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� - <br /> 1 �. <br /> PROBLEM ASSESSMENT REPORT <br /> SOIL AND GROUNDWATER <br /> UTILITY DISTRICT <br /> N <br /> EAST BAY MUNICIPAL <br /> STOCKTON CENTER, STOCKTON, CALIFORNIA <br /> 1.0 INTRODUCTION <br /> This report presents the methodology and results of a soil and groundwater investigation <br /> requested by the San Joaquin County Public Health Services, Environmental Health <br /> Division (EHD) at the East Bay Municipal Utility District (EBMUD)Stockton Cenier, <br /> 1804 <br /> West Main Street, <br /> Stockton, California (Figure 1). The information presented herein is <br /> based on previous investigation work by J.H. Kleinfeider, Inc. and on additional work <br /> Weston, <br /> cSThe <br /> RtiGuidelines <br /> pe <br /> ndix <br /> performed by Roy F. has asheformatohis <br /> A) Problem AssessmenRe ort {PAR} armat <br /> report. <br /> 1.1 PreyiQus Work - <br /> Three 1000 gallon capacity undergroundline storage tanks were in removed <br /> April 989 and two were <br /> wasemoved emoved in <br /> EBMUD Stockton yard. One was <br /> September 1989. The following inforrnatiaMunicipal <br /> �n c alptltlty District'from the Kdated November"Soil <br /> and Groundwater Assessment, East Say p <br /> 1989: <br /> In July 1967,East Bay Municipal Utility District(EBMUD) removed a 1,000-gallon regular <br /> ga:oline underground storage tank from its Stockton yard. The storage tank was <br /> ccotained in a cement vault. On July 29, 1987, Polymatrix Associates sampled soil <br /> beneath the cement vault floor near both ends of the former storage tank. Analytical <br /> results from the soil sample from the east end of the tank indicated the presence of <br /> gasoline constituents above the method detection limits. <br /> In May of 1988, Kleinfelder prepared a sail and ground water assessment workplan to <br /> assess the presence of gasoline constituents in the soil and ground water at the EBMUD <br /> Stockton facility. The workplan was prepared in direct response to a request from Cottle <br /> Engineering of Antioch, California. on September 30, 1988 EBMUD received approval <br /> from the San Joaquin Local Health District (SJLHD) to implement the scope-of-work <br /> outlined in the Kleinfelder workplan. n April <br /> ri the SJLHDeldter rr. e lved 9of 8t Kleinfeldorization to <br /> Proceed d with the scope-of-work approvedY <br /> drilled four exploratory soil borings and drilled and installed three around water monitoring <br /> wells. Soil samples were collected in each of the toit boringsuene and celeenes ted samples <br /> were and <br /> analyzed for total hydrocarbons and benzene, <br /> organic lead. Gasoline constituents were detected in soils collected from borings near the <br /> former tank location. . . Analytical results for samples collected in borings B-1, B-3 and <br /> B4 were none detected for BTEX. Results from boring B•2, sample number 37379(11 <br /> --------- _ _- -__ _._....._fe.e% contained concentrations of toluene, ethyl benzene and xylenes above the method <br /> detection limit.- <br /> Total hydrocarbons were detected at 39 milligrams..per-.kilogram (mg/kg <br /> in the 11-foot sample from boring B-1 and 140 mglkg in the 6-foot sample from boring B-1. <br />