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Former Thrifty Co.Station No.172 Workplan for Additional Soil and Groundwater Assessment May 8,2017 residential area, and one well was located to the northwest on the Carden school property. A number of wells were identified in a small commercial center south of the site; however, they were reported as not used because the occupants utilized the City of Stockton water system. SSB identified the Mosher Slough as the nearest down-gradient surface water body approximately 3,000 ft north of the site. Five Mile Creek was identified approximately 350 ft to the west (up-gradient) of the site. In 1993, RESNA Industries (RESNA) performed a sensitive receptor survey and well search. No public or private water supply wells were located within 2,500 and 1,000 ft, respectively, of the site. One school was identified approximately 700 ft from the site. No basements or subways were identified within 1,000 ft of the site, and the nearest surface water body was identified as Five Mile Creek, located less than 100 ft west of the site. According to the Department of Water Resources (DWR) well search, 37 wells (including industrial, municipal, domestic, and monitoring wells) were identified within the '/2 mile search radius of the site. Of the wells located within the search area, no public water supply wells were located within 2,500 feet of the site, and no domestic water supply wells were located within 1,000 feet of the site. In September 2011, Cardno ATC performed an internet-based search for other potential sensitive receptors, including hospitals, schools, nursing homes, and day care facilities, located within '/2-mile of the site. Two schools, Lincoln Elementary School (Pre-K to 8) and Carden School of Stockton (K to 8) were identified approximately 2,000 feet south and 700 feet west- northwest of the site, respectively. Two nursing homes, Elmhaven Care Center and Dane's Guest House were identified approximately 2,250 feet south-southeast and 2,400 feet east- northeast of the site, respectively. No hospitals or day care facilities were identified within %- mile of the site. Cardno ATC also reviewed aerial photographs for the site vicinity to better- determine the location of Five Mile Creek. Cardno ATC has determined that Five Mile Creek is located directly west (up-gradient) of the site; however, due to development activities within the region, the segment of Five Mile Creek adjacent to the site appears to be the northern-most portion and appears to be seasonal in nature. In June 2016, ATC confirmed that Carden School of Stockton, also known as Carden Academy, is no longer in business and Lincoln Elementary School has relocated outside the search radius. 2.4 Characterization Status As presented in ATC's Site Conceptual Model and Human Health Risk Assessment, dated September 30, 2011, the majority of hydrocarbons in soil have been found in the area of the former USTs. Further assessment of the vertical extent of total petroleum hydrocarbons in the gasoline range (TPH-g) and benzene in soil and groundwater beneath the source areas (former UST and dispenser islands) was recommended. In February 2012, ATC supervised the installation of on-site groundwater monitoring wells MW-17 and MW-19 through MW-22, soil boring SB-1, and the collection of shallow soil vapor samples SV-1 through SV-5. The initial groundwater samples collected from the recently-installed groundwater monitoring wells indicate the highest dissolved-phase petroleum hydrocarbon concentrations are located immediately down-gradient of the former USTs. The highest dissolved-phase petroleum 6