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. We also received FY26 funding through Congressional add to initiate a study in the American Bottom area which includes Cahokia Heights. This study will be implemented in partnership with the Illinois Department of Natural Resources. (American Bottom General Reevaluation Report)

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. 

Project 2: System Mapping and Digitization

Under the Disaster Relief Supplemental Appropriations Act for 2025 we received an appropriation to comprehensively digitize the city's sewer system. We will deliver a map that provides the full function needed to allow the city to meet the consent decree requirements and also contains placeholders for the data attributes that are needed. The placeholders will allow for data collection and populating by city or other contracts outside of USACE should we not receive follow on funding.

Project 3: East Interceptor System

The U.S. Army Corps of Engineers will provide construction assistance to the City of Cahokia Heights for a new sanitary sewer interceptor known as the East Interceptor Project to address frequent sanitary sewer overflows, inflow/infiltration (I/I) issues and backups into homes in its northern neighborhoods of Ping Pong and Parkside. The sanitary sewers in these neighborhoods currently drain northward into the City of East St. Louis. The new interceptor sewer will cut off, or intercept, these north-flowing sanitary sewers through a series of new pump stations and force mains and redirect these flows to the south into the main trunkline of the Cahokia Heights sanitary sewer system. Managing these additional flows will be possible due to the current construction project that is restoring system capacity and performance by removing excess inflow and infiltration. This East Interceptor project incidentally reduces strain on East St. Louis’s combined sewer system, mitigates frequent sanitary sewer overflows and back-ups into homes, and improves reliability and resilience of the sewer infrastructure. Overall, the mutually beneficial project supports public health, community growth and environmental protection in the City of Cahokia Heights. 

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.