SITE INFORMATION AND CORRESPONDENCE FILE 2

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ENVIRONMENTAL HEALTH DEPARTMENT SAN JOAQUIN COUNTY UnitSupervisors Donna K.Heran,R.E.H.S. Carl Borgman,R.E.H.S. y: < Director 304 East Weber Avenue, Third- 708 Mike Huggins,R.E.H.S.,R.D.I. Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. • cgcikBP`'sv Laurie A.Cotulla,R.E.H.S. Robert McClellon,R.E.H.S. Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. Program Manager APR 0 4 2002 BOB COCHRAN CHEVRON PRODUCTS COMPANY BLVD V-1140 PO BOX 6004 SAN RAMON CA 94583-0904 RE: Former Chevron #9-4054 SITE CODE: 1780 2103 Country Club Blvd. RO#: 0000635 Stockton, CA., 95204 San Joaquin County Environmental Health Department (EHD) has reviewed the March 13, 2002 "Report of Sampling Activities, Well Search, and Human Health Risk Assessment," submitted on March 15, 2002 by SECOR Consulting and offers the following comments. Although EHD appreciates the time and effort spent on compiling the data to support the Human Health Risk Assessment (HHRH) conclusions, the application of Risk Based Corrective Action (RBCA) Tier I and Tier II has not been accepted for use in this area for evaluating the clean up goals for leaking underground storage tanks (UST). The Water Quality Control Plan (Basin Plan) for the Central Valley Region (Sacramento River and San Joaquin River Basins) has been adopted under California Water Code Section 13240 and is supported by the Federal Clean Water Act. This code requires states to adopt water quality standards and provides that the Central Valley Regional Water Quality Control Board establish resolutions to ensure adherence to the standards. Resolution 92-49 governs policies and procedures for investigation and cleanup and abatement of discharges under Water Code Section 13304. The Basin Plan has designated the groundwater in this area as "beneficial use' and under provisions within the Porter-Cologne Water Quality Control Act states, "Water quality objectives for groundwaters designated for domestic or municipal (beneficial) use shall not contain concentrations of chemical constituents in excess of the maximum contaminant levels (MCLs) specified in the provisions of Title 22 of the California Code of Regulations, Section 64444." SECOR's statement under "Potential Exposure Pathways" states `That the first encountered groundwater beneath the site is not a current or potential drinking water resource....."is not accurate and establishes a false premise for the rest of the assessment. Additionally, comments included within the Summary, Conclusions, and Recommendation are of concern to EHD. Your consultant has determined that "Operation of the DPE/AS system should continue only until gasoline hydrocarbon mass can no longer be removed from the subsurface. At that time, SECOR would propose closure of the site based on its status as a low-risk groundwater case."