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RECEIVED JAN 12 .2011 San Joaquin County Pauiry Environmental Health Department DIRECTOR Donna Heran,REHS 600 East Main Street Stockton, California 95202-3029 pRobert McCelon,REHSRS Jeff Carruesco,RENS,RDI Website:www sjgov.org/ehd Kasey Foley,REHS "'' trFOR Phone: (209)468-3420 Linda Turkatte,REHS Fax: (209)464-0138 January 11, 2011 Mrs. Margaret A. Marci 20 Mobile Lane Crescent City, California 95531-8409 Subject: Marci Property 2969 Loomis Road Stockton, California 95205 —• Dear Mrs. Marci: The San Joaquin County Environmental Health Department (EHD) has reviewed the correspondence dated 22 November 2010 issued by Ms. Tamorah Bryant, PE, of Geological Technics Inc., that requested the EHD to help resolve the status issue of your site with the State Water Resources Control Board Cleanup Fund (CUF) Five-Year Review unit(5YRU). In view of the high residual mass of total petroleum hydrocarbons quantified as diesel(TPHd)estimated to be impacting soil on your site and the high groundwater usage in the area around your site, the EHD had approved pilot testing of various remediation technologies on your site and had directed additional pilot testing to identify an effective remediation technology to reduce the w potential for impacting local water supply wells. The 5YRU issued an annual Five-Year Review update letter dated 31 August 2010 that recommended the EHD to consider this site for closure as a low-risk site. The EHD contacted the 5YRU and provided information the EHD considered sufficient to justify additional remedial pilot testing, but after reviewing the information the 5YRU restated their recommendation for closure consideration. This site has been a concern to the EHD due to the large residual contaminant mass, the high groundwater usage of the area, with several water supply wells within 550 feet of the site, and the lack of monitoring wells screened across the water table. During the last reported monitoring event, the water table was four to five feet above the screens of MW-5, MW-6, MW-7 and MW-8 (all in the source area, or up-gradient to cross- gradient of the source area), 10 feet over MW-4, and 18 to 24 feet over MW-1, MW-2 and MW-3. Monitoring well MW-2 (groundwater 21 feet over screen)is a down-gradient well for the `deep' zone. While there are no shallow zone wells down-gradient or obliquely down-gradient of the source area, two water supply wells are located approximately 600 feet south of the plume core and two more are located approximately the same distance east of the core, with no intervening shallow monitoring wells. Although the EHD considers it prudent to make every reasonable attempt to reduce the very large estimated mass of total petroleum hydrocarbons quantified as diesel (TPHd, over 107,000 pounds) impacting your site to further safeguard the groundwater resource in your area when the plume is no longer monitored, the EHD will accede to the now trice considered opinion of Confirmation Sampling Directive Letter and Request for No Further Action Request Report 0111