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LH-SF TEL ho . 1 415 243 9 Aug 06 ,90 10 : 21 F .03iO3 <br /> MEMORANDUM <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION <br /> 3443 Routier Road, Suite A Phone: (916) 361.5600 <br /> Sacramento, CA 95827.3098 ATSS Phone: 8-495-5600 <br /> TO: Antonia Vorster FROM: Richard McHenry <br /> Senior Engineer Area Engineer <br /> DATE: 30 July 1990 SIGNATURE: <br /> SUBJECT: REVIEW OF LINCOLN VILLAGE CENTER'S PHASE IIB SITE ASSESSNENT WORK PLAN, <br /> STOCKTON SAN JOAQUIN COUNTY <br /> I have reviewed the above referenced report dated 14 June 1990. Our concerns presented <br /> from previous versions of this work plan are addressed by: <br /> 1 . Monthly water level contour maps were submitted. The contours showed a general <br /> northeast direction of flow that shifts direction by about 45° throughout the <br /> year. Monthly contours should continue to be developed to confirm this trend. <br /> 2. All water and soil samples will be analyzed for EPA 601 and EPA 8010 compounds <br /> respectively and not PCE only. <br /> 3. The effected County municipal wells will be videoed and two 150-foot and a <br /> 310-foot monitoring well will be installed to help determine the extent and cause <br /> of vertical migration. If the wells are shown to contribute or cause downward <br /> migration of pollution, remediation or closure will be necessary. <br /> 4. Pollution appears to be off-site along the sewer line west of MW-4. Theplan <br /> proposes to conduct a soil gas survey along the sewer easement between McClellan <br /> Way and Benjamin Holt Drive to Vicksburg Place. The sewer line direction of flow <br /> has not been submitted to support this proposal . It is possible that flow from <br /> Lincoln Village flows north or south along Gettysburg Place. <br /> The work plan also includes the following items: <br /> 1 . Seven shallow ground water monitoring wells to further define the shallow aquifer <br /> plume. Two of the wells (MW-10, MW-11) on the properties eastern border are <br /> installed at the Dischargers' decision, to assure the pollution has not migrated <br /> off-site. <br /> 2. Eight soils borings, 20 feet in depth with split spoon samples at 5 foot <br /> intervals, will be performed to confirm the results of the previous soil gas <br /> survey. While acceptable, it may produce useful data to complete the borings to <br /> ground water. <br /> 3. An aquifer pump test will be done. <br /> RPM:ej <br />