SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 155-3000 Sacramento, CA 95827-3098 CALNET: 8-494-3000 TO: GORDON L. BOGGS FROM: ELIZABETH A. THAYER UGT Program Coordinator Associate Engineer DATE: 15 September 1993 SIGNATURE: ._ SUBJECT: FINAL REMEDIAL PLAN (FRP), GEWEKE, 16 SOUTH CHEROXF.F LANr,, LODI, SAN JOAQUIN COUNTY I have reviewed the Final Remedial Plan (FRP), dated 30 IuIy 1993, prepared by Geweke's consultants, Geological Audit Services (GeoAudit). For soil remediation options, the PRP includes excavation, vapor extraction, and in-situ bioremediation. Excavation was considered not viable and costs were not given. Costs were given for vapor extraction but not for in-situ bio. However, it is implied that costs for in-situ bio of soil are minimal. For ground water remediation options, the FRP includes pump and treat and in-situ bio. Costs were provided for pump and treat only. However, it is implied that costs for in-situ bio of ground water are minimal. No (Aber options were discussed for either soil or ground water. Based on their discussions of remedial options, GcoAUdit recommended in-situ hio for both soil and ground water. 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. Without an available hydrocarbon food source, the bacterial population dies hack, 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 bioremediate the soil, they propose to introduce the bacteria it, the subsurface through vadose zone wells, VW1 through VW4, and the dry monitoring wells, MWI, MW3, MW4, and MWS. 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 basis. The borings will be sampled every five feet and monitored in the field with a YID, Selected soil samples will be analyzed for TPHg and RTRX. The results will be compared to baseline samples. GeoAudit states that this soil bioremediation procedure will not affect the ground water, and therefore no Regional Board permit will be required. To bioremediate the ground water, they propose to introduce the bacteria through existing unspecified monitoring wells. To monitor the effectiveness of the bioremediation, GeoAudit recommends monitoring off-site monitoring wells, MW8, MW9, MW 11, MW 12, and MW 13 on a monthly basis during the first quarter after inoculation. This monitoring is to ensure that the TO' d 800' ON ££:6 £6' 91 dog ' ON Ili