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San Joaquin County <br /> Environmental Health Department DIRECTOR <br /> �• —�f •O Donna Heran,REHS <br /> s:` y 600 East Main Street <br /> PROGRAM COORDINATORS <br /> ,. Stockton, California 95202-3029 Robert McClellon,REHS <br /> •.I L+SL1 . <br /> •' Jeff Carruesco, REHS,RDI <br /> Cq •.�..•��P Website: www.sjgov.org/ehd Kasey Foley,REHS <br /> Phone: (209)468-3420 Linda Turkatte,REHS <br /> Fax: (209)464-0138 <br /> September 24, 2010 <br /> Terrence Fox <br /> Cal Trans District 6 <br /> 2015 East Shields Avenue, Suite 100 <br /> Fresno, CA 93726 <br /> Subject: Stockton Yard Maintenance Station <br /> 1604 B Street <br /> Stockton, CA 95201 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Site <br /> Investigation and Air Sparging Pilot Test Report (Report) dated September 2010, submitted on <br /> your behalf by AMEC Geomatrix (AMEC) and has the following comments. <br /> In the Report, AMEC discusses the installation of cone penetration test (CPT) borings utilizing <br /> membrane interface probe (MIP) technology, one air sparge (AS) point and three observation <br /> wells, and conducting an AS pilot test. The objective of the scope of work was to confirm the <br /> location and depth of petroleum hydrocarbon impacts within the contaminant source area at the <br /> site, and to determine if AS would be a feasible remedial alternative to implement. <br /> Based on the data collected during the investigative and pilot testing work, AMEC concludes <br /> that AS can be used successfully to remediate the soil and groundwater contamination <br /> remaining at the site. A 16-foot zone of influence was observed, contaminant concentrations <br /> were lower after the test, and groundwater parameters are appropriate for biodegradation of <br /> petroleum hydrocarbons enhanced by AS. Increases in PID readings of vadose zone soil taken <br /> during the sparge test indicate that soil vapor extraction (SVE) will need to be implemented to <br /> capture vapors stripped during the proposed remediation. <br /> The EHD agrees with AMEC's conclusion that AS/SVE is a feasible remedial alternative for this <br /> site. Please proceed with submittal of a Remedial Action Work Plan (RAWP). The RAWP is due <br /> for submittal to the EHD no later than November 30, 2010. <br /> If you have any questions please contact Lori Duncan at (209) 468-0337, or by email at <br /> Iduncan@sjcehd.com. <br /> Lori Duncan, REHS Nuel C. Henderson, Jr., PG <br /> Senior Registered Environmental Health Specialist Engineering Geologist <br /> c: James Barton, CVRWQCB, 11020 Sun Center Drive #200, Rancho Cordova CA 95670 <br /> Eileen Gower, AMEC Geomatrix, 10670 White Rock Road, #100 Rancho Cordova CA 95670 <br />