KENTWOOD, Mich. — Work has begun to expand methane collection, containment and monitoring after the potentially explosive gas was found seeping from a closed landfill in western Michigan.

Efforts started last month to collect the gas leaking from decomposing waste underneath the soil at Kentwood Landfill near Grand Rapids, the Grand Rapids Press reported .

Crews worked to drill a 94-foot-deep (28.6-meter-deep) hole into the soil, sediment and mostly decomposed garbage Sept. 5. The holes are designed to draw methane from deep and shallow underground areas of the old landfill.

The hole is one of six being drilled in that area of the landfill, positioned in a line along a fence separating the property from Kentwood’s public works complex. Another dozen wells are expected to be drilled in an area between the Kentwood Justice Center and Kent District Library’s Kentwood branch.

The system is designed to protect the nearby library, civic buildings and neighborhoods from the explosive gas detected outside the facility’s perimeter. Kent County issued notices last year to 150 properties in the surrounding area.

Methane occurs naturally in landfills, is nontoxic and dissipates quickly when exposed to air. But the gas can be flammable, especially when trapped in closed-in spaces.

“This is a complex geological site, and the presence of methane at varying depths below ground meant that the system needed to be able to collect from each of these different depths,” said Molly Sherwood, the county’s environmental compliance manager.

All the wells are clustered on the landfill’s western edge because methane seeping from the landfill naturally moves uphill along an underground layer of clay that’s higher on the west end of the property, Sherwood said. She said the extraction points are aimed at slowly drawing on that constantly seeping methane, to be burned off.

The landfill dates back to the 1940s. It’s managed by the Kent County Department of Public Works and monitored by the U.S. Environmental Protection Agency and the state Department of Environmental Quality.


Information from: The Grand Rapids Press, http://www.mlive.com/grand-rapids

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