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•N= :�: ..� MEMORANDUM <br /> -,SFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION <br /> 3443 Routier Load Phone: (916) 361-5600 <br /> Sacramento, CA 95827-3098 ATSS: 8-495-5600 <br /> TO: GARY REENTS FROM: TWILA LECLERC <br /> Senior Engineer Area Engineer <br /> DATE: 17 March 1989 SIGNATURE: <br /> SUBJECT: Martinez Construction, Woodbridge <br /> I have reviewed the report, "Soil Gas Investigation, California Fuels <br /> Property, Woodbridge, CA, " dated February 1989, prepared by GHH <br /> Engineering, Inc. , and have the following comments: <br /> 1. The proposed soil excavation is acceptable. <br /> 2 . The proposal needs a soil-sampling rationale more specific than <br /> "random" soil samples to be taken during the excavation. <br /> 3. The data in Table 1 show that contamination levels increase with <br /> depth which is an indication that the ground water may be <br /> contaminated from past leakage. Accordingly, it will be <br /> necessary to install a 4-inch-diameter monitoring well in the <br /> center of the impacted area to determine if the ground water has <br /> been impacted. <br /> 4. Monitoring well screen should be installed at least 10 feet <br /> above and 20 feet below the water table. <br /> 5. Continuous coring should be utilized for logging the lithology <br /> during the well construction. <br /> 6. Appropriate screen and filter pack sizes should be specified and <br /> used. <br /> .7. Well development must be performed to produce a surging action. <br /> Simple bailing is not adequate. <br /> 8. If the well is developed appropriately, it is not necessary to <br /> wait 24 hours before collecting ground water samples. <br /> 9. If the well recharges too slowly to effectively purge, it should <br /> be evacuated to dry and samples collected as soon as there is <br /> adequate water. . The proposed methodology in the workplan is not. <br /> acceptable. <br />