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STA'IF7 OF'CALIFORNIA GEORGE DEUKMEJIAN. Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— <br /> CENTRAL VALLEY REGION <br /> 3443 ROUTiEH ROAD, SUITE A <br /> SACRAMENTO, CA 95827-3098 111j.y7r, <br /> 31 January 1990 <br /> T 0 <br /> FEB 2 MR9 <br /> ENVIRONMEINITAL HFA�"_T!­ <br /> Mr. David Ng C.r <br /> Sunboro Development Corporation P E iR PANI T/'Ji,r�V <br /> _S <br /> 1307 South Mary Avenue <br /> Sunnyvale, CA 94087 <br /> SOIL AND GROUND WATER INVESTIGATION, SUNBORO DEVELOPMENT CORPORATION PARCEL B, <br /> TRACY, SAN JOAQUIN COUNTY <br /> We have reviewed your report, "Soil Quality Investigation, Sunboro Development <br /> Corporation Parcel B, Tracy, California" (5 September 1989) , and Workplan (26 <br /> September 1989), prepared by Levine-Fricke. The report found that the soils <br /> along the northern boundary of the prope ty (see attached map) contained <br /> petroleum hydrocarbons at fifteen feet below the surface and the ground water <br /> was approximately eight feet below the surface. <br /> As a result of the findings, the Workplan proposes to install four 20-foot <br /> monitoring wells to determine the impact on th e ground water due to the petroleum <br /> hydrocarbons. The four monitoring wells are located directly over the area of <br /> contaminated soils and would not provide optimal ground water information. <br /> Comments regarding the workplan are as follows: <br /> 1. Any monitoring well with floating fu product should not be used to <br /> determine the water table elevation since false elevations can be measured. <br /> 2. Monitoring wells installed over the source would confirm ground water <br /> contamination, but will not provide Any information on the extent of <br /> contamination. <br /> 3. The screened interval for the monitoring wells located in the contaminated <br /> ---area should- extend to within two the surface to -1-n-suee -tha�_ n6- <br /> product exists above the ground water table. <br /> 4. Quality Assurance and Quality Control 'QA/QC) data and summary should be <br /> submitted with the sample results in y ur report. <br /> We request that you submit a revised workplan by 30 February 1990 that addresses <br /> the following objectives regarding the hydrocarbon contamination at your site: <br /> 11) source identification; 2) On-site and off-site areal and vertical delineation <br /> of hydrocarbon plume; 3) Determination of the ground water gradient. Please <br /> include a rationale for the new locations of the monitoring wells. You may want <br />