Carolina Bays: A Natural Wastewater Treatment

                               Site Description

                               Operations and Management


                               Ancillary Benefits



                                  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.

                                 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

            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

                   combined = 390 acres
            Bay 4C (Pocosin Bay) = 142 acres
            Bay 4D (Bear Bay) = 170 acres

      Biological criteria (allowable % change)

                            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

                    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
                                                                 iigh-nutrient water in the bays
                                                                 increases plant productivity.
   Aluminum pipes distribute the treated
                                  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.


                                   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

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
                               *  Surfaco Watur
                       Variations in the water quality of Bear Bay are closely monitored.

                               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
                                      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
Pitcher plants occur naturally in the
        Carolina bays.

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

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.

                                 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.
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


      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.