- Building Futures is about identifying projects, ideas and innovation that will create lasting positive change within the building community and the communities it serves.
- This BF reviews the purpose and construction of the Deep tunnel and associated reservoirs, that were built over decades. At least for this system has resolved many of the Chicago metro area flooding problems.
- My professional career has primarily centered around building projects. Almost every project has assumed that there was a power, storm, sewer, telecommunications, transportation, internet “grid” to plug into. For too many decades these systems have been neglected, poorly maintained and not replaced when they were already many years, if not decades past their designed useful life. Driving through Chicago over the past few years has at times been both frustrating (bumper to bumper traffic, except during the first year or two of Covid) and exciting, as major work can be seen on the highways, ramps, El and Metra rails and stations, bridges and data centers…etc. We are still in the early years of reconceiving and rebuilding the core infrastructures that make-up the built environment in which we live, work and play. Building Futures (BF) will initially be focused on this core infrastructure and then over time will come back to the core innovations that will drive the future of building.
The Tunnel and Reservoir Plan (or TARP) was developed to provide flooding relief throughout the entire Chicago area. Although I had a conceptual understanding of the TARP system and have been aware of it since my high school years. On my way to school, I passed a portion of the tunnel construction work, adjacent to the sanitary canal along McCormick Blvd in Skokie. They were constructing shafts that would either provide venting for the deep tunnel or physical access for repairs and maintenance.
In doing the basic research for this Building Future (BF) post, I really began to appreciate the magnitude of concept, design and construction required to execute the TARP system. The original Chicago system was built as a combined sewer and storm system (CSSS). So, all the water from sinks, toilets and storm run-off were combined in the CSSS. The original CSSS was sloped directly to the nearest waterway (think the Chicago River and Lake Michigan) and released. During the 20th century the Metropolitan Water Reclamation District (MWRD) built interceptor sewers to which captured the waste and water in all the old sewers and re-directed it to a series of wastewater treatment plants (there are now a total of 7), where the water was treated and then re-released into the waterways. But, as the population expanded and storms became more severe, the system was overwhelmed flooding basements, streets and land on a regular basis. To reduce the damage, the MWRD would open various gates and allow untreated wastewater to flow directly into the waterways polluting the region’s primary waterways, including Lake Michigan and the surrounding rivers. In the 1960’s the system was overflowing directly into the waterways more than 100 days per year.
The planning for TARP started in 1967, approval was received in 1972. Construction began in 1975 and continues to this day. Final reservoir construction is currently scheduled for 2029. A total design construction period of 62 years, and a projected total cost that ranges between $3-$4 billion. If successful, it will allow the Chicago Metro area to thrive as it continues to grow and experience more and more severe storms.
Next time it storms, check out how the levels of the McCook reservoir rise and fall during and after the storm. This capability may be the primary reason why your home, business or street does not currently flood.
Photo 1: Graphic shows the TARP timetable
Photo 2: Graphic shows original combined sewers flowing to waterways & larger interceptor sewers that take storm and sewer water to the treatment plants. When Chicago had large storms, these systems would be overwhelmed, and valves would be opened allowing the untreated water to be released into the waterways.
Photo 3: Graphic shows the TARP connection to the interceptor sewers. After this was completed the excess water beyond the sewer and treatment plant capacity, created during large storms, is redirected to the Deep tunnels and reservoirs. When the storm subsides, this water is then re-pumped back to the treatment plants, treated and released back into the waterways.
Photo 4: Graphic shows the water from the interceptor sewers into the deep tunnel system and into the reservoirs
Photo 5: Graphic shows the four tunnel sections that together comprise 110 miles of tunnels, and the three reservoirs they flow into. The tunnels are located between 150’ to 300’ below grade. Stage two of the McCook reservoir is currently under construction and should be completed by 2029 and will bring the total reservoir storage to ~18.25 billion gallons. The tunnels provide an additional ~2.3 billion gallons of storage.