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California Regional Water Quality Control Bop and .: <br /> i'::;tv,'i(`�f:.lr�Ml. flEi-iI_�I9 �•'�' :i'_ s <br /> Central Valley Region <br /> Robert Schneider,Chair � <br /> Winston H.Hickox � GrayDavis <br /> Secretary for Sacramento Main Office Governor <br /> Environmental Internet Address: hitp://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 /> 10 October 2003 <br /> 9 <br /> Ms.Nancy Bishop <br /> Western Farm Service <br /> 3650 Mt. Diablo Blvd., Suite 260 <br /> Lafayette, CA 94549 <br /> PARTIAL APPROVAL OF SOIL REMEDIAL ACTION PLAN, WESTERN FARM SER VICE, <br /> VERNALIS, SAN JOA QUIN COUNTY <br /> We have reviewed the 25 August 2003 Soil Remedial Action Plan (Cleanup Plan) prepared on your <br /> behalf by GeoSyntec Consultants for the former tank farm at the Western Farm Service facility in <br /> Vernalis (WFS). Soil beneath the former tank farm contains elevated concentrations of ammonium and <br /> nitrate as characterized in various investigations conducted in 1989, 1991, and 1996, concluding with the <br /> removal of the upper one foot of soil in about 1997. The RAP proposes to explore the potential of insitu <br /> biological degradation of ammonium and nitrate in soil through the following actions: <br /> • Conduct a microcosm study in the laboratory using soil obtained from the former tank farm to <br /> evaluate the efficacy of HRC Primer(a soil-specific formulation of Hydrogen Releasing <br /> Compound®) to degrade ammonium and nitrogen. In addition to a microcosm amended with HRC <br /> Primer, a microcosm will be amended with unsulfured molasses, and one will be an intrinsic control, <br /> all maintained under anoxic conditions. Each microcosm will consist of at least three replicates, and <br /> will be sampled about every other week for nitrogen and carbon compounds in soil and for nitrogen <br /> and other gases in the headspace. <br /> • Submit microcosm test results, evaluation and conclusions to Regional Board staff <br /> • Inject HRC Primer on approximately 10-foot centers throughout the approximately 150 x 50-foot <br /> former tank farm area to depths of two feet below ground surface (bgs) and about 17 feet bgs, which <br /> is at least five feet above seasonally high groundwater depth. <br /> • Obtain depth discrete soil samples annually. <br /> Regional Board staff concur with WFS's microcosm study approach to developing an insitu remedial <br /> strategy for soil that contains high ammonium and nitrate concentrations. At this juncture, however, it is <br /> premature to formulate an implementation plan prior to obtaining the microcosm results. <br /> We concur with the microcosm study portion of the Cleanup Plan providing the following addition is <br /> made to the microcosm setup: if substantial ammonium degradation is not realized in either of the two <br /> California Environmental Protection Agency <br /> ea Recycled Paper <br /> The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways <br /> you can reduce demand and cut your energy cqStsqee our Web-site at http://www.swrcb.ca.gov/rwgcb5 <br />