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Geological Technics Inc. Confirmation GW Sampling WP Project No.770.2 February 28,2011 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. The SJC PHS/EHD previously denied our proposal to test this technology based on its inapplicability to diesel fuel. However, the CPT investigation indicated 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. A second rational for performing the dual phase extraction pilot test is that both the bioventing and biosparging tests could cause a spread of the contamination in heterogeneous soils. GTI conducted a set of bioventing, biosparging, soil vapor extraction and dual phase extraction tests on-site between November 26 and December 14, 2007 to find the best remedial methodology to address the residual diesel contamination in groundwater and soil. Four pairs of shallow/deep, injection/extraction well sets were installed to facilitate the bioventing test, and one deep air sparge well was installed for the biosparging test. The results of this test were submitted on March 5, 2008. GTI submitted the Additional Dual Phase Extraction pilot test work plan on January 23, 2009, which was approved by SJCEHD on March 23, 2009 with some changes to be made in regards to the screen intervals in the new extraction wells (EW-4, EW-5, and EW-6). The �. results of the additional dual phase extraction pilot test were submitted on September 29, 2010. In a letter dated November 22, 2010 GTI requested that further clarification be given regarding the two different opinions on future work to be done at the Marci Property. In a letter dated January 11, 2011, GTI was directed to conduct conformational groundwater sampling in an effort to develop the technical argument to demonstrate a low-risk status for the Site. The following Work Plan was prepared in response to SJCEHD's directive dated January 11, 2011, and proposes conformational groundwater grab samples, sampling of select monitoring wells and water supply wells within 600 feet of the Site. 2. PROPOSED INVESTIGATION 2.1 Well Survey A well survey report was previously prepared for the site (dated January 11, 2001). GTI proposes updating the well survey, which will consist of requesting records from the Department of Water Resources (DWR) regarding historical well information out to a radius of 2,000 feet from the Site. This will be followed by a physical reconnaissance to confirm Geological Tecknics Inc. 3 7702 Confirmation GW Sampling 2-25-1 l.doc