MWRD issues update on Tunnel and Reservoir Plan
In 1972, the Metropolitan Water Reclamation District of Greater Chicago (MWRD) began work on one of the largest public works projects in U.S. history. Known as the Tunnel and Reservoir Plan (TARP) and commonly referred to as the “Deep Tunnel” project, TARP is a system of deep, large diameter tunnels and vast reservoirs designed to reduce flooding, improve water quality in Chicago area waterways and protect Lake Michigan from pollution caused by sewer overflows.
TARP is complete and fully operational except for the McCook Reservoir Stage 2 (McCook Stage 2). Located in Bedford Park between the Chicago Sanitary and Ship Canal and Des Plaines River, the first stage of McCook Reservoir was completed in 2017 and can hold 3.5 billion gallons of capacity. The second stage currently being excavated will add another 6.5 billion gallons of storage for a total of 10 billion gallons, making it the largest reservoir of its kind. McCook Reservoir serves 3.1 million people living in Chicago and 36 suburban municipalities.
McCook Stage 2 is an active stone quarry that is being excavated by Vulcan Materials Company (Vulcan). Vulcan mines and crushes stone and sells it from its McCook Quarry, and these sales are dependent upon the demand for such material in the construction marketplace.
The mining of McCook Stage 2 was originally projected to be completed by Dec. 31, 2028, with an additional year to make McCook Stage 2 operational by Dec. 31, 2029. This schedule was set by a federal consent decree entered on Jan. 6, 2014, and was based on historical mining rates at the McCook Quarry.
To date, the MWRD has met or exceeded all consent decree requirements; however, due to a slowdown in the demand for stone in the Chicago area, the mining will take longer than expected, resulting in a delay in the completion of McCook Stage 2. Such delays were anticipated under the consent decree as it was recognized that the long-term market for stone can be volatile and is outside of the MWRD’s control. As a result, the current estimate for McCook Stage 2 going online is now Dec. 31, 2032.
In the meantime, McCook Stage 1 continues to operate as engineered and has already captured approximately 130 billion gallons of stormwater and wastewater that otherwise would have polluted waterways or flooded basements.
The MWRD recognizes that climate change is bringing more intense storms. We are committed to partnering with local municipalities to improve their local conveyance systems and implement green infrastructure and other stormwater management projects to complement the TARP system.