Permeable resin-bound surfacing may be able to meet Portland's stormwater requirements as the surface of a permeable pavement facility, if the City accepts it as the wearing course. The 2025 Stormwater Management Manual (SWMM) allows permeable pavement for full onsite infiltration, water quality and flow control, provided the site can infiltrate and the section is built on a permeable base. The manual names porous asphalt, pervious concrete and permeable pavers, not resin-bound, and the surface course alone does not make a facility.
Portland asks where the water ends up before it asks what the surface is. The SWMM's Infiltration and Discharge Hierarchy sends a project to full onsite infiltration first, then to the river, slough or creek system, then to the combined sewer, and each level carries different performance standards.
The 2025 SWMM, the hierarchy and Clean River Rewards
The Bureau of Environmental Services (BES) adopted the 2025 SWMM under Portland City Code 17.38, effective March 1, 2025. It applies to development and redevelopment that creates or replaces 1,000 square feet or more of impervious area on property or in the right-of-way, with on-property and right-of-way work counted separately. Portland Permitting and Development (PP&D) runs the development review, and its staff review and issue permits for SWMM compliance.
Level 1 of the hierarchy, full onsite infiltration, applies where tested rates are 2 inches per hour or more. Sites that cannot infiltrate fully move to Level 2a if they drain to the Willamette River, Columbia River or Columbia Slough, or Level 2b if they drain to waters such as Tryon, Fanno or Johnson creeks, where hydromodification flow control can apply. Under the manual's Simplified Approach for combined sewer sites, permeable pavement needs a measured infiltration rate of at least 0.5 inch per hour and no infiltration constraints, and it replaces impervious area at a 1:1 ratio.
Clean River Rewards offers a discount of up to 35 percent of the total stormwater fee for properties that manage their own runoff. The program's listed qualifying solutions are planted areas, drywells and soakage trenches, planters, ecoroofs and trees, so ask BES how a permeable surface would be counted.
Infiltration limits: landslides, contamination and groundwater
The SWMM generally prohibits infiltration, and skips testing, on sites inside the City's Title 33 regulatory landslide hazard area, on contaminated sites and on slopes of 25 percent or more, which rules out many West Hills lots. Where groundwater is a concern, BES can require a groundwater report stamped by an Oregon-licensed engineer or geologist. In the Columbia South Shore Well Field Wellhead Protection Area, the Portland Water Bureau also reviews projects, and some stormwater facilities need spill control features.
Portland's long, wet season means a permeable section is tested by weeks of steady rain, not a single storm. Your engineer will size the stone reservoir to the tested rate and the applicable hierarchy level, and add an overflow route. Portland also has thousands of public underground injection control facilities under a DEQ permit, so any design that sends water down through a sump or drywell must meet UIC registration rules. A resin-bound overlay on existing concrete does none of this: the water still runs off the slab.
Portland projects that suit permeable resin-bound
- Courtyards and walkways in inner eastside multifamily and mixed-use infill, often in combined sewer areas.
- Patios, paths and parking pads at eastside homes where testing supports infiltration.
- School, park and institutional plazas being rebuilt with stormwater goals.
- Restaurant and brewery patios in the Central Eastside and along neighborhood main streets.
Keep it on private property unless the City approves it in the right-of-way, where public works standards apply. On private sites, the hierarchy level still decides how the section is designed.
Specifying permeable resin-bound for PP&D review
Permeable pavement needs a site-specific submittal even under the Simplified Approach, so plan on infiltration test results, a cross-section of the surface and base, slopes between 1 and 5 percent under the Simplified Approach (up to 10 percent with a terraced subgrade under the Performance Approach), an overflow route, and a recorded operations and maintenance form. Projects in Multnomah County have the O&M documents recorded by the City as part of permitting.
Resin Rock supplies the system and does not install it: UV-stable binder, natural stone aggregates, trims and the Rock Crete permeable sub-base, with technical data sheets for your submittal. Contractors can apply for our Oregon installer training, and owners can ask us for an approved installer, usually matched within 24 hours.
Before you specify permeable resin-bound in Portland
- Confirm whether the work creates or replaces 1,000 square feet of impervious area on property or in the right-of-way.
- Find your hierarchy level from infiltration testing and the receiving system.
- Check the Title 33 landslide hazard map and slope before planning infiltration.
- For Simplified Approach sites, confirm at least 0.5 inch per hour and no constraints.
- Keep surface slopes between 1 and 5 percent on Simplified Approach sites, and design an overflow route.
- Ask BES whether the finished area can count toward Clean River Rewards.
Common questions about permeable resin-bound in Portland
Does my patio project trigger the Stormwater Management Manual?
If it creates or replaces 1,000 square feet or more of impervious area, it does, unless a listed exemption applies. Replacing paving counts as redevelopment when the old surface comes out and soil is exposed. A properly built permeable pavement facility is one way to meet the requirement, subject to infiltration testing and City review.
Will permeable resin-bound get me a Clean River Rewards discount?
Not automatically. Clean River Rewards can reduce up to 35 percent of the total stormwater fee for properties that manage runoff on site, but the program's list of qualifying solutions does not name permeable pavement. Contact BES before you build to ask whether your permeable area, and what drains to it, would be counted.
I live in the West Hills. Can I infiltrate under a new driveway?
Possibly not. The SWMM generally prohibits infiltration on sites in the Title 33 landslide hazard area, on slopes of 25 percent or more and on contaminated sites. The manual treats permeable pavement as an infiltrating facility, so ask PP&D and BES early whether a permeable surface can count on your lot. Runoff may need to go to a lined facility or another approved discharge point instead.
Official sources for Portland
- Portland BES: 2025 Stormwater Management Manual
- Portland BES: Clean River Rewards
- Oregon DEQ: Municipal Stormwater (MS4) Permits
Local rules change. We last checked these sources in October 2026. Confirm current requirements with the reviewing agency before you design, and treat this page as a starting point, not engineering or permitting advice.