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Geological Techwa Inc. Page 6 Additional Pilot Test Work Plan Project No.770.2 October 30,2008 with SJC PHS/EHD staff on June 3, 2004 to discuss the site. The challenge of remediating diesel contamination in low permeability soils was discussed at the meeting. It was agreed that our SVE work plan and additional site characterization would be set in abeyance while SJC PHS/EHD would contact the RWQCB for guidance on remedial technologies. In a June ` 17, 2004 email correspondence, SJC PHS/EHD stated that RWQCB staff proffered that bioventing technology was utilized by the Air Force to address diesel releases. The email also included links to relevant technology websites. Upon review of the relevant data and updating the SCM with the October 2005 CPT investigation, GTI recommended that a pilot test be performed for evaluating a combination 4ww of bioventing with low flow biosparging be performed at the site. This involved injecting air into the subsurface to stimulate aerobic biodegradation of the petroleum hydrocarbons. The test involved the installation of injection wells with associated infrastructure to blow air into the subsurface and monitor air flow rates, pressure, vacuum and other parameters. The objective of the pilot tests was to obtain enough data to design a treatment system to address the entire soil and groundwater plumes. GTI in their report dated March 5, 2008 recommended that bioventing and biosparging are two viable technologies for contamination reduction at the site since the test of both technologies at the site between November 26, and December 14, 2007 showed that both bioventing and biosparging increased the level of DO in vadose zone and groundwater respectively that causes the biodegradation augmentation. f GTI also performed a soil vapor extraction and dual phase extraction pilot test utilizing higher vacuum pressures (up to 26" Hg vacuum) than used with standard SVE. This is similar to dual phase extraction technology but without the intent of extracting and treating groundwater during vapor extraction only. The SJC PHS/EHD previously denied our proposal to test this technology based on its inapplicability to diesel fuel. However, the results from the SVE/DPE test between November 26 and December 14, 2008 indicates that this technology is appropriate procedures for mass removal to remediate the groundwater and soil at the site. High concentration of hydrocarbons in vapor extracted from extraction wells during the test shows the sustainability of vapor flow and concentration in case of choosing bat any of these two technologies for groundwater and soil remediation at the site. As the TPH- G and TPH-D concentrations in the extracted soil vapor samples were not assessed, the EHD recommended further pilot studies of SVE or DPE to assess the total contaminant recovery +- rate and sustainability. CPT investigation indicates that some lithologic units of greater permeability are present that might benefit from this technology. The soil micro-fractures structures also may facilitate extraction through silty and clayey soils. With the existing wells that can be used to test high vacuum vapor extraction, soil vapor samples will be collected from extraction well during a two week and are analyzed for TPH-G_TPH-D and BTEX using appropriate EPA method of analysis explained below. GTI has used these two technologies in a pilot test at another gasoline/diesel contaminated site with_success at removing diesel from the subsurface. Due to increasing groundwater elevation_trend at the site GTI prefers to proceed with duan hase extraction test.