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amec selected, the regulatory permitting process for implementation could be streamlined by performing the remediation in accordance with General Order for In Situ Groundwater Remediation at Sites with Volatile Organic Compounds (Order No. R5-2008-0149 [General Order]). The RWQCB also requested bench scale testing to verify the effectiveness of the proposed in situ remediation methods and to identify geochemical changes likely to occur in groundwater as a result of the in situ remediation. This Interim RAP is intended to fulfill the RWQCB request. UniFirst proposes using in situ injection of hydrogen release compound (HRC)to stimulate the naturally occurring reductive dechlorination of the CVOCs in groundwater. UniFirst proposes first to conduct a pilot test to evaluate the effectiveness of this method for this site. The pilot test will be conducted in the area where CVOC concentrations in groundwater are the highest(in the vicinity of monitoring well cluster MW-5). The test will allow the collection of performance data that could be used for subsequent application to other locations, if it is shown to be necessary. This Interim RAP was prepared using the General Order as guidance. A Notice of Intent to conduct the pilot test is presented in Appendix B. 7.1 BENCH SCALE TEST UniFirst proposes to not conduct bench scale testing of HRC injections prior to performing the pilot test. HRC has been utilized for remediation at numerous sites with PCE in groundwater. Information on the performance of HRC at sites similar to UniFirst is readily available (Koenigsberg, 1999; Koenigsberg, 2004). HRC is manufactured by Regenesis, Inc., of San Clemente, California. Material Safety Data Sheets for these materials are provided in Appendix C. HRC contains glycerol tripolylactate, glycerol, and lactic acid. Upon contact with water, FIRC releases lactic acid that acts as a hydrogen source for microbes that degrade CVOCs. The availability of an abundant hydrogen source significantly increases the rate at which the microbes degrade the CVOCs in groundwater. A typical case study involving a dry cleaner located in Texas with groundwater affected by PCE and clayey soil conditions, similar to conditions at the Stockton site, is presented in Appendix D. The results of this and other studies indicate HRC should be effective in reducing the concentration of CVOCs in groundwater at the UniFirst site. These case studies indicate the likely geochemical changes in the aquifer resulting from enhanced reducing conditions due to HRC are well understood. The changes are likely to include reductions in dissolved oxygen, nitrate, and sulfate and increases in dissolved iron. However, these changes are ephemeral and aquifer geochemical conditions at other sites have been shown to gradually revert to their previous condition as the supply of FIRC in the aquifer is exhausted (about 1 to 2 years). AMEC_ Geomatrix, Inc. 1A13000s\13290Wrchive\13290-49.DOG 10