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Department of Toxic Substances Control <br /> 4 i — <br /> Terry Tamminen 8800 Cal Center Drive Arnold Schwarzenegger <br /> Agency secretary Sacramento, California 95826-3200 /�� Governor <br /> Cal/EPA w ceWE�I�'� <br /> August 31 , 2004 SEP 0 2 2004 <br /> aftivr <br /> Mr. Marshall Cloud <br /> Remedial Project Manager <br /> Environmental Office <br /> Post Office Box 960001 <br /> Stockton, California 95296-0250 <br /> COMMENTS ON THE DRAFT FINAL REMEDIAL ACTION REPORT FOR SOLID <br /> WASTE MANAGEMENT UNITS (SWMU), 6 AND 20 SMALL EXCAVATION SITES, <br /> AND SWMU 4 WET SEASON CONTROLS, TRACY SITE, TRACY CALIFORNIA <br /> Dear Mr. Cloud: <br /> The Department of Toxic Substances Control (DTSC), received the above-mentioned <br /> report on June 15, 2004. The report discusses the implementation of the Record of <br /> Decision (ROD), selected remedies for SWMUs 4, 6, & 20. DTSC will focus its <br /> comments on SWMUs 6 & 20 since it has already provided comments for SWMU 4 in a <br /> letter dated November 19, 2003 for the Amendment to the Comprehensive ROD. <br /> SWMU 6 <br /> SWMU 6 is the former location of a 250-gallon concrete sump that was built in 1968 <br /> after the completion of Building 28. The sump was used to dispose of waste materials <br /> from damaged containers. The sump was filled with sand in 1977 and was removed in <br /> 1988. <br /> In 1988, the sand inside the sump was analyzed and concentrations of Trichloroethene <br /> (TCE), tetrachloroethene, 1,2-dichlorobenzene, 1,1,1-trichloroethene, lindane, <br /> dichlorodiphenyltrichloroethane, heptachlor, malathion, trichlorophenoxyacetic acid, <br /> total petroleum hydrocarbons, and xylenes were detected. During the Remedial <br /> Investigation (RI) in 1996, both pesticide and herbicide contamination was detected in <br /> soil beneath the excavation down to the water table. Excavation at SWMU 6 began in <br /> 1999 with the proposed excavation footprint of 10 feet (ft) by 15 ft to a depth of 18 ft, as <br /> specified in the ROD. Following the excavation, a total of six soil confirmation samples <br /> were collected from all the sidewalls and two from the bottom of the excavation. These <br /> samples were analyzed for contaminants of concern (CDCs) listed in the ROD. Three <br /> 0 Printed on Recycled Paper <br />