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.
The cleanup action at the former primary lagoon is a combination of excavation with subsequent landfarming and ex-situ soil-vapor extraction (SVE). This action is targeting an estimated 98 percent, or 13,400 pounds, of VOC mass at the CTA.
