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Mr. Jack Badey - 2 - 21 June 2012 <br /> Groundwater Remediation Pilot Study <br /> UniFirst is conducting a pilot study small-scale in-situ groundwater remediation using a carbon <br /> source to feed indigenous micro-organisms that anaerobically degrade the PCE and TCE. In <br /> June 2011, UniFirst added the slow-release lactate product, HRC, and a less viscous <br /> formulation, HRC Primer, to groundwater near monitoring wells MW-5A, MW-5B, and MW-5C. <br /> The continuing results of this pilot study are included in the Groundwater Monitoring Report. <br /> The data show that the HRC has produced favorable reducing conditions in MW-5A and <br /> MW-513, as evidenced by significant reductions in nitrate, sulfate, PCE, and TCE. Increases in <br /> the concentration of the breakdown products of cis-dichloroethene and vinyl chloride show that <br /> degradation is occurring, and these breakdown products are expected to be temporal. The pilot <br /> study is scheduled to run another year when UniFirst will provide an assessment of the <br /> feasibility of using HRC to remove PCE and TCE. <br /> Comments on Report Assertions <br /> In April 2010, UniFirst proposed monitored natural attenuation (MNA) as a remediation strategy. <br /> In its 2 August 2010 reply, Central Valley Water Board staff stated that "Central Valley Water <br /> Board staff . . . do not concur that monitored natural attenuation is an appropriate remediation <br /> strategy for PCE at this time." Since 2011, the groundwater monitoring reports have stated that <br /> "In an August 2010 letter to UniFirst, the RWQCB [Central Valley Water Board staff] concurred <br /> with the assessment of site conditions and the use of MNA." Central Valley Water Board staff <br /> respectfully request that UniFirst and AMEC Geomatrix remove this statement from future <br /> reports since Central Valley Water Board staff have not accepted monitored natural attenuation <br /> as a remediation strategy at this site. <br /> In the monitoring reports, Central Valley Water Board staff appreciate the report detail, <br /> description of activities, and summary of historical events. However, please modify future report <br /> text to more accurately portray the correspondence record. <br /> Conclusion <br /> UniFirst is making excellent progress in removing PCE and TCE mass from groundwater near <br /> the former source area. Central Valley Water Board staff look forward to seeing the second <br /> year of data from the pilot study, and working with UniFirst to assess a path to closure. <br /> If you have any questions, you may contact me by telephone at (916) 464-4680 or by email at <br /> aterrell@waterlboards.ca.gov. <br /> AMY TERRELL <br /> Private Sites Cleanup Unit <br /> cc: Mr. Nuel Henderson, San Joaquin County Environmental Health Dept., Stockton <br /> Mr. Tom Cosgrave, UniFirst Corporation, Willmington, MA <br /> Mr. Monte Schlittenhard, UniFirst Corporation, Stockton <br /> Mr. William Aravanis, AMEC Geomatrix, Fresno <br />