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California is kegional Water Quality Contio1 Board <br /> \s Central Valley Region 10 <br /> `° y,°°' <br /> Katherine Hart, Chair ��--���` <br /> Linda S. Adams 11020 Sun Center Drive#200,Rancho Cordova,California 95670-6114 Arnold <br /> Secretary for Schwarzenegger <br /> Environmental Phone(916)464-3291 •FAX(916)464-4645 <br /> http://www.waterboards.ca.gov/centralvaIley Governor <br /> Protection <br /> 17 February 2010 <br /> Mr. Allan Fetters Mr. Bud den Ouden <br /> RF Land, Inc. Ripon Farm Service, LLC <br /> 3705 Portsmouth Circle North PO Box 806 <br /> Stockton, CA 95219-3842 Ripon, CA 95366-0806 <br /> CONDITIONAL CONCURRENCE WITH REVISIONS TO PHASE 11 SITE INVESTIGATION <br /> WORK PLAN, RIPON FARM SERVICE, 938 FRONTAGE ROAD, SAN JOAQUIN COUNTY <br /> RF Land, Inc. and Ripon Farm Service, LLC are responsible for investigation and remediation <br /> of nitrogen pollutants at this former Ripon Farm Service facility. In its 30 September 2009 <br /> letter, California Regional Water Quality Control Board, Central Valley Region (Central Valley <br /> Water Board) conditionally concurred with the 7 July 2009 Site Characterization Work Plan <br /> Phase //, prepared by Genesis Engineering & Redevelopment on behalf of RF Land, Inc. In <br /> this conditional concurrence letter, Central Valley Water Board staff requested an Addendum, <br /> consisting of an updated figure illustrating additional sample points, which was received on <br /> 6 November 2009. On 1 February 2010, Central Valley Water Board staff received a Revised <br /> Addendum illustrating revisions proposed by Ripon Farm Service, LLC. This letter reviews the <br /> Revised Addendum (attached) and Site Characterization Work Plan in view of addressing the <br /> remaining site characterization needs. <br /> In summary, deep soil borings have been removed, a total of four deep monitoring wells (to <br /> the depth of about 190 feet below ground surface) are proposed, locations of some shallow <br /> soil borings are repositioned, and a proposed shallow well is removed. <br /> Central Valley Water Board staff concur with the proposed modifications to the shallow soil <br /> sample locations and shallow groundwater monitoring points, but have concerns with some of <br /> the changes to the deep boring locations. <br /> Deep Wells <br /> One of the deep wells is to be located at the site of the former industrial supply well, and the <br /> others are along the northern boundary and at the Western Surface Area Sump. All these <br /> deep wells are adjacent to shallow wells and present well pairs. Central Valley Water Board <br /> staff concur with the location of the deep wells, but does not concur with the removal of the <br /> deep borings near the cement-lined ponds to the east. <br /> A deep soil boring is needed near the cement ponds to provide a vertical nitrogen profile.. The <br /> objective is to assess if the ponds have been a source of nitrogen to groundwater. Soil <br /> samples should be obtained at 10 feet, 15 feet, 20 feet bgs and at 20 foot intervals thereafter <br /> until the deeper water bearing zone at about 190 feet bgs is encountered. A grab groundwater <br /> sample needs to be obtained from the boring terminus and a lithologic log should be prepared. <br /> California Environmental Protection Agency <br /> C'*RecycledPaper RECEIVED FEB 2 3 2010 <br />