Gewalt Hamilton Associates, Inc. (GHA) was retained by Libertyville Township Road District for the drainage analysis & storm sewer improvements to prevent flooding that was observed along the tributary in Oak Spring Woods and Terra Fair Subdivisions during intense rainfall events. A hydrologic & hydraulic model was developed utilizing the Hydraflow Storm Sewers modeling software, HY-8, and FlowMaster to simulate and design storm sewer systems to alleviate flooding.

While most of the improvements were designed to be within the public right-of-way, four easements were required to discharge the floodwaters to the nearby Des Plaines River. GHA worked with the Township and the Lake County Stormwater Management Commission to successfully obtain DCEO (Department of Commerce and Economic Opportunity) funding to resolve this multi-jurisdictional drainage and flooding problem.

The installation of a drop manhole was a key aspect of the project, engineered to reduce the velocity of stormwater and help minimize erosion along the riverbank. During construction, a silt curtain was placed in the Des Plaines River to prevent sediment from drifting downstream, a measure critical for environmental sustainability. The project featured an innovative design to maintain natural wetland and aquatic habitats by allowing low flows to continue feeding existing wetlands while diverting heavier flows toward the Des Plaines River.

GHA’s collaborative approach and innovative design ensured the project’s effectiveness while maintaining environmental sustainability. By effectively addressing a complex multi-jurisdictional drainage problem, GHA demonstrated a commitment to delivering high-quality engineering solutions that meet the community’s needs.