|MWRD from DNAi*/nfo|
The Calumet TARP Pumping Station is the lowest point of the TARP System and lowest point in Chicago.
TARP stands for "Tunnel and Reservoir Plan," which according to MWRD was adopted in 1972 to "comply with federal and state water quality standards in the 375 square miles combined sewer area consisting of Chicago and 51 suburbs." It is more commonly known as the Deep Tunnel project. [DNAinfo]My wife and I toured the Mainstream Pumping Station before it went online. We were also able to walk into the tunnel that feeds it. After it went online, I'm sure they keep the tunnel part sealed off since it is a BIG sewer. That station was also was below 300' because the tunnels are deep so that they travel through solid sedimentary rock their whole distance. It is easier to use a Tunnel Boring Machine in rock rather than in sand or clay. And sedimentary rock is relatively soft compared to igneous or metamorphic rock.