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Interim Corrective Action Plan . Frontier Transportation, Inc. December 20, 2005 Page 7 Cost estimates for in situ SVE range between $10 and $50 per cubic meter ($10 and $40 per cubic yard) of soil Pilot testing typically costs $10,000 to $100,000 Exact cost estimates for contaminant cleanup would not be known until after pilot testing at the site However, since most of the contamination at this site is in dissolved phase, the cost to run a pilot test and perform SVE would be very great for a minimal amount of contaminant removal ' Soil vapor extraction is a corrective action method that is typically used at contamination sites with elevated adsorbed phase contamination and moderately permeable ' soil types This site has elevated contamination levels mostly in dissolved phase, with minor residual amounts adsorbed in the soil Furthermore, the lithologic records indicate that clays are present throughout the site, winch would severely limit the extraction efficiency Soil ' vapor extraction effectiveness is limited by clayey soils with high organic content, as exists at this site Boring logs identify primarily tight-grained fines with clays and silts predominantly Iin the limited vadose zone at the site In addition, groundwater at approximately 10' bgs would be mounded and possibly ' interfere with soil vapor extraction systems at cubic foot per minute capacity necessary to create an achievable zone of influence in the relatively impermeable soil column to 10' bgs Given the soil and groundwater conditions at this site, soil vapor extraction is not a ' recommended treatment method 5.0) CONCLUSIONS I It is concluded that the first groundwater table at the site at 10' bgs is retarded in part by a clayey layer Groundwater at the screened interval from 30' to 40' bgs has typically ' identified low level or no dissolved TPH-gas, BTEX and oxygenates in past monitoring Elevated levels of contaminants were isolated to those shallow screened groundwater monitoring wells during quarterly monitoring performed from 2000 until 2004 Some vertical ' leakage of the aromatic and oxygenate gasoline constituents appears to have occurred in 2005, as evidenced by identification of dissolved phase gasoline aromatics and oxygenates in deep screened (30' to 40' bgs) monitoring wells, which had no detectable concentrations of ' the gasoline constituents in previous testing It is evident that lateral migration of the oxygenate constituents is occurring as identified by recent increasing concentrations of MTBE in MW-9 r ' Several corrective action methods were evaluated for feasibility as well as cost Excavation is not practicable due to the location of the contamination The location of the ' building is directly next to, and possibly over, the source area, driving the cost up and the 1 I