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• <br /> ! <br /> GEO-PHAS E <br /> ENVIRONMENTAL <br /> ' REPORT <br /> Vapor Extraction /Air Sparge Remedial System Construction <br /> Cutter Lumber/Western Lift Site <br /> i ' 3930 S. EI Dorado <br /> Stockton, California <br /> ' March 15, 2005 <br /> GPE Project No. 102.3 <br /> ' CWRCB GID Code T0607700498 <br /> Geo-Phase Environmental Inc., on behalf of the Bank of Stockton constructed an <br /> integrated remedial system consisting of 6 vapor extraction wells, 4 air sparge wells, and <br /> the associated piping and surface equipment intended to complete the engineered <br /> mitigation of the gasoline release at this site. The following sections describe the work <br /> ' completed to construct the system. <br /> 1.0 INTRODUCTION <br /> i ! Field work and groundwater monitoring completed at the site since 1996 show that a I <br /> former leaking underground storage tank impacted the soil and groundwater with gasoline <br /> ' range petroleum hydrocarbons. The previously issued report of a feasibility study <br /> estimated that about 14,000 pounds of gasoline are resident in the soil and groundwater as <br /> a result of the release. <br /> Over the past several years, groundwater monitoring data have been collected from six <br /> monitoring wells situated through and around the contaminant plume. The continued high <br /> ! levels of gasoline and volatile organic hydrocarbons in groundwater samples collected <br /> from on-site wells, however, suggest that natural attenuation is not adequately mitigating <br /> the groundwater plume. In 2003 a pilot test of air sparge and vapor extraction technology <br /> was completed. Based on the results of the pilot test and a feasibility study, a CAP <br /> recommended that corrective action in the form of simultaneous air sparging and vapor <br /> extraction be undertaken. <br /> 2937 Veneman Ave., #B240 Geo-Phase Environmental Inc. Phone(209)569-0293 <br /> Modesto, CA 95356 Fax(209) 569-0295 <br />