SWANA Landfill Gas Management 2

Question 1

Under EPA surface emissions monitoring (SEM) requirements, what surface methane concentration above background triggers corrective action?

Accepted Answer

500 ppm

Answer

Under 40 CFR 60.755, a surface methane concentration of 500 ppm above background measured during SEM requires corrective action to identify and repair the source of emissions.

Question 2

What distinguishes a passive LFG collection system from an active system?

Accepted Answer

Passive systems rely on natural pressure differentials using vents or barriers without mechanical assistance

Answer

Passive systems use the natural positive pressure generated by decomposing waste to vent gas through perforated pipes or gravel trenches, without mechanical blowers or vacuum equipment.

Question 3

What is the typical combustion temperature maintained inside an enclosed ground flare to achieve high LFG destruction efficiency?

Accepted Answer

1,400–1,800°F

Answer

Enclosed flares are designed to maintain combustion temperatures of approximately 1,400–1,800°F (760–982°C), achieving the 98% NMOC destruction efficiency required by EPA regulations.

Question 4

What does RNG stand for in the context of advanced LFG utilization projects?

Accepted Answer

Renewable Natural Gas

Answer

RNG (Renewable Natural Gas) is LFG that has been processed to pipeline-quality natural gas specifications (>95% methane) and injected into natural gas distribution systems or used as vehicle fuel.

Question 5

What pipe material is most commonly used in the construction of vertical LFG extraction wells?

Accepted Answer

High-density polyethylene (HDPE) pipe

Answer

HDPE pipe is preferred for LFG extraction wells because it is resistant to corrosion from landfill leachate, flexible enough to accommodate settlement, and durable under the acidic landfill environment.

SWANA - Solid Waste Association of North America Practice Test

SWANA - Solid Waste Association of North America Practice Test

SWANA Landfill Gas Management 2