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^IAIE U� f..AlIFC1RNIR GroAGE 0EQVMFJ1AN, Cioveruor <br /> CALIFORNIA REGIONAL. WATER QUALITY CONTROL BOARD-- " <br /> CENi HAL VALLEY REGION <br /> 3443 HUU11F_A ROAD, -AME A <br /> SAGRAMENiO, CA $5827.3098 1e <br /> 31 January 1990 <br /> Mr. David Ng <br /> Sunboro Development Corporation JAN 3 1 1990 <br /> 1307 South Mary Avenue <br /> Sunnyvale, CA 94087 FNVUIONMt7vT <br /> ox:QA4m , AC HEAi_TLJ <br /> SOIL AND GROUND WATER INVESTIGATION, SUNBORO DEVELOPMEN-I CORPORATION PAROL 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-Frick . The report found that the soils <br /> along the northern boundary of the property (see attached map) contained <br /> petroleum hydrocarbons at fifteen feet be ow the surface and the ground water <br /> was approximately eight feet below the surface. <br /> As a result of the findings, the Workpl n proposes to install four 20-foot <br /> monitoring wells to determine the impact on the 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 fuel 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 feet of the surface to insure that no <br /> product exists above the ground wat r table, <br /> 4. Quality Assurance and Quality Contr l (QA/QC) data and summary should be <br /> submitted with the sample results ii your 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 /> 1) 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 />