<CLICK HERE> for a pdf version
All large landfills are required to perform Surface Emission Monitoring (SEM) surveys on a quarterly basis to locate landfill gas venting from the landfill. The SEM surveys utilize portable monitoring equipment to detect areas where methane is venting with concentrations greater than 500 ppm. The surveys must canvas the entire landfill surface using a 30m x 30m grid, check all know penetrations (wells, sumps, etc.), and suspected areas of venting (distressed vegetation, crevasses, etc.). All significant vents (>500 ppm) identified trigger reporting requirements and required actions that must be implemented until the venting is corrected (e.g.- improve landfill cover, adjust nearby gas wells, install a new gas well, etc.).
Surface Emission Scans
Technicians check for gas venting using portable equipment. The scan is conducted using a 30m x 30m grid across the entire surface of the landfill. Special attention should be given to all surface penetrations (wells, sumps, etc) and areas of suspected vents (distressed vegetation, crevices, etc.)
The SEM requirements can be onerous for large landfills, but so are the odors that downwind communities might endure if the SEM is not conducted correctly. Many environmental and community advocacy groups suspect that landfills complete the required SEMs with a "check the box" approach as opposed to using the SEMs to effectively reduce emissions and improve the gas collection at the landfill.
Last year EGLE Air Quality Division purchased the necessary equipment, dedicated the manpower and conducted unannounced visits to verify the quality of the SEM surveys being conducted at 9 Michigan landfills (including Arbor Hills). Overall EGLE found:
· ...methane exceedances in excess of 500 parts per million at hundreds of separate locations.
· ...landfills have surface cover integrity issues that are not being addressed monthly nor are these areas being visited and documented during SEM surveys.
· ...results suggest landfills are not conducting required quarterly SEM surveys in a satisfactory manner and are not looking at locations where landfill gas is known to commonly escape from the surface.
EGLE Air Quality Division recently sent all Michigan landfills a letter announcing they will be using their SEM equipment beginning in 2021 to conduct compliance evaluations (i.e. – violations may be issued if necessary) of landfills to check the quality of the SEMs being conducted.
The Conservancy Initiative applauds the Air Quality Division for taking this initiative and believes these more aggressive enforcement measures will pay dividends.
We have included links to the reports from the two SEM surveys EGLE performed at Arbor Hills in 2020 but caution that these are very detailed reports and are not light reading. June 30, 2020 Arbor Hills SEM October 29, 2020 Arbor Hills SEM