Ross council adopts design guidelines to require no net increase in stormwater runoff

The Ross Town Council adopted Resolution 2,516 on July 10, approving design guidelines intended to prevent increases in peak stormwater runoff from development that adds impervious surfaces.

Public Works Director Rich Simons presented the guidelines, which lay out two primary on-site detention methods for small residential projects (generally less than 5 acres): properly constructed permeable paver/rock storage systems and bioretention basins sized to mitigate peak runoff increases. Simons said the guidelines use a safety factor (multiply increased impervious area by 0.08) and allow the town engineer discretion to consider exceptions for small increases on large lots.

Council discussion covered likely costs and enforceability. Councilmember Matt Salter asked whether staff had cost estimates; Simons said recent individual installations suggest modest costs (he estimated roughly $1,500 for a small installation but said it varies by project). Councilmember Elizabeth Kircher and others asked about how the rule applies to common projects such as pools or driveways; Simons said triggers apply only when a project increases net impervious surface and that the rule can be implemented through conditions of approval during planning review. Several council members urged staff to collect cost data from recent local installations and to monitor unintended burdens on small projects.

Simons told the council the guidelines align with the State Water Resources Control Board’s Phase 2 municipal stormwater program and with the town’s recent municipal code updates (chapter 15) that require reduced peak runoff where applicable. He showed local examples—Gardens and backyards where bioretention features had been added and later vegetated—and noted operation and maintenance of such features would be the property owner’s responsibility.

The council approved the resolution on roll call, with Mayor Mary McMillan, Councilmembers Terri Dowling, Kercher and Mayor Pro Tem Robbins voting aye and Councilmember Salter recorded as abstaining. The motion passed with a recorded vote of four in favor.

Staff and the public will use the guideline details to implement conditions for projects that increase impervious area; staff said they will continue to refine cost estimates and provide applicants technical details for construction and maintenance.

Provenance: presentation, council questions, and the recorded roll call are in the July 10 meeting transcript and the posted staff report.