Bend presents preliminary findings from collection system master plan update; few near‑term capacity hotspots identified

City of Bend Chief Operating Officer Russ Grayson told the Community Building Subcommittee on Aug. 11 that the city is updating its collection system master plan (CSMP) and coordinating that work with a separate Water Reclamation Facility (WRF) facility plan update.

"We did strategically make that decision to split them apart," Grayson said, describing the two parallel efforts and the plan to merge findings into a single capital improvement plan (CIP).

The project team said the CSMP update will: refresh land‑use and population assumptions used for hydraulic modeling; evaluate existing infrastructure for condition and capacity; develop a 20‑year CIP for the collection system; recommend operations and maintenance changes; and align sewer projects with a rate strategy for council consideration.

"The purpose of the updated CSMP is to update the existing assumptions around land use and population growth, economic forecast, etcetera," Lisa Cameli, project manager for the CSMP update, told the subcommittee.

Cameli and Jason (principal engineer, wastewater side) said the collection system is predominantly gravity pipe with approximately 2.25 million linear feet of gravity mains, regional pump stations and many smaller residential pressure systems. The last master plan was adopted in February 2014; the city later updated portions in 2018 when the urban growth boundary changed.

Preliminary capacity modeling shows only localized near‑term concerns. Cameli showed maps that use a 5/10/20‑year visualization tied to current comprehensive‑plan density assumptions. "If we left the system alone and just maintained it, this is where we would start to see issues," she said, describing surcharging near Shevlin and Mount Washington in the current and five‑year projections. The team said River Rim pump station and parts of the southern expansion (near Caldera Springs) are areas to monitor as development proceeds.

Ryan Oster, engineering director, said the city has been monitoring flow triggers placed at specified manholes. "Thus far, we're finding that in the concerns around the central interceptor and the east interceptor, we haven't even reached 50% of the trigger flow at this point in time," Oster said, noting that existing flow monitoring data have reduced previous assumptions about infiltration and wet‑weather inflow in some areas.

Staff described the central interceptor as showing condition issues that will require rehabilitation; they said that when sections require repair the city will consider whether to rehabilitate in place or replace and upsize to meet longer‑term needs.

On condition assessment, staff said the city has CCTV and manhole inspection data covering more than 85% of gravity mains. Cameli said the consultant assessed six larger pump stations so far and noted limited data on pressurized force mains because inspection on those pipes is costly and technically difficult.

The team summarized condition risk: most of Bend's gravity system scored in the lower risk band (roughly a 2 on a 1–5 scale). The highest near‑term replacement need is about 10 miles of pipe—roughly 2–3% of the system—identified for priority repair or replacement.

Planned next steps include an optimization workshop, drafting the 20‑year CIP (aligned with the WRF facility plan), a repair‑and‑replacement program using trenchless tools such as cured‑in‑place pipe where appropriate, and an October 2025 milestone for initial optimization results. Staff said they will return to the subcommittee in early 2026 with draft CIP prioritization and then to full council with a combined WRF/CSMP CIP for adoption.

The presentation emphasized that the CSMP is a planning tool: short‑term monitoring and flow triggers will drive when the city needs to move projects into design and construction, and the CIP will be dynamic as growth patterns change.

"These are the preliminary findings," Jason said. "We are showing you what we have."