The Iowa Department of Natural Resources hosted a public meeting and hearing Wednesday on a wastewater permit amendment requested by Interstate Power and Light. The subsidiary of Alliant Energy operates the coal-powered Ottumwa Generating Station.
Wendy Hieb, a DNR coordinator for industrial waste permitting, said the amendment updates wastewater flow data following a new discharge site added by the plant last year.
But most of the public comments have focused on leachate, a contaminated liquid created when rainfall percolates through a landfill or stored waste. Environmental groups claim four of the pollutants in leachate from the Ottumwa coal plant have exceeded federal groundwater protection standards, including cobalt and manganese.
Hieb emphasized the power plant’s current permit and amendment do not allow leachate to discharge into waterbodies protected under the Clean Water Act.
“[Leachate discharge] was mistakenly included in a supporting document that was posted on the web with the permit amendment at renewal last year,” Hieb said.
The Ottumwa Generating Station sends its coal waste to the Ottumwa-Midland Landfill, which is a separate issue from the permit at hand, according to Brian Rath, an environmental engineer with the solid waste and contaminated site section of DNR.
“But there's been a number of comments that have pulled those together, and so that's why we're talking about the landfill,” Rath said.
Like other modern landfills, Rath said a plastic liner and compacted clay layer at the base of the Ottumwa-Midland Landfill separate leachate from groundwater.
A pipe above the plastic liner collects leachate and moves it into a plastic-lined storage lagoon, while a pipe below the landfill moves groundwater to the surface. Rath emphasized these are two separate systems, and the groundwater discharge is monitored for contaminants.
He added that the bedrock below this region of the state has coal and shale deposits with naturally occurring arsenic, along with cobalt and magnesium. Rainfall with low pH can cause these heavy metals and contaminates to dissolve in groundwater.
To determine whether the metals are naturally occurring or from the landfill, DNR requires monitoring wells to compare the levels in the leachate and groundwater, Rath said.
“If the groundwater underground is determined to be impacted, it will be pumped in and treated just as leachate and put in that lagoon the same way,” Rath said.
The monitoring indicates no leachate has passed through the groundwater system, Rath said, indicating that it’s moving into the lagoon.
From there, Hieb said the leachate is used in the air emissions control system at the Ottumwa Generating Station or trucked to the municipal wastewater treatment plant in Ottumwa, which has its own wastewater permit.
Public concerns for leachate
The Sierra Club, Iowa Environmental Council and Environmental Law and Policy Center have challenged Interstate Power and Light’s permit request.
Josh Mandelbaum, an attorney with the Environmental Law and Policy Center, said moving leachate to Ottumwa’s Water Pollution Control Facility shifts responsibility.
“It shifts the risk to the city and to its residents. This is Alliant’s pollution, and this permit is the opportunity to provide accountability and compliance with the rule,” Mandelbaum said.
The three environmental groups argue the draft permit allows Alliant Energy to bypass the federal effluent limitation guidelines from 2024.
“The new rule is clear,” said Raihan Rashidi, energy policy manager with the Iowa Environmental Council. “Discharges of managed leachate must be eliminated entirely, and unmanaged leachate discharges must meet strict numeric limits for arsenic and mercury.”
For managed leachate, plants must move to zero discharge no later than Dec. 31, 2029. Leachate sent to municipal treatment plants must meet pre-treatment standards by May 9, 2027.
“In other words, this permit cannot delay action, and communities and surrounding ecosystems deserve protection now,” Rashidi said. “This matters because Ottumwa has a history of pollution.”
Dee Dorsett, a nurse practitioner in Ottumwa, said she tests patients for toxins and heavy metals.
“They're very high,” Dorsett said. “Some people are in the severe range. So, all I can do is report that to you and ask that you would look further … are we really looking at the people, the impact?”
The U.S. Environmental Protection Agency announced plans in March to reconsider the effluent limitation guidelines from 2024, saying the action “advances the goals of President Trump’s Unleashing American Energy Executive Order.”
The DNR expects to post its final permit amendment and response to public comments online before October.
