What does Underground Injection Control look like?
An underground injection control facility, often called a UIC, collects stormwater runoff from streets, sidewalks, parking lots, pavement, and other hard surfaces. Then, it discharges that water below ground where it can eventually replenish groundwater supplies. Common examples of UICs are sumps, drywells, and trench drains.
With a UIC, stormwater flows from the street's storm drains into a sedimentation maintenance hole. The sedimentation maintenance hole allows solids — dirt and sediment — to settle to the bottom and traps the oil and grease that get picked up by runoff from the street. The "first flush," or runoff from the beginning of a storm, is the dirtiest and carries the highest amount of dirt, trash, oil, and other pollutants.
The water then flows out to the stormwater sump. The sump's perforated sides allow the water to slowly seep into the surrounding soils.
Sometimes, a UIC is located within a swale, green street, or other type of green infrastructure. In this case, small storms can be completely captured and filtered by the swale or green street. During larger rains, the UIC is designed to take the overflow.
Why are UICs Important?
UICs not only help manage stormwater, they also protect surface waters (like lakes, rivers, and streams), replenish groundwater and surface water supplies, prevent sewer overflows and basement backups, and are an important part of the city’s green infrastructure approach to managing stormwater. UICs efficiently manage the rain where it falls instead of transporting it through pipes to a treatment plant.
Groundwater is protected under the federal Safe Drinking Water Act because it is a potential drinking water supply.
Because water from a UIC could allow pollution to flow to groundwater, UICs are regulated by the State of Oregon’s Department of Environmental Quality (DEQ) under the authority of the U.S. Environmental Protection Agency. Learn more about the state’s UIC program in Oregon Administrative Rules (OAR) Chapter 340,Division 40 and Division 44.
The City’s Role in Protecting Groundwater
The City of Portland owns and operates more than 9,000 UICs citywide. Those UICs are regulated under a stormwater permit from DEQ called the Water Pollution Control Facility (WPCF) Underground Injection Control (UIC) permit. The permit establishes construction, operation, and maintenance requirements for UICs to ensure that UICs in Portland protect groundwater according to the requirements of the Safe Drinking Water Act. The City’s UIC Permit Program manages Portland’s WPCF UIC permit.
Portland's UIC Permit Program
In Portland, UICs have been helping to manage stormwater for more than 60 years. About 30 percent of the city relies on UICs as a method to manage stormwater — especially on the east side of the Willamette River where soils support greater infiltration.
UICs are considered part of a "separated system” because they do not connect to the sanitary sewer, which transports wastewater to a treatment plant. However, the City’s UIC permit is separate and different from the City’s Municipal Separate Storm Sewer System Permit, which protects surface water. Read more about the City’s Municipal Separate Storm Sewer System Permit. Find general information about our sewer and stormwater system and the ways Portland manages stormwater.
Although several city bureaus are responsible for implementing UIC permit requirements, Environmental Services leads the administration of and compliance with the City’s UIC permit. The City’s UIC program develops management plans to prevent pollution from UICs, registers and approves new UICs, monitors existing UICs, and takes corrective action when needed. Find information on how to register or decommission a UIC.
UIC Management Plan
The UIC Management Plan presents the City’s comprehensive strategy to meet permit requirements and protect groundwater through spill prevention, education, and best management practices for construction, commercial, municipal, and industrial operations.
Spill or Pollution Hotline
The Spill or Pollution Hotline can be contacted 24 hours a day, seven days a week, to report pollution or spills.
Educational Materials and Resources
Environmental Services has various online educational materials and other resources to help keep our rivers and streams clean and healthy.
- Preventing Pollution
- Protecting Rivers and Streams
- Managing Stormwater
- Invasive Plants
- Community Cleanups
- What You Can (and Can’t) Flush
For more information about erosion control inspections, floodplain maps, and erosion prevention best management practices, view the Erosion Control webpage.
Pollution Prevention Best Management Practices
For more information about requirements and ways you can prevent pollution, visit the Best Management Practices to Prevent Pollution.
Annual Compliance Reports. Find the UIC Management Plan annual reports on eFiles.
Stormwater Discharge Monitoring Plan
The Stormwater Discharge Monitoring Plan describes the City’s monitoring objectives, strategy, and procedures for collecting and analyzing stormwater.
Annual Compliance Reports. Find the Stormwater Discharge Monitoring Plan's annual reports on eFiles.
Related City Code
- Portland City Code 10.10 provides requirements for development and construction related activities in order to control the creation of sediment and to prevent the occurrence of erosion at the source during construction and development.
- Portland City Code 17.38 is intended to provide for the effective management of stormwater, groundwater, and drainage, and to protect and improve water quality in the city of Portland.
- Portland City Code 17.39 provides Environmental Services the authority to ensure the City storm sewer and drainage systems are operated in a manner that protects public health and the environment.