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Treadwell&Rollo <br /> • <br /> Collection and Treatment <br /> Collection and treatment systems typically include several extraction wells connected to a <br /> treatment system,monitoring wills for water level measurement and groundwater sample <br /> collection. Additional costs include system engineering, permitting, operations, and <br /> maintenance. The estimated cost range for a five pumping well, five observation well extraction <br /> system with treatment of hydrocarbon-contaminated water via flow through activated charcoal is <br /> $125,000 to $200,000. Monthly operating, monitoring, and maintenance charges typically range <br /> between $4,000 and $6,000. Operation life is often 18 to 36 months, so the total operations and <br /> maintenance charges could range from$72,000 to $216,000. <br /> 5.0 RECOMMENDED REMEDIAL ALTERNATIVES <br /> 5.1 Operable Unit 1 <br /> • As noted in the Introduction, the DTSC concurs that site remediation activities should, whenever <br /> possible, be performed in conjunction with site redevelopment activities. This approach should <br /> be practical for OU 1, where only soil contamination is present, at levels that should not <br /> significantly impact site grading and redevelopment. The most likely response actions that will <br /> be appropriate for the OU 1 sites are containment and/or spot removal of contaminated soil to <br /> offsite landfills. Treatment of contaminated soil is not a recommended alternative due to the <br /> high capital cost of mobilizing a treatment unit to OU 1 versus the benefit gained. <br /> Cancer and non-cancer hazard-based risk can be effectively mitigated by capping the parcels and <br /> ensuring cap integrity via deed restrictions and proper maintenance. The estimated cost to cap <br /> each parcel of OU 1 is as follows (assumes cap for remediation only): <br /> Area 10-$872,000 <br /> Area 11 —$480,000 <br /> Area 20—$180,000 <br /> • <br /> 39 <br /> 25970318.PGS 15 November 2000 <br />