F-area seepage basins groundwater monitoring report. Volume 1. First and second quarters 1995

Groundwater at the F-Area Seepage Basins (FASB) is monitored in compliance with Module 111, Section C, of South Carolina Hazardous Waste Permit SCl-890-008-989, effective November 2, 1992. The monitoring well network is composed of 86 FSB wells and well HSB 85A. These wells are screened in the three hydrostratigraphic Units that make up the uppermost aquifer beneath the FASB. A detailed description of the uppermost aquifer is included in the Resource Conservation and Recovery Act Part B post-closure care permit application for the F-Area Hazardous Waste Management Facility submitted to the South Carolina Department of Health and Environmental Control (SCDHEC) in December 1900. Data from 9 FSL wells are included in this report only to provide additional information for this area; the FSL wells are not part of Permit SCl-890-008-989. Monitoring results are compared to the SCDHEC Groundwater Protection Standard (GWPS), which is specified in the approved F-Area Seepage Basins Part B permit (November 1992). Historically and currently, gross alpha, nitrate, nonvolatile beta, and tritium are among the primary constituents to exceed standards. Numerous other radionuclides and hazardous constituents also exceeded the GWPS in the groundwater at the FASB during the first half of 1995, notably aluminum, iodine-129, pH, strontium-90, and zinc. The elevated constituents are found primarily in Aquifer Zone IIB{sub 2} (Water Table) and Aquifer Zone IIB{sub 1}, (Barnwell/McBean) wells. However, several Aquifer Unit IIA (Congaree) wells also contain elevated levels of constituents. Isoconcentration/isoactivity maps included in this report indicate both the concentration/activity and extent of the primary contaminants in each of the three hydrostratigraphic units. Geologic cross sections indicate both the extent and depth of contamination of the primary contaminants in all of the hydrostratigraphic units during the first half of 1995