St. Mary Wastewater Engineering Report: Clean Water Engineering Report Grant

Wastewater Engineering Report for the City of St. Mary

The City of St. Mary is a small community of approximately 300 residents situated along the historical riverbed of the Mississippi river.  The existing wastewater treatment and collection systems were constructed in 1978 and have received only minimal repairs and upgrades since that time. The existing collection layout includes individual grinder pump stations for each sewer customer. Many of these pump stations still consist of the original components that were installed back in 1978. Both the existing collection and wastewater treatment systems have far outlived their intended design lives. As a result, the city has dealt with multiple and persistent equipment failures and has struggled recently to maintain a fully functional wastewater system. The cost for repairs has gradually added up to the point where they exceed the normal budget that is available to the city.

Heartland Engineering was retained by the city to conduct preliminary investigation and design of the city’s wastewater facilities as part of a Clean Water Engineering Report Grant (CWERG) through the Missouri Department of Natural Resources. The engineering report compared the cost of options to repair and modernize the collection system and free the city from the extreme financial burden of having to maintain pump stations for every residence. Options were also explored for providing a functional and reliable wastewater treatment system by replacing and upgrading components. The expected cost to repair and upgrade the existing treatment facility equipment were compared versus the cost to construct a non-discharge land application system and other treatment options. In these cases, it is important to compare not only the up-front construction costs, but also long-term operations and maintenance costs, major equipment replacement costs, and the depreciation of assets on-hand over the project lifespan.

Finally, the completed engineering report was used as part of a funding application package through the Missouri DNR State Revolving Fund, to help the city acquire the funding necessary to complete final design and construction of the proposed project. The report was completed in late 2025 and was submitted in early 2026 to the Missouri Department of Natural Resources for consideration for inclusion in the 2026 Intended Use Plan.