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Remedial Investigation Report -9- 8 March 1991 <br /> DDRW, Sharpe <br /> used to select the 39 samples and justification for this finding therefore, is <br /> lacking. <br /> FINDING <br /> 23. Several underground fuel storage tanks have been removed without conducting the <br /> required soil sampling to determine if leakage or spillage has occurred. <br /> RESPONSE <br /> 23. Finding is noted. Sharpe must provide the rationale for the method of <br /> investigation of each underground storage tank. Data must be provided to <br /> demonstrate that potential residual waste constituents from the removed tanks do <br /> not pose a threat to water quality. <br /> FINDING <br /> 24. An area of lead-contaminated soil in the North Balloon Area, near Bldg. 119, has <br /> been identified. Several areas of somewhat elevated lead concentrations have also <br /> been identified. <br /> RESPONSE <br /> 24. I concur with this finding. However, the "elevated" concentrations of lead are <br /> in fact, hazardous based on the total concentrations. Other heavy metals were <br /> found in concentrations which exceeded their respective Total Threshold Limit <br /> Concentration (TTLC) including cadmium and chromium in some of the soil samples. <br /> This indicates that there are several areas of "severe" soil contamination by <br /> heavy metals. <br /> FINDING <br /> 25. An area of DDT-contaminated soil in the North Balloon Area has been identified. <br /> Trace levels of DDT have been identified in the South Balloon Area. This <br /> indicates that pesticides are also a soil contamination problem in some areas of <br /> the site. <br /> RESPONSE <br /> 25. I concur with this finding. However, the concentration of DDT exceeded the TTLC <br /> for the sum of DDT, DDE and DDD which is 1 .0 milligrams per kilogram (mg/kg) . In <br /> addition, Chlorodane has been detected in a soil sample in concentrations which <br /> exceeded the TTLC of 2.5 mg/kg. <br /> FINDING <br /> 26. Ground water levels at SHAD have been declining for the last several years in <br /> response to declining precipitation and consequently increasing ground water <br /> pumpage. <br /> RESPONSE <br /> 26. I concur with this finding. However, the hydrographs presented in Chapter 5 of <br /> the RI do not support this finding because the beginning of the time record (X- <br /> axis) starts after the beginning of the current drought. Specifically, the <br />