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MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 255-3000 Sacramento, CA 95827-3098 CALNET: 8-494-3000 TO: Gordon L. Boggs FROM: Elizabeth A. Thayer Underground T rogram Manager Associate Engineer DATE: 10 March 1995 SIGNATURE: A66 C— a -4 i SUBJECT: MEMO #1, SITE HISTORY, EAST BAY MUD, 1804 WEST MAIN STREET, STOCKTON, SAN JOAQUIN COUNTY We received an in-situ bioremediation proposal with a Report of Waste Discharge (RWD) in September 1994. Patricia Leary of this office will be reviewing the RWD for completeness and preparing the Waste Discharge Requirements, as necessary. This memo contains a summary of the site history, file contents, and a list of reports missing from our file. Tables of ground water data and site maps are attached. Comments on the adequacy of the investigation to date and the remediation proposal are in an attached memo. The East Bay MUD Stockton Service Center is located approximately 1000 feet south of the Turning Basin, at the corner of West Main Street and Los Angeles Avenue in Stockton. According to the Soil and Ground Water Assessment, dated 17 November 1989, by Kleinfelder consultants, EBMUD and Universal Engineering removed a 1000 gallon diesel tank and a 1000 gasoline tank in July 1987. According to Kleinfelder, Universal Engineering prepared 2 reports regarding the tank removal; Final Report, Removal of Fuel Storage Tanks, dated 14 December 1987, and Final Report Data, Underground Tank Closure at EBMUD Yard..., dated 27 January 1988. These reports are not in our file. Kleinfelder stated that the reports contained soil data from the tank pit. Gasoline constituents were detected in soil at the east end of the gasoline tank, with up to 10 ppm benzene and 940 ppm total hydrocarbons. Kleinfelder stated that diesel was not detected in soil samples from beneath the diesel tank. No other diesel sampling has been done and other reports do not mention removal of the diesel tank. As reported in the 17 November 1989 report, Kleinfelder submitted a work plan, dated 11 May 1988 (not in our file), to investigate the extent of gasoline contamination. In May 1989, apparently as proposed in the work plan, Kleinfelder drilled 7 borings and converted 3 into monitoring wells. Their findings were presented in the 17 November 1989 report. Boring logs revealed a clay layer from near the surface to approximately 10 to 12 feet bgs. Under the clay layer is a sand layer to approximately 20 to 24 feet bgs. Depth to ground water was approximately 12 feet. Direction of ground water flow was southwest. A soil sample from B1 at a depth of 11 feet contained 39 ppm TPH. Soil samples from B2 at 6 feet contained 140 ppm TPH and at 11 feet contained low levels of TEX. Soil samples from B3 and B4 were ND. No soil samples were collected from the borings for MW1, MW2, and MW3. Also according to Kleinfeider's November 1989 report, EBMUD removed two remaining underground tanks in September 1989. Kleinfelder stated that they understood that soils from below the tank did not contain hydrocarbons and that on-site observation did not indicate a leak. There is no report in our file regarding the September 1989 tank removal.