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Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Avenue, Room 1000, Portland, OR 97204

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Underground Injection Control (UIC) Program

sump illustrationThe City of Portland has approximately 9,000 UICs (drywells, sumps, trench drains) that collect stormwater from public rights-of-way and discharge it into subsurface soil. UICs are most prevalent in east Portland where subsurface soils support greater stormwater drainage and infiltration rates. For many areas east of the Willamette River, UICs are the only form of stormwater management available.

UICs are an essential element of Portland’s comprehensive watershed strategy to use stormwater as a resource. When UICs infiltrate stormwater into subsurface soils, the soils filter and cool the water. The filtered stormwater eventally passes into groundwater and eventually helps recharge streams.

UICs are an essential element of  green streets, which are vegetated curb extensions or streetside planters. UICs are generally four feet in diameter and about 30 feet deep. They provide an infiltration point for overflow during large storm events when stormwater cannot be fully infiltrated through swales, planters, or other surface infiltration facilities. UICs also preclude the need to install or increase the capacity of piped stormwater infrastructure that eventually discharges into local surface water bodies, including Johnson Creek, the Columbia Slough, and the Willamette River.


Underground Injection Control (UIC) Program Links

Portland UIC Stormwater Monitoring

Washington Hydrogeology Symposium