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Californi*gional Water Quality G, trol Board <br /> Central Valley RegionQa; . ,... ,, <br /> Katherine Hart, Chair ("° �`` <br /> Linda S.Adams 11020 Sun Center Drive#200, Rancho Cordova,California 95670-6114 Edmund G. Brown Jr. <br /> Acting Secretary for Phone(916)464-3291 •FAX(916)464-4645 Governor <br /> Environmental Protection http://www.waterboards.ca.gov/centralvalley RECEIVED <br /> 14 January 2011 .IAN 18 2011 <br /> Mr. Jack Badey EWIRONMENTAL PERMIT SERVIC SLTH <br /> EHS Manager, <br /> UniFirst Corporation <br /> 68 Jonspin Road <br /> Wilmington, MA 01887-1090 <br /> CONITIONAL CONCURRENCE WITH PILOT SCALE STUDY PROPOSAL, UNIFIRST, <br /> 819 HUNTER STREET, STOCKTON, SAN JOAQUIN COUNTY <br /> UniFirst Corporation has proposed an insitu pilot scale study of groundwater remediation for <br /> the dry cleaning solvents tetrachloroethene (PCE) and trichloroethene (TCE) that resulted <br /> from discharges at the previous landowners' dry cleaning facility. The pilot scale study <br /> proposes to inject Hydrogen Releasing Compound® (HRC) to groundwater, which will facilitate <br /> microbiological degradation of the solvents. The remediation proposal and groundwater <br /> quality data are presented in the following documents prepared by UniFirst's consultant, <br /> AMEC Geomatrix. <br /> • 29 October 2010 Groundwater Interim Remedial Action Plan (Pilot Scale Study) <br /> • 3 December 2010 Second Semi-Annual 2010 Groundwater Monitoring Results <br /> As discussed below, California Regional Water Quality Control Board, Central Valley Region <br /> (Central Valley Water Board) staff conditionally concur with the Pilot Scale Study. With some <br /> minor additions, the proposed groundwater injections of HRC can be permitted under existing <br /> Waste Discharge Requirements No. R5-2008-0149, which is a General Order for InSitu <br /> Groundwater Remediation. <br /> PROPOSED REMEDIATION <br /> In the Pilot Scale Study, Unifirst proposes to add HRC Primer and HRC to three water- <br /> bearing zones at the center of the plume mass through individual injection points. The HRC <br /> Primer is a dilute formulation of HRC that degrades quickly, thereby rapidly establishing <br /> reducing conditions. HRC degrades slowly, which maintains the strong reducing conditions <br /> necessary to degrade the chlorinated compounds. About five feet downgradient of the <br /> injection points three existing monitoring wells (MW-5A, MW-513 and MW-5C) will provide <br /> monitoring data from well screens that correspond to the injection intervals. The pilot test <br /> monitoring is anticipated to continue for about two years, when it is expected that the HRC will <br /> have been consumed. The results of the pilot test will determine whether a broader scale <br /> application is appropriate at this site. <br /> Central Valley Water Board staff concur with the Pilot Scale Study's recommendation that a <br /> bench test is not needed. Central Valley Water Board staff have sufficient experience with <br /> California Environmental Protection Agency <br /> CjRecycled Paper <br />