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.�.y f~ <br /> ' SER��C�S <br /> PUBLIC klEALTH <br /> SAN JOAQUIN COUNTY r <br /> ENVIRONMENTAL HEALTH DIVISION -' <br /> Ernest M. Fujimoto, M. D., M.P.H., Acting Health Officer <br /> 304 E. Weber Ave., Third Floor • P. O. Boz 3,88 • Stockton, CA 95201;.0388-,, <br /> k <br /> 209/468-3420 : <br /> 1 !99? <br /> STELLA RUIZ <br /> 4491 W DURHAM FERRY RD <br /> TRACY CA 95376 <br /> RE: Ruiz Grocery SITE CODE: 1551 <br /> 4491 West Durham Ferry Road <br /> Tracy CA 95376 <br /> San Joaquin County Public Health Services, Environmental Health Division <br /> (PHSIEHD) has completed review of the ",tuarterly Groundwater Monitoring Report <br /> - Fourth Quarter 1996" and the "Revised ;Remedial Action Plan" both dated <br /> November 12, 1996 and prepared by Clearwater Group. PHSIEHD has the <br /> following comments for your consideration~. <br /> The quarterly report included the results of the October 18, 1996 groundwater <br /> sampling event which evidenced, separate phase hydrocarbons in MW1 and <br /> significant groundwater contamination in 'samples collected from MW2 of 27,000 <br /> ppb TPH-gas, 3,000 ppb benzene and 3,500 ppb methyl tertiary butyl ether <br /> (MTBE). No contaminants werei:detected!in the samples collected from the on site <br /> domestic well. Selected samples collected during the next quarter's groundwater <br /> sampling event, during first quarter 1997, should undergo MTBE analysis utilizing <br /> EPA Method 8260, to confirm the detections of MTBE observed utilizing EPA <br /> Method 8020. <br /> The Revised Remedial Action Plan proposed air sparging and soil vapor extraction <br /> utilizing the existing wells and an additionrai vertical vapor extraction well and a <br /> horizontal well to be installed in the utility,trenching. This revision certainly <br /> presents a much more cost effective remedial alternative. Please proceed with <br /> obtaining pre-approval for the additional well, quarterly groundwater monitoring and <br /> preparation of a detailed remediation system design and specification package for <br /> the solicitation of construction bids necessary for the installation of the revised <br /> remedial system. <br /> Once the system is installed, initial treatment will consist of thermal oxidation to be <br /> followed with catalytic oxidation when influent concentrations have reduced the <br /> cost effectiveness of thermal oxidation,.- It is anticipated that prior to the <br /> completion of the remedial treatment that,influent concentrations will be reduced to <br /> levels such that a small blower and activated carbon will be used to treat vapors <br /> A Division of San Joaquin County Health Care Services <br />