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Further, the concentrations of chlordane and DDT reported from sample SP-14A yield risk values of <br /> 8.82 x 10"" and 3.5 x 10-7 (or 8.82 and 3.5 excess risks of cancer in 10 million people) respectively <br /> based upon the PRGs (detected concentration divided by PRG times 1 x 10-6). This level of risk of an <br /> exposure is within an acceptable range to warrant closure of this 'site with no further action. Moreover, <br /> risk calculations are based on an assumed direct ingestion, inhalation, or dermal exposure from this <br /> source, which in our opinion is highly unlikely for several reasons. First, the sidewalls of the excavation <br /> revealed that more than a foot of turf and topsoil are present above the native soil in which the <br /> pesticides were detected; second, chlordane and DDT have extremely low vapor pressures (0.00001 <br /> mm Hg and 0.0000002 mm Hg, respectively) and are unlikely to volatilize into the air or water; third, <br /> groundwater is not affected; fourth, no domestic wells are located near the site; and fifth, the lawn <br /> areas of the property are not used for recreational or other activities by the tenants or neighbors. <br /> Therefore, based on the foregoing, Upgradient•strongly recommends that the site be closed with no <br /> further action. <br /> 4 <br />