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-' <br /> !{ r <br /> RESNA Wt%TrRWORK CORP. <br /> INDUSTRIES <br /> January 7, 1991 .�; _ .... <br /> Diane Hinson JAN 1 8 12`1 <br /> San Joaquin County Public Health Services ENV!,-'U4'i-N 7AL HEi'll H <br /> Environmental Health Division F /�;"?`;!CIS <br /> P.O. Box 2009 <br /> Stockton, CA 95201 <br /> Re: Tri Valley Growers, Plant T, 26200 Nowell Road, <br /> Thornton, CA <br /> Dear Diane: <br /> This letter outlines the remediation system set-up and testing <br /> program at the above re.erenced site (Figure 1). <br /> in late November 1990, the remediation, system was set--up in an <br /> r existing shed on the site. The system consists of 2 two-hundred <br /> pound carbon filters, connected in series. Extracted groundwater <br /> } is treated through the filters. Treated effluent is then pumped <br /> { to a storm drain connected to Tri <br /> Valley Growers' <br /> of the carbon <br /> collection system (Figure 2). Typical <br /> filtration system is shown on Figure 3. <br /> The system was started and a pumping test was conducted on the <br /> extraction well (MW4) using the outerlying wells to monitor the <br /> effect of pumping on the watertable, the optimal pumping rate, <br /> and to acquire aquifer characteristics. Well MW4 was pumped at a <br /> rate of one liter per minute (lpm) for 21 hours 57 minutes. Near <br /> the end of the pumping test a slight drawdown was noted in all <br /> the test duration was insufficient for <br /> non-pumping wells, but <br /> interpretation of the drawdown in these wells (Pump test data is <br /> included in Attachment 1). Transmissivity and zone of capture <br /> were estimated using pump test data. The capture zone is <br /> estimated at 91.55 feet downgradient of ;he extraction well <br /> (MW4). Gradient direction and magnitude was determined prior to <br /> commencement of the pumping test. Pumping data is included in <br /> cts the static groundwater level <br /> Attachment 1, Figure 4 depi <br /> contours. Gradient d'rection is assumed to be perpendicular to <br /> I contour lines. Calculations are contained in Attachment 2. <br /> The_-estimated life of the carbon filters, based apcn the levels <br /> — -- -- -- - -- - -rate,- _is--_7--months'- -- <br /> of contamination, temperature and -pumping - - - - <br /> When carbon filter 1 . (IC) is nearly spent, it will be out of <br /> service and sent to be regenerated. Filter 2 will be moved to <br /> 1710 MAIN STREET • ESCALON,CA 95320 • (209)834883$87.1249 <br /> 2350•A WALSH AVENUE • SANTA CLARA.CA 95051 ( ) <br />