underground tunnel below street with equipment

NS 12 – Collector System Improvements

Project Update

The NS 12 Collection System Improvements Project will be completed by the end of September. With the work underground completed, the contractor’s crew will be restoring the site post-construction. This work includes:

  • laying down new topsoil,
  • seeding with protective matting,
  • installation of new fencing, and
  • reconstruction of the roadway.

The project installed 2,570 feet of 84” diameter pipe. That’s just over 7 football fields in length. The new pipe has a volume of ~740,000 gallons of water over the length of the pipe.

The project team wants to thank the school staff and parent community of the Hope Christian School, the Howard Fuller Academy, and our partners at Green Tech Station, NWSCDC, and Reflo, for their patience and understanding during the construction of this critically important infrastructure.

Project Overview

Since before 2003, MMSD has experienced hydraulic issues with the North Shore 12 (NS12) near surface collector system. This dual-purpose system conveys flows from the City of Milwaukee combined sewer in West Hopkins Street to the MMSD’s Inline Storage System (Deep Tunnel) when available and to Lincoln Creek during extreme wet weather events. Currently, the system cannot deliver enough combined sewage to the Deep Tunnel when it is available.

The NS 12 – Collector System Improvements project resolves to accomplish two goals. First, the construction of approximately 2,600 feet of tunneled 84-inch sewer will increase capacity to the Deep Tunnel reducing the risk of premature overflows. Second, the construction of 530 feet of double 72-inch by 120-inch box culvert will provide greater capacity to handle excess combined sewage during extreme wet weather events. The level of service for this improvement will only increase once the MMSD’s West Basin Stormwater Management Project is complete and online.

Partners

Project Map

Project Goals:

  • Help prevent unintended Combined Sewer Overflows (CSOs)
  • Help prevent combined sewage from discharging to grade during large storm events

Timeline –

  • Design: Completed July 2023
  • Construction – December 2023 to June 2025
  • Post-construction – September 2025

Get Involved/Stay informed:

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Project Resources

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    Work crew prepping the pipe before installing.

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    Lowering a length of pipe into the shaft.

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    Hanging turnbuckles for the cables that support an existing 84 -inch pipe while crews excavate around it.

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    Finishing excavating under the existing 84-inch pipe.