TAG reports Volume 4, Number 3;
October, 1995
009 Superfund Site Remedial Investigation: Testing and Preliminary Remedial Action At The Landfill
Overview
Progress is occurring on several projects at the 009 landfill. The neighborhood cleanup
has reached its final stages; the testing and cleanup of the schoolyard is progressing;
and, the preliminary in situ experiments are underway at the landfill. Remediation and
retesting of Nix Lane/Benedict Road occurred in the spring of 1995. At the completion of
the neighborhood remediation soil over about 4 acres was removed to a depth of 1 foot and
new soil cover added. The contaminated soil is now in a "temporary" cell at the
009 site. Roads, driveways, walkways, playgrounds, gardens, lawns and homes were cleaned
of toxaphene residue left from transportation a decade and a half ago.
Recent testing on the Altama Elementary schoolgrounds adjacent to the Hercules 009
Superfund Landfill identified several new areas of toxaphene contamination. These testing
results show contamination in areas near the drainage stream, within and around spoil
piles left over from ditch dredging activities, and in the wooded areas closest to the
dumpsite. Earlier testing performed in 1990 indicated contamination only on the banks near
the stream. This new data shows that contamination is more widespread than previously
predicted, necessitating additional studies to guide remediation efforts on school
property.
In September, 1995, the remediation contractor mobilized at cell 1 of the landfill to
perform tests of the in situ stabilization process. Cell 1 was selected based on earlier
studies indicating this cell is the most complex and challenging of the six containment
cells. A cement formulation compatible with site soils was formulated after nearly one
year of laboratory testing.
Cleanup and Retesting of the Neighborhood
An extensive cleanup was performed in the neighborhood adjacent to the 009 dumpsite.
Residents were evacuated due to safety concerns arising from toxic dust and movements of
heavy equipment. Topsoil was removed from around the homesites, driveways, the roadbeds of
Nix lane and Benedict Road, and playgrounds near the Beverly Shores Baptist church.
Numerous contaminated trees and shrubs were also removed during this process.
Prior to excavation the site was surveyed using a composite sample grid testing system.
Composite testing is a form of sampling using several "discrete" (individual)
samples mixed together. The area is subdivided into a gridwork of testing cells. Several
samples are taken from each cell, mixed, and tested as a composite. The value obtained is
applied to the entire grid cell. A survey in the neighborhood utilized a series of 900
square-foot grid cells (30'x30') placed immediately adjacent to Nix Lane and Benedict
Road. Five individual samples were taken from each cell and composited for testing.
Control cells used only discrete samples for testing. These control cells are important to
ascertain the degree of dilution from using composite testing. The main disadvantage of
composite testing occurs when one of the individual samples used in the combination is
much lower than the others. The resulting dilution of the composite leads to under
reporting the chemical of concern.
In the interior lots, away from the road, 3,600 square- foot testing cells were used,
again with five samples composited for testing. Even further from the road 8,100
square-foot testing cells were used. Unfortunately, the testing contractor did not perform
controls for the larger 3,600 and 8,100 square-foot grid cells. Consequently, the data
from testing of the larger cells has poor scientific value and the possibility of under
reported toxaphene levels does exist.
After the initial round of testing for toxaphene the excavation and filling of the
neighborhood began. An 8,000 cubic yard temporary holding cell for contaminated soil was
constructed on-site. The entire length of Benedict road and Nix Lane was removed and
reconstructed. The original fencing between the site and the neighborhood was reworked.
Many trees and shrubs that contained contaminated soil were lost during the cleanup. New
access roads to the site were added. Trucks can again enter directly from GA Spur 25
rather than driving through the neighborhood. The Hercules gate to the property was also
moved from the end of Nix Lane to Benedict Road further alleviating traffic. In the course
of the cleanup most driveways were excavated and restored. Drainage improvements should
assist in preventing runoff from the dump moving towards the homesites. Roughly 10,000
cubic yards of toxaphene waste was removed to the dumpsite.
After excavation and backfilling with clean soil the area was again tested for toxaphene.
Regrettably, while the initial testing used an instrument procedure (Gas Chromatography/
Mass Spectrometry) the retesting employed an immunoassay-based test. Data analysis shows
very poor agreement between the two testing procedures.
The use of increasing grid size, lack of controls and mixed testing protocols is a biased
pattern of testing. However, despite the fact that testing procedures contained many
technical flaws, and was of poor scientific merit, neighborhood contamination was shown to
be more widespread than previous estimates. Altogether, about 4 acres around the homesites
were found to exceed EPA standards for human health.
Due to the biased nature of the testing procedures it is not easy to assess the additional
risk to the residents imposed by toxaphene. High levels of toxaphene were found, although
the average sample was in the range of 1 to 5 ppm. Since the EPA accepts a level of 0.25
ppm for residential areas, it is highly likely that residents were exposed to increased
cancer risks. It is also fair to say that, given the extent of the cleanup, the increased
risk is now minimal. However, new discrete testing may reveal toxaphene contamination
missed by the composite testing, leading to a re-evaluation of the safety of the
neighborhood.
Background of Schoolyard Testing Activity
The Hercules 009 toxaphene dumpsite is adjacent to the Altama Elementary School. The
proximity of the dump to the school is controversial within the community since toxaphene
is considered by authorities as potentially carcinogenic to humans. Additionally, the
dumpsite is uncapped and erosion towards the schoolgrounds is documented. The dump closed
in 1980 after toxaphene waste was found off-site in the drainage ditch next to the school.
However, not until 1992 did testing results of the school property become publicly
available. The testing showed contamination in a high percentage of the samples taken from
the banks of the shallow drainage ditch that separates the school from the dumpsite.
During the 1980's work crews customarily removed built up materials that restricted water
flow in the drainage ditch. This ditch drains stormwater from the landfill and mall areas.
The dredged material was deposited on the banks of the stream as "spoil piles."
It is assumed that the toxaphene discovered in 1992 on schoolgrounds came directly from
this dredging activity. In 1993 Hercules conducted a voluntary testing of the school
playground areas for toxaphene. This study examined only the immediate vicinity of the
playground and areas where bus activity occurs. These samples were all found to be
negative, ensuring that no children were directly exposed during school activities. Also
in 1993, Hercules agreed as part of the Record of Decision to remove the spoil piles on
school property and perform additional off-site testing.
1994/95 Testing
During the summer of 1994 Hercules mobilized their engineering resources for a cleanup of
the neighborhood. During this time Hercules contractors also removed the dredge spoil
piles lining the stream banks on school property. Samples of the surface soils along the
stream bank and around the woods outside of the playground were taken to determine
potential migration of contamination on the school property. All of the spoil material was
transferred to the temporary cell for later processing at the landfill. Unfortunately, the
spoil material was not tested for toxaphene levels. Such testing would provide insight
into the amount of toxaphene in the ditch over the several years of the landfill. Samples
from beneath and around the spoil piles were found to be extensively contaminated,
indicating migration has occurred to a greater extent than thought previously.
Current testing scenario
More extensive testing is now planned for the schoolgrounds area. The plan appears to call
for testing after removal of contaminated surface soil in the vicinity of the spoil piles.
A strip 15-feet wide running the length of the former piles will be removed to a depth of
1 foot. Composite testing will occur in a grid pattern along these areas. A row of 30-foot
grids will be sampled parallel to the spoil area, followed by 60-foot grid cells parallel
to the row of 30-foot cells. The workplan estimates that sampling will extend 150 feet
east of the drainage ditch towards the school. Additional excavation will occur as needed,
based on the sampling results. Clean fill dirt will be added to the excavated areas and
antierosion measures will be utilized to stabilize the excavated stream bank.
Some trees may need to be removed in the process of remediating the stream banks. All
contaminated materials will be deposited in the temporary storage cell for later
stabilization. As yet there is no plan for final redesign of the drainage ditch. The
current workplan lists five options for engineering the drainage ditch:
No action;
Construction of a concrete channel;
Installation of filter fabric;
Installation of a clay cover, or;
Installation of a storm sewer pipe.
The workplan calls for community input on the final design: "Discussions with
Glynn County representatives will be required to obtain critical input for evaluation of
alternate design options for the drainage ditch." At a public meeting in 1993 county
engineers advanced the concept of an inexpensive PVC storm sewer pipe used as a culvert
and covered with fill. This would provide the maximum protection with little long-term
maintenance.
In situ stabilization testing
The Record of Decision between the EPA and Hercules calls for testing of in situ
stabilization at the landfill. Although underground stabilization is used at other sites
to immobilize toxic inorganic material, the process is considered experimental for
chlorinated hydrocarbon pesticides such as toxaphene. If the process does not fully
immobilize toxaphene at the site, the ROD requires use of the more expensive process of
extraction by soil washing. Over the past year site soils have been studied under
laboratory conditions to develop a cement formulation that reduces toxaphene migration and
tolerates weather conditions expected at the site. Additionally, the site is now more
fully characterized for buried debris, extent of contamination, and soil conditions.
At this time an experimental workplan is underway to test theories on the best way to
proceed with in situ stabilization. Cell 1, the northern most cell was chosen since that
cell is the most complex and therefore the most difficult to remediate. During these
studies hollow augers are drilled into the cell and subterranean concrete mixing
immobilizes the waste. A precise timetable is not yet available for data on hardness,
permeability or toxaphene migration from the study areas. However, success or failure will
likely take several months to determine.
LINKS:
Jump to top of page
visit TAG Advisor R. K. Pegg's Homepage
Return to TAG table of Contents