Most people never think about where their wastewater goes once it leaves the house. The folks who build and run treatment plants think about it every day, and in Skokie, they're about to spend the next four years building something big.
On Oct. 8, the Metropolitan Water Reclamation District of Greater Chicago broke ground on Battery E, a nearly $400 million addition at its Terrence J. O'Brien Water Reclamation Plant. According to the MWRD's announcement, it is one of the largest investments the district has made in a single project in its 137-year history.
The plant opened in 1929 and today helps protect water quality for more than 1.3 million people. It returns treated water to the North Shore Channel, which connects to the North Branch of the Chicago River. The MWRD says the plant now faces new challenges, including changing flows and weather patterns, emerging pollutants and excessive nutrients in wastewater.
"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," said MWRD President Kari K. Steele.
What's being built
Battery E will include new aeration tanks, final settling tanks, ancillary structures and supporting equipment. It will also use enhanced biological phosphorus removal, a treatment process that relies on naturally occurring microorganisms to pull phosphorus out of wastewater before it goes back into the channel.
The reason is regulation. Too much phosphorus in waterways can feed algae, lower oxygen levels and harm aquatic life. The MWRD says Battery E will help it meet new phosphorus discharge limits that take effect in 2027 and get stricter 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."
Steele said the project is about more than new 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," she said.
A long run of work at O'Brien
Battery E is one piece of a bigger, multi-year plan. The MWRD started process improvements at O'Brien in 2023 with work on Battery D, including a sidestream fermentation zone and other infrastructure for biological phosphorus removal. That work is expected to be finished in 2026.
Adding Battery E gives the plant the capacity to take its older batteries offline for major rehab. Three of the plant's four existing batteries are approaching 100 years old. Starting in 2031, the MWRD plans to upgrade Batteries A, B and C in phases, bringing them up to modern standards and adding biological phosphorus removal.
The district is also putting in a chemical backup system, awarded in 2025, to help meet the new phosphorus limits.
The groundbreaking drew MWRD commissioners along with Evanston Mayor Daniel Biss, U.S. EPA Region 5 Administrator Anne Vogel, State Rep. Kevin Olickal, Skokie Mayor Ann Tennes and Michels Construction Vice President Josh Senk. The MWRD's announcement does not say what role Michels has on the project.
The MWRD expects Battery E to take about four years to build. The district says it will create opportunities for skilled workers throughout the project, and it named the trades: electricians, ironworkers, laborers, millwrights, operating engineers, pipefitters, plumbers, steel erectors and truck drivers.
For a sense of scale, think of what goes into a new treatment battery. Aeration and settling tanks mean a lot of excavation and a lot of concrete, then the piping, pumps, blowers, valves and controls that make a biological process work. Every one of those pieces has to tie into a plant that keeps running the whole time, treating wastewater every day of construction.
Why it matters for Contractors
A nearly $400 million, four-year project is a long, steady run of work for the heavy civil and industrial trades in the north suburbs. The MWRD's own list says it all: electricians, ironworkers, laborers, millwrights, operating engineers, pipefitters, plumbers, steel erectors and truck drivers. Concrete, excavation, process piping and electrical and controls subs should pay especially close attention. Building next to a live, century-old plant takes careful sequencing, so firms with water and wastewater experience have an edge. And Battery E is not the end of the line. With Batteries A, B and C slated for phased upgrades starting in 2031, O'Brien should keep contractors busy well into the next decade.