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During investigations conducted in August 1996, the U.S. Environmental Protection Agency (EPA) sampled several former lagoon and overflow lagoon areas and a former underground collection basin (the Pit) at the CTA. Primary findings included the detection of trichloroethylene (TCE) at elevated concentrations in lagoon-area soils and in underlying groundwater.
On June 27, 1996, the Missouri Division of Geology and Land Survey (DGLS) injected fluorescein dye into a small pond which is located approximately 200 feet northeast of the CTA Pit. The dye was detected in the Gibson Spring entry into Hickory Creek, an entry which is approximately 2 miles north-northeast of the injection site. The travel time of the injection was calculated at between 875 and 2,100 feet per day.
Over 200 private drinking water wells, located northerly and generally downgradient of the CTA, have been sampled to date. Of these wells, approximately 39 have been shown to exceed the Maximum Contaminant Level (5.0 micrograms/liter) for trichloroethylene. These 39 wells are generally located in the same downgradient direction defined by the DGLS dye detection in Hickory Creek.
In August 1998, EPA entered into an Administrative Order on Consent with Teledyne Industries, Inc (Teledyne) and Boeing North American, Inc. (ABoeing). Under terms outlined in the Administrative Order on Consent, Teledyne and Boeing agreed to, inter alia, (1) conduct a removal site evaluation at the CTA and (2) prepare an Engineering Evaluation/Cost Analysis (EE/CA) that focused on contaminant source area removal at the CTA.
The removal site evaluation was documented in a report entitled "Removal Site Evaluation Report, Components Test Area, Pools Prairie Site, Newton County, Missouri," dated August 1999. Extensive soil and groundwater sampling indicated the potential presence of significant source areas at several areas. The area that was indicated as having the most VOC mass (approximately 13,448 pounds) and, generally, the highest soil concentrations was the former Primary Lagoon area.
The EE/CA was documented in a report entitled "Final Engineering Evaluation/Cost Analysis, Components Test Area, Pools Prairie Site, Newton County, Missouri," dated March 2001.
Actions for this site are detailed in PRP monthly progress reports, the "Interim Removal Construction Report" (Forrester, 2004), the "Revised Removal Construction Report" (Haley & Aldrich, 2005) and the "Removal Action Report" (MWH, 2009). A summary of these actions is as follows:
The removal action commenced at the former primary lagoon in 2003. Approximately 30,900 cubic yards of soil, weathered bedrock, and other miscellaneous buried structures were removed from the fomer primary lagoon area and treated from 2003 to 2005. Impacted soil was treated by spreading thee soil out and aerating in shallow layers using bulldozers and/or tilling. Soils were treated to an average concentration of approximately 0.3 milligrams per kilogram, which was below the 1.0 milligram per kilogram treatment standard. As estimated 14,000 pounds of volatile organic contaminant (VOC) mass was removed as a result of this action.
An active soil-vapor extraction (SVE) system was installed in July 2006, as system that targeted "secondary," or less-contaminated areas of the CTA. The system was operated from August 2006 to December 2008 during non-winter months. An estimated 3,680 pounds of VOC mass was removed as a result of this action.
No further removal actions are planned at the CTA.
This action will be considered complete when Respondents submit payment for EPA oversite, and when EPA has issued a notice of completion to Respondents.
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