Township engineer briefs commission on stormwater rules, permit duties

Eric Thorne, the township engineer for Cascade Charter Township, told the planning commission May 9 that the township’s stormwater ordinance requires developers to design projects to protect water quality, limit channel erosion and reduce downstream flooding.

Thorne said the ordinance’s technical requirements are implemented through the township’s stormwater standards manual and the site-review process staff uses when Andrea, the planning staff lead, forwards applications. He described the ordinance’s three core objectives—handling the first inch of runoff (the “first flush”), capturing roughly 80% of suspended solids in that runoff, and accounting for post-development flow increases so downstream areas are not exposed to higher flood risk.

The engineer said the township’s program is regulated under Michigan’s MS4/MPDES framework and enforced through periodic EGLE audits. “The township has to maintain that permit on a five‑year cycle,” Thorne told commissioners, and staff recently completed an EGLE audit of parts of the program. He also described routine coordination with Kent County’s Drain Commissioner, the Kent County Road Commission, and the Grand Valley Metro Council (GVMC), which helps many communities comply with MS4 permit requirements.

Thorne told commissioners the stormwater standards manual provides engineers a practical design playbook—detention pond pretreatment, outlets, emergency overflow capacity and minimum slope limits—while the ordinance supplies the regulatory requirements. He said certain sites that are already connected to nearby county drainage facilities may rely on those facilities to meet some requirements, but applicants must demonstrate appropriateness with engineering calculations and approvals from the drain office.

Commissioners asked how the ordinance applies to smaller projects and non‑single‑family work. Thorne said the ordinance generally applies to developments disturbing one acre or more or those that are part of a larger common plan; he noted the ordinance typically does not apply to a homeowner adding a single‑family garage. He also advised the commission to expect a continuing stream of site‑specific review memos from his office: “If it goes through site plan review, Andrea sends it to me and I assess it for stormwater review,” he said.

Thorne flagged a set of stormwater memo comments for the Old National Bank proposal on Charlavoy Drive and said staff had worked with that applicant to address deficiencies. He emphasized that failure to meet permit or ordinance obligations can lead to enforcement action: “Pay attention to what your developers are doing in your area. You will feel the wrath,” he said.

The presentation closed with a reminder that stormwater compliance is both a technical and administrative process: developers must meet the ordinance, the manual and any MS4 permit conditions; engineering details are resolved in plan review; and some variances or appeals may require review by the Zoning Board of Appeals or higher approvals.

The commission did not take formal action on the ordinance itself during this meeting; Thorne’s briefing was provided as staff education ahead of ongoing permit work and site‑plan reviews.