BAILEYVILLE – A blowout on an underground pipe was blamed Thursday for spilling an estimated 3.5 million gallons of untreated wastewater into the St. Croix River.

Domtar Industries pulp and paper mill officials said that in excess of 1 billion gallons of river water flowed past the area, making the spill volume equivalent to less than a half of 1 percent of the total volume.

The spill occurred around 4 a.m.

General Manager Debby Feck ordered the mill to be shut down to stop the leak. Mill officials said late Thursday the spill would have no adverse impact on the river.

The wastewater is a byproduct of the papermaking process. “At a pulp mill, we are trying to take pieces of wood and we are trying to remove the brown stuff out of the wood to make white paper. We do that by adding chemicals to help separate the fiber quickly, then steam and water,” said Jay Boudoin, the mill’s environmental superintendent. “So when we talk about organic matter, we are talking wood residuals.”

Because the river is a boundary line between Maine and New Brunswick, Canada, company officials notified state, provincial and federal officials on both sides of the border. The list included the Maine Department of Environmental Protection, Maine State Police, U.S. Coast Guard, U.S. Environmental Protection Agency, the National Spill Response Center, the Passamaquoddy Tribe, the St. Croix International Waterway Commission and Environment Canada.

Officials at the St. Croix International Waterway Commission did not return a telephone call Thursday. The commission has international jurisdiction over the river.

Calais City Manager Linda Pagels said that when city officials learned of the spill, water plant operators shut down the city’s water pump system located near the industrial park. Pagels called it a precautionary move. “Because there could be a possibility there is a tie between the river and our wells, we shut down both pumps and don’t intend to turn them both on until the plume has gone down past the site,” she said.

Beaudoin explained how the mill’s system worked. “The mill was built in 1905 and everything was designed to go straight to the river. In the 1970s and 1980s, we installed a large series of pipes and pumps to redirect everything uphill about 120 feet to the lagoons” Beaudoin said.

Before the wastewater gets to the lagoon, there is a primary system that removes rocks and fiber. “We have a pumping station that pumps through a three-foot line to that clarifier, and early this morning about a 20-foot section, which is buried underground, failed and blew out part of the river bank, which [consists of] old fill and rubble and riprap,” he said.

Beaudoin said mill officials were investigating why a pipe that was installed in 1993 failed. He said the pipe had been inspected on numerous occasions and no problems were noted.

Independent analysts were dispatched along the river to assess the impact.

Beaudoin said the company discharges about 5,000 pounds of organic matter into the river, even though the mill’s permit allows 17,000 pounds. “We typically operate at about a third of what a permit allows us,” he said.

But because a line ruptured and the system was bypassed, Beaudoin said, the mill violated its state and federal permits.

To help mitigate the impact, company officials opened the lower dams to flush the system.

This is not the first time the mill has breached its system. In 2003, the mill, Washington County’s largest employer, entered into an administrative consent agreement with the state concerning discharge violations. The mill was ordered to pay $88,000 in water quality and wastewater discharge fines. The agreement covered a myriad of violations beginning July 18, 2001, including a breach at the paper mill pump house when more than 100,000 gallons of hazardous black liquor, which consists of water, sodium hydroxide, wood solids and wood extract used in papermaking, spilled into the river.

Domtar’s Woodland Mill is an integrated pulp and paper mill and produces premium quality specialty papers and northern hardwood market pulp. The pulp and paper mill has been at its current location since it first operated as St. Croix Paper in 1906. Domtar employs more than 550 people.