West Linn staff previews city stormwater manual, ordinance to give city engineer enforcement authority

City engineering staff and consultants presented a draft West Linn Stormwater Management Manual at the March 3 council work session and said the city will post the manual for public comment before formal adoption. Staff also introduced an ordinance that would give the city express authority to adopt and enforce the manual and delegate revision authority to the city engineer.

Why it matters: The manual is meant to bring West Linn’s post‑construction stormwater standards into clearer compliance with the Department of Environmental Quality’s NPDES/MS4 permit, better reflect local soils and terrain than the City of Portland’s manual (which West Linn currently references), and make submittal requirements and design reviews more consistent.

Engineering staff described the background and proposed changes. “It was only 200 pages, which is significantly less than the one we’re using currently,” Clark Lumpkin of the engineering department told the council, noting the draft is shorter than the manual West Linn has referenced from the City of Portland. Staff said they retained construction erosion and sediment controls in the city’s public works design standards and focused the new manual on post‑construction management practices—stormwater facilities such as ponds and infiltration features required when development or redevelopment creates or replaces 1,000 square feet or more of impervious surface.

Consultant and staff comments emphasized clearer submittal lists, stronger reliance on measured soil infiltration rates, and an emphasis on on‑site infiltration to minimize discharge to the city’s storm system. “This permit essentially allows the city to discharge our storm system into state waters ... and we have to meet certain pollution reduction requirements,” Jamieson (engineering staff) said, describing the DEQ permit obligations.

City Attorney (name not specified) summarized the accompanying ordinance staff drafted to give “express authority to adopt and enforce the manual,” and to delegate to the city engineer the ability to revise the document when federal or state requirements change, when industry practices improve, or when best management practices evolve. The ordinance requires any revisions be posted 30 days before they take effect and gives code enforcement and the city engineer authority to enforce the manual.

Staff outlined the timeline: the draft manual will be posted for public comment; staff plans to bring the ordinance to the March 17 special meeting and then return the manual to council for adoption by resolution at the April 14 business meeting after public comment.

Potential impacts for developers: Staff said the manual clarifies and slightly expands submittal requirements to reduce back‑and‑forth reviews, which staff expects will ultimately streamline the permitting process. The manual does not change the types of stormwater facilities required, but it emphasizes infiltration sizing, which staff said may change design approaches and requires accurate soil testing.

No formal action was taken at the work session; council gave informal consensus to move the ordinance and public comment steps forward.