SITE INFORMATION AND CORRESPONDENCE

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San Joaquin County ,oP° ; so Environmental Health Department O2O nna DHeFan, REFS 1868 East Hazelton Avenue Stockton , California 95205 -6232 RR GR MClOOR�D ENSORS Jeff Canuesco, REHS, RDI . �P Website: www.sjgov. org/ehd Kasey Foley, REFS r- o Linda Turkatte, REHS Phone: (209) 468 -3420 Fax: (209) 464m0138 August 19, 2013 ! Ms . Marion Canepa Canepa's Car Wash 1536 North Hunter Stockton, California 95204-5915 Subject: Canepa's Car Wash 6230 Pacific Avenue Stockton, California 95207-3712 Dear Ms. Canepa : '! By electronic mail dated 01 August 2013 , your consulting firm , Advanced GeoEnvironmental Inc. (AGE) , proposed sampling monitoring wells MW-2 and MW-3 semi-annually and collecting depth-to-water measurements from all eleven site wells during the pending sampling event. AGE provided justification for sampling these two wells and dismissed the need to sample additional wells noting "The 'core' set of wells are stable in concentration for petroleum hydrocarbons following the last remediation (dispensers) and new data should resemble previous events (December) , providing no relevance to the dissolved petroleum plume dynamics." The San Joaquin County Environmental Health Department (EHD) has reviewed the historical groundwater analytical data , well constructions, depth-to-water measurements and flow directions. The EHD approves the semi-annual sampling of MW-2 and MW-3, both screened between fifty and seventy feet below surface grade (bsg) ; however, it is important to note that first groundwater is currently about thirty feet bsg resulting in both of these wells having a column of water approximately eighteen feet above the screen interval which makes these two wells inappropriate for monitoring the most intensely impacted shallow groundwater near the water table. In addition to sampling MW-2 and MW-3, the EFID directs that groundwater be collected from soil vapor well SV-4 during the next sampling event since this well is screened between eight ! and forty-eight feet bsg and will provide needed information about impacted groundwater in the shallow zone. The EHD also notes that a well, screened in the shallow zone, east of the source area near MW-3 will be needed to monitor down-gradient shallow groundwater contamination and evaluate the effectiveness of future remediation planned for this site. Future planning for the site should include installation of such a well .