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PCB OU thermal incineration unit, 1996 |
Each environmental contaminant and circumstance requires a unique approach to cleanup. Many alternatives are considered, researched, tested, and evaluated. Several groups are involved with cleanup negotiations at Crab Orchard National Wildlife Refuge including the FWS, USEPA, Illinois EPA, and parties financially responsible for cleanup, when applicable. Criteria for alternative selection include: overall protection of human health and the environment, effectiveness, efficiency, implementability, and cost. The CERCLA process highly values public input, and public comments are also considered in selection of cleanup alternatives.
Physical cleanup begins as soon as cleanup action plans are completed
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PCB OU Repository under construction |
and agreed upon. Cleanup
of any number of Operable Units (OUs) can be occurring at any one time.
The CERCLA cleanup at the Refuge has
been divided into seven Operable Units based on types of contamination. These OUs are in different phases of investigation, cleanup, and long term monitoring
and include the following:
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EMMA OU site of a detonated land mine |
Since 1982, several OUs have been designated and closed as cleanup was completed:
- Five lead-painted water towers in the Water Tower OU were removed, and approximately 2800 cubic yards of lead contaminated soils underneath them excavated and transported offsite for treatment.
- Cleanup was completed in 1996 at three sites comprising the Metals OU. Nearly 40,000 cubic yards of soil contaminated with heavy metals was excavated, treated, and placed in an engineered landfill on the refuge.
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MISCA OU Site 36 digestor lid removal |
- In 1996, Slumberger Industries excavated and incinerated over 117,000 tons of soils contaminated with PCBs, heavy metals, and TCE from a fifty-acre site known as the PCB OU. This soil was placed in an engineered landfill on the refuge.
- In 1999, the U.S. Army excavated and replaced soils contaminated with explosives and lead as part of the Explosives/Munitions Manufacturing Areas (EMMA) OU.
The Army burned 800 pounds of TNT removed from these areas, excavated 20 acres
containing unexploded ordinances, and reforested 84 acres disrupted by
activities.
As contaminant removal is completed, OUs on Crab Orchard National Wildlife Refuge are officially closed. These closures are approved by the DOI, USEPA, and Illinois EPA. Operable Unit closures mark the successful completion of contaminant cleanup to safe levels for humans, plants, and wildlife, and are the ultimate goal for the FWS.
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Water Tower 1, once supplying water to the Crab Orchard National Wildlife Area residents, was felled and removed August 2000 |
It
was discovered that groundwater at 2 sites is
contaminated with solvents including TCE above
regulatory standards. In June, 2000, USEPA issued
an
Explanation of Significant Differences (ESD) to
the PCB OU. The ESD selected multi‑phase extraction
of chlorinated solvent contaminated groundwater,
with limited phytoremediation and monitored natural
attenuation, as the remedial technology to address
the groundwater contamination. The results of the
pilot test conducted as part of design studies
indicate that multi‑phase extraction will not be
effective in significantly reducing TCE
contamination at the site. USEPA plans to issue an
Amendment to the Record of Decision to select a
second remedy.
Site 14 is an approximately 2
acre site contaminated primarily with petroleum
hydrocarbons (benzene, toluene, ethyl benzene, and
xylene). A Record of Decision issued in October
2001, selected a remedy consisting of demolition of
a building, excavation and off-site disposal of
soils into a permitted landfill, treatment of
groundwater that seeps into the excavation area, and
groundwater monitoring. A Unilateral Administrative
Order was issued by USEPA to Diagraph (Illinois Tool
Works is the successor to Diagraph) directing the
remediation of the site. Illinois Tool Works
completed the excavation and off-site disposal
portion of the remedial action in the Summer of
2007. They excavated to lower cleanup numbers in
lieu of completion of a limited human health risk
assessment and performance of monitored natural
attenuation of groundwater. Illinois Tool Works
will conduct groundwater monitoring to evaluate the
performance of the remedy in achieving groundwater
cleanup standards.
The Lake Monitoring Operable Unit consists of the
water and sediment within the boundary of Crab
Orchard Lake. A Preliminary Screening Analysis
was conducted in 2000-2001 to assess contaminants in
the lake to evaluate risk. As there is a
potential risk to some ecological receptors, the
USFWS is conducting further evaluation; however,
that investigation will be incorporated into other
OUs.
The
Illinois Department of Natural Resources (IDNR)
publishes advisories of fish consumption.
An advisory against the consumption of certain
species of fish at Carb Orchard Lake has been in
effect since the early 1980s because of elevated
levels of PCBs and recently mercury. PCB
levels in fish have decreased since the original
advisory.
Additional and
Uncharacterized Sites (AUS) OU
DOI formed the AUS
OU from 1997 to 1999 to address potential releases of hazardous substances not
included in existing OUs at the Refuge. The AUS OU sites are spread throughout
the former Illinois Ordnance Plant area and include former manufacturing
facilities, industrial storage areas, and disposal areas. The Preliminary
Assessment/Site Inspection revealed elevated levels of heavy metals and
pesticides in soils and concentrations of solvents, including trichloroethylene
(TCE), exceeding groundwater regulatory standards. Thirty-two sites are
recommended for remedial investigation. An
Administrative Order on Consent
(AOC)
was entered into with General Dynamics Ordnance & Tactical Systems (GDO&TS) for
performance of the RI/FS at the AUS OU with USFWS conducting the baseline risk
assessment. The RI/FS will further define the nature and extent of
contamination.
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