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Revised Site Investigation Report & Case Closure Request Country Market 10476 West Linne Road, Tracy, California a ntea g ro U p Antea Group Project No. CTRYMKTUST i Concentrations of TPH-P (GRO), BTEX, MTBE, and 1,2-DCA were not reported above the laboratory's respective MRLs for the groundwater sample collected from the domestic well on February 28, 2014. The absence of gasoline constituents in the well water sample suggests that residual contamination is only present in soil at the site and is not a source of groundwater pollution. 3.2. 1 Sensitive Receptors The closest water-production well screened within the shallow water-bearing zone is the domestic well on-site approximately 100-feet east of the former tank locations. Despite proximity to the former tanks, petroleum hydrocarbons were not reported in the groundwater sample collected from the well. According to the City of Tracy 2010 Urban Water Management Plan, the closest municipal wells (PW-1 through PW-4) are approximately 4,200 feet southwest of the site (Erler & Kalinowski, 2011); however, these wells draw water from, the lower water-bearing zones of the Tulare Formation below the Corcoran clay at depths of 300 to 700 feet bgs. Although intermittent, the closest potential body of surface water appears to be a pond of unknown construction and use located approximately 2,300 feet east of the site. In addition, active quarries such as those located as close as 250 feet to the south and southwest of the site, can generally collect water in mined depressions. 3.2.2 Benzene and MTBE Concentrations Neither benzene nor MTBE were reported at concentrations above the reporting limit of 0.50 micrograms per liter (ug/L) in the 2014 groundwater sample, far below the lowest SB 2012-0016 threshold value of 1,000 pg/L (Appendix E). 3.3 Petroleum Vapor Intrusion to Indoor Air This section reviews criteria specific to petroleum vapor intrusion to indoor air. According to the SB 2012-0016 Technical Justification for Vapor Intrusion Media-Specific Criteria, benzene is the primary risk driver for vapor intrusion. No benzene was reported in soil from the tank removal or the recent investigation or in groundwater from the on-site well at concentrations greater than the laboratory reporting limits of 5.0 ug/kg, 0.0050 mg/kg and 0.50 pg/L, respectively. In addition, the Country Market building is located approximately 25-feet southeast of the former UST pit. The soil data from the recent site investigation suggests TPH-P (GRO) contamination is minimal and limited in extent and the groundwater sample results indicate no — presence of LNAPL or dissolved-phase petroleum hydrocarbons., Therefore, the vapor intrusion exposure pathway is not considered a threat to human health atthe site. 3.3. 1 Un-weathered LNAPL in Groundwater and Soil Un-weathered LNAPL was not observed beneath the tanks or in the soil borings or detected in the on-site domestic well . 6 www,anteagroup. com