One of the biggest construction projects in the nation is right under your feet, but we don’t hear much about it these days.
People who have lived in Chicago for a while know about the TARP—Tunnel And Reservoir Plan, more commonly known as The Deep Tunnel. For a while it was a rite of passage for local TV reporters to do a report from inside the gaping maw of one slice of tunnel or another. But lately, they’ve lost interest in it.
For newcomers, and those with shortened memories, the Deep Tunnel is a massive civil engineering project that involves slurping unexpected excesses of rain water and sewage into an underground network of giant tunnels and pushing it into reservoirs to be stored until they can be processed into clean, safe water and set free in the Calumet River. The nasty stuff extracted from the clean water becomes a type of fertilizer that has been used on farm fields and parks around the region.
The project started in the mid-1970’s, and isn’t expected to be completed until around 2029. Recently, the Metropolitan Water Reclamation District of Greater Chicago set off the final explosion at the future Thornton Reservoir, which will be able to hold 7.9 billion gallons of runoff.
Eight billion gallons of water seems like a lot, but it’s not really, when you’re battling Mother Nature. So the tunnels, themselves, can hold 2.3 billion gallons, the future McCook Reservoir will hold another 10 billion gallons, and an additional 350 million gallons can be stashed at the Majewski Reservoir out near O’Hare airport.
Moving that amount of water around generates some pretty interesting numbers from a physics standpoint, which is why you may have seen giant manholes scattered around Chicagoland. There’s one on South Jefferson Street, just south of Presidential Towers in the West Loop. Nearby is a sign that says something to the effect of “If you see a geyser of water and poop screaming 100 feet into the air from this manhole, please take what’s left of this sign to a telephone and let someone know about it.”
But enough about poop geysers. Here’s the press release about the explosion late last month:
‘Last Blast’ signals end of major excavation at Thornton Reservoir
Over 152 billion pounds of 400 million year old dolomite limestone has been blasted and removed from the Thornton Composite Reservoir since 1998, and the very last blast took place today.
Located along interstate 80 in southern Cook County, this important component of the Metropolitan Water Reclamation District of Greater Chicago’s (MWRD’s) Tunnel and Reservoir Plan will be operational by December 2015.
The MWRD executed an agreement with the owner of the Thornton quarry 15 years ago to mine the north lobe of the quarry for use as a component of the MWRD’s Tunnel and Reservoir Plan (TARP).
“Part of the MWRD’s mission is to protect the Chicago area waterways from raw sewage while protecting homes and businesses from flood damage, and this project will be doing both,” said MWRD Commissioner Michael Alvarez, chairman of the MWRD’s stormwater management committee. “The Thornton Reservoir will greatly benefit communities throughout the southside of Chicago and south suburbs of Cook County once it’s completed.”
The second phase of TARP involves the construction of three reservoirs which, when completed in 2029, will provide more than 18 billion gallons of storage capacity. Besides the Thornton Reservoir, the McCook Reservoir is also under construction. Stage 1 of McCook Reservoir is scheduled for completion by Dec. 31, 2017, and will add 3.5 billion gallons of storage capacity. Stage 2 of McCook Reservoir will add 6.5 billion gallons of storage capacity. The Majewski Reservoir was completed in 1998 and provides 350 million gallons of CSO storage. Since it went online, the Majewski Reservoir has provided over $250 million in flood reduction benefits to its service area in Arlington Heights, Des Plaines, and Mount Prospect.
The first phase of TARP was completed in 2006 and consists of 109.4 miles of deep, large diameter tunnels that have a total storage capacity of 2.3 billion gallons; the tunnels have provided millions of dollars in flood protection benefits. TARP’s large tunnels and reservoirs are designed to reduce the amount of combined sewer overflows (CSOs) and hold the polluted water until it can be fully treated at MWRD water reclamation plants. Since the TARP tunnels went online, the average annual number of days with CSOs has reduced to 50 from 100.
TARP was the first system of its kind to address pollution and flooding and is emulated by cities around the world, including London, Singapore, and Vienna. While these projects are large and costly, TARP has provided solid evidence that such a system is effective and valuable infrastructure.
The Thornton Reservoir is set to come online at the same time as disinfection facilities at the MWRD’s Calumet Water Reclamation Plant in Chicago, which also serves the southern area of the county. Working in tandem, the combination will maximize water quality while minimizing flooding.
Additional information about TARP can be found at www.mwrd.org/irj/portal/anonymous/tarp.