HAMPDEN – Pine Tree Landfill’s gas extraction system will return to full operation Monday with the conclusion of a two-week shutdown designed to track landfill gases.

Landfill and state Department of Environmental Protection officials had kept open the possibility of extending the shutdown, but decided Friday enough information had been collected, Don Meagher, manager of planning and development for Casella Waste Systems Inc., which owns the landfill, said Friday.

“There’s a lot of data to analyze, evaluate and write a report on,” he said.

The shutdown is designed to identify the amount and direction of gases escaping from the conventional landfill, the oldest portion of the facility that was constructed in 1975 under different ownership. Some gases, including odorless methane, have been detected in surrounding soil and groundwater, particularly to the east of the landfill.

The testing did not affect the gas collection system in the newer sections of the landfill.

The targeted section of the system will be watched closely next week to ensure it is properly tuned as it comes back on line, Town Manager Susan Lessard said Friday.

“Once it’s turned on they need to make sure the system is balanced,” she said.

Odor complaints will continue to be monitored round the clock through next week, Lessard said.

Since the testing period began July 17, the landfill has received 11 odor complaints, Meagher said, correcting a statement he made earlier this week that none had been received.

He had not been informed of those complaints because the usual odor reporting system was changed during the testing period, he said.

However, none of those complaints can be attributed to the shutdown, Meagher said. Six were associated with gas outside the conventional landfill, and five were detected upwind from the landfill so cannot be tied to Pine Tree, he said.

A report detailing the findings from the shutdown will be completed this fall, Meagher said.