Contact(s): Jason Knutson, DNR Wastewater Section Chief, (608) 267-7894
September 3, 2019 at 1:37:08 pm
OAK CREEK, Wis. - The Wisconsin Department of Natural Resources today will submit the proposed wastewater discharge permit variances for the We Energies Oak Creek Power Plant and Elm Road Generating Station to the U.S. Environmental Protection Agency as part of its final review of water quality standard variances for arsenic and mercury.
The variance terms and conditions apply solely to Outfall 007, which discharges treated process wastewater from the Oak Creek Power Plant and accounts for approximately 0.2 percent of the total wastewater discharged from the facility.
Following review of extensive public comments received during the public hearing and comment period held earlier this year, the DNR made two significant changes to the terms related to the variances in the proposed permit.
"Public participation is essential to the permitting process, so we appreciate that so many people shared their thoughts. After considering more than 600 comments we made some notable changes to the proposed permit and variance terms and conditions," said Jason Knutson, DNR wastewater section chief.
One change involves moving a compliance date forward by two years for ending the discharge of bottom ash transport water. Bottom ash transport water is used to flush coal ash out of a power plant's boiler and has historically been discharged to waters of the state after treatment. With this change, two units at the Oak Creek Power Plant must cease discharge of bottom ash transport water by December 31, 2021, a full two years earlier than the previously proposed date of December 31, 2023. We Energies may be allowed up to six additional months if approval for a capital construction project is required by the Public Service Commission of Wisconsin. All other units at the facility are already in compliance with this requirement.
Another change resulting from public input applies specifically to the mercury limitation on Outfall 007. The new permit reduces the interim mercury discharge limitation from the proposed value of 4.1 parts per trillion to 3.7, setting the first-ever cap on mercury from this outfall. The cap will serve as a backstop to prevent an increase in mercury loading from Outfall 007 until it is brought into compliance with the monthly average wildlife water quality criterion of 1.3 parts per trillion.
Relying on treatment alone to achieve 1.3 parts per trillion of mercury was determined to be technologically infeasible, so the mercury variance requirements in the permit require We Energies to implement source reduction measures to bring the outfall into compliance with the standard. Short-term and long-term fuel source analyses are examples of two such measures that were added in response to public comments.
A variance to water quality standards for arsenic is also included at Outfall 007. This outfall currently discharges arsenic at concentrations lower than ambient lake levels. Water withdrawn from Lake Michigan has an average concentration of 0.92 parts per trillion, while Outfall 007 discharges at an average concentration of 0.43 parts per trillion. Despite that, source reduction measures for arsenic are also included in the proposed permit.
Despite the variances, data indicates that, via its outfalls used for normal operations, the facility withdraws water from Lake Michigan with higher levels of mercury and arsenic concentration than it returns to the lake, and the permit requires strong action to make further progress to reduce arsenic and mercury,
Separate from this Oak Creek Power Plant /Elm Road Generating Station permit reissuance process, the DNR will also investigate potential sources of elevated metals levels reported in surface waters and ditches near the facility. Local citizen groups recently submitted sampling data for metals to the department.
Multiple programs at the department continue to review the data and will investigate to identify the source. The Oak Creek Power Plant/Elm Road Generating Station does not discharge wastewater to these surface waters under its WPDES permit, and elevated metals concentrations have not been linked to the facility.
Before the permit can become effective, the EPA has 60 days to review the variances and either approve or deny them. If approved, reissuance of the permit is expected and will take effect this fall. The new permit will enact several positive steps toward protection of water quality including more stringent phosphorus limitations, first-time mercury and arsenic limitations and source reduction requirements, and important coal ash handling requirements.