Millcreek, PA Environmental Rules: Stormwater Management (2026)

Millcreek Township Code § 116-12 sets the baseline for every regulated activity not exempted by § 116-27. The applicant must prepare and implement an approved SWM site plan, show adequate capacity to meet the volume and rate control requirements of §§ 116-15 and 116-16, and keep the approved plan on site for the duration of the work. Nothing starts before the Township's written approval.

The design standards sit behind that gate. Section 116-15 requires pollutant load reductions across disturbed areas of 85% for total suspended solids, 85% for total phosphorus and 50% for total nitrate. Section 116-16 ties postdevelopment peak discharge rates to the release rate map for the Lake Erie Watershed in Appendix A. Under § 116-12I, watercourses crossing a development site need drainage easements at least 20 feet wide that include the one-hundred-year water surface, with a freeboard allowance of 0.5 foot. The easement terms prohibit excavation, fill, structures, shrubbery, trees or fences without the Township's prior written approval. Concentrated discharge onto an adjacent property requires the applicant to document adequate downstream conveyance and provide an easement (§ 116-12G).

Small projects get a lighter path. Section 116-27A exempts any regulated activity that would create 5,000 square feet or less of impervious area from the full plan, though the Township can require a plan for developments creating more than 1,500 square feet of impervious area where drainage problems exist. The exemption table asks for documentation of impervious area from 1,000 to 1,500 square feet, volume controls with the Simplified Method or a small project SWM application from 1,500 to 5,000 square feet, and rate and volume controls with a full SWM site plan above 5,000. The exemption is cumulative over a five-year period, and proposed gravel counts as impervious. The Township can deny or revoke any exemption for a project that threatens public health, safety, property or the environment (§ 116-27E).

Developments outside the chapter under § 116-3 still need a grading plan approved by the Township Engineer before any building or local street access permit (§ 116-17). Once a plan is approved, § 116-18 bars anyone from modifying it without the Board of Supervisors' prior approval.