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Council poised to approve new wastewater master plan

Sewer rates likely to rise


The Lake Oswego City Council is poised to approve a sewer master plan that will lead to higher wastewater rates in coming years.

The plan aims to deal with infrastructure needs coming down the pike, including repairs, upgrades and expansion of the city’s sewer pipes and pump stations. The city council will consider it at a meeting starting at 6 p.m. Tuesday at city hall.

While the city recently completed the $90 million Lake Oswego Interceptor Sewer project, many more sewer pipes and pump stations are coming to the end of their lifespan.

The work on the LOIS project “was a piece of the puzzle, granted it was a huge, integral part of it because it collects a lot,” said Erica Rooney, assistant city engineer. The updated wastewater master plan “focuses on the rest of the system.”

“Upstream from LOIS, there are all these other pipes and things that go up into the hills and serve all of the neighborhoods,” she said. The master plan is essentially a replacement schedule for the wastewater system, outlining its age, condition and needs.

In all, the work is expected to cost about $70 million over the next few decades.by: SUBMITTED - When a sewer overflows, backs up or has too much rainwater in it, it can spill over into the street through a manhole. Thats what happened here on Cardinal Lane a few years ago. While this location was improved during recent work on the interceptor sewer, other areas of the city remain at risk of similar sewer capacity problems.

The city still needs to settle on a plan to finance the projects. Last week, the council reviewed a few options, which varied in how quickly projects would be completed and when and how fast sewer rates would rise.

None supported a scenario putting off projects and foregoing rate increases for a number of years, a period that would be followed by spikes in rates.

Instead, most councilors favored ratcheting up rates by 3 percent annually to gradually increase revenue for projects. This approach would result in the lowest average fees: about $78 monthly for the typical household over the next 15 years.

Another option is to increase the rates more at first so the city could complete projects sooner.

Councilor Mary Olson said she likes the idea of gradual fee increases, “something people can plan on and budget for.”

She also urged officials to prioritize any projects that show Lake Oswego is reducing its sewage flows, which could minimize the city’s costs for future upgrades at the Tryon Creek sewage treatment plant.

Councilor Mike Kehoe also supported steady increases but said he’d like to review some of the assumptions driving the updated master plan.

Councilor Sally Moncrieff said she supports any approach that raises rates gradually, although she preferred the option that starts more projects sooner. It’s less expensive to maintain the system than to repair it after a major failure.

“The sooner we fix it, the more options we have and the least costly things are,” she said.

Moncrieff also stressed the need to protect the public’s $90 million investment in the LOIS project, which was designed with the caveat that additional infrastructure upgrades would later be needed to deal with inflow and infiltration.

By far, the city’s biggest wastewater problem stems from inflow and infiltration, engineers said.

Inflow happens when drainage pipes that should be part of the stormwater system are mistakenly connected to the sewer system, funneling rain into sewer pipes instead. Infiltration occurs when the ground becomes saturated by rain, and the excess water seeps through loose joints in pipes. In either case, too much water flows into the sewer system.

During big storms in Lake Oswego, there is so much water in the sewer pipes, it sometimes looks like a combined system, the type in which the pipes are actually meant to handle both wastewater and stormwater.

“You have a separated system that is responding and looking a lot like a combined system,” Engineer Bob Eimstad of Carollo Engineers, a firm hired by the city in 2010 to provide technical expertise, told the city council last week.

If the city doesn’t fix pump stations, they could eventually suffer catastrophic failures, with sewage welling up through manholes in the streets and overflowing into Oswego Lake and the Willamette River, consultants said.

If a pump station fails it either overflows or backs up elsewhere in the system, Eimstad explained.

“It will come out somewhere,” he said. “The flow keeps coming, and if you’re not pumping it out it will come out of people’s basements (and) all sorts of places, none of them good.”

If a pump station had an overflow, officials would be obligated to report it to the department of environmental quality, which could take enforcement action against the city, he noted.

The wastewater master plan is required as part of the city’s comprehensive plan. It has been updated two other times over the past 45 years. The last review was in 1989. The new plan aims to guide sewer infrastructure projects through 2045.



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