MDE regulations

June 15, 2023

On June 12, 2023, the Maryland Department of the Environment (MDE) published its final regulation addressing the control of landfill gas (LFG) methane emissions from municipal solid waste (MSW) landfills in the state (promulgated under COMAR 26.11.42). Methane is a potent greenhouse gas (GHG) with a global warming potential more than 25 times greater than carbon dioxide. The rule has been several years in the making and is modeled after similar rules in California and Oregon. The rule also incorporates provisions from the EPA’s federal landfill air regulations under NSPS & EG 40 CFR 60 Subparts Cf and XXX and NESHAP CFR 63 Subpart AAAA and stands among the most stringent in the US.

The new regulation will be submitted to the EPA for approval as part of Maryland’s state plan for MSW landfills (state plan). The state plan will be equivalent to or more stringent than the EPA’s NSPS & EG 40 CFR 60 Subparts Cf and XXX and NESHAP CFR 63 Subpart AAAA and will apply to smaller and mid-sized landfills not currently subject to the EPA’s federal rules. MDE estimates that 32 active and closed MSW landfills in the state will be subject to the rule. The rule is effective June 12, 2023.

Some key provisions of the rule include:

• The rule applies to active and closed MSW landfills that have accepted waste after 11/8/1987 and that have a design capacity greater than or equal to 2,750,000 tons and 3,260,000 cubic yards, and active and closed MSW landfills that have accepted waste after 12/31/1993 that have less than 2,750,000 tons or 3,260,000 cubic yards of waste but greater than 450,000 tons of waste in place.
• By September 10, 2023, applicable landfills must prepare an initial waste-in-place report, calculate their methane generation rate, and submit a report to MDE.
• Closed or inactive landfills, or closed inactive areas of an active MSW landfill, that have commenced installation of solar panels or arrays on or before 1/1/2024 are exempt from the rule if they meet certain requirements.
• MSW landfills with a calculated methane generation rate greater than 8,548 tons per year must install a gas collection and control system (GCCS).
• MSW landfills with a calculated methane generation rate between 732 tons per year and 8,548 tons per year can either install a GCCS or evaluate surface methane emission rate, the results of which would determine if a GCCS is required.
• If required, landfills must operate the GCCS for a minimum of 15 years and until the point that the methane generation rate has reduced to below 732 tons per year.
• Specific requirements for the use of control devices such as enclosed or open flares. The use of open flares is permitted only until 1/1/2025 unless MDE approves its use in writing. The rule includes minimum control requirements for devices and initial and annual source testing.
• Evaluation of surface methane emission rates through both instantaneous (500 ppm) and integrated (25 ppm) monitoring requirements and standards.
• Leak monitoring and standards (500 ppmv) for GCCS components that contain LFG and are under positive pressure.

This rulemaking has been several years in development and is consistent with Maryland’s GHG Reduction Act of 2009 and the recent Climate Solutions Now Act of 2022 that requires Maryland to become “net zero” for GHG emissions by 2045, with an interim goal of achieving 60% GHG reductions by 2031 (over 2006 levels). MDE estimates this rule will achieve a 25-50% reduction in GHG emissions from affected landfills.

Additional information on MSW regulations and GHG emission reductions:

• Contact Josh Roth or Jake Shepherd for details,
• Outside of Maryland, please contact
• Clean Air Act
• Greenhouse Gas Monitoring and Control

January 19, 2023

MDE Regulatory Alert: Maryland Landfill Air Regulation

On December 30, 2022, the Maryland Department of the Environment (MDE) published a proposed regulation addressing the control of landfill gas (LFG) methane emissions from municipal solid waste (MSW) landfills in the state. Methane is a potent greenhouse gas (GHG) with a global warming potential of more than 25 times greater than carbon dioxide. The proposed regulation is modeled after similar rules in California and Oregon, incorporates provisions from the EPA’s federal landfill air regulations under NSPS & EG 40 CFR 60 Subparts Cf and XXX and NESHAP CFR 63 Subpart AAAA, and would become among the most stringent in the US.

The new regulation will be submitted to the EPA for approval as part of Maryland’s state plan for MSW landfills (state plan). The state plan will be equivalent to or more stringent than the EPA’s NSPS & EG 40 CFR 60 Subparts Cf and XXX and NESHAP CFR 63 Subpart AAAA, and will apply to smaller and mid-sized landfills not currently subject to the EPA’s federal rules.

MDE estimates that 32 active and closed MSW landfills in the state will be subject to the proposed regulation.

Some key provisions of the rule include:

• The rule will apply to active and closed MSW landfills that have accepted waste after 11/8/1987 and that have a design capacity greater than or equal to 2,750,000 tons and 3,260,000 cubic yards, and active and closed MSW landfills that have accepted waste after 12/31/1993 that have less than 2,750,000 tons or 3,260,000 cubic yards of waste but greater than 450,000 tons of waste in place.
• Closed or inactive landfills, or closed inactive areas of an active MSW landfill, that have commenced installation of solar panels or arrays on or before 1/1/2024 are exempt from the rule if they meet certain requirements.
• MSW landfills with a calculated methane generation rate greater than 8,548 tons per year must install a gas collection and control system (GCCS).
• MSW landfills with a calculated methane generation rate between 732 tons per year and 8,548 tons per year can either install a GCCS or evaluate surface methane emission rate, the results of which would determine if a GCCS is required.
• If required, landfills must operate the GCCS for a minimum of 15 years and until the point that the methane generation rate has reduced to below 732 tons per year.
• Specific requirements for the use of control devices such as enclosed or open flares. The use of open flares is permitted only until 1/1/2025. The rule includes minimum control requirements for devices and initial and annual source testing.
• Evaluation of surface methane emission rates through both instantaneous (500 ppm) and integrated (25 ppm) monitoring requirements and standards.
• Leak monitoring and standards (500 ppmv) for GCCS components that contain LFG and are under positive pressure.

This rulemaking has been several years in development and is consistent with Maryland’s GHG Reduction Act of 2009 and the recent Climate Solutions Now Act of 2022 that requires Maryland to become “net zero” for GHG emissions by 2045, with an interim goal of achieving 60% GHG reductions by 2031 (over 2006 levels). MDE estimates that once implemented, this rule will achieve a 25-50% reduction in GHG emissions from affected landfills. MDE estimates the capital costs associated with rule compliance would range from $1 to $3 million, annual operating and maintenance costs range from $150k to $400k, and additional costs for monitoring (~ $60k annually), recordkeeping, and reporting.

MDE has scheduled a virtual public hearing on the proposed action at 10:00 am on February 1, 2023. Comments can be submitted by 5:00 pm (Eastern Time) on February 1, 2023, to Mr. Randy Mosier of MDE at .

For additional information on MSW regulations and GHG emission reductions, please visit scsengineers.com or one of SCS’s nationwide offices.