To effectively address widespread street and structure flooding issues, the Village embarked on a Stormwater Action Plan in 2013. The study area includes approximately 1,720 acres west of Ridge Road extending east to the North Branch of the Chicago River that is served by the Village’s separate storm sewer system. CBBEL developed and calibrated a hydrologic and hydraulic model using flow monitoring data combined with detailed accounts and pictures from residents collected during open house meetings. The model was verified based on the high water marks observed during the April 2013 storm event.

CBBEL and Village staff identified near-term and long-term capital improvement projects to reduce flooding. The near-term drainage improvements such as green infrastructure would be incorporated into the Village’s current infrastructure projects. These long-term capital improvements projects ranged in cost from $44 million to $75 million to provide a 10-year level of protection.

After considerable deliberation, the Village chose the Neighborhood Storage option that consisted of localized stormwater storage in three neighborhood parks and associated storm sewer improvements to convey the excess runoff to the parks. After optimization of the plan and considerable coordination with the Wilmette Park District and School District, the plan was finalized to provide 42.5 acre-ft of underground stormwater storage at three parks and install nearly 26,000 linear feet of storm sewer that would provide 10-year flood protection to 98% of vulnerable structures during a 10-year storm event.

The total construction cost was estimated to be approximately $68M and construction started in 2019 on the first phase of the project. Through continued coordination with the Park District and School District, the construction of the remaining phases progressed through 2020, 2021 and 2022 despite the COVID pandemic. Careful planning allowed for safe pedestrian and vehicle access to the schools and throughout the Village during construction. After construction was completed at each park, improvements were made to the drainage and park amenities, including recreational enhancements and native plantings.

The multi-year construction project is scheduled to be completed on time at the end of 2022 and the total construction cost is anticipated to be $62 million, which is 10% under the Village’s budget.



The Details


Wilmette, Illinois

Construction Cost/Fee

$62 million


Village of Wilmette