Carolina Bays: A Natural Wastewater Treatment
Program
Background
Site Description
Operations and Management
Performance
Ancillary Benefits
Awards
Acknowledgements
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Background
In cross section, Carolina bays are shallow, bowl-shaped depressions, often
filled with peat and surrounded by sandy ruins.
Carolina bays are mysterious land
features often filled with bay trees
and other wetland vegetation.
Because of their oval shape and
consistent orientation, they are
considered by some authorities to
be the result of a vast meteor
shower that occurred thousands of
years ago. Others think the natural
forces of wind and artesian water
flow caused the formation of lakes,
which later filled with vegetation.
Whatever their origin, over
500,000 of these shallow basins
dot the coastal plain from Georgia
to Delaware. Many of them occur
in the Carolinas, which accounts
for their name. Most Carolina bays
are swampy or wet areas, and most of the hundreds present in coastal Horry County, South Carolina, are
nearly impenetrable jungles of vines and shrubs. Because of population growth and increased tourism in
Horry County, expansion of essential utility operations was required. The regional water utility, the
Grand Strand Water & Sewer Authority (GSWSA), retained CH2M HILL in the late 1970s to evaluate
wastewater treatment and disposal options.
Locations to dispose of additional effluent were extremely limited because of sensitive environmental
and recreational concerns. The slow-moving Waccamaw River and Intracoastal Waterway, into which
existing facilities discharged, could not assimilate additional loading without adverse effects on water
quality and resulting impacts on tourism and recreational activities.
On the basis of extensive research and pilot studies, CH2M HILL recommended discharging effluent
from a new 2.5 million gallon per day (mgd) wastewater treatment plant to four nearby Carolina bays.
The U.S. Environmental Protection Agency (EPA) considers the use of wetlands to be an emerging
alternative to conventional treatment processes. As a result, EPA Region IV and the South Carolina
Department of Health and Environmental Control awarded an Innovative /Alternative Technologies
funding grant for the Carolina bays treatment project, enabling GSWSA to provide expanded collection,
treatment, and disposal services at affordable costs.
This grant was used for planning, pilot testing, design, and construction of the full-scale Carolina Bay
Natural Land Treatment Program.
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Site Description
After 5 years of intensive study to evaluate viable
treatment and disposal alternatives, four Carolina bays
were selected as treatment sites. Site selection criteria
focused on three primary factors: 1) distance from the
wastewater source, 2) available treatment area, and 3)
environmental sensitivity. The bays chosen for the
GSWSA treatment complex had been previously
affected by man and were the least environmentally
sensitive of the bays considered.
Fourbays covering 700 acres make up the Carolina
. . , . Bay Natural Land Treatment System. Plant
Carolina Bays 4-A and 4-B are joined along a portion succession in these bays is naturany controlled by
of their margins and encompass about 390 acres of fire as seen in Bay 4B (secondfrom left).
dense, shrubby plant communities with scattered pine
trees. This plant association is called "pocosin" after an Indian word describing a bog on a hill. A
powerline right-of-way bisects Bay 4-A and also cuts through the southern end of Bay 4-B.
The 240-acre Pocosin Bay (Bay 4-C) is also dominated by pocosin vegetation and is filled with up to 15
feet of highly organic peat soils. This bay had received the least amount of prior disturbance and is being
used only as a contingency discharge area. Bear Bay (Bay 4-D) covers 170 acres and is dissimilar from
the other bays because it is densely forested by pine and hardwood tree species. A large portion of this
Carolina bay was cleared for forestry purposes in the mid-1970s but has since been revegetated with a
mixture of upland and wetland plant species.
Carolina Bay Project Summary
George R. Vereen WWTP
Design flow = 2.5 mgd
Pretreatment by aerated lagoons in
parallel trains, one completely
suspended lagoon and three partially
suspended lagoons per train
Lagoon total area = 4.4 acres
Total aeration = 192 hp
Disinfection by contact chlorination
Carolina Bays
Average hydraulic loading rate = 1 in./week Effluent distribution system
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7,000 feet of 10-inch aluminum piping 30,000 feet of elevated boardwalks
Final effluent permit limits
BODS monthly average 12 mg/1
TSS monthly average 30 mg/1
NH3 summer (Mar-Oct) 1.2 mg/1
NH3 winter (Nov-Feb) 5.0 mg/1
UOD summer (Mar-Oct) 481 Ib/day
UOD winter (Nov-Feb) 844 Ib/day
Total treatment area = 702 acres
Bay4A
combined = 390 acres
Bay4B
Bay 4C (Pocosin Bay) = 142 acres
Bay 4D (Bear Bay) = 170 acres
Biological criteria (allowable % change)
Bay
4A 4B 4C 4D
Canopy cover 15 15 0 50
Canopy density 15 15 0 50
Subcanopy cover 15 15 0 50
Plant diversity 15 15 0 50
Project Cost Summary
Pilot system $411,000
VereenWWTP 3,587,000
Effluent distribution system
(including land) 2,490,000
Engineering (pilot and
full scale) and monitoring 1,332,000
Total cost $7,820,000
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Operations and Management
The carefully planned and monitored use of Carolina bays for
tertiary wastewater treatment facilitates surface water quality
management while maintaining the natural character of the bays.
After undergoing
conventional primary and
secondary treatment
processes at the George R.
Vereen Wastewater
Treatment Plant, the
wastewater is slowly released
into a Carolina bay for
tertiary treatment, rather than
directly to recreational
surface waters of the area.
The plants found in the
Carolina bays are naturally adapted to wet conditions, so the
addition of a small amount of treated water increases their
productivity and, in the process, provides final purification of the
wastewater.
iigh-nutrient water in the bays
increases plant productivity.
Aluminum pipes distribute the treated
effluent.
The treated effluent can be distributed to 700 acres within the four
selected Carolina bays through a series of gated aluminum pipes
supported on wooden boardwalks. Wastewater flow is alternated among the bays, depending on effluent
flow rate and biological conditions in the bays.
Water levels and outflow rates can be partially controlled in Bear Bay through the use of an adjustable
weir gate. Natural surface outlets in the other three bays were not altered by construction of the project.
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Performance
BQd£ TSS merited, TN
Compliance with biological criteria protects the Carolina Bay plant
communities from undesirable changes.
Operational water quality since 1987 indicates significant assimilation
of residual pollutants is occur ing in Bear Bay.
In 1985, after site selection was completed and before wastewater distribution began, baseline studies
were conducted on the hydrology, surface water, and groundwater quality and flora and fauna of Bear
Bay. Treated effluent was first discharged to the bay in January 1987, and monitoring was continued to
measure variations in the water quality and biological communities. By March 1988, the pilot study had
been successfully completed and the Carolina Bay Natural Land Treatment Program was approved for
full-scale implementation by EPA and South Carolina regulatory agencies.
In October 1990, the Carolina Bay Natural Land Treatment System was dedicated as the Peter Horry
Wildlife Preserve and began serving the wastewater treatment and disposal needs of up to 30,000 people.
Ongoing monitoring indicates that significant assimilation is occurring in Bear Bay before the fully
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treated effluent recharges local groundwater or flows into downstream surface waters. Biological
changes have been carefully monitored, with the main observed effect being increased growth of native
wetland plant species.
Pan-* Wwi
LEGEND
* Surfaco Watur
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Variations in the water quality of Bear Bay are closely monitored.
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Ancillary Benefits
The Carolina Bay Natural Land Treatment Program not only serves
wastewater management needs but also plays an important role in
protecting the environment. Although the Carolina bays have been
recognized as unique, 98 percent of the bays in South Carolina have been
disturbed by agricultural activities and ditching. The four bays in the
treatment program will be maintained in a natural ecological condition.
These 700 acres of Carolina bays represent one of the largest public
holdings of bays in South Carolina.
The use of wetlands for treatment can significantly lower the cost of
wastewater treatment because the systems rely on plant and animal
growth instead of the addition of power or chemicals. Also, the plant
communities present in the wetlands naturally adjust to changing water
levels and water quality conditions by shifting dominance to those
species best adapted to growing under the new conditions.
Wetland plan communities
easily adjust to changing
conditions
Carolina bays provide a critical refuge for rare plants and
animals. Amazingly, black bears still roam the bays' shrub
thickets and forested bottom lands just a few miles from the
thousands of tourists on South Carolina's beaches. Venus
flytraps and pitcher plants, fascinating carnivorous plants that
trap trespassing insects, occur naturally in the Carolina bays.
In addition, the bays are home to hundreds of other interesting
plant and animal species.
The Carolina Bay Nature Park, to be managed by GSWSA, is
currently being planned. The focal point of the park will be an
interpretive visitor center open to the public. This simple
structure will be designed and built in harmony with its
surroundings on a sand ridge overlooking two Carolina bays. The center will feature displays about black
bears and Venus flytraps as well as theories on the origin of the Carolina bays, their native plant
associations, including the associated sandhill plant communities, and their use for natural land
treatment.
Pitcher plants occur naturally in the
Carolina bays.
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The visitor center will be the hub for three hiking trails, including
a 5-minute walk through an adjacent cypress wetland; a 45-
minute trail though Pocosin Bay and associated titi shrub swamp
and long-leaf pine uplands; and a one-hour walk through a
heavily forested Carolina bay and its adjacent sandhill plant
communities.
Combined with the interpretive nature center, the hiking trails
and boardwalks will provide public access, scientific research,
and educational opportunities that were previously unavailable.
The designation of the Peter Horry Wildlife Preserve in October 1990 was the first step in establishing
this park.
_. -:l^
An interpretive visitor center is planned as the focal point of the
Carolina Bay Nature Park.
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Awards
—m
In 1991, the Carolina Bay Natural Land Treatment Program won
the Engineering Excellence Award, Best of Show, from the
Consulting Engineers of South Carolina.
The American Consulting Engineers Council (ACEC) Grand
Conceptor Award, considered the highest national honor in the
consulting engineering field, was awarded to CH2M HILL in
1991 for its implementation of the Carolina bays project. ACEC
selected the project from a field of 127 national finalist entries,
each of which had earlier won in state or regional engineering
excellence competitions.
Acknowledgements
Numerous individuals and organizations have shared the vision necessary to implement the Carolina Bay
Natural Land Treatment Program. Some of the key organizations and individuals include the following:
Grand Strand Water and Sewer Authority
George R. Vereen, Former Chairman
Sidney F. Thompson, Chairman
Douglas P. Wendel, Executive Director
Fred Richardson, Engineering Manager
Larry Schwartz, Environmental Planner
South Carolina Department of Health and Environmental Control
Samual J. Grant, Jr., Manager, 201 Facilities Planning Section
G. Michael Caughman, Director, Domestic Wastewater Division
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Ron Tata, Director, Waccamaw District
U.S. Environmental Protection Agency
Harold Hopkins, Former Chief, Facilities Construction Branch, Region IV
Robert Freeman, 201 Construction Grants Coordinator, Region IV
Robert Bastian, Office of Wastewater Management
CH2M HILL
Richard Hirsekorn, Project Administrator
Robert L. Knight, Project Manager and Senior Consultant
Douglas S. Baughman, Project Manager
South Carolina Coastal Council
H. Stephen Snyder, Director, Planning and Certification
South Carolina Wildlife and Marine Resources Department
Stephen H. Bennett, Heritage Trust Program
Ed Duncan, Environmental Affairs Coordination
U.S. Fish and Wildlife Service
Harvey Geitner, Field Supervisor
U.S. Army Corps of Engineers
Don Hill, Director, 404 Section
This brochure was prepared by CH2M HILL for the U.S. Environmental Protection Agency.
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