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Department of Toxic Substances Control <br /> Maureen F. Gorsen, Director <br /> Linda S.Adams 8800 Cal Center Drive Arnold Schwarzenegger <br /> Secretary for Sacramento, California 95826-3200 Governor <br /> Environmental Protection <br /> IREUM vED <br /> June 26, 2006 JUN 9 0 2006 <br /> ENVIRONMENT HEALTH <br /> Mr. Marshall Cloud <br /> PERMIT/SERVICES <br /> Defense Logistics Agency <br /> Defense Distribution Depot San Joaquin, Sharpe Site <br /> Post Office Box 960001 <br /> Stockton, California 95296-0250 <br /> COMMENTS ON THE DRAFT NATURAL ATTENUATION INVESTIGATION (NA) <br /> RESULTS TECHNICAL MEMORANDUM, FOR DEFENSE DISTRIBUTION DEPOT <br /> SAN JOAQUIN COUNTY (DDJC), SHARPE SITE, LATHROP, CALIFORNIA <br /> Dear Mr. Cloud: <br /> The Department of Toxic Substances Control (DTSC) received the above-mentioned <br /> technical memorandum on June 5, 2006. The memorandum discusses the soil and <br /> ground water field investigations DDJC-Sharpe performed to determine whether biotic <br /> natural attenuation of volatile organic compounds is occurring at the site. <br /> The natural attenuation fieldwork included a total of nine cone penetrometer test (CPT) <br /> locations, 28 discrete soil samples, and 27 discrete ground water samples collected <br /> within the North Balloon. Lithologic characterization for all locations was completed <br /> using CPT electronic logging techniques. The initial CPT push at each location was <br /> done to collect CPT-interpreted lithology readings. Both soil and groundwater samples <br /> were collected in separate CPT boreholes adjacent to the first lithology push for that <br /> area. Hollow Stem Auger techniques with a split-spoon sampler were implemented at <br /> three of the nine CPT locations to collect soil samples and develop these borings into <br /> triple-nested monitoring wells (MW); MW300, MW303, MW304. <br /> Field sampling efforts followed the United States Environmental Protection Agency's <br /> (USEPA) "Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents <br /> in Ground Water." The guidance recommends that analytical data be collected from at <br /> least eight locations in and around the plume. DDJC-Sharpe sampled nine locations in <br /> and around the North Balloon Tricholorethene ground water plume. Once collected, <br /> these data were evaluated and scored according to USEPA's guidance to determine the <br /> type and extent of biodegradation processes occurring within the plume. <br /> S Printed on Recycled Paper <br />