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City of Evanston Combined Sewer Relief Program

A stormwater management model that mitigates severe flooding and basement backup problems

  • $188M

    Construction Value

  • Evanston, Illinois

    Evanston, Illinois

A cost-effective citywide facility plan and implementation program

Severe flooding and water backing up in basements affected the City of Evanston for over 50 years. To alleviate the problem, our team provided planning, design engineering, contract documents, assistance during bidding, and construction engineering services for the City's 10-phase, $188 million combined relief sewer project.

We used a Stormwater Management Model—a hydrologic and hydraulic model—in conjunction with flow monitoring data to define specific problems and develop cost-effective solutions. Project scope included 42 miles (68 kilometres) of large diameter relief sewer installed by open-cut construction. Eight miles (13 kilometres) of larger diameter relief sewer was installed by pipe jacking or tunneling. Work included replacement or rehabilitation of existing, structurally deficient combined sewers and existing water mains, some of which were over 100 years old. We prepared the facilities plan, which defined the proposed relief sewer and tunneling system layout based on computer modeling and drainage basin assessments.

The recommended plan included innovative use of flow restrictors, maximum use of existing facilities, and a 50 percent reduction in costs over previous plans.

At a Glance

  • City of Evanston, Illinois

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