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e!ar�y California Regional Water Quality Control Board V1ckox Environmental Protection 16 September 2002 Mr. Bob Cochran Chevron Products Co. PO Box 6004 San Ramon, CA 94583 Central Valley Region Robert Schneider, Chair Sacramento Main Office Internet Address: http://www.swrcb.ca.gov/rwgcb5 3443 Routier Road, Suite A, Sacramento, California 95827-3003 Phone (916) 255-3000 • FAX (916) 255-3015 Ivern and Roger Baffoni 1175 Orangewood Drive Lodi, CA 95240 REVIEWSECOND QUARTER 2002 PROGRESS REPORT, FORMER CHEVRONSTATION #9-5775, 301 WEST AETTLEMAN LANE, LODI, CLEANUP AND ABATEMENT (C&A) ORDER NO. 5-00-704 Board staff reviewed the 15 July 2002 Quarterly Progress Report, Second Quarter 2002 (2Q02 Report) submitted by Secor International Incorporated (Secor) for the former Chevron Station #9-5775 (Chevron). The 2Q02 Report documents decreasing trends of petroleum hydrocarbon and MtBE constituents in on-site monitoring and extraction wells due to continued remedial activities at the site. Concentrations of petroleum hydrocarbons and MtBE have decreased significantly since the soil vapor extraction (SVE) and groundwater Waxtraction and treatment (GET) systems began operation in July 2000. As of December 2001, 6.6 million llons of contaminated groundwater from the former Chevron site has been extracted, treated with carbon, and discharged to the City of Lodi industrial sewer line. The average treatment system influent MtBE concentration has stabilized at 84 micrograms per liter (µg11). The SVE mass removal rate for MtBE has decreased to zero pounds per day. Based on this data, Secor recommends pulsing the SVE system on a quarterly basis, and suggests shutting off the SVE system for the fourth quarter of 2002, and then restarting it in January 2003. Shutting off the SVE system for three months seems excessive; however, due to the influent air concentrations at zero pounds per day, Secor's recommendations are appropriate, and therefore approved. We would like to reiterate that the focus of further remedial activities at this site should be directed at the high concentrations of contaminants consistently identified in extraction well EX -1. (The maximum concentration of MtBE remains at extraction well EX -1 at 15,000 pg/l.) Prior to issuing a no further action required letter for this site, groundwater concentrations in all monitoring and remedial wells will need to show decreasing trends toward meeting water quality objectives within a reasonable time. Therefore, if contaminant concentrations in groundwater continue to stay elevated, it will be necessary to evaluate modifications to the remedial system (e.g. adding SVE or groundwater extraction wells), or evaluate alternate technologies (e.g. air / ozone sparging, etc.). If modifications or alternate technologies will increase the technical and economic feasibility of continued remediation in a cost effective manner, then these modifications or enhancements should be made to the systern. L p0mgYM] California Environmental Protection Agency SEP 17 2002 CoRecycled Paper -------- The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy costs, see our Web -site at http:/Iwww.swrcb.ca.gov/rwgcb5