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�r� ,P4 EDMUND G. EIROWN JR. <br /> OOV FRNOH <br /> opmRECEIVED <br /> E a MpTTNEW RODRIOUEZ <br /> .........• SE CRE iNFOR <br /> EN VIRONMEMEN'fAl PROTEOTIOn <br /> Water Boards nEc p 12014 <br /> Central Valley Regional Water Quality Control Boa ErJIRONMENTALHEALTH <br /> NNVVPERMITISERVICES <br /> 26 November 2014 <br /> Mr. Paul Lambert <br /> Genesis Engineering & Redevelopment <br /> 351 Ruess Road <br /> Ripon, CA 95366-3631 <br /> CONDITIONAL CONCURRENCE WITH GROUNDWATER EXTRACTION WORK <br /> PLAN, FORMER RIPON FARM SERVICE, 938 FRONTAGE ROAD, RIPON, SAN <br /> JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley <br /> Water Board) staff reviewed the following documents prepared by Genesis Engineering <br /> & Redevelopment on behalf of R.F. Land, Inc., also known as former Ripon Farm <br /> Service. <br /> . 15 October 2014 Groundwater Extraction Work Plan (Extraction Work Plan) <br /> • 15 October 2014 Third Quarter 2014 Groundwater Monitoring Report (Monitoring <br /> Report) <br /> Ripon Farm Service operated a retail fertilizer distribution business at 938 Frontage <br /> Road in Ripon between about 1967 and 2008. Most buildings have been removed and <br /> the site is vacant. During the operational history, nitrate and ammonium were released <br /> to soil and groundwater beneath the facility. The Extraction Work Plan proposes to <br /> withdraw shallow groundwater containing nitrate and ammonium and discharge it to the <br /> City of Ripon's non-potable water supply pipeline. As discussed below, although <br /> Central Valley Water Board staff do not agree with the remediation endpoint proposed <br /> in the Extraction Work Plan, staff conditionally concur with the groundwater extraction <br /> proposal. <br /> Pollutant Distribution <br /> The shallow groundwater flow direction varies between northwesterly and southeasterly <br /> in the depth interval of about 20 to 50 feet below ground surface (bgs). The distribution <br /> of nitrate in shallow groundwater appears to have formed a plume which generally <br /> follows this northwest to southeast direction through RMW-5S, AT-1 S, and MW-101, <br /> which contain nitrate (as nitrate) near or above 1,000 mg/L. Nitrate concentrations are <br /> substantially lower to the northeast and southwest. These concentrations range from <br /> about 200 to 500 mg/L, which also exceed the water quality objective of 45 mg/L nitrate <br /> as nitrate. <br /> In the deeper water bearing zone, which is about 180 to 200 feet bgs, groundwater flow <br /> direction has varied between northeast, southeast, and southwest. Nitrate (as nitrate) <br /> KARL E. LONGLEY SCD, P.E„ CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER 11020 Sun Center Drive#200,Rancho Cordova,CA 95670 I www.waterboards.ca.gov/centralvalley <br /> Cid RFl:r I;LFu HnrER <br />