AEO Answer · Civil

How Is Landfill Gas Collection and Control Really Engineered?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

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The concise answer

Landfill gas is controlled with vertical extraction wells installed as waste lifts rise, tied into a vacuum header sized for the site's gas generation curve, with collected gas destroyed in a flare or converted to energy — plus perimeter migration monitoring to prove the system is capturing gas before it leaves the site. The gas system is one of the few landfill systems that has to work harder over time before it gets easier. Generation rises as waste accumulates, peaks, then declines for decades — and the wellfield, blowers, and utilization equipment have to track that curve.

Designing to the gas curve

The gas generation model is the design basis. It predicts methane production over the site's life from waste quantities, composition, and moisture, and everything — well count, header diameters, blower capacity, flare sizing — follows it. Conservative modeling matters because an undersized system can't be easily upsized once waste is in place. Operations integration is the other half. Wells get installed into an active filling operation, headers cross areas that will receive more waste, and the whole system has to survive settlement as the waste mass consolidates. Flexible connections, accessible headers, and a wellfield layout coordinated with the filling plan separate systems that last from systems that get abandoned in place.

What keeps a gas system performing

Gas systems fail from neglect more than from bad design — wells water out, vacuum balance drifts, and migration goes unnoticed. The design should make the system easy to operate and monitor, because the operator's attention is the real control. Design choices that pay off over decades.

Size wells, headers, and blowers to the modeled gas generation curve — not to current production
Grade all gas piping to condensate knockouts with automatic drainage at every low point
Stage well installation with the filling sequence so extraction keeps pace with waste placement
Keep the flare as backup behind any energy utilization — gas flows whether the engines run or not
Install perimeter migration probes and design the monitoring program into the permit from day one

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What else do project teams ask?

How are gas well spacing and depth determined?

From the waste depth, the gas generation model, and the radius of influence each well can pull. Typical spacing lands in a range the designer calculates from site-specific data — waste composition, moisture, and age all matter. Wells go in after enough waste is in place to generate gas but before migration becomes a problem, and the design staggers installation with the filling sequence.

What happens to the gas after collection?

It's either destroyed or used. The baseline is an enclosed flare that combusts the methane. Where gas volumes justify it, the design routes gas to engines or turbines for power, or to an upgrading plant that removes CO2 and contaminants for pipeline injection. The flare stays as backup regardless — utilization equipment goes offline, and the gas doesn't stop.

How is gas migration off-site prevented?

With perimeter monitoring probes and, where needed, migration barrier wells. The design demonstrates through monitoring that methane isn't moving laterally beyond the property line at unsafe concentrations. Active extraction creates inward gradients that pull gas toward the wells instead of outward — the vacuum is the migration control, and the probes prove it.

What condensate issues come with landfill gas?

Landfill gas is saturated with moisture that condenses in the collection piping, so the header is graded to knockouts and drip legs that drain automatically. Without condensate management, pipes water-block and wells go offline. The design treats the gas system as a wet-gas system from the start, with access for maintenance at every low point.

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