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. I <br /> GEOMATRIX <br /> • The vertical extent of petroleum hydrocarbons in soil ranged between approximately <br /> 36 and 80 feet bgs in borings SB-15, SB-16, and SB-19 through SB-21. <br /> l Concentrations of the CAM 17 metals detected in the selected soil samples were <br /> 1 less than the PRGs. <br /> • Evidence of petroleum hydrocarbons in groundwater was observed and/or detected <br /> in borings SB-15 through SB-21,ASB-1, ASB-2, ASB-4 through ASB-7, ASB-10, <br /> and ASB-11. <br /> ;� • TPHd was only detected in the grab groundwater samples collected from SB-15, <br /> SB-21, and ASB-1 after a silica-gel preparation procedure, indicating that the <br /> material quantified as "TPHd" without the silica-gel preparation procedure was <br /> primarily polar components that may be due to intrinsic bioremediation of <br /> petroleum. <br /> ] • The TPHd detections in the grab groundwater samples collected at about 96 to <br /> 100 feet bgs from SB-15 and SB-21 might be due to cross-contamination of affected <br /> soil and/or groundwater from shallower depths since field evidence of petroleum <br /> L. <br /> hydrocarbons was not observed below about 76 and 80 feet bgs in these borings, <br /> respectively. <br /> L, Analytical results of the water sample collected from the supply well located within <br /> the Arcos property were less than the drinking water standards. <br /> Based on the results of these and previous investigations at the site, Geomatrix has developed <br /> the following conclusions. <br /> Soil and groundwater at the site have been affected by petroleum hydrocarbon <br /> _. constituents as a result of former pump station operations and possibly former site <br /> uses subsequent to the pump station. <br /> Soil and groundwater downgradient of the site have been affected by petroleum <br /> hydrocarbon constituents,possibly a result of former pump station operations and/or <br /> lother off-site sources. <br /> J The primary area of significantly affected soil and groundwater at the site is in the <br /> vicinity of the former pump house, heater house, and boiler house. <br /> • The petroleum-affected soil has been primarily observed from depths greater than <br /> about 36 feet bgs,except for borings SB-2, SB-10, ASB-2, and ASB-4 at which <br /> petroleum-affected soil has been observed from depths of about 10 feet bgs. <br /> • The maximum depth of petroleum-affected soil at and downgradient of the site is <br /> 1 limited to about 80 feet bgs. <br /> .J <br /> 1..TRO1ECI15000si5011.000\5011.03.do 20 <br />