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%W/ <br /> San Joaquin County <br /> Environmental Health Department DIRECTOR <br /> �.• _.�� .o Donna Heran, REHS <br /> 600 East Main Street <br /> PROGRAM COORDINATORS <br /> N Stockton, California 95202-3029 <br /> `3 Robert McClellon,REHS <br /> • __=• Jeff Carruesco,REHS, RDI <br /> Website: www.sjgov.org/ehd Kasey Foley, REHS <br /> c��iFo•Ri��P <br /> Phone: (209)468-3420 Linda Turkatte, REHS <br /> Fax: (209)464-0138 <br /> February 1, 2011 <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 Remedial <br /> Action Work Plan (RAW) dated December 28, 2010, submitted on your behalf by Geocon <br /> Consultants, Inc. (Geocon) and has the following comments. <br /> Based on the results of feasibility testing and recommendations made in their <br /> September 2010 Site Investigation and Air Sparging Pilot Test Report, Geocon proposes the <br /> installation of seven air sparge wells (AS) and three soil vapor extraction wells (VW) to <br /> initiate remediation of the site by air sparging and soil vapor extraction (SVE). The proposed <br /> wells will enhance the previously installed AS-1, VW-1 and VW-2 to provide coverage of the <br /> entire contaminant plume at this site. The emphasis of the remediation is directed at the <br /> contamination remaining in the groundwater; the proposed SVE is to capture volatilized <br /> contaminants released from the groundwater. <br /> The EHD is concerned that the proposed VW wells may not be able to fully capture the <br /> volatilized contaminants. As such the EHD approves the VW installations with the condition <br /> that the screen intervals are shortened so they do not intercept the sandy intervals located <br /> above approximately 30 feet below surface grade (bsg), as shown on the provided <br /> cross-sectional diagrams. In addition, the two VW's already on site, VW-1 and VW-2, need <br /> to be either separately manifolded or have valves so they may be isolated from the rest of <br /> the system, as their screen intervals do intersect the shallow sand units. <br /> Please proceed with submittal of a well permit application and fees, and with scheduling the <br /> well installations. If you have any questions please contact Lori Duncan at (209) 468-0337, or <br /> by email at Iduncan@sjcehd.com. <br /> Sincerely, <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, Ste 200, Rancho Cordova CA 95670 <br /> , Rebecca Silva, Geocon, 3160 Gold Valley Drive, Suite 800, Rancho Cordova CA 95742 <br />