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David Wang, P.E. , Chief <br /> Page 4 <br /> March 6, 1991 <br /> o Ground water levels at DDRW Sharpe have been declining due to <br /> drought conditions and increased usage. <br /> o The South Balloon Ground Water Treatment System has been <br /> extracted over 300 million gallons of contaminated water. The <br /> system has removed over 400 pounds of TCE. <br /> o Elevated levels of metals and pesticides (primarily arsenic, <br /> selenium, and bromacil) have been identified in the ground <br /> water, and have been detected predominantly in the shallowest <br /> aquifer. <br /> SOIL CONCLUSIONS: <br /> o Seven areas of TCE contaminated soil have been identified, <br /> containing an estimated aggregate of more than 26, 000 cubic <br /> yards of soil contaminated above 100 ug/g. <br /> o Soil concentrations of arsenic off-site are indistinguishable <br /> from those on-site. <br /> o Several underground fuel storage tanks have been removed <br /> without conducting the necessary soil sampling to determine <br /> if leakage and or spillage has occurred. <br /> o Several areas of elevated lead contamination in soil have been <br /> detected. <br /> o An area of dichlorodiphenyltrichloroethane (DDT) contaminated <br /> soil has been identified in the North Balloon. Trace amounts <br /> of DDT have been detected in the South Balloon. <br /> GENERAL CONCLUSIONS: <br /> o An investigation of DDRW Sharpe' s sewer system, a potential <br /> repository for hazardous and/or toxic material, demonstrated <br /> no evidence of contamination. <br /> o Data analyzed by eight different laboratories correlates very <br /> well. <br /> o Spatial and frequency distribution patterns of arsenic <br /> occurrences in soil and ground water do not support an on-site <br /> source. <br /> o Selenium contamination, both soil and ground water, is <br /> minimal . <br /> 0 Bromacil contamination for soil and ground water is minimal. <br />