North Bend is growing, with the potential for 655 new homes in the next few years, based on building project applications in progress at the city’s planning department. However, its aging sewer system may not be up to future demands.

The city’s 60-year-old wastewater treatment plant is permitted by the Environmental Protection Agency to handle 2.58 million gallons of wastewater per day, but because of a “pinch point” in the system, “the functional limit is 1 million gallons,” City Administrator Londi Lindell told the Record, recapping the information from a March 25 council work session on the issue.

Another EPA-regulated measure, the biochemical oxygen demand, or BOD, which indicates how much oxygen is consumed in breaking down waste material, is on the rise, to a level greater than city officials can understand.

“We are exceptionally high, based on our buildout,” said Lindell. “We only have about 1,300 customers on sewer… our (BOD) load should be around 1,500.”

Despite these problems, the plant is still adequate to the city’s needs, for a while.

“Right now, our remaining capacity is only about 1,200 homes,” Lindell said. “That’s why we’re not doing a sewer moratorium.”

Currently, just over 200 of the expected 655 new homes are permitted.

North Bend has already begun reviewing its options regarding the flow and BOD problems at the 1954 plant, as well as recommendations to improve the reliability of operations, increase safety, and the perennial challenge of reducing odors from the facility.

Among the recommendations were nearly $3 million in urgent needs, as presented by former Public Works Director Frank Page, and another $1.5 million in near-term needs. Project manager Don DeBerg has been acting as public works director since Page resigned last month to return to Wyoming.

Page’s recommendations included new and upgraded equipment at the plant to address the 1 million-gallon flow limitation, and three additional full-time staff at the two-man plant, recommended for this year. Additional improvements recommended for the following four years included reducing the BOD levels and decreasing the inflow of storm or groundwater runoff. Long-term recommendations included updates to the collection system and, based on an estimated 3 percent growth rate that would put the city at its BOD cap around 2021, exploring the idea of a shared regional wastewater facility.

The city’s sewer capital facilities fund has a budgeted $2 million for 2014, Lindell said, and staff is currently reviewing the recommendations to determine which to advise the city council to implement, and which, if any can be delayed, to postpone.

Solving the BOD issue, however, will take consumer education and enforcement.

“We have to go back up the collection system to find out who’s putting materials in that shouldn’t be in there,” Lindell said, and then explain to them the proper disposal methods for things such as cooking oils, or chemicals.

Some of the high-BOD material is now being tested, she said, in an effort to find out where it originated.

Lindell is confident the source of the contaminant is a commercial user, noting that “There was a huge uptick in the BOD around 2012… a single household creates about two pounds of organic matter, so the reason it’s so high is not a household. There must be something else going on.”

Prior to 2011, the city’s monthly maximum BOD load hovered at 1,100 or 1,200, but since then, the load has increased to 2,000 in 2012, and to almost 2,500 last year.

If the BOD levels return to the expected levels, and North Bend makes the capital improvements to address the flow limitation — which only developed recently with the exceptionally wet weather in March, Lindell said — the city’s plant shouldn’t need an expansion. The facility was built in 1954 but has been updated in 1978, 1997, 2000, 2001, 2004 and 2009.

Although the full scope of the solution is still being determined, Lindell expected the city to be responsive to the problems. “We’re not in a sewer moratorium,” she said, “but our goal would be to get the work done in the next two years.”