A malfunctioning float valve at Searsport District Middle and High School caused up to 1,500 gallons of oil to spill out of the building the morning of Dec. 14, sending students home for the day and triggering a massive clean-up effort.

Searsport Fire and Police departments were called in, as well as Maine Department of Environmental Protection, the Coast Guard and Clean Harbors Environmental Services. A few personnel from Clean Harbors remained at the school Dec. 20, nearly a week after the spill.

According to Regional School District 20 Superintendent Chris Downing, the equipment failure was discovered at approximately 10:30 a.m. by Russ Flagg, who is the buildings, grounds and transportation director, during an "almost daily" boiler inspection.

Town Manager James Gillway said the heating system was turned off while cleanup efforts were underway. Students and faculty were evacuated, then sent home, because of fumes and cold conditions at the school, he said. Downing noted students did not have school Monday, but it was not related to the spill — it was a snow day.

Searsport Fire Chief Andrew Webster confirmed the spill was caused by a "mechanical issue."

A 6,000-gallon underground heating oil tank supplies a 100-gallon "day tank" inside the boiler room with a pump to draw the oil in.

"A float came up and got stuck," Flagg and Webster both said, which caused too much oil to be pumped into the day tank. The excess oil flowed through a "vent" outside the building, Webster said.

Flagg said a very small amount of oil, "maybe a cupful," leaked inside the building.

In all, Webster estimated, approximately 1,200 to 1,500 gallons of No. 2 heating oil spilled.

DEP and Coast Guard personnel were called in because of concerns the oil would flow through a catch basin behind the school's gymnasium and into nearby Mill Stream, and eventually into the bay.

Containment booms were positioned in the small stream that crosses Mt. Ephraim Road to Mill Stream and left there over the weekend, in the hope of extracting any "residue." According to Webster, "Not much made it down to the stream."

A Coast Guard plane flew over the area to see if it could spot the heating oil, which is dyed red, in the water. But "they didn't see anything," Webster said.

Scott Davis, who drives a truck for Clean Harbors, said he "sucked up mostly water" at the spill site. Davis said Dec. 20 he will take the spilled material to Portland for processing at a facility where "they put it in big tanks and treat it with heat and chemicals" to expel the water, then recycle it.

Downing said, "It was a team effort that rectified the problem" and prevented the spill from becoming far worse. "From dispatch, to fire and police departments, to DEP, Clean Harbors and the Coast Guard," Downing said, "it is a great team."