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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

 .1

 I
 3> 30
 lil
    20
Pocosin Bay
(Bay 4-C)
        Mineral
      or Sediments
               Mineral
               Sediments
Mineral
Sediments
       Dashed lines are approximate.
      fl vffl  * *  b -^ h.V^*^ " ^*\
                                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
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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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