Bend projects tackle near-capacity sewer system

Bend’s sewer collection system is near capacity — and in some areas, existing sewer pipes routinely approach overflow levels, city officials said Friday as they outlined projects underway to relieve the problems.

The Sewer Infrastructure Advisory Group, a citizen panel charged with finding an affordable solution for Bend’s pressing sewer problems, were presented the results of Bend’s sewer capacity modeling on Thursday.

The results confirm three major sewer upgrades already underway are needed now.

The Southeast Interceptor—partially built—is a gravity pipeline that will serve a large portion of Bend’s south, southeast and eastside neighborhoods. The pipeline also diverts flow from the City’s downtown sewers relieving pressure on those sewer lines. This will allow for additional development and infill to occur on the west side of the river and in the central part of the service area.
The Colorado Lift Station, an “up-sizable” sewage pumping facility currently being designed, is the other critical project needed to convey wastewater from Bend’s west side.
The North area sewer improvements, consisting of pipeline/flow solutions, will add capacity to Bend’s north employment lands in the vicinity of the Highway 20 and 97 confluence.

The modeling results show significant dollar savings for solving capacity issues in Bend’s outmoded collection system, compared to an earlier system improvement plan, city officials said.

The current planning process also reveals how projects could be phased over the next 20 years.

“Phasing these critical projects over time reduces the need for significant immediate rate increases and allows future Bend residents and businesses that will benefit to help shoulder the cost for upgrades,” said Assistant City Manager Jon Skidmore.

With the proposed project schedule, the first five years of capacity projects can be completed for about $40 million. Additional projects won’t be started until sewer flow data collected confirms the need.

“We will focus all of our effort and resources on fixing the sewer collection system’s biggest problems first,” said Tom Hickmann, the city’s engineering and infrastructure planning director.

Project cost estimates and effects on sewer rates will be presented at the May 1 SIAG meeting.

Bend is using an optimized modeling and planning process which utilizes advanced computer algorithms to evaluate tens of thousands of infrastructure design alternatives to find the right mix of pipes, pumps, storage and treatment. The modeling team, headed by Murray, Smith & Associates, Inc., includes a diverse group of consultants.

Joel Wilson. P.E., of WCS Engineering and Optimatics, has provided the optimization modeling software and expertise allowing for the identification of the lowest life cycle cost solutions. Both firms have an international focus completing similar projects for other utilities around the world. City of Bend staff and other local engineers contribute a critical local perspective to ensure solutions are practical and implementable.

“Bend’s sewer collection system is reaching capacity in many parts of town. That’s a problem needing immediate action,” said Wilson. “My role is bridging the gap between new, innovative optimization modeling technology, the sound engineering judgment of Bend’s professionals, and input from SIAG,” Wilson explains.

Sewer Infrastructure Advisory Group members will present the optimization findings to the Bend City Council on May 21. The group is also offering presentations to neighborhood associations, civic groups and other organizations before making their final recommendations in the fall. Community members can learn more at bendoregon.gov/siag.