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San Joaquin County <br /> Environmental Health Department DIRECTOR <br /> Donna Heran,REHS <br /> 600 East Main Street <br /> Q. PROGRAM COORDINATORS <br /> W ( � { Stockton, California 95202-3029 Robert McClellon, REHS <br /> • - <br /> Jeff Carruesco, REHS, RDI <br /> Website: www.sjgov.org/ehd Kasey Foley, REHS <br /> L F o R Linda Turkatte, REHS <br /> Phone: (209) 468-3420 <br /> Fax: (209) 464-0138 <br /> November 22, 2011 <br /> Mr. Weldon Church Ms. Lacey N. Skelton <br /> 1958 Yosemite Road 25969 South Corral Hollow Road <br /> Berkeley, California 94707 Tracy, California 95376-9108 <br /> Subject: Weldon Church Property <br /> 104 West Beverly Place <br /> Tracy, California 95376 <br /> Dear Mr. Church: <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Crawl <br /> Space Air Investigation Report — Third Quarter 2011 (report), dated 07 November 2011, <br /> submitted by your consulting firm, Advanced GeoEnvironmental, Inc. (AGE) on your behalf <br /> for the above-referenced site. By letter dated 01 September 2011, the EHD had approved <br /> the collection of duplicate air samples in the crawl space beneath the residence at your site <br /> for analysis of chemicals of concern to evaluate the accuracy and precision of the original <br /> crawl space analytical results. <br /> Included in the report were analytical results for one field blank sample, two ambient air <br /> samples collected from the southwest and southeast areas of the backyard, and duplicate <br /> air samples collected from the crawl space beneath the dwelling. The air samples were <br /> collected in six-liter Summa canisters over a period of approximately 24 hours. <br /> Concentrations of contaminants of concern for the duplicate crawl space samples were <br /> reported well above those concentrations initially reported for Crawl Space-1 sample <br /> collected in May 2011. Duplicate crawl space air samples, Crawl Space-2 and Crawl <br /> Space-3, had similar analytical results with total petroleum hydrocarbons as gasoline <br /> (TPH-g) reported at 120,000 micrograms per cubic meter (Ng/m3) in both samples, benzene <br /> at 930 and 830 Ng/m3, toluene at 8,400 and 8,600 pg/m3, ethylbenzene at 1,300 and 1,400 <br /> Ng/m3, and total xylenes at 6,900 and 7,500 pg/m3, respectively. These results are well <br /> above the Environmental Screening Levels (ESLs) established by the California Regional <br /> Water Quality Control Board, San Francisco Bay Region for indoor air for residential land <br /> use. The relevant ESLs are 10 Ng/M3 for TPH-g, 0.084 Ng/m3 for benzene, 63 ug/m3 for <br /> toluene, 0.98 pg/m3 for ethylbenzene, and 21 Ng/m3 for total xylenes. Using the maximum <br /> benzene concentration of 930 Ng/m3 and RISC5 software, AGE calculated the cancer risk at <br /> 6.8 x 10.4 and the hazard index at 23. These results are above the thresholds of concern for <br /> life-time carcinogenic risk of 1 x 10_e and the non-carcinogenic hazard index of 1.0 <br /> established by the United States Environmental Protection Agency. <br />