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Cold, high water volume lessen environmental impact of historic floods

The Fenton Water Treatment Plant was knocked offline due to historic flooding.
Bill Greenblatt | UPI
MSD's flooded treatment plant in Fenton on Dec. 31, 2015.

Warnings to avoid contact with flood water. An executive order temporarily waiving Missouri Department of Natural Resources regulations. Periodic updates on the millions of gallons of raw sewage flowing into the Meramec River due to shuttered wastewater treatment plants.

St. Louis Public Radio referenced these announcements as they happened in the course of reporting on the human and economic toll wrought by the record-high waters. But what impact, if any, do those warnings and waivers have on the environment?

Environmental waiver

For the next two weeks the Missouri Department of Natural Resources is waiving a 25-year ban on dumping large appliances like refrigerators and air conditioners at landfills. Landfills will also be able to accept yard waste until at least Jan. 22.

Missouri Gov. Jay Nixon Wednesday paved the way for the waiver Wednesday, when he ordered the department to temporarily ease environmental regulations to help with the flood cleanup.

“The faster we can remove debris, the faster these communities can get back on their feet,” Nixon said Wednesday when he announced the order.

Many large appliances, including air conditioners and freezers, contain refrigerant gases such as Freon, which can damage the ozone if they leak into the environment.

In her notice announcing the waiver, Missouri Department of Natural Resources Director Sara Parker Pauley said “cities and counties should coordinate collection” of the appliances so the refrigerant gases “can be legally recovered.”

According to U.S. Environmental Protection Agency spokesman Chris Whitley, the EPA has been tasked by FEMA to coordinate that collection and collect the refrigerant gases in the St. Louis region.

“It is highly doubtful no major appliances will enter Missouri’s landfills as part of the recovery but certainly part of our mission is to capture just as many of them as we can and recycle them after we have these gases removed,” said Whitley.

Sewage in rivers

According to environmental scientist Randy Miles it is common for fecal matter and other sewage to enter rivers at higher concentrations during flooding because wastewater treatment plants often get overrun, reducing the amount of treatment sewage running through the plant receives before it enters the river.

“Many times wastewater may not be as well-treated as under normal conditions,” said Miles, who is associate professor emeritus at the University of Missouri. “And many times we may not know where it is going because of the topping over of wastewater systems.”

MSD staff placed sandbags at Grand Glaize Wastewater Treatment Plant in Valley Park all day Tuesday and Wednesday to keep the flood waters out and keep the plant in operation.
Credit Provided by the Metropolitan Sewer District
MSD staff placed sandbags at Grand Glaize Wastewater Treatment Plant in Valley Park in an attempt to keep the plant open, but floodwaters eventually overwhelmed the plant.

  Because wastewater often isn’t fully treated during a flood, the risk of E. coli or other parasites increases if someone is exposed to flood water, Miles said, adding that the high volume and quickly moving water caused by flooding also helps to dilute the concentration of the sewage.

“There is a problem with the water quality there, however because there’s a larger volume (of water) and it’s faster moving, the (untreated wastewater) gets dispersed and diluted out,” Miles said.

Because municipal water systems test water quality, Miles said the greatest danger in drinking water after a flood comes from personal water sources, such as wells. He recommends that well owners hire a professional to test their wells before using them after a flood.

Miles said the dilution should quickly reduce the risk of exposure to pathogens even when millions of gallons of wastewater are entering a river without any treatment at all, like in the case of the Metropolitan St.  Louis Sewer District’s shuttered treatment plants along the Meramec River.

“I would have a concern as the flooding recedes and the water slows down if you have pools or pockets of this poorly treated wastewater that seems to coalesce in an area,” Miles said of the situation at the MSD plants. “I’ve seen this at various flooding events over the last 25 or 30 years. The water slows down it gets stagnant even without the wastewater because of the organic material in there naturally.”

MSD treatment plants

Echoing Miles’ comments about the dilution of pollutants during flooding, MSD’s Jay Hoskins said the impact of the untreated wastewater entering the Meramec River at Valley Park and Fenton is lessened because of the river’s swiftly moving current.

“The flow in the Meramec River is so high right now because of the flood waters that the total flow coming from our plants represents less than one percent of the total flow in the river,” said Hoskins, who focuses on water quality for MSD.

“In the long-term, and when I say long-term I’m thinking about years, MSD’s treatment plants are going to return to normal operation and the Meramec River should recover from whatever impact raw sewage had on it,” Hoskins said. “The Meramec River in the short-term will have regional water quality issues but we’re working on it and we’re trying to work as quickly as we can to fix it.”

Hoskins said the impact of the flood was also lessened because it took place during the winter.

“There’s never a good time to have a flood, but one of the things we’re always concerned about with sewage going into the river is oxygen levels,” Hoskins said. “Colder water has a higher potential for dissolved oxygen. So the colder temperatures should help the aquatic life.”

Even during the height of the flooding, Missouri American Water was able to treat the Meramec River sufficiently to supply its customers without a boil order.

“When flood waters rise water quality decreases dramatically, so we’d already adjusted our treatment process when the MSD plants shut down,” said Missouri American Water spokeswoman Ann Dettmer.

Environmental impact for fish

According to Kevin Meneau of the Missouri Department of Conservation, flooding can actually boost fish populations in rivers.

“They evolved in stream systems over the eons and many of the fish that larger fish like to eat will expand their populations in flood plains during floods,” Meneau said. “In the quieter backwaters they can be relatively safe and find plenty of food.”

Meneau said sewage in rivers during floods also generally isn’t a problem for fish.

“Organic-type pollutants aren’t much of a problem for fish unless it’s during summer and there isn’t a lot of flow and you get low oxygen conditions,” Meneau said.

Follow Camille Phillips on Twitter: @cmpcamille.