Aspen staff propose simpler stormwater thresholds to make permitting clearer

Trisha Aragon, the city engineer, told council the Urban Runoff Management Plan update aims principally to modernize stormwater control measures, update technical standards and improve the URMP's readability and usability. "The changes that we're presenting tonight are intended to simplify the process and improve consistency while maintaining the city's ability to effectively manage runoff, protect our community, and protect the river health," Aragon said.

Project staff explained the current framework uses percentage-based calculations and multiple documents, which can produce inconsistent interpretations, especially for mixed-scope projects. Kyla Smiths, a project manager in the engineering department, said the proposed approach replaces percentage thresholds with gross-square-foot thresholds so that as project impact increases, engineering requirements increase in a clearer, more consistent way. Under the proposal, projects disturbing less than 400 square feet would typically require no engineering review; medium-impact projects would go to a minor engineering review; projects disturbing more than 1,000 square feet of exterior area would be a major engineering review.

Presenters emphasized the update is intended to simplify administration rather than expand or reduce the types of projects captured for review. Staff also said they will align URMP definitions and supporting documents, update submittal checklists, and coordinate the changes with permitting systems before returning with a full URMP update for council approval.