Bend releases draft single‑lot stormwater template as code change will require plans for small residential lots

City of Bend staff presented a draft “post-construction template” for single‑lot residential stormwater controls at the Water Advisory Group’s October meeting and asked members to review the form ahead of a tight implementation timeline.

“This is part of our requirement in our MS 4 permit to make sure that people are installing, stormwater controls for new development that creates or replaces 5,000 square feet of impervious surface,” said Elizabeth O'Keefe, water services department, stormwater program, explaining why the city is updating submittal requirements.

The draft template

City consultant Brian Wilkinson of AKS Engineering walked members through a one‑lot example intended for typical single‑family detached lots. The model lot is 100 feet by 50 feet (5,000 square feet). Wilkinson described a common layout in which roof areas are split into two basins (roughly 1,200 square feet each) and routed either to a subsurface infiltration gallery or to a shallow landscaped swale or pond sized to infiltrate on-site.

He described two sizing regimes: if a safe overflow path exists for extreme storms, facilities can be sized to hold the 25‑year runoff volume; if no safe overflow path exists, a facility must be sized to retain the 100‑year runoff volume. He explained typical setbacks and dimensions used in the template: facilities must be set back approximately 10 feet from foundation faces and 5 feet from side and rear property lines, and a representative infiltration gallery for the example lot could occupy roughly a 13‑by‑25‑foot footprint and be about 4 feet of rock depth (roughly a 6‑foot excavation when topsoil and cover are included).

Implementation and permitting

Elizabeth O'Keefe told the group that council reviewed code changes in September; staff said the amendments have a second reading scheduled and that the code will be implemented 30 days after the second reading. “We went to council in September… they have the second reading tonight. And then it will be implemented in code 30 days after a second reading,” she said; staff and consultants said the new requirement will be enforced as part of the building‑permit submittal checklist beginning Nov. 1.

To meet the deadline, staff asked the advisory group to review the draft quickly. Wilkinson said the team will circulate an autofillable version of the template and collect comments; Elizabeth asked for feedback by the end of the week if members wanted changes incorporated before implementation.

Practical considerations raised

Builders, contractors and landscape representatives at the meeting warned that retrofitting full-sized stormwater control facilities on finished single lots is often impractical. One contributor with long experience as a landscape contractor said when plans require large excavations on a finished lot, builders, excavators and landscapers frequently find the designs difficult to implement.

Several members noted the new template will make the limitations of lot‑level solutions apparent, strengthening the case for subdivision‑level stormwater facilities and earlier, pre‑application coordination with developers. Members also raised interactions with tree‑protection rules and landscape code: sinks or galleries placed in backyards can conflict with tree‑protection radii and mature canopy goals.

Where the proposal matters

City staff said the move responds to the MS4 permit and the drainage‑and‑density conversation already underway; it will change routine building‑permit reviews and make stormwater tradeoffs more visible during subdivision design. The template is intended as a compliance aid, not a prescription for final landscape design, and staff said they will refine wording and examples based on advisory-group feedback.

Next steps

Staff committed to circulating the draft template to Water Advisory Group members and to soliciting comments. Elizabeth said the city would incorporate edits if members provide feedback quickly to meet the implementation schedule.