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E(O CnN ORG. BROWN JR. <br /> RECEIVED <br /> C L I f O P N l• 1 I I'tl 25 <br /> /LOIL `� MCN NAN RonRinuez <br /> L <br /> WaterBoards L/ \ �J FNVIRUNMLNIAL VROILCIIUN <br /> ENVIRONMENTAL HEALTH <br /> Central Valley Regional Water Quality Contr9%6'6MRVICE8 <br /> 21 June 2012 <br /> Mr. Jack Badey <br /> EHS Manager, UniFirst Corporation <br /> 68 Jonspin Road <br /> Wilmington, MA 01887-1090 <br /> REVIEW OF REPORTS, UNIFIRST CORPORATION, 819 HUNTER STREET, SAN JOAQUIN <br /> COUNTY <br /> UniFirst Corporation, a wet-washing laundry operation, purchased property at 819 Hunter Street <br /> that had been previously occupied by a dry cleaning establishment. UniFirst does not use dry <br /> cleaning solvents, but the dry cleaning solvents tetrachloroethene (PCE) and trichloroethene <br /> (TICE) are found in groundwater beneath and downgradient of the UniFirst site. UniFirst is <br /> removing solvent vapors from beneath the building with a subslab depressurization system, and <br /> implemented an insitu pilot study to evaluate the effectiveness of Hydrogen Releasing <br /> Compound® (HRC) to degrade PCE and TCE in groundwater. The results of these two <br /> remediation actions are reported in the following documents prepared by AMEC Geomatrix: <br /> 0 6 June 2012 First Semiannual 2012 Sub-Slab Depressurization System Monitoring Report <br /> • 31 May 2012 First Semiannual 2012 Groundwater Monitoring Report <br /> The reports show that UniFirst is successfully removing PCE and TCE vapors from beneath the <br /> building, and degrading PCE and TCE in groundwater in the building vicinity. <br /> Sub-Slab Depressurization System <br /> In late 2008, UniFirst collected air quality samples from within the UniFirst building. The results <br /> showed that a vapor removal system was appropriate to protect workers from inhalation <br /> hazards. This vapor removal system uses a blower to create negative pressures beneath the <br /> concrete floor and withdraw vapors to an exhaust port. The vapor removal system is preventing <br /> PCE and TCE from accumulating beneath the floor. The concentrations have been generally <br /> declining since the system was installed in 2009. <br /> In 2012, a warning light should have alerted UniFirst plant staff that the vapor removal system <br /> was not working. Pursuant to an 11 June 2012 telephone conversation with Mr. William <br /> Aravanis of AMEC Geomatrix, plant staff have been advised as to the significance of the <br /> warning light and actions to be taken when the warning light indicates a system failure. Even <br /> with the system malfunction, the data showed that vapors did not significantly accumulate <br /> beneath the building. In the next semi- annual 2012 sub slab depressurization report, AMEC <br /> Geomatrix will evaluate whether the vapor removal system is still needed. In addition to <br /> protecting worker health, the vapor removal system is also removing contaminant mass that <br /> could contribute PCE and TICE to groundwater. <br /> KARL E. LONGLEV ScD, P.E., CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER <br /> 11020 Sun Center Drive#200,Rancho Cordova.CA 95070 1 www.waterboard5.ca.gov/centralvalley <br /> RFCVCLFD PAPFR <br />