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San Joaquin County <br /> Pv_u. ni DIRECTOR <br /> co� Environmental Health Department Donna Heran,REHS <br /> e �••— 2 600 East Main Street <br /> PROGRAM COORDINATORS <br /> �(�,� ,,`✓� Stockton, California 95202-3029 Robert McClellon,REHS <br /> • Jeff Carruesco,REHS,RDI <br /> Kasey <br /> Website: www.sjgov.org/ehd Linda Foley,RENS <br /> C4'�f k o Ra�P Linda Turkatte, REHS <br /> Phone: (209)468-3420 <br /> Fax: (209)464-0138 <br /> March 4, 2012 <br /> Mr. Victorio A.randa <br /> c/o Victor Aranda <br /> 1318 East Scotts Avenue <br /> Stockton, CA 95205 <br /> Subject: Former Electro Delta <br /> 821 South Wilson Way <br /> Stockton, CA 95205 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed In-Situ Air <br /> Sparging Pilot Test Report (Report) dated January 25, 2012, submitted on your behalf by <br /> Advanced GeoEnvironmental, Inc. (AGE). The Report documents a 72-hour insitu air sparging <br /> (IAS) pilot test conducted at your site from December 19 through December 22, 2011. <br /> The onsite soil vapor extraction (SVE) system was operated during the air sparge test to <br /> capture released hydrocarbon vapor. AGE concluded in the Report that laboratory analytical <br /> results showed that the pilot test effectively stripped dissolved hydrocarbons into the vapor <br /> phase which was then removed by the onsite SVE system. Influent vapor samples collected at <br /> the end of the test had increased hydrocarbon concentrations compared to previous vapor <br /> samples collected in October 2011. <br /> In the Report, AGE recommended preparation of a corrective action plan (CAP) evaluating the <br /> feasibility of groundwater remedial technologies. By electronic mail (email) dated 02 March <br /> 2012, AGE changed the recommendation to continuing the pilot test for a 60-day period to <br /> further evaluate IAS technology effectiveness on the dissolved plume and following the <br /> extended pilot test with preparation and submission of a CAP. <br /> Although the data presented in the Report is favorable for the AGE interpretation, the EHD is of <br /> the opinion that more background measurements should have been collected to characterize <br /> the natural variability of dissolved oxygen concentrations and that the SVE system should have <br /> been operated longer prior to the IAS operation to better characterize pre-IAS concentrations. <br /> With the sparge point approximately 35 feet below the water table, the overlaying contrasting <br /> soil types, with differing permeabilities, might be expected to cause lateral migration of injected <br /> air, which would mute and delay the sparge effect at shallow depth. Providing that these issues <br /> are addressed in the extended pilot test, the EHD approves the 60-day SVE/IAS pilot test. <br /> SVE and IAS Pilot Test Comment Letter 0312 <br />