City of Springfield (Illinois) Carpenter Street underpass pump station

Project Summary

Hanson designed the Carpenter Street underpass, between Ninth and 11th streets in Springfield, Illinois, as part of the first stage of the Springfield Rail Improvements Project, which is part of the Illinois High-Speed Rail Chicago to St. Louis program. The underpass provides improved access to the community’s major medical facilities and reduces delays for emergency vehicles.

The city lacked a deep storm sewer near the project site, so Hanson designed a pump station to dewater the underpass. Water enters the pump station through a 24-inch-diameter collector pipe from the underpass collection system. The duplex station is rated for one pump operation, with the second pump as backup. Both are submersible, low-RPM centrifugal pumps with a 10-inch discharge. The pumps are capable of passing a 6-inch solid object without jamming, and the station incorporates storage to minimize its impact on the receiving sewers. Three 10-foot-diameter manholes, each 50 feet deep, provide a buffer to store the stormwater while keeping the underpass dewatered. The discharge main parallels the underpass before discharging into the 30-inch combined sewer.

The lift station’s electric controls consist of a pump controller connected to a cellular-based communication system that alerts the city to alarms at the station and provides pump operational data and station faults. A high-water alarm alerts the city if water levels reach 1 foot below the top of the lowest casting in the underpass.

The project was completed in 2016, and the station worked as designed during a 5.2-inch rain event that year. Carpenter Street was the only underpass in Springfield that was free of standing water after the rainfall.