The 72-acre former landfill is one of 88 Superfund sites in Michigan monitored by the U.S. Environmental Protection Agency and the state Department of Environmental Quality. Methane gas was identified in the footprint of the Kentwood Public Library when it was built in 2010, and efforts have been underway to mitigate the threat of gas buildup since then, according to an annual federal report on the site.

Initially, passive venting of methane "didn't prove very effective," said Daria Devantier, a unit chief in the DEQ's Superfund section. An active system of gas wells that suck methane out of the landfill and burn it now is being used.

The county will consider doubling the size of that system in hopes of mining more methane so that it doesn't spread to neighboring properties, Baas said.

"We've got to put more wells in to draw from a larger area," Baas said. "It should put an end to it."