TUNNEL CHICAGO FULL

Within the combined sewer areas there were over 450 outfalls that released polluted combined sewer overflows (CSOs) into the waterways. During rain events, the sewer system and treatment plants could not accommodate the additional flow, and combined sewage would overflow to the local waterways over 100 days per year. The persistence of the problem was due mainly to the fact that Chicago and many of the older suburbs are served by combined sewers, in which both sanitary and storm flow are conveyed through the same pipes.Īs the area developed and more land was paved, the amount of rain water entering the sewer system dramatically increased. Combined Sewer Overflowsĭespite the reversal of the Chicago River, and even the construction of the largest wastewater treatment plant in the world, contaminants continued to accumulate in the rivers, canals and Lake Michigan.

TUNNEL CHICAGO FULL

All captured combined sewer flow pumped to the WRP receives full secondary treatment prior to being discharged to the waterway pursuant to the National Pollutant Discharge Elimination System permits. After a storm event, pumping stations dewater the tunnel systems as Water Reclamation Plant (WRP) capacity becomes available, making the tunnel and reservoir capacity available for the next storm event. The separate tunnel systems and their service areas are shown on Figure 1. Phase I of TARP, intended primarily for pollution control, is made up of four distinct tunnel systems: Mainstream, Des Plaines, Calumet and Upper Des Plaines. TARP’s main goals are to protect Lake Michigan-the region’s drinking water supply-from raw sewage pollution improve water quality of area rivers and streams and provide an outlet for floodwaters to reduce street and basement sewage backup flooding. The MWRD adopted TARP in 1972 as the Chicago area’s plan to cost-effectively comply with Federal and State water quality standards in the 375 square miles combined sewer area consisting of Chicago and 51 suburbs. One of the largest civil engineering projects on earth, TARP has been extremely effective and widely emulated since the initial tunnels went online in 1981.Construction on the McCook Reservoir Stage 2 is scheduled for completion in 2029. That is more than 4,666 gallons for each person in its service area. The system will have a combined sewage capacity of 17.5 billion gallons when Stage 2 of McCook Reservoir is completed. The four TARP tunnel systems capture and convey combined sewage and stormwater to the Majewski Reservoir, Thornton Composite Reservoir and McCook Reservoir (Stage I). TARP includes four tunnel systems totaling 109 miles of tunnels, 8 to 33 feet in diameter and 150 to 300 feet underground. This stored water is pumped from TARP to water reclamation plants (WRPs) to be cleaned before being released to waterways. TARP captures and stores combined stormwater and sewage that would otherwise overflow from sewers into waterways in rainy weather. TARP, also known as “Deep Tunnel,” 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 one of the country’s largest public works projects for pollution and flood control. Unmatched in size throughout the world, the Tunnel and Reservoir Plan (TARP) works to protect and improve area waterways and reduce flooding throughout Cook County.

Tunnel chicago