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MEMORANDUM 0 CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 255-3000 Sacramento, CA 95827-3098 CALNET: 8-494-3000 TO: GORDON L. BOGGS FROM: ELIZABETH A. THAYER UGT Program Coordinator Associate Engineer DATE: 20 September 1993 SIGNATURE:I Csf (? . SUBJECT: FINAL REMEDIAL PLAN (FRP), GEWEKE, 16 SOUTH CHEROKEE LANE, LODI, SAN JOAQUIN COUNTY I have reviewed the Final Remedial Plan (FRP), dated 30 July 1993, prepared by Geweke's consultants, Geological Audit Services (GeoAudit). SUMMARY OF THE FRP For soil remediation options, the FRP includes excavation, vapor extraction, and in-situ bioremediation. Costs were submitted for vapor extraction but not for excavation or in-situ bio. Excavation was considered not viable. For ground water remediation options, the FRP includes pump and treat and in-situ bio. Costs were provided for pump and treat only. It was implied that costs for in-situ bio of both soil and ground water are minimal. No other options were discussed for either soil or ground water. Based on their discussions of remedial options, GeoAudit recommended in-situ bio for both soil and ground water. In the FRP, case study information was provided for two sites, one in Ukiah and one in Apple Valley. They provided graphics for the Apple Valley site, and graphics and a table of ground water data for the Ukiah site. The Ukiah site was an ex-situ soil case in which the soil was treated above ground and then placed back in the pit. They have recorded a drop in ground water contamination since the soil was removed from the pit. The bacteria that GeoAudit will use for in-situ bio are indigenous to soil (although not indigenous to the site), non-pathogenic, and have been isolated from sites severely contaminated with hydrocarbons. The bacteria will be inoculated into wells that are screened through the contaminant plume. After inoculation, a low-pressure air source will be manifolded to the wells to provide additional oxygen and accelerate bioremediation. GeoAudit asserts that essential nutrients are generally available in the soil, however, if supplements are needed, the amounts will probably be very low. The only equipment required for this procedure, is a blower unit to introduce air to the subsurface. To bioremediate the soil, they propose to introduce the bacteria to the subsurface through vadose zone wells, VW1 through VW4, and the dry monitoring wells, MW1, MW3, MW4, and MW5. Three additional vadose zone wells may be installed at specified locations. To monitor the effectiveness of the soil bioremediation, GeoAudit proposes to drill one or two borings on a biannual