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/1�COM AECOM 916 361 6400 tel <br /> 10461 Old Placerville Road 916 361 6401 fax <br /> Suite 170 <br /> Sacramento,CA 95827 <br /> www.aecom.com <br /> JUL 1 9 2:110 <br /> July 15,2010 EIVIRuivivitiv i HEALTH <br /> Mr. James L. Barton PERMIT/SERVICES <br /> Central Valley Water Board <br /> 11020 Sun Center Drive, Suite 200 <br /> Rancho Cordova, California 95670-6114 <br /> Subject: Quarterly Remediation Status Report for the Second Quarter of 2010 <br /> Cleanup and Abatement Order No. 5-00-707 <br /> 5400 and 5606 Pacific Avenue, Stockton, California <br /> Chevron#306620 (former Unocal #5098) <br /> AECOM Project#60146576—M109 <br /> Dear Mr. Barton: <br /> AECOM, on behalf of Chevron Environmental Management Company(CEMC), is documenting the <br /> second quarter remediation activities for the former Montgomery Ward, LLC (Wards) auto service <br /> center located at 5400 Pacific Avenue and former Unocal Service Station#5098 located at <br /> 5606 Pacific Avenue, Stockton, California, which are referenced collectively as the Site. Remediation <br /> activities have been conducted pursuant to requirements of Cleanup and Abatement Order <br /> (CAO) No. 5-00-707 issued to Wards, Unocal, Surry California Limited Partnership, and Stone <br /> Brothers and Associated General Partnership (Stone Bros.)on September 8, 2000 by the Central <br /> Valley Water Board (CVWB). <br /> Remediation System Update <br /> On December 28, 2009, the combined air sparge (AS) and soil vapor extraction (SVE) remediation <br /> system was shut down as part of the rebound testing for the Site. As noted in the Semi-Annual <br /> Groundwater Monitoring and Remediation Status Report for the First Quarter of 2010, AECOM <br /> recommended keeping the remediation system turned OFF until the completion of the first soil vapor <br /> investigation sampling event in order to evaluate the soil vapor risks without interference of the <br /> induced air movement in the subsurface by the AS and/or SVE systems. AECOM installed the three <br /> soil vapor wells on May 13, 2010 and conducted the first soil vapor investigation sampling event on <br /> May 20, 2010. A report documenting both the well installation and soil vapor sampling activities will <br /> be submitted to the CVWB under separate cover. <br /> AECOM re-started the AS system on June 3, 2010. The AS system operated continuously through <br /> the remainder of the Second Quarter 2010 (June 30, 2010). On July 9, 2010, AECOM observed that <br /> although the AS system was operating,the AS system was not delivering air to the subsurface in the <br /> intended manner.The functionality of the AS system was corrected on July 9, 2010. <br /> Future Work <br /> Consistent with the California State Water Resources Control Board Resolution No. 2009-0042 and <br /> the letter dated July 8, 2009 letter from the CVWB,the groundwater monitoring frequency at the Site <br /> has been reduced to semi-annually, with monitoring occurring in the first and third quarters. <br /> Gettler-Ryan Inc. (G-R) was contracted by CEMC to perform the semi-annual monitoring events for <br />