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EOMUNO G. BROWN JR. <br /> GOVERNOR <br /> O L I I O N N I• EC EIV E® a MATTHEW RODRIQUEZ <br /> Water Boards eNVIETNRY FOR <br /> ENVIRONMENTAL PROTECTION <br /> Central Valley Regional Water Quality Control Board CNUMONMENTAL <br /> PERMIT/SERACESLT� <br /> 7 February 2014 <br /> Mr. Jack Badey <br /> EHS Manager, UniFirst Corporation <br /> 68 Jonspin Road <br /> Wilmington, MA 01887-1090 <br /> REVIEW OF REMEDIATION, UNIFIRST CORPORATION, 819 HUNTER STREET, <br /> SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br /> Board) staff, have reviewed the following documents prepared on UniFirst's behalf by AMEC <br /> Environment & Infrastructure. <br /> • 31 May 2013 First Semiannual 2013 Groundwater Monitoring Report <br /> • 8 October 2013 Groundwater Remediation Pilot Test Evaluation Report (Pilot Test Report) <br /> • 24 October 2013 Second Semiannual 2013 Sub-Slab Depressurization System Monitoring <br /> Report <br /> • 26 November 2013 Second SemiAnnual 2013 Groundwater Monitoring Report <br /> UniFirst is a wet-wash laundry operation which built its building on property that had previously <br /> been owned and operated by Parisian Laundry. Parisian Laundry handled the dry cleaning <br /> solvent, perchloroethene (PCE). Site investigations show that PCE was released to site soil <br /> and PCE has been detected beneath the new building, and in groundwater beneath and <br /> downgradient of the property. In 2009, UniFirst began operating a sub-slab depressurization <br /> system to prevent PCE vapors from entering the building. This system continues to remove <br /> PCE from the subsurface. In June 2011, UniFirst implemented pilot-scale insitu groundwater <br /> remediation of PCE, by injecting Hydrogen Releasing Compound® (HRC) into the first three <br /> water bearing zones as authorized by General Order No. R5-2008-0149-029 (General Order). <br /> Remediation Effects <br /> Monitoring wells MW-5A, MW-5B, and MW-5C are proximate to the HRC injections in each of <br /> the three water-bearing zones. Two years of monitoring shows that PCE reductions were <br /> significant in the first two water bearing zones. In the first water-bearing zone, the concentration <br /> of PCE decreased in MW-5A from 94 ug/L in April 2011 to about 20 ug/L in March 2013, but <br /> subsequently increased to 40 ug/L in September 2013. In the second water-bearing zone, the <br /> concentration of PCE decreased in MW-5B from 500 ug/L in April 2011 to 20 ug/L in September <br /> 2013. <br /> An increase of alkalinity in MW-5A and MW-5B, along with an increase of PCE degradation <br /> products trichloroethene, cis-1,2-dichloroethene, chloroform and vinyl chloride is further <br /> evidence that biological degradation has been occurring. Central Valley Water Board staff <br /> expect that degradation will continue in MW-5A and in MW-513 because dissolved organic <br /> KARL E. LONGLEY SCD, P.E.,CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER <br /> 11020 Sun Center Drive#200,Rancho Cordova,CA 95670 1 www.waterboards.ca.gov/contralvalley <br /> IHI,CYCLtU P "H <br />