During the 40+ years that Hercules
produced toxaphene in Brunswick, Georgia, pesticide waste was pumped into
the Terry Creek area in the expectation it would dilute and disappear.
However, high concentrations are still found, and the contamination is
extensive. Much of the toxaphene remains in the drainage, even though
dumping was stopped over 25 years ago
Toxaphene coats the bottom, sides,
banks, and islands of the Terry Creek Disposal Area. Toxaphene is found
several feet deep in marsh sediments, and components of toxaphene are
extracted from fin and shellfish that breed and forage in the marsh.
Toxaphene is a carcinogenic
mixture of chemicals banned from use and manufacture two decades ago. The
material is a "biocide," a broad-spectrum toxin that kills a diversity of
animals including insects, fish, birds, and man. Toxaphene exerts lethal
effects by enzyme inhibition and mutation, and possibly by steroid mimicry.
It is extremely stable in the environment, with a half-life (time to break
down) of around 10 years. Its breakdown products are potentially harmful as
well. In the class of organochlorines, toxaphene is a mixture of several
hundred different chemicals produced by treating and chlorinating pine tar.
Unfortunately, although the
Environmental Protection Agency (EPA) has known of the problem at Terry
Creek for a quarter century, historical site monitoring was conducted so
poorly that we have no information on how fast toxaphene is undergoing
natural attenuation, or even if it is breaking down. Worse still, dredging
operations were allowed to continue during this period, which has created
additional problems of toxaphene distribution.
The Terry Creek Site is an
estuary. Estuaries occur where fresh water from upland rivers mixes with
ocean salt water. Plants and animals that live permanently in an estuary
must be adapted to a life of changing salinity (salt concentration),
temperature, current direction, and silt flow. During high tides the estuary
may have mostly open-ocean species of fish, during low tide the fish
populations may reflect the freshwater river system. Estuaries are
recognized as the oceans "nurseries" since they often function as the
primary breeding ground for open water species. The Terry Creek system is
bordered by "wetlands" -- areas of mostly terrestrial plants and animals
adapted to occasional flooding. The scientific literature does not show
another example of an estuary/wetland system polluted to this degree with a
single complex pesticide. However, since the area is clearly a productive
fishery, it is fair to assume that the site impacts a much broader area than
just the local creeks. Additionally, the area is a forage zone for Federally
protected waterfowl and turtles, both of which may be adversely affected.
Based on the historical
descriptions in the Site Record, the marshes of the Terry Creek system were
relatively undisturbed in the early part of this century. The area seems to
have been a major source of shrimp, crabs, fish and shellfish. In the late
1930's, portions of the drainage were dredged to allow access of commercial
vessels. This dredging was conducted by the U. S. Army Corps of Engineers
(the USACE, or “Corps”) and the channels were maintained at irregular
intervals until the present. The dredge spoils were placed as either spoil
islands or spoil banks along the channel.
Hercules began manufacturing
toxaphene at the current plant site in 1948. Toxaphene dumping into
Dupree/Terry Creek occurred throughout the history of the product. Estimates
are that 250-300 pounds per day were emptied directly into the estuary
before 1972 when legislation forced Hercules to treat waste before it left
the plant. Although there were some spills and overflows during the final
years of toxaphene production, the amounts released between 1972 and 1980
seem to have been close to background levels. During the peak of toxaphene
production and pollution of the Terry Creek system, the USACE dredged the
waterways to relieve silting of the channels. Consequently, some
toxaphene-contaminated silts were dredged and placed in spoil impoundments.
A network of berms and dikes occur
within the marsh. These are constructed to reduce flooding of upland areas
near the marsh. Weirs are also placed within the dikes to improve sediment
settling. Weirs control water flow out of an impoundment area. By regulating
the height of the weir drain, a ponding action allows sediments to settle
out before water is released, resulting in cleaner water released to the
system. A weir regulates water outflow between the Hercules Outfall ditch
and Dupree Creek. Over the decades there have been numerous dike raisings,
new berm constructions and dredging operations. Some of the construction
used toxaphene contaminated soil, others did not. Extensive testing has not
been performed in these areas to evaluate for the presence of pesticide.
Dredging operations were in the Terry Creek portion of the estuary. Dupree
Creek has apparently not been dredged, and toxin occurrence has not been
evaluated sufficiently in that portion of the creek.
The Back River forms the
northeastern boundary of the site. Terry Creek forms the southern boundary,
and the northwestern edge is Dupree Creek. The area is roughly triangular,
with the southern edge parallel to Torras Causeway.
Running into Dupree Creek from the
Hercules plant is the "Outfall Ditch" where toxaphene and other waste from
the Hercules Plant were released into the marsh. Toxaphene concentrations
are high enough in this area to consider it a "source" of continued
contamination. The Outfall Ditch merges with the marsh near the confluence
of Dupree and Terry Creeks. This contamination zone extends eastward along
the bed and banks of both creeks.
There are four spoil deposition
areas. Area 1, the Main Dredge Spoil area is a 72 acre rectangular area
between Terry and Dupree Creeks. Toxaphene concentrations in this area are
as high as 240 ppm (parts-per-million) in surface samples, and in subsurface
samples up to 430 ppm. The area is surrounded by a 22-foot high dike, built
in two stages. The second round of construction likely used toxaphene
contaminated dredge material. Three weirs drain water from the impoundment
into the marsh along the Dupree creek border. There are no linings or other
barriers to prevent toxaphene from migrating vertically beneath the site.
Area 2, the Riverside Dredge Spoil
Area, is adjacent to the residential housing along Norman and Crandall
Streets, and Riverside Road. This area, about 52 acres, is parallel to the
Back River. Pesticide concentrations in subsurface soil range to 23 ppm.
Area 3 comprises about 7 acres
within a residential area on Terry Creek Drive, directly south of Area 1 and
Terry Creek, parallel to Torras Causeway. Concentrations in this area are as
high as 9 ppm.
Area 4 is the Carter’s Island
Spoil Area, a small deposition area just south of the confluence of Terry
Creek and the Back River. Toxaphene concentrations reach 100 ppm in this
There are nine trailers and four
houses within Area 3; Areas 1, 2, and 4 are unpopulated. Some portions
within Area 2 may be developed in the future.
There are two aquifers underlying
the site. The main source of municipal drinking water used by local
residents is the Upper Floridan aquifer, which appears unaffected by the
site. According to documents in the Repository, the shallower surficial
aquifer is not utilized around the site. Documentation for this conclusion
was not readily apparent, and some citizens have questioned the conclusion.
However, it seems unlikely that toxaphene would migrate to the aquifer from
the marsh site in sufficient amounts to constitute a hazard to any well in
the area. Surface water, sediments, and local soils are the main concern.
Air pollution is not now a problem, however depending on the choice of
cleanup methods, air pollution may become a problem in the future. There are
a number of other toxins in the system, consistent with the site being used
for 60+ years as an industrial chemical dump. The range of these chemicals
is poorly defined in site documents.
The site repository documents
indicate legal complexities at this site. It is not clear if these events
are inhibiting the pace or nature of the cleanup. There appear to be some
disputes over toxaphene origins and cleanup responsibility at this site. The
Administrative Record shows correspondence from the Corps of Engineers
disputing EPA claims that spoil impoundments controlled by the USACE are a
"source" of toxaphene contaminated materials. Further, EPA suggests that
toxaphene in the creek channels may come from Area 1 weirs that regulate
water flow to Dupree Creek. The Corps disputes that. A recent study seems
to support the USACE’s position that toxaphene is confined within the berms
of the Main Dredge Spoil Area. There seem to be jurisdictional disputes
over ownership of some lands impacted by toxaphene spoils placed on shore.
Long-term residents all agree that dredge spoils, possibly containing
toxaphene, were used to reduce wetland marsh areas. Some of these areas may
now contain residences. The Record provides only general locations for these
areas, the investigation appears poorly performed, incomplete and
Conclusions, Part I
The full extent of the
contamination is poorly defined at this time. Based on the testing, there is
contamination in residential neighborhoods bordering the marsh. Testing and
information from local residents seems to support claims that dredge spoils
were used to form residential areas. Thorough studies are still needed to
better understand the scope of the problem.
Part 2 of this series will discuss
toxaphene analysis and sampling at this site. It appears that some of the
methodology used is compromising integrity of the assessment and may be
under-representing the full extent of the problem.
Part 3 will discuss cleanup
options for the dredging and treatment of the marsh.
by R. Kevin Pegg, Ph.D.; edited by Dr. Mary S. Saunders. Copies of the
newsletter are available from the GEC, at the Glynn County library, or at
www.NucleicAssays.com/tags on the Internet.
"This project has been
funded wholly or partly by the U.S. Environmental Protection Agency under
Assistance Agreement Number
to The Glynn
Environmental Coalition, Inc. The contents of this document do not
necessarily reflect the views and policies of the U.S. Environmental
Protection agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use."