Brentwood advances plan to require 40% green space and new permit for residential rebuilds

The Brentwood Board of Commissioners on Monday discussed an ordinance to require a minimum 40% green space across most residential zoning districts and a new Residential Infill Development Permit to limit stormwater impacts from teardown‑and‑rebuild projects. Chair (speaker 1) said the ordinance would make the AR, R‑1 and R‑2 zoning requirements match OSRD by setting a 40% green‑space minimum and help address drainage concerns from larger infill homes.

Consultant Christina Hoehager said the RIDP targets legacy neighborhoods that lack subdivision‑level stormwater facilities and applies when a net increase in impervious area is 800 square feet or greater. "The goal of this residential infill development permit ... is to basically provide some stormwater requirements for these single family residential redevelopments to increase impervious areas," Hoehager said, adding the permit will use a tiered approach so smaller increases face lighter requirements.

Under the proposal, Tier 1 would cover net increases from 800 to 8,500 sq ft and focus on treating the first inch of rainfall; Tier 2 (8,500–20,000 sq ft) would require calculations for the 2‑year event and attenuation for the 10‑year event; and Tier 3 (over 20,000 sq ft) could require a full stormwater management plan. Hoehager gave examples of green infrastructure practices that would be eligible, including modified dry (gravel) trenches, rain gardens and permeable pavement.

Staff clarified the RIDP will be added to Chapter 56 (grading and subdivision regulations) with a $150 permit fee added in Chapter 14. Commissioners asked how the $150 RIDP fee interacts with the building‑permit fee scale; staff said the $150 is an additional administrative fee and the regular building permit fee scale still applies.

Officials emphasized several limits and exemptions in the draft: the RIDP would not apply to lots within developments that already have approved stormwater management plans adopted after June 1, 2008, and engineering staff can elevate a site to a higher tier where local constraints (slope, known downstream flooding) warrant more stringent review. Staff and consultants said industry experience in the region suggests most remodels will fall into Tier 1 and that the approach tracks similar programs used by neighboring jurisdictions.

No formal vote on the ordinance or the RIDP was recorded in the transcript; the item was discussed in detail and will return for later action after staff and the consultant finalize code language and any technical tweaks.