Procedures are in place to prevent a repeat of an October chemical discharge from Kalispell Regional Medical Center into the city's sewer system.

On Oct. 27, the hospital accidentally discharged thousands of gallons of a heat transfer fluid, which killed some of the waste-eating bacteria at the city's sewage-treatment plant, Kalispell City Attorney Charles Harball said. The hospital has offered to pay for any repair costs at the sewage plant.

No one was harmed by the October discharge.

City and hospital officials huddled Monday to discuss the situation and issued a joint press release Thursday.

Last June, the cooling system serving the main Northwest Healthcare building was ruptured, and it spilled a significant amount of heat transfer fluid - propylene glycol - into the city's sewer system, harming the bacteria that devours the sewage at the plant, the release said.

Northwest Healthcare, the hospital's parent corporation, repaired the system and filled it with water and the remaining propylene glycol - resulting in a diluted fluid.

In late October, the hospital recharged the system, replacing the diluted fluid with fresh propylene glycol, and drained the diluted solution into the sewer system without notifying the city. During the recharging, a few gallons of the fluid also ended up in the storm water sewers.

The hospital's maintenance people thought the diluted solution was harmless, the release said. But the discharge resulted in unusual suds and smells at the sewage-treatment plant, as well as killing the bacteria.

Investigators could not figure out how many gallons of propylene glycol were spilled in the June and October incidents, because the dilution skewed any calculations, Harball said. The system is capable of holding 12,000 gallons.

Harball said the October discharge was thousands of gallons.

Since then, the hospital has revamped its procedures for hazardous-waste disposal, and city staff has signed off on the changes. The hospital and city will do further studies of the appropriate designs, procedures and hazardous-material responses at the health center.

"They've been really great to work with on this," Harball said of the hospital.

Because the effluent from the sewage treatment plant met state requirements during and after the incident, no state violations occurred, said Scott McCullough, an environmental specialist with Montana's Department of Environmental Quality.

Propylene glycol is a clear, colorless, odorless, slightly syrupy liquid used in anti-freeze and de-icing solutions and in solvents in the painting and plastic industries. It also is an ingredient for food coloring and flavoring.

When added to food, it is generally considered safe, according to the federal Agency for Toxic Substances and Disease Registry's Web site. If taken in large amounts, propylene glycol can increase the amount of acids in the human body, the Web site said. It can harm animals if they drink enough of it.

The chemical breaks down after several days in the soil or in water.

Reporter John Stang may be reached at 758-4429 or by e-mail at jstang@dailyinterlake.com.