Permeable resin-bound surfacing can serve as a stormwater practice in Spokane only where the city's engineers accept an infiltrating section, and here infiltration comes with a condition: much of the city sits over the Spokane Valley-Rathdrum Prairie Aquifer, a sole-source drinking water supply, so treatment comes first. Over an existing slab it is a finish only.
Spokane is also changing manuals. Projects have long followed the Spokane Regional Stormwater Manual, and the city's draft 2026 program plan (March 2026) says it plans to adopt Ecology's 2024 Stormwater Management Manual for Eastern Washington with a local addendum in late 2026. Confirm which standard applies at your pre-development conference.
From the regional manual to Ecology's eastern Washington manual
The Spokane Regional Stormwater Manual was developed jointly by the City of Spokane, Spokane County and Spokane Valley, and the city still mandates it for development and redevelopment. The draft 2026 program plan says the 2024 eastern Washington manual has outgrown it, and that an addendum will keep SRSM provisions that protect the aquifer. Until adoption, either standard may be used with approval from the relevant city department.
For commercial building permits, any new construction that adds or replaces impervious surface needs a stormwater report and plan, and disturbance of 5,000 square feet or more also needs an erosion and sediment control plan. The municipal code points designers to the Eastern Washington Low Impact Development Guidance Manual. The city has tested permeable pavement itself: Sharp Avenue between Pearl and Dakota streets was rebuilt in 2018 as a pilot with pervious concrete and porous asphalt.
Basalt, aquifer gravels and freeze-thaw
Spokane's stormwater splits roughly three ways, according to the city's permitting guide: about a third goes to separate storm drains and on to the Spokane River and Latah Creek, a third enters combined sewers, and a third soaks in through swales, drywells and ponds. On the south side, where rocky geology doesn't readily allow infiltration, combined sewers carry much of the runoff. The Moran Prairie and Five Mile special drainage districts exist because shallow groundwater, standing water and steep slopes make stormwater hard to manage there.
North of the river, gravels drain fast, which is why treatment matters before water reaches the aquifer. Infiltration structures deeper than they are wide, such as drywells, fall under Ecology's underground injection control rules. Hard winters add freeze-thaw cycles, snow storage and traction sand, which can clog a porous surface, so the engineer should size the base for frost and plan winter maintenance.
Good fits around Spokane
- South Hill homes. Patios and paths over shallow basalt, designed to drain across and away rather than to infiltrate.
- North side and Northwest neighborhoods. Walks and courtyards on gravelly soils, where a permeable section may be feasible with treatment questions answered.
- Downtown and riverfront infill. Plazas and courtyards on private land near the Spokane River.
- College and hospital campuses. Pedestrian routes and outdoor seating with light loads.
- Older concrete. Where stormwater credit isn't the goal, see concrete resurfacing in Spokane.
Moran Prairie and Five Mile need extra care: shallow groundwater there can leave a stone reservoir sitting full, so ask the city how the special drainage district rules apply before you design for infiltration.
Approvals in Spokane and how Resin Rock helps
The city strongly recommends a pre-development conference, where plans examiners and engineering staff identify the stormwater requirements and any design deviation. Submittals go through the Development Services Center at City Hall, 808 West Spokane Falls Boulevard, and the owner keeps responsibility for maintaining a permitted private system up to the city connection.
Resin Rock supplies UV-stable resin binder, natural stone aggregate blends, trims and Rock Crete permeable sub-base. Bring our technical data sheets to the conference. We don't install. We train and approve installers and can match you with an approved installer, usually within 24 hours.
Before you specify permeable resin-bound in Spokane
- Ask at pre-development whether the regional manual or the 2024 eastern Washington manual applies.
- Check whether the site is in a CSO basin or a special drainage district.
- Confirm treatment needs before infiltrating over the aquifer.
- Register any drywell or deep infiltration structure with Ecology's UIC program.
- Design the base for frost and keep traction sand off the surface.
Common questions about permeable resin-bound in Spokane
Can my South Hill patio be permeable for stormwater?
Often not in the infiltration sense. The city notes that rocky geology on the south side doesn't readily allow infiltration, and much of that area drains to combined sewers. A resin-bound patio can still drain freely and avoid puddles, but your engineer may route water to a swale or the storm system rather than count on soaking in.
Why does the aquifer matter for a driveway?
Water that soaks in across much of Spokane ends up in the Spokane Valley-Rathdrum Prairie Aquifer, the region's drinking water. Driveways and parking areas carry oil and metals, so the city expects treatment before infiltration. A permeable driveway section may need treatment layers or a different approach, decided at plan review.
Does road sand ruin a permeable surface?
It can clog the pores if it is tracked or pushed onto the surface every winter. Keep sanding off the resin-bound area where possible, sweep it in spring, and include vacuum cleaning in the maintenance plan. The engineer can also limit run-on from sanded pavement next to the permeable area.
Do I still need a stormwater report for a small commercial patio?
Probably. The city's permitting guide says any new construction on a commercial building permit that adds or replaces impervious surface needs a stormwater report and plan, and disturbance of 5,000 square feet or more also needs an erosion and sediment control plan. Confirm exemptions at the pre-development conference rather than assuming one applies.
Official sources for Spokane
- City of Spokane: Stormwater
- City of Spokane: Understanding Stormwater Permitting (PDF)
- Spokane Regional Stormwater Manual (hosted by Spokane Valley)
- Washington Ecology: 2024 Stormwater Management Manual for Eastern Washington
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.