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California Renal Water Quality Antrol Board <br /> vCentral Valley Region , <br /> Steven T.Butler,Chair <br /> Winston H.Hickox - Gray Davis <br /> Secretaryfor Sacramento Main Office Governor <br /> Environmental Intemet Address: http://www.swrcb.ca.gov/—rwgcb5 <br /> Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255-3000•FAX(916)255-3015 <br /> 31 October 2000 JZ Gl ::d <br /> Mr. W.T. Nickerson <br /> UNOCAL Asset Management Group <br /> 8788 Elk Grove Blvd, Bldg 3, Suite 15 <br /> Elk Grove, CA 95624 <br /> CONDITIONAL APPROVAL OFAQUIFER TESTING WORKPLAN, WESTERNFARM <br /> SERVICE(FORMER PUREGRO), STOCKTON,SANJOAQUIN COUNTY <br /> We have reviewed the 9 October 2000 Aquifer Testing Work Plan (Work Plan) prepared by Sierra- <br /> Pacific Group for the former PureGro facility at 1905 North Broadway Avenue in Stockton. In the Work <br /> Plan, Sierra-Pacific proposes to log three continuous soil borings to a depth of 100 feet below ground <br /> surface, install an extraction well and two observation wells, and perform a step-drawdown pumping test <br /> to estimate aquifer properties. The wells will be installed at property adjacent to the former PureGro <br /> facility owned by Mr. Anthony Giglio. Access agreements are in place, according to Mr. Eric Chase of <br /> Sierra-Pacific. <br /> The final design of the extraction well and observation wells will depend upon the geologic <br /> interpretation of the continuous soil logs as compared to the continuous log Sierra-Pacific obtained from <br /> downgradient well MW-7 in 1996. Decisions regarding screen depth and intervals, and single or nested <br /> observation wells will depend upon Sierra-Pacific's assessment of aquifer lateral continuity as <br /> interpretted from the soil logs. <br /> Sierra-Pacific expects to generate several thousand gallons of purge water from the extraction well <br /> during the aquifer test. This purge water will be stored in portable tanks and then treated with a portable <br /> air stripper followed by carbon filtration. According to the work plan, the treatment system will also <br /> serve as a pilot system to evaluate long-term disposal options of groundwater. <br /> The Work Plan introduced three purge water disposal options: 1) discharge to the City of Stockton <br /> munipal sewer under a Special Discharge Permit; 2) use as fertilizer make-up water at the Western Farm <br /> Service facility; and 3) injection/infiltration of treated purge water into the aquifer. All three are viable <br /> disposal options, although the injection/infiltration option will require UNOCAL to obtain Waste <br /> Discharge Requirements (WDRs) for the discharge. Before WDRs are prepared,UNOCAL will need to <br /> provide a Report of Waste Discharge (RWD),which fully characterizes the discharge. Enclosed is the <br /> RWD form (Form 200). <br /> Use of the purge water as fertilizer make-up water should be considered the most desirable option for the <br /> aquifer test purge water, since water is recycled rather than disposed of. This and the municipal sewer <br /> California Environmental Protection Agency <br /> ea Recycled Paper <br />