MWRD breaks ground on $400 million Battery E Project at O’Brien Water Reclamation Plant

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Representing one of the largest investments that the Metropolitan Water Reclamation District of Greater Chicago (MWRD) has made for a single project in its 137-year history, the MWRD broke ground Oct. 8 on the nearly $400 million construction of a new battery of infrastructure at its Terrence J. O'Brien Water Reclamation Plant (OWRP). The ceremony marked a major milestone in the modernization of the nearly century-old facility in Skokie that works each day to protect water quality for over 1.3 million people.

The scheduled four-year project of Battery E will include a new aeration tanks, final settling tanks, ancillary structures and supporting equipment, along with an advanced biological process designed to significantly reduce phosphorus in treated wastewater before it is returned to the North Shore Channel.

"As the O'Brien Water Reclamation Plant approaches 100 years of service, we are making an investment that will help ensure this facility is prepared for the decades ahead of protecting public health and our waterways," MWRD President Kari K. Steele said. "Battery E is about more than meeting new environmental standards. It provides the capacity and flexibility we need to modernize this facility, rehabilitate its aging infrastructure and incorporate new technology that will improve water quality for generations to come."

Since opening in 1929, O'Brien has treated wastewater from surrounding communities before returning treated water to the North Shore Channel. Today, the facility faces new challenges, including changing flows and weather patterns, emerging pollutants and excessive nutrients in wastewater.

Improving phosphorus removal

While phosphorus is an essential nutrient, excessive amounts entering waterways can contribute to excessive algae growth, reduce oxygen levels and harm aquatic ecosystems. Because the North Shore Channel connects to the North Branch of the Chicago River and ultimately the larger regional waterway system, improving phosphorus removal at O'Brien contributes to water quality improvements beyond the plant itself.

Battery E will incorporate enhanced biological phosphorus removal, a treatment process that uses naturally occurring microorganisms to remove phosphorus from wastewater. The project will help the MWRD meet new phosphorus discharge limits taking effect in 2027, with additional requirements becoming more stringent in 2030.

"This isn't just some big piece of equipment," said MWRD commissioner Cam Davis. "It's a big investment in the health of our waterways, jobs, and helping our downstream neighbors."

The MWRD began process improvements at O'Brien in 2023 with work on Battery D, including installation of a sidestream fermentation zone and ancillary infrastructure to support enhanced biological phosphorus removal. That work is expected to be completed in 2026.

Adding Battery E will provide the capacity needed to implement biological phosphorus removal while allowing the MWRD to take existing batteries offline for extensive rehabilitation. Three of the plant's four existing batteries are approaching 100 years old. Beginning in 2031, the MWRD plans to upgrade Batteries A, B and C in phases, bringing the aging infrastructure up to modern standards and incorporating biological phosphorus removal capabilities.

The MWRD is also implementing a chemical backup system, awarded in 2025, to provide additional support for meeting the new phosphorus discharge requirements.

Investing in infrastructure and people

Battery E is anticipated to take approximately four years to construct and will create opportunities for skilled workers throughout the project, including electricians, ironworkers, laborers, millwrights, operating engineers, pipefitters, plumbers, steel erectors and truck drivers.

The groundbreaking was attended by MWRD commissioners and representatives from federal, state and local government, including Evanston Mayor Daniel Biss, U.S. EPA Region 5 Administrator Anne Vogel, Illinois State Rep. Kevin Olickal, Skokie Mayor Ann Tennes and Michels Construction Vice President Josh Senk.