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Ms. Amy Terrell <br /> 20 August 2007 <br /> Page 2 <br /> groundwater zone at 28 locations in the test plot. Post-injection monitoring has continued to the <br /> present, in accordance with California Regional Water Quality Control Board, Central Valley <br /> Region (RWQCB) Monitoring and Reporting Program (MRP)No. R5-2003-0815. <br /> On behalf of WFS, Geosyntec prepared a Pilot Study Assessment Report that was submitted to <br /> the RWQCB on 20 April 2007. The report recommended modifying the existing pilot test in <br /> order to confirm the ability of in-situ anaerobic methods to degrade COCs still present in <br /> groundwater at the Site. <br /> RWQCB staff discussed the report recommendations with Geosyntec on 13 June 2007 and <br /> requested that a Work Plan be submitted with the following information: <br /> • Comparison of HRC-X®to HRC®chemistry; <br /> • An additional monitoring well downgradient of the test plot; and <br /> • A detailed layout of the injection test plot, proposed monitoring wells, and existing Site <br /> facilities. <br /> This Work Plan includes the specific information requested by the RWQCB and presents a plan <br /> for modifying the existing pilot test. <br /> TECHNOLOGY DESCRIPTION AND HRC-X®CHEMISTRY <br /> HRC-X® is a Regensis product that will be injected into the uppermost groundwater. Like <br /> HRC®, which was used during the previous pilot test, HRC-X®is a viscous material, composed <br /> of glycerol tripolylactate. According to Regenesis, HRC-X®is chemically identical to the HRC® <br /> product used for the previous pilot test conducted at the Site <br /> (http://www.regenesis.com/products/enhAna/hrcx/). The only difference between the two <br /> compounds is that the viscosity of HRC-X® (200,000 centipoise [cp]) is significantly greater than <br /> that of HRC® (20,000 cp). The increase in viscosity should allow for a longer, controlled-release <br /> of lactic acid; thereby extending the life of the product in the ground. <br /> Once injected into the subsurface, the compound slowly releases lactic acid for periods in excess <br /> of 3 years. This source of lactic acid is then metabolized by naturally occurring microorganisms <br /> producing consistent, low-level concentrations of hydrogen. Reducing conditions developed by <br /> PAPR.12003REM\WFS\VER\VERF\2007 Expanded Pilot Work Plan\Expanded_Pilot Test WP.doc <br /> engineers I scientists I innovators <br />