The recent near-overflow of the Thornton reservoir in Chicago has brought attention to the city's Deep Tunnel flood-control system, a massive infrastructure project that has been in the works for 50 years. This system, which includes over 100 miles of underground tunnels and three reservoirs, is designed to manage stormwater and sewage during heavy storms. However, the Thornton reservoir's near-capacity situation highlights the ongoing challenges in flood control, especially with the increasing intensity of thunderstorms due to climate change.
The Thornton reservoir, located in South Holland, is part of the Deep Tunnel program and holds billions of gallons of stormwater and sewage. It was nearly full after a rainy July Fourth weekend, preceded by a wet spring and early summer. The reservoir is now draining, but the process will take at least a month, according to Patrick Thomas, a spokesman for the Metropolitan Water Reclamation District. This district is responsible for treating sewage and managing stormwater, and they are pumping the water to sewage-treatment plants like the Stickney plant in Cicero, which can process more than three times the wastewater of the Calumet plant in a single day.
The Thornton reservoir's capacity is 83% as of Saturday, and it is being drained to prevent overflow. The McCook reservoir, another part of the Deep Tunnel system, is also draining to the Stickney plant. The Majewski reservoir, the third reservoir in the program, is reportedly empty, holding less than 3% of the total capacity of the Deep Tunnel system.
The Deep Tunnel project, officially known as the Tunnel and Reservoir Plan, began construction 50 years ago and is still expanding. The district acknowledges the need for further mitigation measures as extreme thunderstorms become more frequent and intense due to climate change. However, Kari Steele, president of the water reclamation district's elected board, emphasizes that there is no single solution to flooding.
One issue that has arisen is the putrid smell from the sewage in the Thornton reservoir, which has caused complaints from neighbors. The district is spending $5 million on technology to reduce odors, including carbon filters and a mist system, in addition to existing odor monitors. This highlights the ongoing challenges in managing the infrastructure and the impact on the surrounding community.
In conclusion, the Thornton reservoir's near-overflow event serves as a reminder of the complex and ongoing efforts required to manage stormwater and sewage in Chicago. While the Deep Tunnel system is a crucial part of the city's flood-control infrastructure, it must continue to adapt to the changing climate and its impacts on extreme weather events.
