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e <br /> a <br /> �• .. 7 �' . < ' _- �s" _ me <br /> p <br /> RESIVA WATERWORK CORP. <br /> INDUSTMES , <br /> EC <br /> APR <br /> January 7, 1991 ENVTF '?r';0.4!",i r^' Run L <br /> r r <br /> I wiil/;,,L,,YLa <br /> Diane Hinson <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> P.O. lox 2009 <br /> Stockton, CA 95201 <br /> Re: Tri Valley Growers, Plant T, 25200 Nowell Road, <br /> Thornton, CA <br /> Dear Diane: <br /> This letter outlines the remediation system set-up and testing <br /> program at the above referenced site (Figure 1). <br /> In late November 1990, the remediation system was set-up in an <br /> 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 <br /> med <br /> to a storm drain connected to Tri Valley Growers' waste <br /> collection system (Figure 2). Typical design of the carbon <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 /> non-pumping wells, but the test duration was insufficient for <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 the extraction well <br /> (MW4). Gradient direction and magnitude was determined prior to <br /> commencement of the pumping test, Pumping data is included in <br /> Attachment 1. Figure 4 depicts the static groundwater level <br /> contours. Gradient direction is assumed to be perpendicular to <br /> contour lines. Calculations are contained in Attachment 2. <br /> The estimated life of the carbon filters, based upon the levels <br /> of contamination, temperature and pumping rate, is 7 months. <br /> When carbon filter 1 (1C) 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)838-3507 <br /> 2350•A WALSH AVENUE • SANTA CLARA.CA 95051 • (408)496-1249 <br />