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k`■ KLEINFELDER 6 DISCUSSION OF FINDINGS A geophysical survey was conducted to assess the potential presence of underground storage tanks (USTs) within the proposed March Lane Extension traversing the building area of Blossom Ranch. The survey was conducted within a 100 foot strip, based on previously marked centerline stakes. The buildings, equipment, and supplies in the building area limited the interpretation of the magnetic contour map. However, four areas of interest were reported, two of which applied to Kleinfelder's scope of work as suspect UST areas. A limited soil assessment was conducted in these two areas (See Plate 2). During the limited soil assessment of the project site, a total of 17 soil samples were collected during the advancement of 5 shallow soil borings and two drilled soil borings. Five (5) soil samples were collected form five shallow soil boring advanced in an orchard and row crop area of the proposed March Lane Extension (See Plate 2). Each of the five soil samples were analyzed for selected agricultural chemicals. Twelve soil samples were collected from two soil borings advanced to a depth of about 30 feet in the building area of Blossom Ranch (Plate 3). The two borings in the building area were located in suspected UST areas based on a geophysical survey and Kleinfelder's field observations. Eight of the twelve soil samples collected from these two borings were analyzed for petroleum constituents. 6.1 ORCHARD AREA SOIL SAMPLING A total of five soil samples were collected from five shallow soil borings. Four were collected in the Blossom Ranch orchard area and one soil sample was collected in the row crops of the adjacent Sperry property (see Plate 2). Each of the five soil samples were collected about %i foot bgs and were submitted for selected analyses for pesticides and herbicides (See Section 5.1 for a summary of the requested analyses). The only analyte detected was 4,4'-DDE, which was found in each of the five soil samples ranging in concentration from 7.32 to 25.5 µg/kg (See Table 5.1 for a summary of the analytical results). The results of the analyses conducted were compared to the U.S. EPA Preliminary Remediation Goals (PRGs) for residential sites. Residential PRGs were selected for comparison due to the potential for residential development in the vicinity of the proposed March Lane Extension and the fact that the Residential PRGs are the most stringent. PRGs are contaminant concentrations in environmental media (i.e. soil, air, water), calculated by the U.S. EPA, that can be used as screening tools to evaluate a site for potential human health risks. PRGs are calculated using standard assumptions and are specific for land use conditions (e.g. residential or industrial). The chemical concentrations calculated by the U.S. EPA typically correspond to a fixed level of risk (usually 10', or 1 in 1,000,000 cancer risk, or a non-cancer hazard quotient of 1) for soil, air, and 20-3712-08.E02/2018R1090 Page 11 of 17 ©1998,Kleinfelder,Inc. December 23, 1998