Consultants tell Mount Clemens commission separating combined sewers could cost about $37 million; recommend phased approach

At a Mount Clemens city commission work session, consultants from AEW presented a preliminary feasibility review that estimated the cost to fully separate the city's combined sewer system at just under $37,000,000 and recommended a phased approach, further investigation and exploring state revolving fund options.

The consultants, led by Ashley (identified in the packet as a presenter), told commissioners the estimate reflects construction-level allowances and a 25% engineering contingency but does not include hydraulic modeling, detailed topographic surveys or a comprehensive CCTV condition assessment. "The initial preliminary cost estimate is just under 37,000,000 to separate the entire city," Ashley said. She cautioned the figure is high-level and would be refined after hydraulic studies and additional field work.

Why it matters: many of the city's older neighborhoods are in combined-sewer areas, meaning stormwater can enter sanitary sewers during large rain events and contribute to basement flooding. The presentation cited heavy summer rains and historical mapping (plus partial CCTV from a 2018 SAW program) as the basis for the review and noted the maps do not show footing drains or roof-drain connections that could increase the system load.

Key details from the presentation: the city was mapped into colored shapes representing combined areas; areas were classified as easy, medium, difficult or very difficult based on right-of-way owner, surface type, run length and conflicts with utilities. Some map shapes were excluded from the city's cost spreadsheet because the right-of-way is MDOT, county or Clinton Township, or because planned projects (such as the Gratiot separation) will address portions of the combined system.

Consultants recommended several next steps before committing to construction: televising storm sewers to confirm connections and assess condition, conducting hydraulic studies and modeling to understand system impacts, and overlaying historical basement-flooding complaints on the map to prioritize high-risk areas. Ashley said televising untelevised stormlines and uncovering unexpected conditions could increase project costs.

Interim and funding options discussed included enforcing the city's roof-drain ordinance (disconnecting roof and footing drains from sanitary leads), pursuing CWSRF/SRF loan programs (with potentially different scoring and loan-forgiveness outcomes), and phasing work to address the highest-risk areas first. "The city's ordinance right now does not allow that. It has to be disconnected," Ashley said about roof-drain connections.

Commissioners asked whether individual shapes could be done separately, whether separation could be paired with road rehab projects to share costs, and how rate impacts would be managed. Staff noted water and sewer funds are separate from the general fund and that financing (loans or loan forgiveness) affects the degree to which rates would need to cover repayment.

Next steps recorded in the session: commissioners asked staff to overlay historical complaint data on the map and return with answers to commissioner questions; the consultants said they could return for a follow-up work session if requested. No formal separation project was authorized during the work session.

Speakers quoted are identified in the meeting transcript; the presentation and recommendations were framed as preliminary and contingent on further study and funding decisions. The work session adjourned without a vote on a sewer separation project.