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Someone is regularly dumping large amounts of a carcinogen hazardous to aquatic life into Helena’s sewers, and the chemical is killing nitrogen-eating bacteria at the city’s wastewater plant, causing the facility to discharge more than five times the permitted amount of ammonia into the ditch flowing to Prickly Pear Creek.

The discovery of chromium entering the sewage plant has prompted criminal investigation by the U.S. Environmental Protection Agency, the Montana Department of Environmental Quality and the Helena Police Department.

According to the EPA, “the metal chromium is used mainly for making steel and other alloys. Chromium compounds, in either the chromium (III) or chromium (VI) forms, are used for chrome plating, the manufacture of dyes and pigments, leather and wood preservation and treatment of cooling tower water. Smaller amounts are used in drilling muds, textiles, and toner for copying machines.”

City officials detailed the problem in a group interview Friday.

After weeks of mystery punctuated by serendipity, officials identified their problem Thursday, Helena Wastewater Superintendent Don Clark said, when they and investigators were at the plant and noticed a sudden spike in the acidity of the incoming waste, which also turned a bright shade of yellow-green.

A lab test identified high levels of the particularly harmful variation known as hexavalent chromium, ending the puzzlement of the entire city wastewater staff, three consultants and several government investigators, and shifting efforts toward the criminal investigation. The dumping breaks federal, state and local laws.

Officials are asking the person or business to stop dumping the hazardous material, and police are pursuing attempts to uncover the source, an effort that includes the use of monitoring equipment across the city’s sewer system.

Police are asking for leads from the public, and tipsters who wish to remain anonymous can contact Crime Stoppers at 443-2000 or at Helenacs.com.

Clark said the city expects the problem to cost roughly $20,000 by the time it’s resolved. They’ve had to truck in 84,000 gallons of sewage sludge from East Helena, Bozeman and Missoula to reseed the plant’s bacterial population, and so far the microbes have failed to rebound. The city also has had to pay consultants to investigate the problem, and some staffers have worked overtime to address it.

If the dumping stops today, the plant will still have higher levels of chromium for at least six weeks.

The bacteria may continue to fail to regenerate, meaning the city will continue to discharge higher-than-permitted amounts of ammonia to the watershed in the coming months, potentially spurring algae growth downstream. And if the problem doesn’t abate, the city may eventually have to suspend programs that use solid sludge as an agricultural fertilizer and a component in composting operations.

If levels of chromium continue to rise in the sludge, Clark said, the city will begin disposing sludge in the county landfill. Testing shows the sludge now contains less than one-fifth of the regulatory limit of chromium, but the amount is a tenfold increase over the plant’s average.

“We’re going to go to extraordinary levels to make sure this stuff isn’t toxic for our composter or our land-application,” Clark said.

For Clark and his team, the headaches began Oct. 23, when test results showed the spike in ammonia. The permitted discharge changes monthly — last month, the limit was 2 parts per million. This month, the limit is 4 ppm, and the city is discharging more than 20 ppm. It’s gone as high as 32 ppm, Clark said.

Plant records show sudden, short-term spikes in wastewater acidity six more times since the initial discovery a month ago.

“It’s not just a one-time hit,” Public Works Director John Rundquist said. “Someone is dumping and then re-dumping. It’s every few days.”

“In the amounts it’s going through, it seems like it’s somebody who should know they shouldn’t be doing it,” Police Chief Troy McGee added.

Though the city has had incidents of illegal dumping in the past, this is the first occurrence since the plant was upgraded in 2000 and the most severe in recent memory.

“We haven’t seen anything like this (in years),” Clark said.

“Compliance is huge for us,” he added, noting his staff has been working hard to deal with the issue. “It’s got a dark cloud of the staff. (Compliance) is our No. 1 job.”

Clark said his office is always willing to help people and businesses find proper ways to dispose of hazardous materials. Contact him at 457-8556 for more information.

Reporter Larry Kline: 447-4075 or larry.kline@helenair.com

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