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Revised Site Investigation Report & Case Closure Request Country Market O 10476 West Linne Road, Tracy, California a n to a r0 U Antea Group Project No. CTRVMKTUST g p 1.3 UST Removal Activities During the tank removal activities, Jim Thorpe stated that the tank bottoms were 7-feet below ground surface (bgs). Jim Thorpe collected a soil sample at approximately two feet below each tank at 9-feet bgs (samples named Tank-A 9' and Tank-B 9'); Tank-A refers to the 500-gallon tank and Tank-B refers to the 350-gallon tank. Samples were also collected at approximately 3-feet bgs along associated former product piping (Tank-A 3' and Tank-B 3'). The soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPH-g), benzene, toluene, ethylbenzene, and total xylenes (collectively referred to as BTEX), di-isopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), methyl tert-butyl ether (MTBE), tert-butanol (TBA), and ethanol . - Concentrations of TPH-g were reported at 3 .5 milligrams per kilogram (mg/kg) and 530 mg/kg in soil samples Tank-A 9' and Tank-B 9', respectively. Concentrations of total xylenes, toluene, and ethylbenzene were reported in soil sample Tank-B 9'at 3,780 micrograms per kilogram (pg/kg), 27.7 pg/kg, and 226 µg/kg, respectively. No other constituents were reported above analytical laboratory reporting limits in sample Tank-A 9' or Tank-B 9' . No constituents were reported above laboratory reporting limits in samples Tank-A 3' and Tank-B 1pripe� P• P 1.4 Hydrogeologic Setting The site is located above the Tracy Subbasin within the San Joaquin Valley Groundwater Basin in the southern portion of the Great Valley Geomorphic Province of California (DWR, 2006). Unconsolidated to semi-consolidated continental deposits increasing in thickness from west to east comprise the Tracy Subbasin and include the Tulare Formation, Older Alluvium, Flood Basin Deposits and Younger Alluvium. According to the 1981 Preliminary Geologic Map of the Tracy Quadrangle by Thomas Dibblee, Jr., surficial Holocene alluvium underlies the site ( DWR, 2006) . The San Joaquin River and Corral Hollow Creek drain the Tracy Subbasin northward into the Sacramento River and San Joaquin Delta ( DWR, 2006) . Most larger agricultural, municipal, and industrial wells extract water from the Tulare Formation beneath a confining layer identified as the Corcoran clay (DWR, 2006) typically 200 to 800 feet bgs and 50 to 120 feet thick (Frisk and Kues, 1954). Smaller irrigation and domestic wells extract water from above the Corcoran clay, which is often of poorer quality (DWR, 2006) . 2.0 ANTEA GROUP SITE INVESTIGATION 2.1 Pre-Field Activities Prior to initiation of field activities, Antea Group prepared a Health and Safety Plan (HASP) in accordance with Title 8; Section 5192 of the California Code of Regulations. Field personnel performed a daily review of the HASP containing a list of emergency contacts as well as a hospital route map to the nearest emergency facility. Antea Group obtained the necessary boring permits from the SICEHD (Appendix A). Antea Group contacted Underground Service Alert (USA) and contracted a private utility locator at least 72 hours prior to the initiation of 2 www.anteagroup.com