OLD TOWN – The boiler at the former Georgia-Pacific Corp. mill has been shut down temporarily due to a dip in energy prices.

The state Department of Environmental Protection is continuing to work with new owner Red Shield Environmental to address recent environmental concerns, but final findings have yet to be made.

“We’re expecting a complete report later this week,” Ed Logue, DEP eastern Maine regional manager, said Tuesday.

Red Shield Environmental, a group of private investors, has been using the boiler to heat the facility and produce electricity to sell on the power grid.

Employees also are using the lull in operations to make upgrades to the machinery.

There have been problems in recent weeks with toxic levels of lead being found in ash samples taken from the boiler, and in two separate incidents with soot falling onto homes and yards in neighboring Bradley. Bradley is directly across the Penobscot River from the mill.

Red Shield previously shut down the boiler to make repairs to the soot collection system, and state DEP Commissioner David Littell said Tuesday that the system is working better.

“They have substantially fixed the problems in the air controls and the ash hopper that led to the sooting events, and that’s good news,” Littell said.

Before the air emissions problems, Red Shield had been burning a mixture of construction and demolition debris and green wood chips.

The boiler is permitted to burn up to 500 tons of fuel a day. Half of that fuel can be construction and demolition debris, which is less expensive than green chips.

The higher price of fuel when using all green chips, coupled with a drop in energy prices between the winter heating season and summer air conditioning season, have resulted in the indefinite shut down of the boiler.

DEP still is waiting for more substantial test results on the ash and fuel source before making a decision on whether, or with what restrictions, Red Shield will be allowed to burn the waste wood fuel again.

The Feb. 28 and March 3 ash incidents and concern over whether the soot that fell in Bradley contained toxic levels of lead has created a lot of public interest in the incident. DEP officials previously said they wouldn’t be testing soot that fell onto homes and yards because it potentially could have been contaminated by coming in contact with other objects and chemicals after it left the boiler and before it reached the ground.

Littell, however, said that DEP officials on Monday did gather some soot from a home in Bradley and intend to test it.

The air emissions incidents are being considered violations, which likely will result in a monetary penalty to the company, Littell said.

“That’s part of the issue of why we’re asking for the data to ensure that we’ve got the fullest picture of what happened,” he said.