Clackamas County awards $7m design contract for Tri-City wet-weather expansion
Clackamas County, Oregon · Meeting date: November 5, 2026 · Published: November 6, 2026
Water Environment Services has selected Jacobs Engineering Group, supported by Carollo Engineers, to design landfill remediation and advance preliminary design for new peak-flow treatment at the Tri-City Water Resource Recovery Facility. The programme is intended to support treatment of up to 105mgd through 2040 while meeting discharge-permit requirements.
Key points
- WES approved a $7,003,049 contract with Jacobs Engineering Group for the Tri-City Wet Weather Expansion Project, funded from sanitary sewer construction funds.
- The project is intended to provide dedicated wet-weather treatment capacity for peak flows of up to 105mgd through 2040.
- Jacobs will complete landfill-remediation design and take the wet-weather facilities to 30% design; later-stage facility design would require a future contract amendment.
- The proposed works include screening, ballasted sedimentation, disinfection, connecting pipework and electrical upgrades, with construction planned in two packages.
- WES has received a $210,000 FEMA Hazard Mitigation Grant Program award for evaluation of electrical and backup-power reliability.
Full report
Clackamas County’s Water Environment Services has approved a $7,003,049 engineering-services contract with Jacobs Engineering Group for the Wet Weather Expansion Project at the Tri-City Water Resource Recovery Facility, setting in motion a capacity programme that also addresses remediation obligations at the adjacent Old Rossman Landfill.
Jacobs, with Carollo Engineers as a major subconsultant, was selected through qualifications-based RFP #2025-94. The contract is funded through WES sanitary sewer construction funds and runs to June 30, 2031.
The Tri-City facility is expected to assume a larger regional role under the Willamette Facilities Plan, treating flows from Gladstone, Oregon City and West Linn, as well as flows transferred from the Kellogg Creek service area through the Intertie Pump Station. A companion facilities plan recommended dedicated wet-weather treatment facilities to enable the plant to reliably handle peak flows of up to 105 million gallons per day through 2040 while continuing to meet discharge-permit requirements.
The planned wet-weather expansion includes new screening, high-rate ballasted sedimentation, disinfection, connecting pipework and electrical improvements. The treatment facilities are planned on part of the Old Rossman Landfill beside the existing plant, requiring site remediation before construction. That work includes management of contaminated soil, landfill capping and gas collection, and will address WES obligations under a DEQ-approved Prospective Purchase Agreement for the landfill property.
The Jacobs contract authorises full design of the landfill remediation package, as well as permitting, geotechnical investigation, surveying and a basis-of-design report. It also takes the wet-weather treatment facilities to 30% design. WES expects that milestone in October 2027, while the landfill remediation design is expected to reach 100% in March 2028.
The phased approach allows WES to refine the construction-cost estimate and confirm the delivery strategy for the treatment facilities before committing to the remainder of design. The landfill remediation is planned as a traditional low-bid contract. The wet-weather facilities are anticipated to use a construction manager/general contractor approach, bringing a contractor into design to address cost, constructability and schedule risk within an operating treatment plant. WES said the delivery method will be confirmed as design advances.
The engineering work will also evaluate reliability of existing electrical and standby-power systems, following outages experienced during the 2020 Labor Day fires and 2021 ice storm. WES has been awarded a $210,000 FEMA Hazard Mitigation Grant Program grant for that evaluation and expects to use it to offset part of the contract cost.
This summary was generated by AI based on the source document and may contain errors.
Source: Board of County Commissioners Business Meeting, Clackamas County