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San Joaquin County <br /> op4u' IN • c Environmental Health Department DIRECTOR <br /> ? ' -= Q Donna Heran, REHS <br /> it `y 1868 East Hazelton Avenue <br /> WA <br /> Stockton California 95205-6232 PROGRAM COORDINATORS <br /> Robert McClellan, REHS <br /> Jeff Carruesco, RENS, RDI <br /> cq' • . . , ,;, . 40e Website: www.sjgov. org/ehd Kasey Foley, RENS <br /> r F o R Linda Turkatte, REHS <br /> Phone : (209) 468-3420 Rodney Estrada, REHS <br /> Fax: (209) 464-0138 Adrienne Eltsaesser, REHS <br /> September 5, 2014 <br /> Mr. Brian Waite <br /> Chevron Environmental Management Company <br /> 6101 Bollinger Canyon Road <br /> San Ramon , California 94583 <br /> Subject: Former Chevron Service Station No. 98632 <br /> 575 West Grant Line Road <br /> Tracy, California 95376-2551 <br /> Dear Mr. Waite : <br /> The San Joaquin County Environmental Health Department (EHD) has received and reviewed <br /> Low-Threat Closure Evaluation (LTC Evaluation) , dated 19 June 2013, and First Semi-Annual <br /> 2014 Groundwater Monitoring Report (2014 GWMR) , dated 28 July 2014. Both reports were <br /> submitted by your consulting firm, Conestoga-Rovers & Associates (CRA) , on your behalf for <br /> the above-referenced site. <br /> In 2013 and in 2014, the EHD evaluated the site for possible closure under the Low-threat <br /> Underground Storage Tank Closure Policy (LTCP) utilizing the LTCP checklist; the 2014 <br /> evaluation currently is available for public review on the State Water Resources Control Board <br /> (State—Water—Board)--GeoTrackej:--website. a-2D14_GW-MR CRA IistesLthe_criteria_ that�reLe <br /> identified by the EHD as not being met as follows: <br /> General Criteria, item f — Secondary source has been removed to the extent practicable; <br /> • Media Specific Criteria: Petroleum Vapor Intrusion to Indoor Air; and <br /> • Media Specific Criteria: Direct Contact and Outdoor Air Exposure. <br /> In 2014 GWMR, CRA stated that the LTCP criteria listed above had already been addressed in <br /> LTC Evaluation. Specifically, in response to the first bulleted criterion above, CRA indicated in <br /> LTC Evaluation that the secondary source had been removed to the extent practicable, stating <br /> that: <br /> "Remedial excavation in 1994 removed approximately 650 cubic yards of impacted soil <br /> from the former source areas (Figure 2) that was either disposed offsite or aerated and <br /> re-used as backfill onsite. Based on overall stable to decreasing concentrations in <br /> groundwater, there does not appear to be significant secondary source material <br /> remaining that would change these trends." <br /> Regarding the second bulleted LTCP criterion , CRA stated in LTC Evaluation: <br /> "Although the detected concentrations in soil vapor and soil do not satisfy the <br /> characteristics of Scenario 4 of criteria (a) above , under the current land use scenario <br /> the site should be considered low threat as there appears to be no significant risk to <br />