CPWM Landfill Gas Management and Energy Recovery 3

Question 1

What is the typical methane concentration range found in landfill gas collected from a well-managed MSW landfill?

Accepted Answer

35–60% methane by volume

Answer

10–20% methane by volume

Answer

70–80% methane by volume

Answer

90–95% methane by volume

Question 2

What minimum operating temperature must an enclosed combustion device maintain when treating landfill gas under EPA 40 CFR Part 60 Subpart Cf?

Accepted Answer

1,500°F (815°C)

Answer

500°F (260°C)

Answer

1,000°F (538°C)

Answer

2,000°F (1,093°C)

Question 3

Which LFG collection well configuration is most commonly used in completed waste cells at an active landfill?

Accepted Answer

Vertical extraction wells drilled down through the waste mass and connected by header pipes

Answer

Horizontal collectors installed beneath the final cover system

Answer

Perimeter gas fence trenches along the landfill outer boundary

Answer

Surface collection blankets placed on top of intermediate cover

Question 4

What is the primary function of condensate management components (drip legs and collection sumps) in an LFG collection network?

Accepted Answer

To remove liquid water condensate from collection pipes that would otherwise block gas flow

Answer

To increase the flow velocity of gas through collection headers

Answer

To filter particulate matter and dust from the extracted gas stream

Answer

To continuously monitor methane concentration in the collection system

Question 5

Which financial instruments generated by LFG-to-energy projects can provide additional revenue through environmental commodity markets?

Accepted Answer

Renewable Energy Credits (RECs) and verified carbon offset credits

Answer

Clean Air Act operating permits and allowances only

Answer

RCRA Subtitle D closure trust fund disbursements

Answer

Municipal bond proceeds earmarked for environmental projects

Question 6

In an LFG collection system, what does a negative wellhead pressure (vacuum) measurement indicate?

Accepted Answer

The blower system is actively drawing gas from the waste mass toward the collection system

Answer

The extraction well has become blocked with condensate

Answer

The landfill has reached its maximum gas generation phase

Answer

The gas composition at that well contains excess air infiltration

Question 7

Which trace compound found in landfill gas is classified as a hazardous air pollutant (HAP) and a known human carcinogen?

Accepted Answer

Vinyl chloride

Answer

Nitrogen gas (N₂)

Answer

Water vapor (H₂O)

Answer

Carbon dioxide (CO₂)