ARCHIVED REPORTS_2003_6 - Laserfiche WebLink

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NOT PROPOSED AT THIS TIME Soil Cover and Drainage Improvements Soil cover and drainage improvements are not proposed as corrective action because groundwater impact was not indicated in the EMP. However, the County will enhance soil cover at the site and ensure drainage facilities comply with the Waste Discharge Requirements and Title 27, Section 20365. This will increase assurances that minimal amounts of water will enter the landfill, reducing the potential for accelerated landfill gas production. The County will prepare a Cover and Drainage Plan (anticipated in 2004), in which the drainage system will be improved as needed to ensure minimal water infiltration. Landfill Gas System A Landfill Gas(LFG) System is not proposed at this time due the lack of VOC contamination at this time. Title 27 (Section 20425 (b)(3)) suggests that an LFG System is the appropriate corrective action measure if the source of contamination is landfill gas. Such indication would include the presence of VOCs in groundwater. Therefore, an LFG System would be considered as the corrective action measure if groundwater contamination due to landfill gas is verified. Closure of Module "I" Closure of Module"I"is not proposed as corrective action because VOCs were not detected in this EMP, and groundwater impact is not indicated. The County intends to proceed with the development of the landfill, and closure of the landfill surface, as the final elevations are reached. However,the County will evaluate closure of Module"I"as corrective action against groundwater contamination by leachate migration,if closure is found to be appropriate. Closure of Module"I"is contra-indicated as corrective action against landfill gas impact indicated by the presence of VOCs. Decreasing the permeability of the landfill surface by installing a closure cap would increase the pressure within the landfill and promote migration of LFG into the vadose zone and closer to the groundwater. Present practices at the site to reduce water infiltration are apparently successful, such that no further corrective action appears to be needed at this time. Although not proposed as corrective action, the County intends to close Module"I"in coordination with the development of the surrounding lined landfill modules. At this time it is understood that placement of waste over Module"I", made possible by.the installation of an adjacent lined modules,will require a composite liner or equivalent between the new refuse and the refuse of Module"I", constituting internal closure of the affected portion of Module"I". It is anticipated that approximately 13 acres (16% of the footprint) of Module"I"would be covered with the expansion of Module 1 up the southern slope of Module"I"within the next five years. Engineering Feasibility Report 6 Foothill Sanitary Landfill October 30,2003 San Joaquin County Solid Waste