This paper presents the final design of a conveyance and storage tunnel that will be built about 230 ft below ground surface for the city of Indianapolis. The TBM tunnel will run nearly 8 miles in limestone with a finished inside diameter of 18 ft. It provides a minimum storage volume of 54 million gallons of untreated excess wet weather overflow. A pump station is planned for dewatering of the tunnel and discharging the CSO flow to a surface advanced wastewater treatment facility with a capacity of 150 million gallons per day. The pumps will be located within a 70 ft wide and 80 ft high deep mined rock cavern. The project also has several deep shafts including the TBM launch and retrieval shafts, the pump room cavern access and discharge shafts and the grit and screening wet shaft with an inside diameter ranging from 25 to 44 ft. For these circular shafts slurry wall technique will be used in the overburden soil, and drill and blast excavation method in the shale and limestone.
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