The U.S. Army Corps of Engineers, St. Louis District is supporting the community of Cahokia Heights, Illinois, with project and technical assistance under two separate authorities in two specific areas of the community.    

Wastewater infrastructure assistance is occurring under the Section 219 Environmental Infrastructure Assistance Program under the Madison and St. Clair Counties, Illinois Authority to support construction projects in Cahokia Heights. The purpose of the project is to assist this community with much needed wastewater infrastructure improvements.  

Project 1: Sanitary Sewer Trunkline Rehabilitation

Our first project involved Cured-In-Place Pipe Lining of the City’s most downstream section of their trunk sewer. The City identified that of the approximate three mile long (of nine mile long) trunk sewer that cleaning, televising and lining was the most important. In February 2024 a contract was awarded and addressed this largest, deepest and most downstream section of the trunk sewer addressing pipe deficiencies such as cracks or breaks, restoring structural stability and ensuring long-term reliability of this main wastewater transport.  Phase 1 was completed in May 2025.          

Additional contract work is being planned with additional financial resources that have been secured for this effort. We are also engaging City leaders and the Congressional offices about follow on support that will assist the City with repairs to this crucial piece of infrastructure.      

Project 2: System Mapping and Digitization

Under the Disaster Relief Supplemental Appropriations Act for 2025 we received an appropriation for investing in smart infrastructure with a comprehensive mapping and digitization of the city’s sewer system. This tool will allow for real-time system management, supporting both day-to-day operations and long-term planning. Federal funds are secured, and we are finalizing the scope before requesting the local sponsor’s cost share. We anticipate the system will be up and running within one year which is a major step forward for the city’s operational capabilities.

Project 3: East Interceptor System

This proposed project will reroute flow that currently moves north toward East St. Louis, where frequent flooding occurs. The new East Interceptor System would direct that flow into the rehabilitated trunkline, easing pressure on the northern system. This project is under active funding consideration, with strong local and federal support. Once constructed, it will significantly reduce flood risk and improve system reliability.

USACE has provided technical assistance at no cost to the cities of Cahokia Heights and East St. Louis, Illinois. The projects were funded under the USACE Flood Plain Management Services program and is authorized by Section 206 of the 1960 Flood Control Act (P.L. 86-645), as amended. The goal on both of these projects was to evaluate flood-prone areas, provide engineering analysis and develop mitigation alternative with conceptual cost estimates. 

Project 1:  Cahokia Heights & East St. Louis Flood Hazard Analysis is bordered by Illinois Route 157, Interstate 255, St. Clair Avenue, and Lake Drive and is located in St. Clair County, IL. The study was broken into individual watersheds (Edgemont, Parkside, and Ping Pong) because they are hydraulically independent. The alternatives were developed to provide varying levels of flood risk reduction using structural measures based on cost. The final report can be reviewed for public awareness of risk and actions that the respective Cities are taking to mitigate that risk. The final report transmittal occurred in September 2023.    

Project 2:  Piat Place & Harding Ditch Flood Hazard Analysis is located west of Harding Ditch and includes the geographic areas of North Wetland/Summit Avenue, North of State Street, Piat Place and lower Harding Ditch. The goal was to evaluate flood-prone areas, provide engineering analysis, and develop mitigation alternatives with conceptual cost estimates. Our team accelerated the draft report to help the city meet tight deadlines for grant applications. We used storm sewer survey data collected by IDNR and modeled a 24-hour, 1% annual chance storm that was equivalent to 7.64 inches of rain. The updated model shows underground containment during a 10% storm, and during a 1% storm, any surface water would be limited to streets. As a result, the city secured a $10 million CDBG-DR grant from St. Clair County to implement the preferred solution. The final USACE report was delivered to the city in February 2025.