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.r <br /> San Joaquin County <br /> Environmental Health Department °IREna H <br /> �,.•�,��-.•p Donna Heran, RENS <br /> a -2� 600 East Main Street <br /> Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> { Robert McClellon,REHS <br /> .'• Jeff Carruesco,REHS,RD[ <br /> ov.or <br /> Website: www.sigov.org/ehd Kasey Foley,REHS <br /> 19 9 <br /> Phone: (209)468-3420 <br /> Fax: (209) 464-0138 <br /> February 23, 2010 <br /> Carl Navarra <br /> 475 Blewett Road <br /> Tracy, CA 95376 <br /> Subject: Navarra Property <br /> 7500 W. Eleventh Street <br /> Tracy, CA 95376 <br /> The San Joaquin County Environmental Health Department (EHD) has received and reviewed <br /> Groundwater-Quality Monitoring Report, July 2009 (GQMR), dated October 2009, prepared by <br /> The San Joaquin Company, Inc. (TSJCI). In the GQMR, TSJCI requested site closure. The EHD <br /> has reviewed pertinent site data, including Work Plan for Evaluation of MTBE Migration and Soil <br /> Gas Survey (WP), dated April 2009, and will discuss your site status with the Central Valley <br /> Regional Water Quality Control Board (CVRWQCB) at our next meeting later this month. <br /> The EHD has found the following during the review of your site: <br /> • The plume of dissolved contaminants, primarily total petroleum hydrocarbons quantified <br /> as gasoline (TPHg) or as diesel (TPHd), benzene, toluene, ethylbenzene and total <br /> xylenes (BTEX) and methyl-tert butyl alcohol (MTBE) appears to be delineated laterally <br /> and vertically, and locally appears to have declined in concentration. <br /> • To date, none of the local water supply wells that have been in your monitoring program <br /> has been impacted by contaminants associated with the unauthorized release from your <br /> former underground storage tank (UST) system. <br /> • Free product has not been detected in your groundwater monitoring system since <br /> October 2005. <br /> • The disappearance of free product in monitoring well MW-7 and the lack of it in <br /> monitoring well MW-13 greatly reduces the likelihood that a significant free product <br /> plume is underlying the Eleventh Street roadbed. <br /> • Contaminant species and their concentrations in soil and groundwater, proposed to be <br /> left in place, were compared to the San Francisco Bay Regional Water Quality Control <br /> Board's Environmental Screening Levels (ESLs).-Comparison to the most conservative <br /> site scenario (Tier 1), soil in four limited locations and groundwater in several wells failed <br /> to pass the ESLs, but utilizing site specific conditions and the `groundwater not a <br /> drinking water source' scenario, impacted soil and passed the Tier II evaluation, as did } <br /> groundwater concentrations in February and July 2009. <br /> • Due to the very shallow depth to groundwater and the capillary fringe zone, TSJCI <br /> determined that soil gas sampling would not yield reliable data from which to evaluate <br /> Site Closure Request Response Letter 0210 <br />