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Stantec August 15,2013 Page 7 of 8 3. Direct Contact and Outdoor Air Exposure Release sites where human exposure may occur satisfy the media-specific criteria for direct contact and outdoor air exposure and shall be considered low-threat if they meet any of the following: (a) Maximum concentrations of petroleum constituents in soil are less than or equal to those listed in Table 1 for the specified depth below ground surface... Petroleum constituents in soil are less than those listed in Table 1 of the LTCP for commercial or industrial properties. The site is currently used as a convenience store; based on the location and current zoning designation (neighborhood commercial) of the site property, residential buildings are not reasonably expected to be constructed at the site in the future. Specifically: • None of the soil samples collected from five feet bgs contained benzene or ethylbenzene at concentrations above laboratory reporting limits. Soil samples were not collected at five feet bgs from soil sample locations MW-3 and MW-8, which contained the maximum benzene and ethylbenzene concentrations at the site. The shallowest soil sample from MW-3 was collected at 15 feet bgs and contained benzene at a concentration of 2.89 mg/kg and ethylbenzene at a concentration of 8.26 mg/kg, which do not exceed the commercial values in the LTCP Table 1; based on the trends observed elsewhere at the site of soil concentrations decreasing in shallower soils, it is likely that the soils at this location from zero to 10 feet bgs also do not exceed the commercial threshold values in the LTCP Table 1. • Benzene and ethylbenzene concentrations in the soil sample collected from MW-8 at 10 feet bgs were reported as 6.2 mg/kg and 73 mg/kg. These concentrations do not exceed the commercial/industrial thresholds listed in the LTCP Table 1. As stated above, it is likely that the soils at this location from zero to 10 feet bgs also do not exceed the commercial threshold values in the LTCP Table 1. • Soil samples collected from MW-5, MW-7, and GP-7, which are located on the west site of the site, closest to the residential apartments west of the site, did not contain benzene or ethylbenzene concentrations above laboratory reporting limits. The area of soils which contain petroleum constituents at concentrations exceeding the residential threshold from zero to 10 feet is a small area in the southern portion of the site, bounded by MW-4, 1-4, and the former UST basin, which was backfilled with gravel and clean soil. As stated above, concentrations in this area do not exceed the commercial threshold values in the LTCP Table 1. • None of the soil samples were analyzed for naphthalene. However, the relative concentration of naphthalene in soil can be conservatively estimated using the relative concentrations of naphthalene and benzene in gasoline. Gasoline mixtures contain approximately 3% benzene and 0.25% naphthalene. Therefore, benzene can be directly substituted for naphthalene concentrations with a safety factor of ten. Based on this estimation, it is highly unlikely that naphthalene concentrations in the soil, if any, exceed the threshold. V:\1857\active\7- Eleven\active\185750063_711_14117\05_report_del iv\reports\14117_2013_08_15_closu re_report.doc