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e San Joaquin County Publ orks - 2 - 9 January 200 W 46 system including operation and maintenance of the system for a period of five years. By incorporating these components into the hypothetical release scenario the estimated costs for corrective action will ensure that adequate funds are available to address the requirements of Title 27. Harney Lane Sanitary Landfill Harney Lane Sanitary Landfill is a closed unlined landfill that has not received waste since 1991. The landfill was closed in 1994. San Joaquin County initiated corrective action in 1996 with the installation of a landfill gas extraction system. VOCs continue to impact groundwater from landfill gas migration and elevated concentrations of inorganics have also been detected in site groundwater wells. San Joaquin County's "Hypothetical Release Scenario" includes landfill gas escaping from the bottom of the landfill that migrates to groundwater resulting in low level VOC impacts. San Joaquin County has proposed as a corrective action to mitigate a "reasonably foreseeable release" the installation of 15 vent wells fitted with a one-way valve and wind turbine. The estimated cost for this proposed corrective action is $84,000.00. Staff believes the hypothetical release scenario is insufficient to adequately address the range and complexity of a "reasonably foreseeable release" that is likely at this site. Staff also disagrees that the proposed corrective action is consistent with the types and magnitude of corrective action commonly mandated by the Regional Water Board. San Joaquin County should reevaluate the hypothetical release scenario and corrective action to include costs associated with possible horizontal and vertical delineation of a landfill gas plume north, south, east, and west of the WMU, installation of gas extraction wells and infrastructure to support additional wells, and the installation of a groundwater pump and treat system including operation and maintenance of the system for a period of five years. By incorporating these components into the hypothetical release scenario the estimated costs for corrective action will ensure that adequate funds are available to address the requirements of Title 27. Foothill Sanitary Landfill Foothill Sanitary Landfill is an operating landfill that consists of an inactive unlined unit (Module 1) and a lined unit (Module 1). During 2006, San Joaquin County had initiated a Site Improvement Plan (SIP) that includes for Module I an "Interim Final Cover" for the top deck, a side slope barrier, a landfill gas collection system, and partial cover on the surfaces that are not covered by the side slope barrier or "Interim Final Cover." Module 1 is the current active unit and is a lined unit with a leachate collection and recovery system. This landfill continues to have VOC detections in wells monitoring the vadose zone and groundwater. The SIP is scheduled to be completed in January 2007 and the landfill gas system operational. San Joaquin County's "Hypothetical Release Scenario" includes landfill gas escaping from the bottom of Module I that migrates to groundwater resulting in low level VOC impacts. Under this "Hypothetical Release Scenario" San Joaquin County has proposed as a corrective action the installation of four (4) deep gas extraction wells. The estimated cost for this proposed corrective action is $215,743.00. Staff agrees the "Hypothetical Corrective Action" for the Foothill Sanitary Landfill is an appropriate response under the "Hypothetical Release Scenario" for the gas release and the costs appear reasonable. However, under this scenario groundwater was also impacted by