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Water Environment Services
Water Environment Services
Tri-City Influent Pump Station Expansion Project
Sewage from Oregon City, West Linn and Gladstone arrives to the Tri-City Water Resource Recovery Facility (WRRF) through a large pipe approximately 40 feet underground. In order to treat the incoming flow through the facility, the Influent Pump Station (IPS) pumps the flow up to ground level for subsequent flow through the treatment process. The IPS was originally constructed in 1985 and was sized to pump up to 50 million gallons per day. However, in recent years the pump station has been operating beyond its firm capacity during some winter wet weather events, meaning all five pumps and supporting equipment must be in service in order to pump flow that arrives to the plant during those storms. A major capital upgrade is needed to both expand the capacity of the facility and replace obsolete equipment.
Location
The Tri-City WRRF is a regional treatment plant located in Oregon City that serves customers in Gladstone, Happy Valley, Milwaukie, Oregon City, West Linn and unincorporated Clackamas County. Learn more about the Tri-City WRRF.
Project Planning
The recently completed Willamette Facilities Plan charted the path forward for the Tri-City WRRF through the year 2040. As part of the recommended improvements, the immediate need to pump more flow and to accommodate growth was identified for the IPS. Given the urgency for additional capacity, a project was initiated to address the IPS ahead of the future Wet Weather Expansion outlined in the Willamette Facilities Plan.
As of early 2026, the design for these improvements is 60% complete. The project team is currently selecting a Construction Manager/General Contractor to join the team to help finalize the design and begin construction. Work is expected to start in 2027 and will last approximately two years. All construction will take place on the Tri-City WRRF site, and no disruptions to the public are anticipated.
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Inflow and Infiltration Reduction Program (I/I)
I/I is rainwater or groundwater that gets into sewer lines through improper connections or damaged pipes and increases the amount of water that reaches our water resource recovery facilities, which we then have to treat.
I/I also increases the risk of sewer overflows within the collection system.
Reducing I/I in key basins by 2040 would save approximately $120 million in required upgrades and expansion in the collection system and at our treatment facilities.
We’re teaming up with our partner cities that own and maintain their own sewer systems, which deliver wastewater to WES’ treatment facilities to reduce I/I and save our ratepayers money. WES has committed to fund 33% of these projects to help solve this regional issue. We’re pleased to report we have an I/I agreement in place with all of our service area cities.
The WES Technical Advisory Team (TAT) reviews proposals from member communities for program funding.
Projects approved
updated 11/25
| Member Community | Project Name | Estimated Cost | Date Approved by TAT |
|---|---|---|---|
| Oregon City | I/I Program Management through 2026 | $8,500,000 | 3/31/2022 |
| Gladstone | I/I Rehab Design | $482,911 | 3/31/2022 |
| Oregon City | Linn Phase 2 | $1,200,000 | 3/15/2023 |
| Gladstone | I/I Rehab Construction | $1,103,736 | 6/15/2023 |
| Milwaukie | Waverly Heights | $582,000 | 6/15/2023 |
| Oregon City | Rivercrest Phase 4 | $3,000,000 | 9/21/2023 |
| Oregon City | Applegate | $3,000,000 | 9/21/2023 |
| Oregon City | Linn Phase 3 | $6,400,000 | 9/21/2023 |
| Oregon City | Molalla | $4,000,000 | 9/21/2023 |
| Oregon City | Singer Hill | $3,500,000 | 9/21/2023 |
| Oregon City | 2025 Manhole Sealing | $300,000 | 12/19/2024 |
| Milwaukie | Waverly Heights Construction | $1,231,684 | 6/26/25 |
| Gladstone | Cured-in place pipe 25-27 | $1,114,500 | 10/23/25 |
| Oregon City | 2026 Manhole rehab | $536,000 | 10/23/25 |
Completed projects
| Member Community | Project Name | Estimated Cost | Date Approved by TAT | Status | Final project cost | WES contribution |
|---|---|---|---|---|---|---|
| Oregon City | Rivercrest Phase 3 | $2,900,000 | 3/31/2022 | Complete | $3,002,264.24 | $990,747.20 |
| Oregon City | Linn Phase 1 | $2,900,000 | 3/15/23 | Complete | $3,431,603.62 | $1,132,429.19 |
| Oregon City | 2024 manhole rehab | $210,000 | 9/21/23 | Complete | $229,592.4 | $75,765.44 |
Inspecting the pipes
Close circuit TV cameras capture how easily unwanted water can seep into cracked pipes.
Groundwater (infiltration) seeps into sewer pipes through holes, cracks, joint failures, and faulty connections.
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Executive Sessions: BCC, WES and NCPRD - May 2, 2023 - CANCELED
Executive Sessions: BCC, WES and NCPRD
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