Over the past two decades, the United States has seen a substantial increase in development on closed municipal-waste landfills. The construction value of these projects could be substantial in addition to the numerous end-use benefits such as tax revenues and new jobs. Redeveloping landfills is particularly challenging not only because of the issues associated with cleanup, but also because of the environmental and geotechnical issues of building on refuse. Landfill gas containing elevated levels of methane poses a significant risk of fire and explosion. Other landfill gases such as sulfur-based corrosives like hydrogen sulfide and volatile organic compound vapors pose significant exposure risks to human health, safety and the environment. Hydrogen sulfide can also cause significant odor issues.
To be effective, design strategies for mitigating landfill gas, must incorporate the site’s architectural, structural, and geotechnical features. Applying pilot testing and pneumatic air-flow computational modeling tools is good engineering practice to determine key parameters, including air intrinsic permeability of the refuse, radius of influence, well network, desired air-flow rates, vacuum propagation, and pore-air volume exchanges, for cost-effective designs and more reliable predictions of the mitigation system performance. Detailed evaluation of long-term remedial benefits, potential refuse settlement, seismic hazards, fire and explosion hazards, odor problems, and corrosive-gas impacts on the system constructability and performance should also be performed during the design phase.
Although redevelopment of landfills holds great potential, the means and methods used to design and implement gas mitigation systems are such that human health, safety and the environment are protected for the life of the project. Our ability to effectively remediate such sites means that redeveloping closed landfills for sanctioned use will continue for years to come.
About Omer Uppal, PE
Omer has more than 15 years of experience in the environmental remediation and consulting industry. As Senior Project Engineer at Langan, he is responsible for soil, sediment, and groundwater investigations, field pilot testing, groundwater flow and contaminant transport modeling, risk-based closure and remedial strategy development, and full-scale engineering design. He is experienced in various remedial technologies including in-situ bioremediation, soil vapor extraction (SVE), multi-phase extraction (MPE), air sparging, chemical oxidation, treatment barriers, vapor intrusion, mitigation, and landfill gas mitigation systems.