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San Joaquin County DIRECTOR <br /> o u i N Donna Heran,REHS <br /> oPy Environmental Health Department <br /> ASSISTANT DIRECTOR <br /> s : 2 600 East Main Street Laurie Cotulla,REHS <br /> Stockton, California 95202-3029 <br /> PROGRAM COORDINATORS <br /> • ," Carl Borgman,REHS <br /> Mike Huggins,REHS,RDI <br /> Website: wwwsjgov.org/ehd Margaret Lagorio,REHS <br /> Phone: (209) 468-.3420 Robert McClellon,REHS <br /> Fax: (209) 464-0138 Jeff Carruesco, REHS, RDI <br /> Kasey Foley, REHS <br /> March 23, 2009 <br /> John and Margaret Marci <br /> 20 Mobile Lane <br /> Crescent City,California 95531-8409 <br /> Subject: John and Margaret Marci Property <br /> 2969 Loomis Road <br /> Stockton, California 95205 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Revised Work <br /> Plan - Additional Dual Phase Extraction Pilot Test, (revised work plan) dated January 23, 2009, <br /> prepared by Geological Technics Inc. (GTI) on your behalf. The revised work plan was submitted <br /> in response to the EHD letter dated December 31, 2008,recommending several modifications to the <br /> original work plan involving dual phase extraction (DPE). <br /> In the revised work plan, GTI proposes to install.three additional extraction wells (EW-4, EW-5, <br /> and EW-6) at locations illustrated on Figure 2. The proposed extraction wells will be used to <br /> conduct three DPE pilot tests using high vacuum technology to simultaneously extract groundwater <br /> and soil vapor. GTI proposes the DPE tests to last five days at each proposed extraction well with <br /> nine-day breaks.between tests to.allow equilibrium conditions to be reestablished. During each <br /> pilot test, GTI proposes to collect three gas .and three groundwater samples to be analyzed for <br /> benzene, toluene, ethyl benzene, and total xylenes (BTEX); total petroleum hydrocarbons <br /> quantified as gasoline (TPH-G), and total petroleum hydrocarbons quantified as diesel'(TPH-D). <br /> GTI proposes to monitor vacuum influence, volatile organic compound concentrations using a <br /> photo ionization detector (PID), and depth to groundwater in observation wells MW-4, MW-5, and <br /> MW-7 for all three pilot tests. Other wells to be monitored during one or more pilot tests include <br /> injection wells IW-1, IW-101,and extraction wells EW-1, EW-101, EW-2, EW-102, EW-3 and <br /> EW-103. <br /> The EHD approves the installation of proposed dual phase extraction wells EW-4, EW-5, and soil <br /> vapor extraction well EW-6. All three wells will be constructed using ten-inch diameter augers and <br /> four-inch diameter casings. EW-4 will be screened between forty-five and seventy feet below <br /> surface grade (bsg); EW-5 will be screened between thirty and fifty feet bsg; and EW-6 will be <br /> screened between ten and thirty-five feet bsg. The EHD recommends the annular seal be <br /> approximately three feet for each well instead of the proposed ten feet for EW-4 and eight feet <br /> proposed for EW-5. Also, soil and groundwater generated during drilling must be analyzed for <br /> chemicals of concern, and contained in properly labeled Department-of-Transportation-approved <br /> fifty-five gallon drums, and stored on site until proper disposal. <br /> i <br /> i <br /> i <br />