CORRESPONDENCE_2008 (7/08 TO 12/08)

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i The corrective action envisioned is based on the following: 1. The focus of the corrective action is source control. 2. The low level release of VOCs to groundwater will not require active groundwater cleanup (pump and treat, air sparging, etc.). This approach is justifiable given the remoteness of the landfill and absence of surrounding residences. The performance objective of the corrective action is primarily to stop increases in VOC concentrations in groundwater and secondarily to reduce VOC concentrations in groundwater over time. Corrective action taken to mitigate the hypothetical release scenario will include the following activities: 1. Three additional LFG wells located to collect LFG from the deep waste and underlying vadose zone. The wells will be 70 feet deep and screened at the soil/waste interface. The location of the wells will be selected based on the location of the impact. 2. These wells will be connected to the existing LFG system. Cost Analysis The cost of the corrective action plan and the EMP includes engineering design, field investigations, construction and associated materials, permitting, and final reports. Permitting associated with the project will include RWQCB and SJC well drilling permits. Costs are "contractor based", i.e., based on construction by contractor, not by County staff. The cost for constructing the LFG components are based on a contractor bid received for similar work at the Corral Hollow Landfill in June 2008. Costs for other components were escalated from the original 2007 costs by applying the inflation factor supplied by the California Integrated Waste Management Board. The cost of construction is approximately $314,000. The annual cost over the 30 -year corrective action period, including construction, operation and maintenance is estimated to be $28,000 (Table 1). Corrective Action Financial Assurance Cost Estimate 4 Public Works/Solid Waste Div. Corral Hollow Sanitary Landfill September 30, 2008