Construction: Landfill Gas Vent Trench, City Of Alice, TX

City of Alice Municipal Solid Waste Landfill, Alice, TX

The City of Alice maintains a Landfill Gas Management Plan (LGMP), which outlines the engineering and operational controls necessary to minimize risks posed by landfill gas. It outlines the City’s plan for complying with the TCEQ requirements for Municipal Solid Waste Landfills.

Quarterly monitoring results from the gas probes indicate that concentrations of methane gas were accumulating under or within the landfill structures. A series of landfill gas vent trenches were needed to provide on-site control of the landfill gases.

Time was of the essence due to the City exceeding methane concentrations in its perimeter probes. In order to meet a regulatory deadline, a construction timeline of ninety days was given to construct the project consisting of two 500 + ft. long by 2 ft. wide by 20 ft. deep trenches on the south and southeast boundaries of the landfill. The trenches constructed by installing 40 mil HDPE liner and non-woven geotextile overlapped along the downgradient side of the trench and backfilling with clean non-calcareous stone.

Outcomes and Benefits
Having performed numerous safe excavations in excess of 20 ft. deep takes a team dedicated to safety. SCS completed the project on time, on budget, and safely. The trenches continue to do their job, controlling LFG migration at the landfill.