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CONESTOGA-ROVERS <br /> & ASSOCIATES <br /> January 6, 2011 8 Reference No. 632277 <br /> The TPHg, benzene, and ethylbenzene concentrations in VP-1, and the TPHg concentration <br /> in VP-2, exceeded the commercial/ industrial ESLs. <br /> RECOMMENDATIONS <br /> • CRA recommends continued monitoring and sampling to further evaluate groundwater <br /> quality and concentration trends. However, in accordance with Resolution 2009-0042 and <br /> the associated SJCEHD letter dated July 29, 2009, CRA recommends that the sampling <br /> frequency of the wells be reduced to semi-annual during the second and fourth quarters <br /> (April and October, respectively) . <br /> • In addition, based on the data, we propose the following reductions to the analytical suite: <br /> o MW-1: Eliminate TPHg and BTEX <br /> o MW-5: Eliminate TPHg, BTEX, and MTBE <br /> o MW-6A: Eliminate TPHd, TPHg, and BTEX <br /> o MW-6B: No longer sample <br /> o All wells: Eliminate 1,2-DCA and EDB <br /> • To further evaluate soil vapor quality and concentration trends, CRA recommends an <br /> additional sampling event during the second or third quarter 2011. CRA and Chevron will <br /> work with the tenant to gain access to VP-4. <br /> ANTICIPATED FUTURE ACTIVITIES <br /> • G-R will next gauge and sample the site wells during the fist semi-annual sampling event <br /> in April 2011 in accordance with the above-proposed reduced sampling schedule and <br /> program, unless directed otherwise by the SJCEHD. Upon completion of this monitoring <br /> event and receipt of the data, CRA will prepare a summary of the site conditions and <br /> monitoring results. <br /> • CRA will conduct additional vapor sampling during second quarter 2011 (pending <br /> relocation of the storage container) and will present the results in a groundwater monitoring <br /> or stand-alone report. <br /> Worldwide Engineering, Environmental, Construction, and IT Services <br />