CORRESPONDENCE_2005-2006 - Laserfiche WebLink

Home Browse Search

pipe running across the fill deck to the outside slope or connected to horizontal wells and buried. Where new refuse more than 20 feet deep will be placed on the landfill, new perforated vertical well casing pipe may be strapped to existing well casings as they are extended. This will provide a shallow LFG collection well within the new refuse. The new parallel well will be capped until the perforations have sufficient refuse above them to seal out air infiltration. After refuse filling, disconnected wells will be reconnected. Using this method allows the GCCS to be installed in the landfill in accordance with §60.752(b)(2)(ii)(A)(2)(i) and (ii) while minimizing any interference of the GCCS with ongoing filling operations in adjacent cells. 4.1.9 Integration with Closure End Use Currently, the closure end use for the site is anticipated unspecified to be undeveloped open space, which does not conflict with the operation of the GCCS. Any closure end uses will be reviewed to evaluate their compatibility with the GCCS. Items of concern will be mitigated by either modifying the proposed closure end use or modifying the GCCS in accordance with NSPS requirements. 4.1.10 Air Intrusion Control Air intrusion into the vertical LFG wells will be controlled by constructing the screened collection zone of the LFG wells a minimum depth of 20 feet below the intermediate or final cover. Bentonite seals and/or well bore seals will be installed around the vertical LFG extraction well casings near the landfill surface. In addition, hydrated bentonite seals will be installed at the top of the perforations within the well bore around the solid LFG pipe. Air intrusion into the horizontal wells will be controlled by maintaining a minimum of 20 vertical feet between grade and the well and a minimum of 75'feet horizontally from side slopes. Bentonite will be installed around the horizontal LFG well lateral pipe. Further, air intrusion will be controlled through maintenance of the landfill cover and periodic monitoring and adjustment of the GCCS. If the system operates outside the NSPS operational limits (02 in the collected LFG), the LFG system operator will monitor the gas wells to verify that no unusual circumstances are occurring that could lead to a landfill fire. The primary indicator is an increase in gas temperature. Recommended adjustments to normal operating conditions are proposed in the "Draft Permit Unit Requirements", submitted concurrently with this Plan. 4.1.11 Corrosion Resistance Corrosion resistance of the GCCS will be achieved through the use of corrosion resistant materials or materials that have a corrosion resistant coating or an appropriate corrosion allowance. Coated components will be inspected during routine GCCS monitoring for Foothill Sanitary Landfill 8 Public Works/Solid Waste LFG CS Design Plan County of San Joaquin - March 10, 2005