PSC had successfully completed similar engineering services for El Paso on the previous cells 3 through 6 project. Cells 7 through 10 were the final landfill cells to be developed under the Phase I Site Development Plan.

The project consisted of preparing roughly 37 acres of subgrade and installing a dual liner system. The liner system permitted for this project consisted of reinforced geosynthetic clay liner, overlain by a 60-millimeter HDPE geomembrane liner. A double-sided geocomposite drainage layer was installed to facilitate leachate conveyance and collection. Leachate chimneys were designed and installed to collect leachate conveyed from the geocomposite to one of four sumps. PSC then designed an automated leachate collection system at each sump to convey leachate through a force main system to an existing leachate evaporation pond — a previous PSC project.

Each of the four leachate sumps houses a submersible pump and leachate level transmitter. When the level transmitter senses the leachate level rise to a pre-determined depth, the pumping system is automatically engaged to evacuate the sump, keeping the liner system in compliance with TCEQ regulations. A red LED beacon and a leachate pond level transmitter are programmed to notify the landfill operator if leachate exceeds permitted levels. This streamlines the operator’s checklist of daily landfill activities.

Once construction was complete, PSC then utilized all of the QA/QC logs to assemble the Geosynthetic Clay Liner Evaluation Report and the Geomembrane Liner Evaluation Report and subsequent submittal to TCEQ for approval. The reports were approved by TCEQ upon first review.