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BACKGROUND
Carolina bays are mysterious land
features often filled with bay
trees and other wetland vegeta-
tion. Because of their oval shape and
consistent orientation, they are consid-
ered 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 recre-
ational concerns. The slow-moving
Waccamaw River and Intracoastal
Waterway, into which existing facilities
discharged, could not assimilate addi-
tional 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 recom-
mended 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.
In cross section, Carolina bays
are shallow, bowl-shaped
depressions, often filled with
peat and surrounded by
sandy rims.
50
: 45
^ 40
i. 35
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I
3> 30
lil
20
Pocosin Bay
(Bay 4-C)
Mineral
•or Sediments
Mineral
Sediments
Mineral
Sediments
Dashed lines are approximate.
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r , t j. ' ' " , ' ' *""'"
'' Note difference irihorizorttal artd vertroafsoales.
500 1,000
Horizontal Scale (Meters)
1,500
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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 treat-
ment 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 environmen-
tally sensitive of the bays considered.
Carolina Bays 4-A and 4-B are
joined along a portion of their margins
and encompass about 390 acres of
dense, shrubby plant communities with
scattered pine trees. This plant associa-
tion 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 reveg-
etated 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
two 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
7,000 feet of 10-inch aluminum piping
30,000 feet of elevated boardwalks
Final effluent permit limits
BODS monthly average 12mg/l
TSS monthly average 30 mg/l
NH3 summer (Mar-Oct) 1.2 mg/l
NH3 winter (Nov-Feb) 5.0 mg/l
UOD summer (Mar-Oct) 481 Ib/day
UOD winter (Nov-Feb) 844 Ib/day
Total treatment area = 702 acres
Bay 4A "I
> combined = 390 acres
Bay 4B J
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
Vereen WWTP 3,587,000
Effluent distribution system
(including land) 2,490,000
Engineering (pilot and
full scale) and monitoring 1,332,000
Four bays covering 700 acres
make up the Carolina Bay
Natural Land Treatment
System. Plant succession in
these bays is naturally
controlled by fire as seen in
Bay 4B (second from left).
Total cost $7,820,000
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OPERATIONS AND
MANAGEMENT
The carefully planned and moni-
tored use of Carolina bays for
tertiary wastewater treatment
facilitates surface water quality manage-
ment while maintaining the natural
character of the bays.
After undergoing conventional
primary and secondary treatment pro-
cesses at the George R. Vereen Waste-
water 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.
The treated effluent can be distrib-
uted 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.
High-nutrient water in
the bays increases plant
productivity.
Aluminum pipes distribute
the treated effluent.
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PERFORMANCE
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 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.
Variations in the water quality of
Bear Bay are closely monitored.
Operational water quality since 1987 indicates significant
assimilation of residual pollutants is occurring in Bear Bay.
Tree .
Cover 5
(M2/HA) 4_
30% Decline 3-
50% Decline 2
°S*
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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 waste-
water 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.
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
Wetland plant communities
easily adjust to changing
conditions.
Pitcher plants occur naturally
in the Carolina bays.
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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 overlook-
ing 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 associ-
ated sandhill plant communities, and
their use for natural land treatment.
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.
An interpretive visitor center is
planned as the focal point of
the Carolina Bay Nature Park.
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Awards
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
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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