Laserfiche WebLink
F <br /> San Joaquin County DIRECTOR <br /> Donna Heran, REHS <br /> Environmental Health Department <br /> p C` ASSISTANT DIRECTOR <br /> r.' <br /> 600 East Main Street Laurie Cotulla,REHS <br /> Stockton, California 955202-3029 PROGRAM COORDINATORS <br /> •, :. Mike Huggins, REHS,RDI <br /> •` Margaret Lagorio, REHS <br /> :P Website: www.sjgov.org/ehd Robert McClellon,REHS <br /> cq�iFO•R� <br /> Phone: (209)468-3420 .teff Carruesco,REHS,RDI <br /> Fax: (209) 464-0138 Kasey Foley,REHS <br /> 06 February 2009 <br /> Frank Morita <br /> 6622 Belmont PI <br /> Stockton CA 95207 <br /> Subject: Morita Brothers <br /> 814 E Charter Way <br /> Stockton, CA <br /> San Joaquin County Environmental Health Department (EHD) has reviewed recent <br /> quarterly monitoring results obtained by your consultant Geological Technics Inc. (GTI) <br /> and Report Risk Evaluation Soil & Soil Gas Investigation (RRE), dated 29 April 2008 <br /> and Addendum to Report Risk Evaluation Soil & Soil Gas Investigation (AdRRE), dated <br /> 18 July 2008. The EHD has considered the closure request for your site contained in <br /> AdRRE and has evaluated the current groundwater monitoring and sampling program <br /> for your site. <br /> In RRE, GTI reported that soil gas samples, collected to evaluate the potential for vapor <br /> intrusion into structures on the site, contained less than detectable concentrations of the <br /> chemicals of concern (COCs) or contained concentrations that were less than the <br /> environmental screening levels (ESLs) established by the San Francisco Bay Regional <br /> Water Quality Control Board (SFBRWQCB), and therefore presented no significant risk <br /> of vapor intrusion into structures on your site. The EHD concurs with this conclusion. <br /> GTI also reported in RRE that CDCs in soil collected from the boring advanced in the <br /> former underground storage tank (UST) area were less than the SFBRWQCB's ESLs, <br /> except for the methyl tert-butyl ether (MTBE) in the soil sample collected 40 feet below <br /> surface grade (bsg), which is also approximately 10 feet below the water table; the <br /> MTBE concentration of 0.029 milligrams per kilogram (mg/Kg) slightly exceeded the <br /> ESL of 0.023 mg/Kg. GTI considers the 0.029 mg/Kg to essentially be the same as <br /> 0.022 mg/Kg due to possible measurement error and does not represent a significant <br /> threat to groundwater quality. The EHD also believes that the 0.029 mg/Kg MTBE <br /> encountered in soil at 40 feet bsg does not represent a significant threat to groundwater <br /> quality, noting that the concentrations of dissolved MTBE in monitoring wells MW-107, <br /> immediately down-gradient of the former UST pit, have declined from a high of 77 <br /> micrograms per liter (tag/L) in 2001 to undetectable concentrations less than 0.5 lag/L in <br /> 2008. This shows that the transfer rate (the flux rate) of MTBE stuck to soil dissolving <br /> Closure Request Response and Monitoring Frequency Letter 0209 <br />