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a <br /> Advanced <br /> GeoEnvironmental, Inc . <br /> 17 August 2009 <br /> AGE-NC Project No. 96-0235 <br /> Ms. Vicki McCartney FF)MMYED <br /> San Joaquin County Environmental Health Department ll ti <br /> 600 East Main Street AUG 2 0 2009 <br /> Stockton, CA 95202 <br /> ENVIRONMENT HEALTH <br /> Subject: WEST CLAY PROPERTY PERWISERVICES <br /> 639 West Clay Street, Stockton,California <br /> Dear Ms. McCartney: <br /> At the request of West Clay Property (WCP), Advanced GeoEnvironmental, Inc. (AGE) has <br /> prepared a response to the EHD letter dated 19 May 2009 for the directive to expand the monitoring <br /> well network at 639 West Clay Street, Stockton, California. Additionally,the EHD has directed a <br /> ground water feasibility study for the southern underground storage tank (UST) site be prepared. <br /> Conversely,soil remediation has been conducted in two separate phases at each UST area;primarily <br /> during the UST removals and subsequently during deep excavations of impacted soils to the upper <br /> portion of the water table. <br /> Previous feasibility pilot test work plans have been submitted for the site. The Feasibility Pilot Test <br /> 11, Work Plan,dated 31 January 2000 was approved by EHD letter dated 17 March 2000.An air-sparge <br /> pilot test was approved as a component of the above plan, which has not been completed. <br /> The performance of field-scale pilot studies for ground water extraction included an 8-hour step <br /> draw-down ground water extraction pilot test conducted at the site. High concentrations of <br /> petroleum hydrocarbons were detected in initial extracted ground water samples. Based on the <br /> results of the July 2001 pilot test, a 24-hour constant rate ground water extraction was performed <br /> at the site on 05 and 06 November 2003 to determine the feasibility of ground water extraction as <br /> c a full-scale remediation alternative for the site. During the 24-hour constant rate ground water <br /> r J extraction feasibility test performed at the site, the detected concentrations of target analytes in <br /> extracted ground water samples from the full scale test were significantly lower than those reported <br /> for the July 2001 pilot test. The feasibility of ground water extraction remediating the dissolved <br /> plume was diminished due to the lack of sustainable recovery of impacted ground water during <br /> ground water extraction;based on the obvious increased duration required for any proposed ground <br /> water plume recovery. <br /> Additionally,Revised Ozone Injection Pilot Study Work Plan, dated 27 October 2005 and Ozone <br /> Injection Pilot Study Work Plan,dated 04 January 2005,were approved by the EHD letter dated 17 <br /> April 2006. Ozone injection has been operational since November 2006. Several episodes of <br /> C° operation have transpired with repairs to the ozone generation equipment between the successful <br /> remediation cycles.The dissolved concentrations ofpetroleum hydrocarbons and fuel additives have <br /> declined and not rebounded in the shallow target zone for ozone injection. <br /> 837 Shaw Road,Stockton,CA 95215 <br /> Telephone (209)467-1006•Fax(209)467-1118 <br />