HAMPDEN – After months without an odor complaint at the Pine Tree Landfill, the rotten-egg smell has resurfaced in the past few weeks.

Landfill officials said on Tuesday that on Feb. 6 they received the first odor complaint in several months and the first in 2008. The recent snowstorms, attempts to get the gas-to-energy project running, and the lack of synthetic liner to cover the landfill has contributed to the returned stench, said Tom Gilbert, environmental compliance manager for Casella Waste Systems Inc., the company that owns the landfill.

Landfill staff periodically surveys the gas levels around the landfill, Gilbert said. In the past few weeks, staff has noticed more areas where gas is escaping from the landfill, he said. In low barometric pressure conditions, gases escape from the landfill. The vibrations from equipment and truck traffic can sometimes create cracks in the temporary landfill cover material and provide an outlet for gas, Gilbert said.

“In the wintertime with cold temperatures and low barometric pressures we are more likely to have landfill gas breakouts than you would have in warm weather,” said Gilbert. “In zero wind, gas follows the contour of the land, and travels farther in the cold.”

The number of odor complaints called in by neighbors and people passing by the site has been minimal since the June 1 deadline, when the landfill stopped accepting odor-causing wastes, such as sludge. The waste stream change is the first step toward the facility’s final closure on Dec. 31, 2009.

Casella started up its gas-to-energy facility in late January that uses landfill gas to run three internal combustion engines to power generators. Before the plant was on site, officials could vacuum gases from the landfill at a higher rate to reduce odor, but now it needs to be monitored more carefully since the gas is needed for the electricity operation, Gilbert said.

The landfill’s flare, used to burn excess gas, will continue to operate, despite the new facility, said Don Meagher, Casella’s manager for planning and development.

“The landfill is producing more gas than the facility can handle at the present time,” Meagher said. “Until the gas declines to a point where there is just enough for all three engines to use,” the flares will be used.

The flame, shape, size and color will change very little and may not be recognized by the naked eye, he said. Landfill staff still is working out the details for the gas-to-energy project, which is not yet producing its highest electricity yield. Landfill staff cannot pull odorous gases from the landfill as aggressively as they once did when it became an issue, because they must monitor it more closely to ensure electricity production, Gilbert said.

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