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down investigation of the western, eastern, and southern boundaries of the site. The <br />proposed investigation will include the following activities: <br />• Installing three hydropunch groundwater zone sampling points and multi-level <br />vadose zone sampling points to the west of the monitoring well MW -4. <br />Installing three hydropunch shallow groundwater zone sampling points and <br />multi-level vadose zone sampling points to the east of the monitoring well <br />MW -2. <br />• Installing three hydropunch shallow groundwater zone sampling points multi- <br />level vadose zone sampling points to the south of monitoring well MW -3. <br />A corrective action response was developed to mitigate the impacts envisioned under the <br />hypothetical release scenario. The extent and complexity of the corrective action <br />response is proportional to the environment threat of the release and is consistent with the <br />type and magnitude of corrective action mandated by the RWQCB at the time this <br />document was prepared. <br />The corrective action envisioned is based on the following assumptions and premises: <br />• The focus of the corrective action is source control. <br />The low level release of VOCs to groundwater will not require active <br />groundwater cleanup (pump and treat, air sparging, etc.). This approach is <br />justifiable given the remoteness of the landfill and absence of surrounding <br />residences. <br />The performance objective of the corrective action is primarily to stop increases <br />in VOC concentrations in groundwater and secondarily to reduce VOC <br />concentrations in groundwater over time. <br />Corrective action taken to mitigate the hypothetical release scenario will include the <br />following activities: <br />• Install a ten additional LFG collection wells, placed in coordination with the <br />existing wells. The new wells will be designed to collect from the soil beneath <br />the landfill, the deep waste and underlying vadose zone. <br />The depth of the wells will reach to the soil beneath the landfill approximately <br />15 feet. The total depth of each well may be 100 feet, depending on the location <br />of the well on the landfill. <br />Corrective Action Financial Assurance Cost Estimate 3 September 30, 2008 <br />Harney Lane Sanitary Landfill San Joaquin County Public Works Department <br />