RESPEC PROJECT

RESPEC prepared the designs and permit application for an 87-acre municipal solid waste landfill expansion. The existing application was updated to include modern design concepts and innovations in landfill design and construction. Efforts for the 30 million cubic yard expansion included complete grading and associated civil designs (including foundation soils and slope stability analyses), stormwater management system design for the nearly 400-acre total drainage area, leachate and wastewater collection and conveyance system designs, landfill gas system collection and conveyance designs, and solid waste disposal liner system design.

Capacity enhancement was provided by the incorporation of a 90 plus-foot high mechanically stabilized earth berm. Landfill subgrade elevations were developed to limit the number of leachate collection sumps needed to achieve an efficient design. A total of nine (9) intermediate development designs were prepared including appropriate intermediate and final development grades, temporary and permanent stormwater, landfill gas, and leachate management system design phases, temporary and permanent access roads and structures.

The extensive stormwater management system was designed to collect and convey flow from 399.17-acre drainage area that flows to, around, and through the 83-acre landfill expansion footprint. The system was analyzed for pre-construction, each development phase, and post-construction conditions for total and peak discharge rate reductions before discharging to the existing local drainage courses. Stormwater management was achieved through the use of flow channels on landfill benches, collection into downchute channels, conveyance to one of two sedimentation basins, and finally on to discharge. Available space was limited for placement of the basins. Due to this and the resulting basin capacity needed, dam designs and permitting was required and completed. Permitting efforts also included updates for an existing landfill NPDES permit, coordination with regulatory agencies on wetland mitigation permitting related to the landfill expansion, and submissions to the local municipality as required by borough ordinances for stormwater management compliance. RESPEC attended pre-application meetings with state Dams and Waterways and Solid Waste regulators, as well as follow-up meetings to review technical and administrative components of the expansion.

Landfill gas collection and control system designs were completed for the entire expansion. Designs were integrated into the existing collection system when appropriate and also were prepared to interface with an onsite landfill gas-to-energy (LFGTE) system. Considerations for gas system designs included extraction well spacing with accessible locations and condensate collection and conveyance components.

The final designs of the expansion yielded a maximization of available waste disposal footprint, facility operational areas and structures, stormwater management, and all other necessary landfill design and operational components. Approvals were obtained from the required state and local regulatory agencies.