Updated Jan. 9 to add Republic Services' filings and Circuit Court order

Following a long afternoon of negotiations, Bridgeton Landfill owner Republic Services has agreed to install two temperature monitoring probes in the landfill's north quarry, near radioactive waste at the adjacent West Lake Landfill.

The agreement came after Attorney General Chris Koster took more legal action against Republic Services this week, out of concern that the underground fire in the landfill's south quarry might be spreading north, closer to the area of radioactivity.

Republic Services had already committed to install a line of 12 new temperature monitors just north of the landfill's neck. According to Friday's St. Louis County Circuit Court order, two of those probes (TMP-24 and 26) will be relocated even farther north, near the radioactive waste, instead.

In a written statement, Koster said he was pleased that Republic Services agreed to install the monitors "where recent data shows they are desperately needed."

But to Koster's disappointment, his office failed to convince either Republic Services or Judge Michael Jamison that his other demands for more monitoring and sampling were warranted.

By Jan. 16, all the parties will need to submit more information to the court for ― or against ― additional carbon monoxide monitoring.

Judge Jamison also asked for more information related to his court's jurisdiction to order Republic Services to collect soil samples for radioactivity testing, without the U.S. Environmental Protection Agency being a party in the state's case. The EPA has regulatory authority over the radioactive waste at the adjacent West Lake Superfund Site, and up until now has been the only agency testing for radioactivity at the landfills.

The court referred all the other issues raised by Koster's motions "to a Special Master for report and recommendation, based on an amendment to the Agreed Order to be negotiated between the Parties."

"We look forward to the court’s resolution of the remaining legal issues," Koster said. "We will continue our effort to compel Republic to share vital information and, ultimately, to hold Republic responsible for its conduct.”

Republic Services has argued that conditions at the Bridgeton Landfill are in a managed state that do not require any additional action beyond the monitoring the company has already agreed to do.

In its filing with the court, Republic Services characterized Koster's actions this week as an "attempt to spread panic and fear amongst his constituency by making baseless accusations, misconstruing data, and filing 'emergency' motions for no real purpose."

The company argued that the state's motions should be denied for the following reasons (quoted directly from p.3 of Republic's response):

The North Quarry is safe and stable. There is no new data or other exigency that warrants circumventing the Agreed Order entered by this Court and the procedures (including dispute resolution) embodied therein. The State lacks authority, and its witnesses lack expertise, with respect to the radioactive impacted materials (RIM) at the site. The State’s thinly veiled attempt to usurp US EPA’s authority over the West Lake Landfill should be denied, or addressed as the federal question that it raises by the agency or, if appropriate, judge with jurisdiction over such issues.

Republic Services also filed 12 exhibits: here's a list of those.

Maryland Heights resident and citizen activist Dawn Chapman came to the county courthouse with her young son, hoping to hear a decision favorable to the attorney general.

She was visibly angered by the standoff between Republic Services and the state. "I’m mad that there’s even a standoff. Real-time data benefits Republic, it benefits their shareholders, it benefits the state of Missouri, it benefits the community," Chapman said.

The mother of three said there is only one reason that Republic Services would push back on providing more information to the state: money. "And I don't want to hear that," Chapman said. "They own this landfill. This is their problem. They're obligated to pay for it."

According to Republic Services, it has already invested more than $125 million to control the impacts of the "pyrolysis" ― the smoldering trash in the oxygen-depleted environment inside the landfill.

Updated Jan. 8 to add details about the state's legal filings

As St. Louis Public Radio reported on Monday, the state has now taken legal action against Bridgeton Landfill owner Republic Services out of concern that an underground fire at the landfill is not under control.

Missouri Department of Natural Resources

On Wednesday, Missouri Attorney General Chris Koster filed two new motions with the Circuit Court of St. Louis County.

One asks for a temporary restraining order against Republic Services, to require the company to comply with demands described in a Dec. 26 letter from the Missouri Department of Natural Resources.

Specifically, the state wants the court to require the landfill owner to do the following:

Submit weekly temperature readings from 10 gas extraction wells in the north quarry, beginning on Jan. 9; Submit monthly carbon monoxide measurements from 13 gas extraction wells in the north quarry, beginning on Jan. 20; Install two new temperature monitoring probes in the north quarry near the radioactive waste by Feb. 1; Install slope monitoring stakes at 50 foot intervals along the northern slope of the north quarry by Feb. 1. Those would allow the state to measure how much the landfill surface is sinking. Accelerated sinking would be one sign of a subsurface heating consuming waste underground.

In their affidavits, state landfill fire consultants Todd Thalhamer and Timothy Stark argue that recent monitoring results suggest an underground fire in the south quarry of the landfill may have spread north, close to radioactive waste in the adjacent West Lake Landfill ― or alternatively, that a new fire may be starting in the north quarry.

The state's second motion asks the court to compel Republic Services to collect samples of landfill waste and soil as it installs new temperature monitoring probes. That would include the two new probes the state wants installed near the radioactive waste, plus nine others that the company has already agreed to install just north of the landfill's neck.

Those samples would allow the state's consultants to better assess underground conditions in the north quarry, including changes caused by subsurface heating, or the presence of any radioactive waste.

In a written statement, Republic Services said it is committed to the safety of its employees and neighbors, and that the landfill is safe and stabilized.

A hearing on the matter is scheduled before Judge Jamison at 11:00 a.m. on Friday.

Read our original story from Monday, below:

The Missouri Attorney General's office will soon be taking more legal action against the owner of a smoldering landfill in Bridgeton.

Missouri Department of Natural Resources

An underground fire has been heating up the southern part of the Bridgeton Landfill for more than four years.

The Attorney General filed suit against Republic Services for environmental violations related to the south quarry fire in March 2013. He filed an amended petition expanding those claims in October of last year.

Now the state is concerned that temperatures may also be rising in the north quarry ― the area closest to radioactive waste in the adjacent West Lake Landfill.

Republic Services strongly disagrees, saying there is nothing to indicate that subsurface heating has spread or that additional action is needed.

But in an interview with St. Louis Public Radio, Attorney General Chris Koster said that in the coming days, he would ask the St. Louis County Circuit Court to order Republic Services to provide more data.

"This is information that Republic has been slow in providing to the state, but we think that there is cause for some level of concern," Koster said. "We don't know what level of concern is appropriate, but we know that the information we have seen in the past weeks requires us to ask more questions."

Koster's announcement follows a letter the Missouri Department of Natural Resources sent to Republic Services in late December, in response to data provided by the company.

In that letter, the MDNR described what it called unexplained temperature and carbon monoxide fluctuations from mid-October through mid-December in some gas wells near the radioactive waste. The agency said the fluctuations were "outside trends previously reported."

The state is demanding that Republic Services install two new temperature probes by Feb. 1, and to immediately start providing weekly temperature data and monthly carbon monoxide data from certain gas extraction wells in the north quarry.

Both of those new probes would be close to the known border of the radioactive waste.

Missouri Department of Natural Resources

Republic Services sent a response to MDNR on Monday in which it denied that there is any cause for concern. The company said that the well conditions within the area that the state characterized as an "area of concern," are consistent with prior monitoring results, in compliance with regulatory standards, and "well below any trigger level established for further action by MDNR's own experts."

Republic said it would not comply with the state's demands and requested a meeting to discuss them.

The company has already committed to install nine new temperature monitoring probes just north of the neck of the landfill, starting this week.

Meanwhile, Attorney General Koster said he would also consider taking legal action against the U.S. Environmental Protection Agency, which he said was moving so slowly that it might make any permanent resolution to the issues plaguing the landfill impossible.

"Nothing is off the table to bring some type of a solution to this landfill problem, including legal action," Koster said, although he cautioned that might not be the quickest way to achieve results.

"There is broad agreement among the people who live in north county, and the state government as well, both the Attorney General’s office and the Department of Natural Resources, that the EPA needs to show more leadership in this area than they have over the last several years," Koster said.

Koster said that the steps he soon would be taking against Republic Services would give the EPA an opportunity "to come in and make their voice heard, hopefully in a productive manner."

"This is the most significant environmental case in the state of Missouri," Koster said. "There’s no doubt about that. And this case has our full attention, and we intend to work it with everything we’ve got for as long as I’m attorney general."

Both Koster and EPA Regional Administrator Karl Brooks will be moving on from their current positions in January 2017.

Brooks has told the St. Louis area congressional delegation that his agency will issue a new decision about how to deal with the radioactive waste at the landfill before then.

Follow Véronique LaCapra on Twitter: @KWMUScience