Yellow tubes snake from the top of converted landfill vents, running underground for a few hundred feet before leading back above ground to a flame fed by a steady supply of methane gas.
The system is designed to protect the nearby library, civic buildings and neighborhoods from the potentially explosive gas, constantly seeping from decomposing waste underneath the soil at the closed Kentwood Landfill.
Prompted by detection of methane migrating outside the perimeter of the facility last year, work began in August to expand methane collection, containment and monitoring at the site. Methane, which occurs naturally in landfills, is non-toxic and dissipates quickly when exposed to air. But the gas is flammable, specifically when trapped in closed-in spaces.
Near the property’s southern extension, crews used heavy equipment on Tuesday, Sept. 5, to slowly drill a 94-foot-deep hole into the soil, sediment and mostly decomposed garbage beneath their feet. The hole is one of six being drilled in that portion of the landfill, positioned in a line along a fence separating the property from Kentwood’s public works complex at 5068 Breton Road SE.
Another 12 wells will soon be drilled near the closed landfill’s northwest corner, in the area between the Kentwood Justice Center and Kent District Library’s Kentwood (Richard L. Root) branch.
The holes are drilled in pairs, with one about 20 feet deep and another about 90 feet deep. They are designed to draw methane gas from both deep and shallower underground areas of the landfill.
In total, the county is adding new deep and shallow wells at nine different collection sites, plus seven new gas monitoring probes.
The new wells will join nine existing wells in diverting methane captured beneath the surface to two flares. The existing flare is located near the Kentwood library, and a second flare will be installed next to it later this fall.
Molly Sherwood, the county department’s environmental compliance manager, explained why all the wells are clustered along the property’s western edge.
Methane seeping from the landfill, Sherwood said, naturally moves uphill along an underground layer of clay that is higher on the west end of the property. The extraction points are aimed at slowly drawing on that constantly seeping methane, to be burned off by the flare.
Monitoring points and additional vents are also clustered along the landfill’s western edge, measuring what levels of the gas make it past the line of extraction wells.
To read the full story, visit http://www.mlive.com/news/grand-rapids/index.ssf/2017/09/efforts_underway_to_capture_ex.html.