Wilmette Stormwater Management Study

May 17th, 2018

Village of Wilmette

At the completion of a comprehensive stormwater study, CBBEL provided the Village of Wilmette with several alternatives to address widespread flooding in the separate storm sewer system on the west side of the Village. The current storm sewer system is over 50 years old and provides only a 2-year level of service. Flooding during larger storm events impacts hundreds of residential structures and results in roadway flooding several feet deep, making streets impassable throughout many areas. The drainage improvements recommended in the study included near-term improvements that can be incorporated into the Village’s infrastructure projects, green infrastructure and long-term capital improvement projects. The study looked at providing flood relief for the 10-year to the 100-year return interval storm events. After significant deliberation and meetings with residents, the Village chose the 10-year level of service.

To provide the 10-year level of service, CBBEL offered three alternatives for long term capital improvement projects that included combinations of larger conveyance storm sewers, a centralized stormwater storage facility, and neighborhood stormwater storage facilities. The results of the study were analyzed by the Village and independently verified by another consulting firm. The costs for the three alternatives ranged from $45 million to $80 million with varying levels of benefits for storm events greater than the 10-year event.

After several open houses, an active campaign to solicit resident input and deliberation by the Village Board, this April Trustees decided to proceed with the alternative that provides neighborhood stormwater storage at a cost of approximately $45 million -$55 million. This option allows the Village to work with the Park District and implement the improvements sooner than the other alternatives while leaving the possibility of including additional conveyance alternatives in future planning. The Village’s goal is to start on the first neighborhood storage project and have it operational by the Fall of 2020.

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Darren Olson, PE
Senior Project Manager
Water Resources Department

Dave Buckley, PE
Senior Water Resources Engineer
Water Resources Department