizers lost to stormwater can be reduced. Another
pollutant reduction process would be to establish and maintain buffers along the lagoons. This
' allows the grass surrounding the lagoons to filter out pollutants from the water before it reaches
the lagoons.
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Village of Bald Head Island, North Carolina
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The golf course also spray irrigates the golf holes with treated wastewater effluent or reuse water.
This reuse water is a highly treated wastewater and it's irrigation is monitored by the NCDENR -
Division of Water Quality. This water does contain plant nutrients to stimulate growth of the
vegetation on the course which reduces fertilizer requirements. Commercial fertilizer application
rates should be determined taking into account the nutrients that have already been applied
through the spray irrigation system. Otherwise, there will be an overload of plant nutrients which
cannot be assimilated by the existing vegetation and will be absorbed into the groundwater or
runoff during rain events.
Organic matter is another source of pollution for the lagoons. This matter comes in the form of
grass clippings, leaves, and various other decaying vegetation that is collected by stormwater
runoff. As this organic matter decays, it can serve as food for algae and bacteria that can
deplinish the amount of oxygen available for aquatic life. A decrease in lagoon water quality can
also impact groundwater quality.
Cleaning these lagoons will increase the amount of storage available for stormwater while also
increasing available irrigation water and improving the infiltration of the groundwater. It will also
enhance the quality of the surface water and the islands aquifer. By removing decaying organic
material from the bottom of the lagoons, it will create an aesthetically pleasing environment for
golfers as well as encourage the possibility of aquatic life in these lagoons. Once these lagoons
are initially cleaned of the decaying organic matter and accumulated sediment, they will only need
to be cleaned once every seven to ten years.
Connectivity of the lagoons will allow for better flow of the stormwater from flooded areas and
allow for its eventual discharge into Lighthouse Creek. It will aid in flushing out harmful
nutrients and pollutants if a storm event occurs. It will also aid in flushing out the fecal matter in
Bald Head Creek. By using these lagoons as detention/retention basins, it also allows biological
activity to take place, which consumes many pollutants.
4. Nutrient Removal
One of the functions of a stormwater management plan is nutrient removal. The State of North
Carolina requires stormwater permits to allow for an 85% removal of Total Suspended Solids
(TSS) which are fine solid particles which do not readily settle. We the objective of this report
is not to obtain a permit, the guidelines set forth by the State will still be followed. The following
stormwater BMPs and their efficiencies are listed, which may be used together to achieve the
required removal efficiency of 85%.
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Village of Bald Head Island, North Carolina
Table 3-1. Best Management Practice Efficiencies
Best Management Practice
Efficient
Wet Detention Ponds
85%
Extended Dry Detention
50%
Extended Detention Wetlands
85%
Pocket Wetlands
35%
Sand Filters
85%
Bioretention Area
85%
Grassed Swales
35%
Filter Strips
35%
Infiltration Devices
85%
Some of these BMPs, such as grassed swales and infiltration devices are not applicable for all for
areas of the island due to the high groundwater table and soils present. Some plants required for
these devices may not be able to survive in the soils that are currently on the island. Sand filters
are also not practical either since they are used to treat large amounts of runoff in an impervious
area.
Filter strips, which are bands of close growing vegetation can be used close to lagoons or other
bodies of water to slow the runoff or to collect some of the sediment and organic matter before it
reaches the water bodies. However, this practice may not be aesthetic pleasing for use along the
golf course lagoons. Only low maintenance vegetation indigenous to the area can be used in these
areas.
The setbacks that are required from the Zoning Ordinance are also good ways to remove the
t nutrients from the stormwater before it reaches water bodies. These setbacks allow more time for
the nutrients to be removed from the runoff and also limits the built -upon density of the area.
5. Comprehensive Site Planning for Future Development
Generally, Bald Head Island has a very low development density, with approximately an estimated
' 10% impervious area for the island, as previously discussed. Limiting the land disturbing activity
of the area greatly reduces the impact of stormwater on receiving water bodies. Leaving the
' natural drainage patterns of the island intact also allows for more natural drainage to take place
instead of relying on man-made structures. Natural drainage ways furthermore allow for nutrient
and pollutant removal to occur.
' Bald Head Island is a community which has planned its developnent, as much of the land has
already been platted and recorded to aid in development. Since this land is undeveloped, it is
' easier to administer stormwater practices before the lots are bunt upon. Minimizing the land
disturbance will reduce the impact when developing the land, as well as reduce the amount of
erosion and sedimentation control measures that will be necessary. The Village currently has a
' Zoning Ordinance that requires new homes being constructed to limit the amount of land
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Village of Bald Head Island, North Carolina
disturbing activity that takes place. Also, where natural drainage ways cannot be maintained,
installing yard inlets or other outlets to nearby lagoons will greatly reduce the amount of
stormwater flooding that may occur when the building density increases.
Some of the worst flooding has occurred due to the high groundwater on the island. During the
flooding of 1998, the levels of the lagoons and shallow groundwater reached a level of between 5
and 6 feet above the mean sea level, according to Kent Mitchell. The Federal Emergency
Management Act (FEMA) requires that be first floor of new homes be built 2 feet above the 100
storm flood elevation. In Bald Head Island's case, most of the island is within the 100 year
floodplain, and 2 feet above the 100 year floodplain is somewhere between 9 and 19 feet above
' the mean sea level and is not feasible on the island. According to the National Flood Insurance
Program of FEMA, 10 year storms would reach an elevation of 5.8 feet. Therefore, any storm
event over the 10 year storm would cause flooding. Howver, to insure access to all areas of the
' island during 10 year storm events or smaller, roads and driveways should be constructed at a
minimum of 6 feet above mean sea level.
' Another preventative measure that can be taken is to cover any construction equipment or
materials that are left outside during construction. Doing this would prevent metals and toxic
substances from entering stormwater during a storm event. This would will protect equipment
from rust or other damage that storm events can cause.
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Village of Bald Head
Island, North Carolina
Chapter 4
Stormwater Management
Alternatives Analysis

Village of Bald Head Island, North Carolina
4. Stormwater Management Alternatives
Analysis
' The management of the stormwater on Bald Head Island is critical because of the dependence on
the island's water resources. Stormwater aids in the recharging of the fresh water aquifer which
' provides the residents with a potable water supply, fills the golf course lagoons which later supply
the golf course with irrigation water, and may have an adverse impact on the wildlife found on
Bald Head Island. The management of stormwater can be accomplished in many ways.
' However, due to the flat topography and limited available land, many typical stormwater
management options are not available to Bald Head Island. This section will discuss several
' alternatives available to the Island along with their advantages and disadvantages.
The two methods for managing stormwater are to provide storage in the areas adversely affected
' by stormwater runoff and/or to provide a means for transporting the stormwater runoff to an area
which has adequate storage. There are two methods for obtaining more storage capacity for
stormwater during storm events without the occurrence of flooding that will be studied in this
section. They are a subsurface drainage system and a surface swale or ditch system. A means for
transporting the Stormwater runoff through a collection system to areas of adequate storage will
also be investigated. These systems are described in detail below.
' A. Subsurface Drainage System
' As stormwater infiltrates into the ground, groundwater levels can become temporarily perched
above normal levels. High groundwater tables limit the amount of available storage capacity
within the soils for storage of rainwater. A method for assuring that the groundwater table
remains at or below a certain level is to install a subsurface drainage system.
' A subsurface drainage system will collect and discharge groundwater as its levels increase in the
soils. The groundwater is captured by subsurface drainage lines, which are typically a perforated
polyvinyl chloride (PVC) or high density polyethylene (HDPE) pipe surrounded with a gravel
' filter media or a geotechnical filter fabric. The lowering of the groundwater levels increases the
available water storage capacity within the soil. By removing the water stored in the soils near
the ground surface, the storage capacity in those soils is available for the storage of stormwater.
' This reduces the potential for surface flooding by providing temporary storage for the stormwater
runoff in the soils near the ground surface.
' This method is fairly maintenance intensive. The subsurface drains must be installed with clean
outs and periodically flushed to assure that there is no clogging of the perforations. If the gravel
or geotechnical fabric filter is compromised and the perforations become clogged, excavation and
' replacement of the failed portion of the system is required.
MacConnell & Associates, P.C. 4-1

Village of Bald Head Island, North Carolina
This type of system also has a large land requirement. If the area being drained is not in a
common area, then the existing property owner will need to be very careful with all landscaping
or construction activities to assure that the drain lines are not damaged. When possible, this type
of system should be in a common area so that the potential for damage to the system is
minimized. The advantages and disadvantages of subsurface systems are presented in Table 4-1,
and cost information is presented in Table 4-2. A schematic drawing of a typical subsurface
system is presented in Figure 4-1.
Table 4-1: Advantages and Disadvantages of a Subsurface Drainage System
IAdvantages
r
• Increases available soil storage by lowering groundwater levels.
• It is typically a gravity system with no electrical costs.
• Provides a free flowing conduit for rapid conveyance of runoff to disposal or
recharge area.
• Provides marginal contaminant removal in the soil matrix prior to entering the
drain.
• Easy to install,
Disadvantages
• Permanently lowers groundwater table elevation.
• Difficult to clean a clogged filter surrounding the perforated pipes.
• High installation cost.
• Large land requirement.
Table 4-2: Ranges of Typical Installed Costs that may be Incurred During Construction of
a Subsurface Drainage System
Item
Estimated Cost
Subsurface Drainage Pi 6-4ch
$8-10/foot
Earthwork
$4-6/cubic yard
Filter Material Around Drainage Pi
$3-5/cubic yard
Inlet Structure
$1,000-5,000/each
Outlet Structure
$1,000-5,000/each
Pumping Station site dependent)
$10,000-20,000/each
* The estimated costs are installed costs. All of the items listed may or may not be required.
MacConnell & Associates, P.C. 4-2

Village of Bald Head Island, North Carolina
PERFORATED PIPE
SOLID PIPE TO OUTLET GEOMEMBRANE
GRAVEL MEDIA
EXISTING GRADE
SURFACE WATER
GRAVEL MEDIA
GEOMEMBRANE
PERFORATED PIPE
SOLID PIPE TO
OUTLET AT
SURFACE WATER
Figure 4-1: Typical Subsurface Drainage System with Outfall Discharge
B. Surface Swales and Ditches
A method similar to subsurface drainage would be a surface network of drainage swales and
ditches. This method works in two ways. First, it will keep the groundwater at a level consistent,
or below, the bottom of the ditch network. Second, it provides a preferred path for the
accumulated stormwater runoff to flow by gravity downstream towards a treatment, storage or
discharge structure.
As groundwater levels increase in the soils, the water enters the. bottom of the ditch where it flows
downslope to an area of storage, disposal or recharge. This sets the permanent high elevation of
the groundwater table to the low point in the ditch at each individual area. This increases the
available soil storage capacity which decreases the chance for surface flooding. Also, this system
provides a means oftransporting the runoff to the area of storage or disposal
This system is a very low maintenance stormwater management system. Other than establishment
and maintenance of a vegetative cover, there is no other significant maintenance. The vegetative
cover is also beneficial in terms of contaminant removal during transport of the runoM The
vegetation will use the nutrients for growth and the soils will break down other contaminants in
the soil matrix. This method is similar to the subsurface drainage system in that it too helps to
lower the groundwater elevations within the ditched areas. The advantages and disadvantages of
a surface swales and ditches system are presented in Table 4-3, and cost information is presented
in Table 4-4. A schematic drawing of a typical surface swale and ditch system is presented in
Figure 4-2.
MacConnell & Associates, P.C. 4-3

Village of Bald Head Island, North Carolina
Table 4-3: Advantages and Disadvantages of Surface Swales and Ditches
IAdvantages
0
C
C
1
k
• Provides contaminant removal while conveying runoff to a point of disposal.
• It is typically a gravity system with no electrical costs.
• Provides additional localized soil storage capacity.
• Very low maintenance.
• Low installation, operation and maintenance expenses
• Visually pleasing
Disadvantages
• Permanently lowers the groundwater table elevation
• Permanently alters the ground surface
• Does not control runoff peak flows
Table 4.4: Estimated Costs that may be Incurred During Construction of a System of
Swales and Ditches
Item
Estimated Cost
Earthwork
$4-6/yaro
Culvert Installation
$10-18/foot
Pavement Repair
$30-40/square yard
* The estimated costs are installed costs. All of the items listed may or may not be required.
Swale as wide as possible
Figure 4-2: Typical Grass Swale with a Check Dam for Velocity Control
(Ref. NC-DENR, Stormwater Management Guidance Manual)
MacConnell & Associates, P.C. 4-4

Village of Bald Head Island, North Carolina
U
1
C. Surface Runoff Collection System
A surface runoff collection system consists of an underground network of pipes, and pumps in
some instances, which is connected to drop inlets, yard inlets, or other surface runoff collection
devices. These devices collect surface runoff and transport it through the underground network
of pipes to the chosen discharge locations, typically a detention pond, infiltration basin, stream, or
some other body of water. The collection and transportation of surface water to an area with
adequate storage for it minimizes the potential for surface flooding in the areas serviced by the
collection system This is the type of system currently used in the marina area of Bald Head
Island.
In the case of the Village, the subsurface drainage system and the surface swale/ditch network will
not be studied further. The Village uses the freshwater aquifer for it's drinking water supply. By
using subsurface drains or a swale/ditch network, the groundwater table would be permanently
lowered. This would decrease the hydrostatic pressure on top of this freshwater aquifer and
increase the possibility of saltwater intrusion. The desalination of salt water for use as a potable
water source is much more difficult than the purification of fresh water. Therefore, lowering of
the groundwater table is totally undesirable and a surface runoff collection system will be the only
option explored for handling large volumes of stormwater runoff and flooding. However, some
shallow swales are being recommended along roadways that are less severely flooded.
If the Village decides that potential groundwater lowering stormwater management practices are
desirable, an investigation into the acceptable minimum groundwater levels can be performed.
Hydraulic modeling, which is not within the scope of this document, would indicate the
hydrostatic pressure required within the freshwater aquifer to prevent salt water intrusion. This
analysis could then be used to recommend a minimum elevation for all groundwater lowering
devices based upon the modeling results.
1. Stormwater Sewer with Outfall Discharge
A stormwater sewer is a network of underground pipes which is used to transport stormwater to
a desired point of discharge. These types of networks require initial planning for the
establishment of utility easements within an area of planned development. Retrofitting a
previously developed area is difficult due to the complications brought on by structures such as
homes, driveways, etc. potentially blocking the most advantageous pathway to route the
stormwater collection system. However, if the stormwater is creating a nuisance or hazard
condition, typically the homeowners will be agreeable to the necessary easements and renovations.
' The outfall discharge typically consists of a pipe, connected to the upstream stormwater collection
system, terminating at a detention pond, infiltration basin, stream, or some other body of water.
These stormwater runoff storage areas will then allow the runoff to infiltrate into the groundwater
' aquifer or maintain a controlled discharge into a body of water which ultimately flows into a river
system, sound, and the ocean. The runoff storage area (Le. detention pond, infiltration basin,
' stream, or some other body of water) should have adequate volume to store the anticipated
stormwater runoff volume. This will ensure that the runoff storage area does not exceed its
MacConnell & Associates, P.C. 4-5
1

k
k
k
Village of Bald Head Island, North Carolina
capacity, flooding the surrounding areas. The advantages and disadvantages of a storm sewer
with an outfall system are presented in Table 4-5, and cost information is presented in Table 4-6.
A schematic drawing of a typical subsurface system is presented in Figure 4-3.
Table 4-5: Advantages and Disadvantages of a Storm Sewer with an Outfall Discharge
Advantages
• Rapid draining of large volumes of collected runoff.
• Does not permanently lower groundwater table elevation.
• Low operation and maintenance requirements if no pumping systems are
required.
Disadvantages
• Flooding may occur during large storm events.
• Storm sewer provides no contaminant removal
• Yard inlets may pose a hazard to the public
• Yard inlets are not aesthetically pleasing
• Somewhat expensive to install depending upon whether pumping systems are
necessary
Table 4.6 Estimated Costs that may be Incurred During Construction of a Stormwater
Sewer with an Outfall Discharge
Item
Estimated Cost
Yard Inlets
$200-1,000/each
Collection Pi
12-inch
$12-16/foot
Collection Pi
(I 5-inch
$15-20/foot
Collection Pi
(I 8-inch)
$18-22/foot
Collection Pi
(30-inch)
$40-50/foot
Pump Station
$10,000-20,000/each
Force Main
$8-12/foot
* The estimated costs are installed costs. All of the items listed may or may not be required.
MacConnell & Associates, P.C. 4-6

Village of Bald Head Island, North Carolina
SLOPE TOWARDS OUTLET
IFigure4-3: Typical Storm Sewer with Outfall Discharge
' 2. Stormwater Sewer with an Infiltration Basin
This system is fairly similar to the system described above in that there is an underground network
of pipes which transports the stormwater to a place of ultimate disposal. The difference here is
the means of disposal.
' An infiltration basin is a pond which is situated in an area of very well drained, highly permeable
soils. Groundwater tables should be a minimum of two feet below the bottom of the infiltration
basin. During times of low rainfall, this would be a dry basin; it would only hold water during
' times of recent rainfall. This type of system is advantageous because it works as a purification
and groundwater recharge system The only problem is that with such a high groundwater table
and poorly drained soils in the area, an infiltration basin rely would not work. A basin of this
' type may be supported in the higher elevations of Bald Head Island where the sandy, well drained
Newhan soils are prevalent, however, this would require an elaborate pump and piping system to
' transport all of the Village's stormwater to this point. In addition, a hydrogeological investigation
would be required to assure that the soils had a high enough infiltration rate to dispose of all of
the stormwater without overtopping its banks. The advantages and disadvantages of a storm
sewer with an infiltration subsurface systems are presented in Table 4-7, and cost information is
presented in Table 4-8. A schematic drawing of a typical storm sewer with an infiltration basin
system is presented in Figure.4-4.
1 Table 4-7: Advantages and Disadvantages of a Storm Sewer with an Infiltration Basin
I
Advantages
• Rapid draining of large volumes of collected runoff.
' • Recharges the groundwater system.
• Provides contaminant removal through detention and infiltration through the
soil matrix..
MacConnell & Associates, P.C. 4-7

Village of Bald Head Island, North Carolina
f
Disadvantages
• Infiltration basins require large land areas.
• Pumps required to get runoff to higher elevations that have the desired
distances to the groundwater table and more permeable soils
• Heavy maintenance requirements - Sediment must be removed from the basins
prior to rainfall to prevent clogging of the soils.
• Historically high failure rate
• Storm sewer provides no contaminant removal.
• Yard inlets may pose a hazard to the public.
• Yard inlets are not aesthetically pleasing.
• Fairly intensive operation and maintenance requirements.
• Somewhat expensive to install depending upon whether pumping systems are
necessary.
Table 4-8: Estimated Costs that may be Incurred During Construction of a Stormwater
Sewer with an Infiltration Basin
Item
Estimated Cost
Yard Inlets
$200-1,000/each
Collection Pi 12-inch
$12-16/foot
Collection P' 15-inch)
$15-20/foot
Collection Pi 18-inch
$18-22/foot
Collection Pi 30-inch
$40-50/foot
Station
$10,000-20,000/each
Infiltration Basin
$4-6/ and excavation
Infiltration Basin
$3-5/ and disposal of Moil
* The estimated costs are installed costs. All of the items listed may or may not be required.
MacConnell & Associates, P.C. - 4-8

Village of Bald Head Island, North Carolina
Adapted from Schueler 1987.
Riprap inlet protection
Embankment Ile
' r Flat basin
Afloor
;Emergency
,. spillway
underdrairi
�Riprap outfall
� protection
Adapted from Schueler 1987.
Concrete
OdGR-Up UI IUC1 U1 all 1114 -
of standing water problems
Embankment
Inlet
Inlet
' Figure 44: Typical Infiltration Basin
(ReL NC-DENR, Stormwater Management Guidance Manual)
' 3. Stormwater Sewer with a Detention/Retention System
Like the two systems discussed above, this type of stormwater system also requires the use of
' some sort of network of underground pipes to collect the stormwater and transport it to the
detention/retention pond.
' A detention or retention pond is basically a basin which is sized to store large amounts of rainfall
which fall over a short period of time. These basins store the rainwater and release it at- a more
' controlled flow rate, minimizing flooding in downstream areas. Although the main objective of
reducing flooding is the same for these systems, some differences exist.
' A retention pond is typically in a shallow, vegetated area which allows for some physical and
biological treatment of the stormwater prior to discharge. This type of system is fairly land
intensive because of the shallow pooling. With the limited land available on Bald Head Island,
' this stormwater management option is not practical and will not be further evaluated in this
analysis.
MacConnell & Associates, P.C. 4-9

Village of Bald Head island, North Carolina
Depending upon the nature of the vegetation within the detention pond and the pond's depth,
' some physical and biological treatment of the stormwater can be achieved. The physical
treatment that occurs is the settling of contaminants within the detention pond. Biological
treatment is achieved in two ways. When the contaminants settle to the bottom of the detention
' pond, they infiltrate into the soils beneath the pond and receive treatment within the soil matrix.
The second way is from contaminant uptake by the vegetation within the pond. This method is
also a fairly land intensive practice for managing stormwater. However, because of the depths
that can be used, this alternative is not nearly as land intensive as the retention pond scenario.
In studying the alternatives available to Bald Head Island, a detention system seems the best
' candidate. The lagoons already in place on the golf course are used as a wet detention type of
stormwater system Physical treatment could be expected within the lagoons by the settling out _
of any solids which may enter the system. Some minimal biological treatment of the stormwater
could be achieved based on the vegetation growing within the lagoons. Also, many chemical
contaminants would be reduced by settling out and receiving treatment in the soil matrix.
' Therefore, using the existing lagoon system as a wet detention pond seems to be the best
management alternative for Bald Head Island. The advantages and disadvantages of a storm
sewer with a detention system are presented in Table 4-9, and cost information is presented in
' Table 4-10. A schematic drawing of a typical storm sewer with detention system is presented in
Figure 4-5.
H
Table 4-9: Advantages and Disadvantages of a Storm Sewer with a Detention System
Advantages
• Rapid draining of large volumes of collected runoff.
• Recharges the groundwater system.
• Provides contaminant removal through detention and the soil matrix.
• Provides a steady discharge into the receiving waters which allows for a
smaller area to be impacted by a decrease in salinity.
Disadvantages
• Detention/Retention basins require large land areas.
• Periodic vegetation removal is required.
• Storm sewer provides no contaminant removal.
• Yard inlets may pose a hazard to the public.
• Yard inlets are not aesthetically pleasing.
• Flooding around the disposal area may occur during large storm events.
• Somewhat expensive to install depending upon whether pumping systems are
necessary - However, the costs will be lower than normal for this type of
system if the existing lagoons are used for detention/retention.
• Detention/Retention basins need periodic removal of sediment and organics.
MacConnell & Associates, P.C. 4-10

Village of Bald Head Island, North Carolina
Table 4-10: Estimated Costs that may be Incurred During Construction of a Stormwater
Sewer with an Detention System
Item
Estimated Cost
Yard Inlets
$200-1,000/each
Collection P'
12-in*
$12-16/foot
Collection Pi
15-inch)
$15-20/foot
Collection Pi
18-inch)
$18-22/foot
Collection P'
(30-inch)
$40-50/foot
Pump Station
$10,000-20,000/each
Detention Pond Excavation
$4-6/yard excavation
Inlet Structure
$1,000-3,000/each
Outlet Structure
$1,000-3,000/each
* The estimated costs are installed costs. All of the items listed may or may not be required.
w •�.,h,.�. • � it , �...:,,• .
ill �!, d;� _ -- _ u.ct•u.,i:.f
_r'lrl�'1Vkj�lfi�1th1 i.y11
• �t r V{ i ,x
;�� � ���'�IJMI ,�q}���? -ti -� i�'R ,•tt,I`Ir ��rl1li �J �.��.
j I� +p;l I,V'i�
d1
r
Marsh plants
t
Irti.f::'
Inlet Riprap
inle
/t protection
_;l- RForebay
Embankment with marsh plants
and spillway to main pool
Riser prevents
/
Stormwater overflowing embankment
Nonnaf
7 ' ` 9 pool level
'
storage volume
Reverse -sloped orifice to
• �� ,'f Maximum
slowly release stormwater Compacted -earth
1�
I. water level
embankment
Riprap outlet
Main pool
protection
Concrete anti- Anti -seep
flotation anchor collars
Figure 4-5: Typical Wet Detention Pond
(Ref. NC-DENR, Stormwater Management Guidance Manual)
MacConnell & Associates, P.C.
4-11

Village of Bald Head Island, North Carolina
Small outlet orifice
to control stormwater
flow into receiving water
g
Stormwater inlet
Stormwater
inlet
Riprap inlet Compacted -earth
Outletprotection
Stormwater detention level
Outlet
protection
I.
Wildflowers temporarily flooded
Perforated •r controlle
release of stormwater Anti -seep collar
Figure 4-6: Typical Dry Detention Pond
(Ref. NC-DENR, Stormwater Management Guidance Manual)
D. Do Nothing Alternative
There currently exists a stormwater flooding problem in many areas on the island. These
problems contribute to many economic, social and public safety issues. Following is a discussion
on each of these issues which makes it clear that some resolution to the flooding is necessary for
the flood prone areas.
MacConnell & Associates, P.C.
4-12

Village of Bald Head Island, North Carolina
There are many economic factors in the frequent flooding of the low lying areas on the island.
' Flooding often causes damage to both the vegetation and the structures on the property. Costs to
correct these damages can be expensive. However, the costs to mitigate the problems may be
significant. Another concern is who is responsible for the cost of these improvements. This
' funding issue is discussed later.
Social issues also arise from the frequent flooding of the low lying areas. Many of these issues
' can be tied back into the economic issues described above. The residents that purchased flood
prone lots at understandably want the flooding problems resolved. However, the solutions to
these problems may require significant expenses. The question is who should pay for these
' facilities to be constructed. The residents who purchased residential lots on higher ground do not
experience any of the problems with the flooding. They may not feel they should have to pay for
the facilities that will not serve them. However, drainage from the lots on higher ground often
' floods the low lying areas. Resolution of this situation could intensify pitting neighbor against
neighbor.
' Flooding also creates a public safety concern. Inundation of roads by floodwaters can keep
emergency vehicles from gaining access to some spots on the island, potentially keeping lifesaving
' equipment out of reach from those in need. Not only can access be limited to areas of the island,
floodwaters create breeding grounds for mosquitoes and can transport harmful bacteria and
pathogens. The public health concerns associated with floodwaters dictates that these flood prone
I
areas must be retrofitted with some type of stormwater collection and disposal facilities.
Based on the large amounts and long durations of the flooding that have been experienced on the
' island, the do nothing alternative is not feasible. The flooding frequency and volume is not only a
public nuisance, it is a safety hazard. When analyzing the economic, social, and public safety
factors surrounding the frequent flooding and sometimes long durations of standing floodwaters,
' it is plain to see that some solution is necessary. Therefore, this alternative is not considered to be
viable.
MacConnell & Associates, P.C. 4-13

n
Village of Bald Head
Island, North Carolina
Chapter 5
Recommendations

Village of Bald Head Island, North Carolina
7
I
n
5. Recommendations
A. General Recommendations
In terms of stormwater management on Bald Head Island, the main problem is finding somewhere
for the water to go. Currently, the only outlet from the island is a culvert crossing underneath
North Bald Head Wynd near its intersection with Lighthouse Wynd. The capacity of this outlet is
very small when compared to the size of the drainage area. Previously, other outlets on the island
were located along North Bald Head Wynd near Phase 1 of Timbercreek and near the Boathouse
Path. Reestablishing these outlets should be investigated by Bald Head Island. Stormwater pipes
to the water's edge are not necessary or allowed. Because pipe discharges into water classified as
SA is not permissible, the culverts will be required to terminate under North Bald Head Wynd and
allow the stormwater to flow overland to Bald Head Creek. These pipes or culverts would be
required to end at least 50 feet from the creek according to Linda Lewis of the Wilmington
Regional office at DENR. Simply installing culverts under North Bald Head Wynd will provide a
path for stormwater to flow off of the island without using the limited capacity of the existing
riser/barrel system near Lighthouse Wynd.
The lagoons surrounding the golf course play a major role in the stormwater management of the
island, as the only outlet from the island is from the lagoon system. According to Mr. Mitchell,
President of Bald Head Island Limited, when the golf course was built over 20 years ago, the
lagoons were interconnected. The interconnectivity of these lagoons is important for controlling
the levels in the lagoons and the management of stormwater. This interconnectivity is also
required based upon comments from the Division of Water Quality's Wilmington Regional Office's
Water Quality Section supporting permitting of the spray irrigation system (Permit No.
WQ0010834) which allows for irrigation of the golf course with treated wastewater effluent.
However, it is questionable whether this interconnectivity still exists, due to degradation of the
system and blockage of the culverts with accumulated debris and sediment. This issue requires
confirmation of which lagoons are actually connected and reestablishing the connectivity of those
that are not connected (except for the lagoon used for treated wastewater effluent storage). The
lagoons will also need to be dredged and cleaned to provide more stormwater storage volume and
to improve the interface between the lagoon bottom and the groundwater table, which in turn will
increase the infiltration rate into the groundwater.
' The construction of roads and years of evolution of the island may have caused blockage of the
connections between the lagoons, if they in fact were connected at one time. The accuracy of this
information cannot be determined due to the lack of documentation of road and lagoon
' construction. One method for checking the connectivity of the lagoons would be to cofferdam
each lagoon and check them individually. Another method would be to use scuba divers to
attempt to locate any connection pipes. If pipes are located, sewer pipe cleaning equipment could
be used in an attempt to verify free flow between lagoons or to clean the pipes out to establish
free flow.
MacConnell & Associates, P.C. 5-1

Village of Bald Head Island, North Carolina
Connectivity of the majority of the lagoons is relatively simple due to their close proximity to each
' other. However, due to ocean overwash, the lagoon near the intersection of South Bald Head
Wynd and the Bald Head Island Club entrance has filled with sand and saltwater on several
occasions. The continued use of this lagoon should be evaluated based upon the level of service it
' provides versus the consequences of introducing saltwater into the entire lagoon system. The
connectivity of the lagoon system in this area can be obtained in one of two ways. One manner is
that the lagoon in question can be restored to it's original condition with culverts connecting it to
' the lagoon at the villas and along fairway 9. Another alternative would be to close this lagoon
permanently and connect the lagoon at the villas to the lagoon on fairways 10 and 18. This
lagoon could be connected to the lagoon between fairways 9 and 11 using a long, large diameter
' culvert. The problem with this scenario is that the culvert would have to cross the driving range.
The driving range is currently filled with many other utilities making crossing the driving range
with such a large culvert extremely difficult. These two potential connectivity solutions should be
' analyzed to determine which is best for stormwater management on Bald Head Island.
' If the lagoon connectivity is restored, and the lagoons are cleaned and maintained, a considerable
amount of stormwater infiltration and storage capacity will be provided. This will also provide
adequate lagoon capacity if a problem arises in one particular area and it needs temporary
pumping to assist in removing flood waters. However, without the required topographic
information and modeling, determining an appropriate surface water elevation to maintain would
be impossible. Once topographic data is available, the required storage volume for the island can
' be determined and a permanent maximum elevation for the riser controlling flow from the lagoons
into Lighthouse Creek can be set. This will assure that storage capacity within the lagoons is
always present. Flashboards can still be used in the riser which would allow for further lowering
' of the lagoon levels from this maximum elevation. This would allow for lowering or draining of
the lagoons for maintenance or to assure adequate storage capacity before a large storm event
such as -a hurricane.
' The golf course lagoons will act as a large stormwater detention basin system once their
connectivity has been confirmed and/or reestablished. This connection will allow for the removal
' of nutrients, pollutants, and suspended solids before being discharged into Lighthouse Creek.
Stormwater flow through the lagoons will allow for sediment to settle out into the lagoons and
prevent deposition into the receiving waters. The flow rate out of the lagoons will also be more
steady creating a more consistent, yet smaller area around the discharge point into Lighthouse
Creek where the salinity of the water may be adversely impacted.
' Another recommendation that may be helpful is to install a trash rack on the riser. During large
storm events when velocities in the lagoons get relatively high and debris is washed into the
' lagoons, blockage of the riser may occur. This blockage can cause a severe backup of water into
the lagoon system which results in flooding areas upstream of this point. A trash rack will help to
alleviate this problem by preventing excess debris from entering, and perhaps clogging, the riser
' or the outlet pipe. The trash rack allows water to flow underneath the trash and out through the
riser assembly. Figure 5-1 shows a typical trash rack configuration.
MacConnell & Associates, P.C. 5-2

Village of Bald Head Island, North Carolina
METAL TRASH RACK
-r7" TRASH RACK
M
w
LI
FLASHBOARDS
M
FLASHBOARD L
DRA
Figure 5-1. Typical Trash Rack
A future recommendation for handling standing water in localized areas would be to purchase a
trailer mounted pump, which could pump ponded water out of an area and discharge it into an
existing lagoon or creek. This will have some impact on the groundwater table as the standing
water and groundwater are connected. Figure 5-2 shows a typical trailer mounted pump.
Figure 5-2. Trailer Pump
MacConnell & Associates, P.C.
5-3

Village of Bald Head Island, North Carolina
B. Future Development
1 All future developments shall be in accordance with the Stormwater Ordinance and Federal and
State regulations. All new developments require erosion and sedimentation control measures
according to NCDENR regulations. If the area of disturbance is greater than one acre, an
approved sediment and erosion control plan from -the NCDENR-Division of Land Resources is
required. Also, the NCDENR-Division of Water Quality requires the approval of stormwater
management plans for developments in areas under the jurisdiction of the CAMA. The following
paragraphs contain more recommendations that concern new developments and construction.
iAnother preventive measure for protecting the delicate ecosystem of Bald Head Island is to
regulate the amount of new development taking place. According to the "Stormwater
' Management Guidance Manual" from the NCDENR, "establishing lower density developments
will reduce the number of pollutant sources, such as septic tanks, roads, and parking lots." The
percentage of pervious versus impervious area greatly influences the number and size of
' stormwater management measures that need to be implemented.
Although the best recommendation for undeveloped areas would be to leave them in their natural
I state, this is not practical except for areas which are set aside as natural areas. Most of the lots
that have been purchased on the island have not yet been developed, and measures should be
made to ensure that these developments follow the Stormwater Master Plan and the proposed
' Stormwater Ordinance of the Village. A potential problem for new construction is that fill
material may be brought in to fill undeveloped lots which will change localized drainage patterns.
Stormwater may be directed away from one lot and onto adjoining lots. If fill material is to be
' allowed, it should be required that an engineer review the plan and assure that no stormwater will
adversely impact adjoining lots. Building on stilts or pilings is the best alternative available for
' new housing to ensure that the home will not be flooded, stormwater will not adversely impact
adjoining lots, and natural drainage patterns are maintained. According to Mr. Sayre, the houses
being built are typically constructed on stilts. The first floor elevation should be built at a
' minimum elevation of 2 feet above the 100-year flood level, according to FEMA, regulations.
Driveways should be constructed at or above 6 feet mean sea level, to permit access but minimize
the impacts to drainage. Along with the houses, wooden driveways can also be built on stilts.
' Along with driveways, roads should be constructed at an minimum elevation of 6 feet above mean
sea level. When constructing new roads, or repairing old roads, drainage pipes should be installed
under them to minimize the diking effect of the road system Elevating the roads to 6 feet above
mean sea level will assure access of emergency vehicles to the entire island during storm events up
to a 10-year, 24 hour storm
' Another recommendation is to eliminate existing septic tanks. Some of the septic systems have
failed in the past, according to Bruce Withrow of the Brunswick County Health Department, the
last failure being in April of 1991. According to the Soil Survey of Brunswick County, the soils in
the area are defined as "severe" for the installation of septic systems. Severe means that the soil
properties or site features are so unfavorable or so difficult to overcome that special design,
significant increases in construction costs, and possibly increased maintenance are required. The
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Village of Bald Head Island, North Carolina
individual reasons listed for each soil type within the survey are: flooding, ponding, low
' percolation rate, wetness, poor filter, and slope. However, new septic tank approvals and existing
septic tank problems are under the jurisdiction of the Brunswick County Health Department. If
the septic systems are abandoned, the existing homes should be connected to the existing
collection system. This may require wastewater permit modification and/or wastewater treatment
plant upgrade.
' C. Site Specific Recommendations
' The site specific areas are considered to be significant problem areas and recommendations have
been made to alleviate these stormwater problems. In most cases the best alternative would be to
elevate the roads while installing proper stormwater piping underneath them. In these places, at a
minimum, drainage should be provided underneath the roads. With proper drainage, the roads
will not create dikes because the stormwater has a flow path through the pipes and under the
roads. Another recommendations is for "shallow" swales to be installed which will not lower the
groundwater table significantly yet will allow for the collection and transportation of the surface
water runoff to an area of final disposal. Final sizing, design, and construction of these structures
can be made after a detailed survey of these areas has been completed.
' Area 1. SnowyEgret Trail/Black Skimmer Trail
g
' The area surrounding Black Skimmer Trail and Snowy Egret Trail at South Bald Head Wynd
experiences perhaps the most extensive flooding on the island during large storm events. By
' visual observation of the site, a portion of this area (at the intersection of Black Skimmer Trail
and South Bald Head Wynd) contains vegetation that would classify it as a wetland. This is based
on the appearance of dying trees, marsh type grasses and other wetlands vegetation. It is evident
' that this area floods frequently, based on our site inspection and discussions with residents. Also,
because part of South Bald Head Wynd and the primary dunes appear to be at higher elevations
than these two roads, runoff is prevented from flowing out onto the beach. A berm around the
lagoons in this area prevents the floodwater from flowing into them For these reasons, a large
amount of water ponds in the low spots during a large rain event. During a site visit, it appeared
that the natural drainage in this area is westward towards lagoons surrounding the villas. Again,
' this information cannot be confirmed until a topographic survey has been performed.
When the area surrounding Black Skimmer Trail and Snowy Egret Trail fills with water during
large storm events, Morning Warbler Trail also experiences flooding from the rising flood waters.
The lagoons surrounding these two areas have elevated berms that appear to keep stormwater
runoff from flowing into them without some sort of underground piping network or pump system.
Therefore, the berms create the remainder of the duce in this area, adding to the flooding problems
that it experiences.
' Since the groundwater table is high at this point due to the low elevation of the area, a basin of
some sort to collect the stormwater is not recommended. However, if one is to be utilized, it
should be placed in the lowest point in the problem area and be fed into the lagoons system from
there by means of pumping or gravity flow, whatever the topography dictates. Another simple
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Village of Bald Head Island, North Carolina
resolution to this problem is to raise Black Skimmer Trail, Snowy Egret Trail, and South Bald
Head Wynd and install pipes underneath them to allow natural drainage to occur. This solution
eliminates the dicing effect of these roads and would allow the streets to be more accessible for
emergency vehicles following a storm event. To eliminate the flooding in the yards and around
the homes of this area, a collection system consisting of swales and/or underground pipes and
yard inlets is also recommended.
An alternate recommendation for this problem area is that when a heavy rain event occurs,
a trailer mounted pump can be placed in a low spot so that it can pump the water into the lagoon
on the fairway of holes number 14 and 18. Pumping the stormwater will not lower the
groundwater levels because only surface (ponding) water will be pumped. � These
recommendations would involve a great deal of costs associated with both the operation and
maintenance of the pumping unit.
It may be desirable to seek approval for discharging the stormwater pumped out of this area onto
the beach and into the ocean. Approval for a permanent discharge to be used on a routine basis
would not be allowed under current State regulations, however approval for use during
emergency situations has been allowed in other areas of the State. This would keep a large
volume of stormwater out of the lagoon system during heavy precipitation events which would
increase the level of service provided by the lagoons for draining the remainder of the island.
Area 2. Dogwood Trail/Dowitcher Trail
The former stormwater drainage pattern in this area apparently flowed across Stede Bonnet
Wynd, through Dowitcher Trail and towards the lagoons at hole #6 of the golf course. As
development occurred, these patterns were blocked and standing water, or flooding, occurs
mostly along Dowitcher Trail until it infiltrates into the soil. The natural drainage patterns need to
be reestablished in this area
Dogwood Trail and Dowitcher Trail have been grouped together for this analysis strictly because
' of their similar location; however, the roads have different stormwater needs. Dogwood Trail
appears to have a problem with standing water while Dowitcher Trail has a problem with
restricted flow. Some of the standing water on Dogwood Trail may be able to be diverted under
' Stede Bonnet Wynd and into a storm drainage system at Dowitcher Trail. A recommendation
that would help establish the previous drainage pattern would be to place a culvert underneath the
' road at Stede Bonnet Wynd just south of its intersection with Dogwood Trail and Dowitcher
Trail.
Dogwood Trail did not seem to represent a drainage problem except for the few houses near the
intersection of Dogwood and Stede Bonnet Wynd. It appeared as though the houses in the area
were located in a low area, and that water naturally drains accumulates in this area. A small
' collection system is recommended for disposing of the stormwater in this area.
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Village of Bald Head Island, North Carolina
Dowitcher Trail, conversely, experiences a great deal of runoff. During small storm events, it
does not appear that any of the runoffflows from Dogwood Trail to Dowitcher Trail because (it
appears as though) Stede Bonnet creates a ridge separating Dogwood Trail and Dowitcher Trail
at their intersection. However, during precipitation events greater than a ten-year storm, there
will be stormwater flow across Stede Bonnet and down Dowitcher Trail towards the loop at the
end of the street. This loop is at a low spot and collects much of the runoff. As stated previously,
the natural drainage pattern appears to flow to the west across Stede Bonnet behind the green on
hole #3, through the common area and towards the lagoon at hole #6. This pattern needs to be
reestablished by installing culverts under Stede Bonnet Trail and between lots on the loop at the
end of Dowitcher Trail. The culvert at the loop on Dowitcher Trail could be installed to drain
towards the lagoon on hole 3 or 6.
Most of the lots on this street were undeveloped when the site visit was made. Lots on
' Dowitcher Trail, as with any other street on the island, should not be filled, without an
engineering analysis to determine localized impacts. It appears that the developed lots on this
' street had not been filled, and given a large storm event, may be adversely impacted by adjacent
lots that are allowed to place fill making them higher than the previously developed lots.
' An overall recommendation for this area includes installing shallow swales or ditches in localized
areas. A collection system with yard inlets can also be installed between some of the lots in these
two areas which will aid in routing the stormwater into the golf course lagoons. Lastly,
' reestablishing the natural flow through strategic placement of culverts in the area will decrease the
amount of trapped stormwater, thereby minimizing flooding in the area.
Area 3. Sabal Palm Trail
Bill Bruce indicated that during a storm event, this area experiences some standing water halfway
to the loop of Sabal Palm Trail. This area does not have an outlet and low areas collect water
along the sides of the road. It appears that the natural drainage pattern diverts the water to the
west but cannot be confirmed without survey information of the area. Building up the road and
installing culverts underneath it would be the best solution for this problem as well as constructing
a shallow swale to carry the water to the lagoon on hole #12.
Another alternative would be to install a collection system that would pipe the stormwater behind
the lots on the northeast side of Sabal Palm Trail and construct shallow swales to route the water
along the side of hole #4 and into the lagoon near the fourth green. This process would involve a
great deal of site work and would increase the cost of construction considerably more than the
previous recommendation.
Area 4. Edward Teach Road and Surrounding Roads
This area has not yet been developed but appears to be in a bowl, or low area throughout.
Edward Teach Road appears to create a small diking effect on the neighboring roads. The lowest
areas, as evidenced by storm events, are the ends of Laurel Cherry Court and Gray Fox Court and
the entire loop of Poor Mares Pepper Trail.
MacConnell & Associates, P.C. 5-7

Village of Bald Head Island, North Carolina
In this situation, homes should continue to be constructed on pilings or stilts. Requiring that no
topsoil be added to fill the area would be one measure to ensure that the natural drainage patterns
would be maintained. Roads and driveways should be built at a minimum elevation of 6 feet
above mean sea level. If the water level of Bald Head Creek is lower than the elevation in these
areas, gravity pipes can be installed and routed under North Bald Head Wynd to allow the
stormwater to flow overland towards Bald Head Creek. This solution will only be able to route
the stormwater that collects on the north side of Edward Teach Road.
Another possibility of alleviating this problem would be the installation of a stormwater collection
system bordering Towee Court and Gray Fox Court and pumping the water underneath North
' Bald Head Wynd to allow it to flow overland towards Bald Head Creek. This recommendation
will certainly be much more intensive from an operation and maintenance standpoint. However,
since the land is currently undeveloped, easements for the utilities would be relatively easy to
' obtain
' The area surrounding Poor Man's Pepper Trail does not have an outlet for stormwater within a
1,000 foot radius. The stormwater that collects in this area will need to be pumped, which will
require a pipe to be routed between lots towards Bald Head Creek. This outlet should terminate
' just on the other side of North Bald Head Wynd allowing overland flow towards Bald Head
Creek. If a collection system is installed in the Laurel Cherry Court and Gray Fox Court area,
these two systems could be tied together allowing one pump station to remove stormwater from
the entire area.
As mentioned earlier in the "Future Development Section," it is recommended that none of these
lots be filled. Also, it is essential that homes be built at a minimum of 2 feet above the 100-year
flood level and driveways at a minimum of 6 feet above mean sea level Homes are already being
built on pilings, according to Mr. Sayre, and driveways can also be built on stilts to avoid water
damage to golf carts and other possessions during a large storm event.
Area 5. North Bald Head Wynd
North Bald Head Wynd is the road that separates PD-1 from Bald Head Creek. Before the road
was built, there were two other drainage outfalls that routed runoff to Bald Head Creek. It
appears that reopening these two former outlets would help divert runoff back into Bald Head
Creek, which would also aid in flushing the creek. This would require the installation of culverts
' under North Bald Head Wynd in low lying areas near Phase 1 of Timbercreek and near Boathouse
Path
There is one other area of concern just beyond North Bald Head Wynd on Federal Road and just
north of the Utilities Department. A culvert under Federal Road is recommended if the area is not
a wetland. If this or any other area is considered a wetland, a 404 permit will be required and the
Corps of Engineers will need to delineate the wetland and assess a value for it depending on the
wildlife habitat and vegetation present. An alternate recommendation would be to leave this area
in it's natural state, especially if the area is uninhabitable.
MacConnell & Associates, P.C. 5-8

Village of Bald Head Island, North Carolina
Area 6. Stede Bonnet Wynd
Most of Stede Bonnet Wynd appears to be properly crowned to allow stormwater to drain to the
sides of the road. From information given by Mr. Mitchell, two areas of Stede Bonnet Wynd
contain submerged pipes that connect the lagoons. However, during a site visit both areas had
lagoons that appeared to be at different levels on each side of the road, therefore signifying the
lack of a connection. Re-establishment of the connectivity is recommended by verification of the
existence of a connection pipe or installation of new culverts if none exist. These two areas are
located where the lagoons along hole numbers 11 and 12 meet at Stede Bonnet Wynd, and also
where hole numbers 16 and 17 meet at Stede Bonnet Wynd.
Area 7. Cape Fear Trail
During large storm events, Cape Fear Trail experiences problems with standing water along the
roadway and in individual lots. The water has no outlet since West Bald Head Wynd borders the
east and a primary dune ridge borders the west.
A possible solution to this standing water is to construct shallow swales to direct the stormwater
through a culvert under West Bald Head Wynd and into the golf course lagoon between West
Bald Head Wynd and Royal Tern Court. A survey of the area would be necessary to calculate the
proper size and location of the culvert.
Area 8. Green Teal Trail
tGreen Teal Trail is experiencing problems similar to Cape Fear Trail. West Bald Head Wynd
borders the east and the primary beach dune borders the west causing stormwater to accumulate
in this area
To eliminate this problem, shallow swales should be constructed directing the stormwater through
a culvert from the northern end of Green Teal Trail to just under North Bald Head Wynd. The
' culvert must end at least 50 feet from Lighthouse Creek. The placement of this culvert will allow
any standing water to flow towards the creek and will not require a stormwater permit since a 50
' foot buffer from the creek will be maintained. This may also aid in the flushing of contaminants
from Lighthouse Creek. Again, a survey of this area will be necessary to ensure proper pipe
sizing and placement.
' Area 9. Middle Island
Middle Island is currently being developed with larger lots than the lots on Planned Developments
I and H. Middle Island currently has setbacks of 15 feet for sidelines and 25 feet for marshes
which property owners must obey. This isolates and minimizes the amount of land disturbing
activities and reduces the impact of land disturbing activities to the adjacent lots.
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MacConnell & Associates, P.C. 5-9

Village of Bald Head Island, North Carolina
Because Middle Island is mostly undeveloped, the recommendations discussed in the future
development recommendations would apply to Middle Island. However, Bruce Withrow of the
Brunswick County Health Department indicated that installing septic systems on Middle Island
does not pose a threat to the water quality of Bald Head Creek. Thus, the recommendation stated
earlier for eliminating septic systems does not apply to Middle Island.
Area 10. Cape Fear Station
Bald Head Island Limited currently holds a stormwater permit for clearing and grading any area
surrounding the Cape Fear Station. This permit regulates all land disturbing activities and
requires the developers to be responsible for sedimentation control at each lot. Any changes to
the land will require approval by NCDENR.
Since the Cape Fear Station is undeveloped, the recommendations stated earlier in the future
development section will apply here.
Area 11. Marina
' The marina area has recently been developed and has already obtained stormwater permits. This
area contains the most impervious area on the entire island. However, a collection system with
outlets to surface waters has been constructed to allow for stormwater drainage and the
' minimization of flooding problems.
' There have not been any complaints about the marina area, so no further recommendations have
been made. Also, any future construction in the area may be difficult because of the lack of
buildable area.
' Area 12. Bald Head Creek
Bald Head Creek currently is experiencing problems with a high concentration of fecal coliform
being present. This situation was discovered and has remained since the fall of 1992. This high
fecal content could be due to many things: failing septic systems, animal waste from the many
' animals that use the creek's resources, stormwater runof, or the stagnant nature of the water.
The creek receives little water to flush it out frequently enough to eliminate the buildup of
contaminants which may be in the water. Reestablishing the outlets as presented in the "Area 5"
recommendation above should help to flush out contaminants in the creek.
There is also a problem with the tidal effects on flushing of nutrients from Bald Head Creek.
According to Mr. Powell, the water does not flow into the Cape Fear River, but keeps flowing
back upstream with the rise and fall of the tides. Adding stormwater into the creek may flush
some of the water out. However, the current small flows of stormwater may have very little
impact on the quality of the water.
MacConnell & Associates, P.C. 5-10

Village of Bald Head Island, North Carolina
D. Environmental Concerns
Water resources and management are very critical to Bald Head Island because of the interaction
between stormwater, surface water and groundwater. Groundwater is Bald Head Island's source
of drinking water. While lowering the groundwater table may help to minimize the stormwater
problems, it would alter the amount of a valuable resource to the entire island. The residents and
' vacationers rely on the freshwater aquifer for their drinking water. However, most of the
recommendations involve yard inlets and pumping or rerouting surface (ponding) water, which
will not significantly reduce the hydrostatic pressure of the shallow aquifer. Reducing the
groundwater table is the only manner in which the hydrostatic pressure on this aquifer would be
reduced. Reducing the hydrostatic pressure may allow for saltwater intrusion into the freshwater
aquifer. Saltwater intrusion is not desired for the Village since it would be detrimental for the golf
course irrigation system and would require additional treatment before being used as a potable
water source.
' Another issue that needs to be addressed is who will be responsible for implementation of the
Stormwater Master Plan. These concerns will be discussed further in the following section.
However, if everyone in the Village feels that some or all of these recommendations need to be
implemented, a compromise between the entities may be required.
I�
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MacConnell & Associates, P.C. 5-11

Village of Bald Head
Island, North Carolina
Chapter 6
Cost Analysis and Responsibilities
I
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Village of Bald Head Island, North Carolina
6. Cost Analysis & Responsibilities
A. Cost of Implementation
1
F,
n
One of the main factors in implementing this plan will be the cost to survey the portions of the
island on which stormwater collection and disposal facilities will be installed. These surveys will
be required for the proper sizing and design of these facilities. Without a survey, flows in certain
areas can only be estimated along with pipe sizes and structures. If construction of stormwater
structures is completed without performing a survey, some of them may not be adequate to
handle the flows during large storm events. This could allow for continued localized flooding
even after installation of stormwater facilities is completed. If facilities are constructed which are
undersized, replacement of them with larger structures may prove more costly to fix than the
original construction.
The cost of cleaning the lagoons will involve the associated costs of a small dredging unit. The
dredge would be used to remove the organics, sediment and other solids which have accumulated
on the bottom of the lagoons since their construction. Once the lagoon bottoms have been
dredged, connecting pipes between the lagoons will need to be cleaned or installed so that
connectivity of all the lagoons is assured. Cleaning out existing culverts will require
cofferdamming the culvert ends and the use of a pipe rodder or high pressure flushing mechanism
to remove any sediment, organics or vegetation from within the pipes. Installation of new
culverts will require cofferdamming the proposed culvert locations, cutting the existing road,
trenching, installing the culvert, backfilling and compaction, and patching the road.
The cost of some of the stormwater collection and disposal structures will be minor when
compared to others and perhaps be just as effective. The installation of culverts underneath
roadways will establish flow paths that stormwater may follow until reaching a disposal site.
Many of the problems on Bald Head Island have been created from the roadways creating dikes
around certain low areas. The simple installation of culverts under these roads may be enough to
reduce the amounts of localized flooding. The installation of piping and culverts under roadways
will involve only minor construction including cutting the road, trenching, pipe placement, backfill
and compaction, and patching the roads after construction.
Table 6-1 lists many estimated costs for placement of these stormwater collection and disposal
facilities. These costs are estimated based on similar previous work and presented as ranges.
Once surveys are performed and the actual facilities are designed, a much more accurate number
of each of the items can be prepared and suppliers and contractors can be contacted for equipment
and construction costs.
MacConnell & Associates, P.C. 6-1

Village of Bald Head Island, North Carolina
F
0
Table 6-1: Cost Estimate for Stormwater Management Facilities
?Overall Recommendations
Description
Unit Price
Unit
#of Units
Total Price
doff Course
Mini 5e- a
$2,000 500
DAY
36
$72,000 000
18" Pipe Installation
18 22
LF
800
$14,400 17 600
--
37 Pipe Installation
$40 - $50
LF
800
$3 000 - $40 000
_----_
Roadwork(Asphalt)—SY
1,500
$45,000 000
_—
Earthwork
CY
200
1 200
rash Rack
$1,000 - $1 500
EA
1 1$1,000
- $1 500
railer Mounted Pump
$5 000 7 000
EA
1
1$5,000 7 000
Spoil Disposal
CY
000 000
Subtotal
200 - $517 300
P3770
Contingencies
74 040 10 460
Surveying
50 1 000
ACRE77,500
• $370 000
_
Engineedng
201yo
$74 040 - $103 460
ota I Cost
780 - UOK22D
j
Individual Reenmmendatienc
Black Skimmer Tr. &
Yard Inlets
1 000
EA
2
000
S_n_o by Egret Tr.
12" Pipe Installation
12 16
LF
400
$4,8DO 400
Roadwork (Asphalt)
SY
25
50 1000
Earthwork
$4 - $6
CY
90
Pum Station*
110 000 000
EA
1
10 000 000
Subtotal
310 - $29,940
Contingencies
2Q%
$3,262 988
Surveying
50 1000
ACRE
25
1 750 000
Engineering
$3 262 988
otaI Cost
584- $66,916
j
'DoWtcher Trail
Yard Inlets
00 1000
EA
4
000
Dog+�ood Trail
19 Pipe Installation
18 22
LF
150
$2,700 • $3,300
Roadwork (Asphalt)
$30 - $40
SY
25
50 • $1 000
_
Earthwork
CY
35
140 10
_
$4,390- $8,510
_Subtotal
Contingencies
20TO
$878 1 702
Surve in
50 - $1,000
ACRE
40
$30,000 000
Engineering
$878 - $1,702
—_ —
otal Cost
$36,246- $53,914
MacConnell & Associates, P.C. 6-2

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Village of Bald Head Island, North Carolina
Table 6-1 (continued)
Individual Recommendations(continued)
North Bald Head
1z Pipe Installation
$12 - 16
LF
70
$840 - $1,120
INynd _ _
15' Pipe Installation
$15
LF
70
$1 050 1400
Roadwork
$30. $40
SY
40
$1 200 1600
--------------Earthwork
---------
CY
90
Subtotal
450- $4,660
Contingencies
90 32
Surveying
750 $1,000
ACRE
70
500 - $70,000
Engineering
90 - $932
!•------.__..--------
ota I Cost
330 - 524
'Stede Bonne_t_Wy_nd_
15" Pipe Installation
15
LF
75
$1,125. $1,500
IT Pipe Installation
$18 - $22
LF
100
$1 800 - $2 200
Roadwork
$30
SY
50
$1,500 2 000
Earthwork
$4 - $6
CY
90
_
Subtotal
785-$6,240
Contingencies
57 • $1,248
------ -- - --
Surveying
$750 - $1,000
ACRE
60
$45,000 - $60 000
--------------
Engineeri
57 • $1,248
— ---
ota I Cost
699 - $6B 736
:Cape Fear Trail
Earthw ork
$4 - $6
CY
80
- $480
3Cr Pipe Installation
$40 - $50
LF
400
16,000 - $20,000
Subtotal
480
ConbWncies
264- $4,096
— --Surveying
$750 - $1,000
ACRE
30
500 • $30,000
—
e
U264 - $4 096
otal Cost
672
;Green Teal Trail
Earthw ork
$4 - $6
CY
30
$120 - $180
Hr Pipe InstaNation
$18 - $22
LF
300
$5,400. $6,600
$5,520- $6,780
_SuUhA31
i
-- ----Conbngencies
o
$1,080 - $1,320
-- ---Surveying
$750-$1,000
ACRE
8
$6,000 000
----Engineering
2070$1080
- $1,320
Total Cost
$13,680- $17,420
All Areas
otal Cost
31, 56/-1,434,402
or rray not be necessary — — —
Note: These costs are rough estinvIes and rray change consideraby once a survey has been completed
MacConnell & Associates, P.C.
6-3

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Village of Bald Head Island, North Carolina
1
B. Responsibilities
tThere are several entities on the Island that provide certain functions. The cooperation of these
different interest groups is going to play a key role in the Island's stormwater management. Each
' of these groups has different needs for the water on the island and would like to see it managed in
a way beneficial to their needs. The different groups on the island are the Village of Bald Head
' Island, Bald Head Island Utilities, Bald Head Island Club, Bald Head Island Limited, Bald Head
Island Conservancy, the Property Owner's Association and the individual home owner's of Bald
Head Island affected by the recurring flooding on the Island. Each of these groups and their
respective roles on Bald Head Island, are discussed below.
1. Responsibility of The Village of Bald Head Island
' The Village of Bald Head Island is the governing body for the entire island. It is responsible for
the preparation of this Stormwater Master Plan and shall be the ruling authority of the plan. They
' shall be responsible for verifying the proper installation of all piping, pumps or any other
equipment required for stormwater management. The Village shall also be responsible for
assuring compliance with the Stormwater Ordinance once it is passed.
' The Public Works Department is an entity under the Village's that is in charge of the
eP rt3' � �
physical structures over which the Village has authority. The Public Works Department is
' responsible for maintenance of the roads on Bald Head Island. Since many of these reads have
led to some of the flooding conditions on the Island by way of blocking natural drainage patterns,
they should be responsible for the installation of culverts underneath the roads where the natural
drainage patterns have been blocked. Because the culverts will then be part of the road network
for which the Utilities Department is responsible, they shall also maintain these culverts once they
' have been installed and assure no blockage occurs.
The Public Works Department should also be in charge of maintaining the flashboard riser that
controls the lagoon levels and allows water to be routed to Lighthouse Creek. The Public Works
Department is in the best position to monitor the water needs of the various parties on the Island.
They should be able to work equally well with Bald Head Island Utilities and the Bald Head
' Island Club which may have conflicting ideas about maintaining the level of the lagoon system.
This includes emergency lowering of the lagoon levels prior to large storm events. The Public
Works Department should also be responsible for major cleanings (dredging) and maintaining the
' culverts between these same lagoons. They are in the best position to fund these activities
through taxes, as everyone on the island benefits from this activity.
' Some of the areas which experience significant flooding are in low lying areas which would have
experienced flooding prior to development. However, the development in the locality of these
areas often increases the problem, due to increased impervious area, filling in of lots, and changes
' to the natural drainage patterns. Therefore, certain property owners receive benefits at the
expense of others. Due to the complex nature of these types of problems, we recommend that the
' Village of Bald Head Island through the Public Works Department be responsible for correcting
these problems. Funding the solutions would be through property taxes. Areas identified as
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Village of Bald Head Island, North Carolina
problem areas should be corrected. In addition, trying to determine which property owners pay
' for, and how much each benefits from the remedial activities, would be extremely difficult.
2. Responsibility of the Bald Head Island Utilities, Inc.
' Bald Head Island Utilities Inc. is responsible for the supply of table water and the collection
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and treatment of wastewater on the Island. They should work closely with the Public Works
' Department to provide information on the maintenance of the lagoon levels.
' 3. Responsibility of the Bald Head Island Conservancy
The Bald Head Island Conservancy ensures that the Island maintains an area in as much it's
' natural state as possible. This is for protection of the Island's wildlife and for wildlife viewing
purposes. These natural areas act as an observatory for many of the visitors to Bald Head Island.
The Conservancy will be responsible for maintaining their properties in accordance with the
' Stormwater Master Plan. The Conservancy will also be responsible for monitoring Bald Head
Creek for any algae blooms or other indicators that the creek is becoming overloaded with
nutrients or other contaminants.
4. Responsibility of the Property Owner's Association
' The Property Owners Association is responsible for looking out for the best interests of the home
owner's of Bald Head Island. They will be responsible for approving any structures (Le. pipes,
' pumps, etc.) that will be required in the common areas of the island. However, the installations
shall require that the land be returned to it's original condition. The Property Owner's Association
will also be responsible for pointing out potential violations of the Stormwater Ordinance to the
' Village of Bald Head Island for investigation.
5. Responsibility of the Bald Head Island Club
Bald Head Island Club provides much entertainment to the island in the way of gold croquet,
tennis, swimming pools and many of the restaurants. The Bald Head Island Club will responsible
' for routine maintenance of the lagoons and maintaining the lagoons that are owned by the golf
course. They will also need to coordinate with Bald Head Island Utilities and other lagoon
' owners to make sure connectivity of the lagoons is established and maintained. They should also
work closely with the Public Works Department to provide information on the maintenance of the
lagoon levels.
' 6. Responsibility of the Bald Head Island Limited
' Bald Head Island Limited is responsible for the continued development of the Island. They will be
responsible for ensuring that land is developed in accordance with the Stormwater Master Plan
and the Stormwater Ordinance. Also, Bald Head Island Limited will be responsible for informing
' future property owners of the flooding possibilities of the area. Many of the flooding problems
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Village of Bald Head Island, North Carolina
are in low lying, wetland type areas where the potential for flooding should have been anticipated
by the Bald Head Island Limited and the current property owners.
7. Responsibility of the Property Owners
Property owners that are experiencing problems with flooding in localized areas, as well as those
which are not impacted by runoff from others, should certainly have to bear the costs of any
stormwater collection and disposal facilities constructed on their property. The entire island
benefits from the resolution of the flooding problems. This will be done by way of propery taxes
under the jurisdiction of the Village.
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' Village of Bald Head
� Island, North Carolina
� Chapter 7
� Conclusions
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*MACCWMLL
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Village of Bald Head Island, North Carolina
7. Conclusions
It is evident that there are many stormwater management issues to deal with on Bald Head Island.
The frequency, duration and volume of flooding presents not only nuisance conditions but also
creates hazardous conditions. Since studies done by FEMA indicate that flooding will reach 5.8
feet mean sea level in a 10-year, 24-hour storm event and over 10 feet above mean sea level in a
' 100-year, 24-hour storm event, one can see that a large portion of the Island will experience
flooding during large storm events. Regardless of whether these flood prone areas could have
been avoided by development, how they have become flood hazards, and who made the decisions
' surrounding these issues, the problem exists and needs to be minimized to avoid a hazardous
situation.
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We feel as though the recommendations contained within this report provide general ideas for
retrofitting currently developed areas with some type of stormwater management system to
reduce the flooding frequency. These are general in nature; however without performing detailed
topographic surveys and hydrogeological investigations, general concepts are all that can be
provided. Detailed plans for constructing the proposed stormwater management systems will be
provided when surveys and analyses have been completed.
We also feel that good guidance for managing stormwater in the currently undeveloped portions
of the Island will aid in minimizing stormwater problems in these areas. This type of guidance can
be enforced through the adoption of the Stormwater Ordinance. Specifically, the minimum
elevations for roads, driveways, garages, first floor elevations and the sort should be incorporated
into the Stormwater Ordinance for all future development. Roads and driveways should be
constructed at a minimum elevation of 6-feet above mean sea level and first floor elevations of all
buildings are required by FEMA to be built 2-feet above the 100-year flood plain elevation, which
equates to a minimum elevation of 12.65 to 13.9 feet above mean sea level depending upon the
location of the proposed construction. This minimum elevation should also be utilized for -all
existing roadway rehabilitation projects.
It is estimated that within approximately six months to one year following a notice to proceed
from Bald Head Island, final design of many of the site specific fixes could be completed. This
includes surveys, design and construction. A significant amount of time is set aside for both
surveys and resolution of regulatory issues. However, the time for completion of these tasks may
actually vary from the time frames projected.
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