Water quality standards pose challenge for treatment plant
MARSHALL – The agenda at Tuesday night’s meeting of the Marshall City Council included several informational presentations. However, not all the news presented to council members was good. In one item of business, Marshall wastewater treatment plant superintendent Bob VanMoer and Marshall City Engineer Glenn Olson said the city faces big challenges related to water-quality standards for the Redwood River.
VanMoer gave council members an update on the process to renew the wastewater plant’s permit to discharge water into the Redwood River. The Minnesota Pollution Control Agency has proposed new, lower limits for chemicals like chlorides, copper and phosphorus in wastewater that won’t be easy for the plant to meet.
“No matter what we do, it’s going to cost us a lot of money,” VanMoer said. “There’s no fast or easy solution.”
VanMoer and Olson said the city will be working with the MPCA and engineering consultants Bolton & Menk to try and work out solutions.
New limits for chlorides, copper and phosphorus in discharged water were proposed for the Marshall wastewater plant in March. In particular, VanMoer said, the limit on chlorides in discharged water “is going to be a hard one.” Marshall wastewater carries a lot of chlorides, primarily from the salt used in residential and commercial water softeners.
Currently, the limit for chlorides in water discharged into the river is 700 parts per million, VanMoer said. The proposed new limit is 261 parts per million.
It won’t be simple to bring down the salt levels in discharged water, VanMoer said.
“Apparently, RO (reverse osmosis) systems are the only way we can remove chlorides,” he said. But the equipment and maintenance for a reverse osmosis system would be expensive. Another possible option could be for Marshall Municipal Utilities to soften raw water at the city water plant.
VanMoer said the proposed new limits for substances like copper and phosphorus would also be expensive. For example, treating water with phosphates helps cut down on the amount of copper from pipes that flakes off into wastewater, but then the phosphates would have to be removed before the water could be discharged into the river. Meanwhile, cutting down on phosphorus in discharged water to comply with the new, lower limits would cost Marshall about $300,000 a year, VanMoer said. The cost to comply with the current phosphorus limit is about $40,000 a year.
Olson and VanMoer said Marshall isn’t alone in struggling with more stringent water-quality standards. The challenge is statewide For example, the city of St. Peter installed a costly reverse osmosis system at its water treatment plant in recent years, they said.
VanMoer said the city will be asking the MPCA for more time to do water testing and come up with possible solutions to the compliance problem. Hopefully the extension would give time to pinpoint the source of copper in Marshall wastewater and to explore doing additional water softening at the MMU water treatment facility.
Council members also heard an update on Avera Marshall Regional Medical Center from Avera Marshall CEO and President Mary Maertens. Maertens said Avera Marshall continued to grow in 2013, with the addition of 13 new physicians and new clinic locations opened in Redwood Falls and Ivanhoe, as well as new programs like palliative care. The number of local clinic visits had also gone up compared to 2012, she said.
Raising funds and breaking ground for the new cancer institute were two big achievements for Avera Marshall in the past year, Maertens said. Construction of the institute is under way, and Maertens said the hospital was in the process of commissioning a linear accelerator, the machine that will provide radiation therapy treatments for cancer patients.