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10 • <br /> San Joaquin County <br /> PAW <br /> Environmental Health Department DIRECTOR <br /> o. .co Donna Heran,REHS <br /> r' + i 600 East Main Street <br /> I - � Stockton California 95202-3029 PROGRAM COORDINATORS <br /> ,, ' Robert McClellon, REHS <br /> -------- Jeff Carruesco, REHS, RDI <br /> p . Kasey Foley, REHS <br /> Website: WW 09)468-3420 hd Linda Turkatte,REHS <br /> Phone: (209) 468-3420 <br /> Fax: (209)464-0138 <br /> December 15, 2011 <br /> Wayne Henry <br /> Fremont Gate LLC <br /> PO Box 5221 <br /> Modesto, CA 95355 <br /> Subject: United Rentals <br /> 2911 East Fremont Street <br /> Stockton, CA 95202 <br /> Dear Mr. Henry, <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Source <br /> Removal Excavation and Indoor Air Sampling Summary Report (Report), dated <br /> November 15, 2011, submitted on your behalf by Lee & Pierce, Inc (L&P): The Report <br /> documents rernediatioh of contaminated soil associated with an unauthorized release-from a <br /> clarifier by over-excavation, the procedures and results of indoor and ambient air sampling, <br /> and presents a risk evaluation of thecurrent site conditions. , <br /> The clarifier was removed and the pit was over-excavated to a depth of approximately 18.5 <br /> feet below surface grade (bsg), leaving deeper impacted soil in place. The excavation was <br /> backfilled to approximately 4 feet bsg with permeable pea-gravel, a catch basin with a <br /> concrete base was installed and pea gravel was backfilled to the floor level, which consisted <br /> of additional concrete. Approximately 170 cubic yards of soil were removed. <br /> Residual soil samples were impacted by total petroleum hydrocarbons quantified as gasoline <br /> (TPHg), toluene, ethylbenzene, xylenes, naphthalene and various other complex <br /> hydrocarbons; only one soil sample, a composite from stockpiled excavated soil, was also <br /> impacted by benzene. Grab groundwater samples collected from soil borings advanced <br /> during an earlier phase of investigation were impacted only by tetrachloroethene (PCE). <br /> Two interior air samples and two exterior 'ambient' air samples were collected for laboratory <br /> analysis for TPHg, benzene, toluene, ethylbenzene and xylenes (BTEX), naphthalene and <br /> other volatile organic or chlorinated hydrocarbon compounds. All four air samples were found <br /> to be impacted by TPHg and BTEX, one interior sample was also impacted by naphthalene; <br /> other volatile organic or chlorinated hydrocarbons were not detected. The benzene <br /> concentrations in all four air samples and the TPHg concentrations in the indoor air samples <br /> exceeded the California Indoor Air Human Health Screening Levels (CHHSLs) and the San <br /> Francisco Bay Regional Water Quality Control Board's Environmental Screening Levels <br /> (ESLs) for commercial/industrial settings; naphthalene in the one indoor air sample .also <br /> exceeded the appropriate CHHSL. To address the health risk and hazard issue signified by <br /> TPHg, benzene and naphthalene exceeding the CHHSLs and ESLs, L&P prepared a site- <br /> specific Tier II evaluation of the analytes. <br /> Comment Letter December 2011 <br />