0203 stormwater

City officials say a new pump station and outfall will better handle stormwater flows from major storm events and keep untreated wastewater from being discharged into Guemes Channel — which, according to a 2019 memo from the Public Works Department to the City Council, “violates the conditions of the city’s National Pollutant Discharge Elimination System permit.” (File photo)

The Anacortes City Council approved a $592,279 contract with HDR Engineering on Monday for design of a pump station that will be part of a new system designed to prevent stormwater and sewer overflows during major storms.

Construction of the pump station is expected to cost about $5 million, and its design is taking place concurrently with that of the new combined sewer outfall, which will replace a current outfall that carries stormwater into Guemes Channel.

The City Council approved on Jan. 25 a $991,523 contract, also with HDR Engineering, for design of the outfall.

All told, the overall cost of the outfall project is expected to cost $22 million. The city will use bond funding but is also seeking a grant from FEMA that would pick up 75% of the cost.

City officials say the new pump station and outfall will better handle stormwater flows from major storm events and keep untreated wastewater from being discharged into Guemes Channel — which, according to a 2019 memo from the Public Works Department to the City Council, “violates the conditions of the city’s National Pollutant Discharge Elimination System permit.”

The city’s stormwater and wastewater systems are largely separate. Stormwater is discharged directly into surrounding waters and is not treated at the city’s wastewater treatment plant.

However, a couple of areas within the city are served by a partially combined sewer system where both the stormwater and sanitary sewer systems are joined, according to the wastewater treatment plant website. Those combined systems — on B Avenue and Q Avenue — have “the potential to allow untreated wastewater combined with stormwater to discharge to Guemes Channel during extreme storm events.”

The wastewater treatment plant has an average daily flow of 1.89 million gallons per day and is permitted for up to 4.5 million gallons per day, according to a wastewater treatment plant report. During a 32-hour rainstorm Feb. 3-4, 2018, the plant released 1.7 million gallons of overflow into the channel via the combined sewer outfall, according to the report.

Once the new outfall is installed, two existing outfalls will be abandoned — the current wastewater treatment plant outfall, which carries treated wastewater to Guemes Channel; and the combined sewer outfall, which carries a mix of stormwater and untreated wastewater to the channel during heavy rains to keep the wastewater treatment plant from being overwhelmed.

With the new outfall, stormwater discharging into the channel is expected to be cleaner. According to the plan, the new outfall will use fine screens to separate solids and debris from flows going into the channel. Public Works Director Fred Buckenmeyer said at the time that the new outfall will be sufficient to accommodate the city through build-out.

“This design is going to be sufficient to handle the effluent during the total design life of the plant — total buildout of the city, according to our latest Comprehensive Plan,” he said. “This outfall will handle all of that effluent. It’s really going to do what we can to eliminate (overflows).”

Buckenmeyer said the project design will take into account predicted increases in rainfall events due to climate change. “We’ve incorporated that. But it’s not to say it’s not exceeded someday,” he said.

Council members asked questions about costs of this project and others related to the wastewater treatment plant.

“I do think it would be useful if sometime in the near future we did take a step back and looked at all the various projects that we’re talking about right now with respect to the wastewater plant,” Councilman Ryan Walters said, an allusion to the costs of the water treatment plant cleanup planning that came in piecemeal, surprising several council members when the total costs were tallied.

Regarding projects at the wastewater treatment plant, Walters said, “There are quite number of them and I think it would be useful for us to have an understanding of all of them at once, including the pieces we don’t have numbers for yet and we don’t know exactly what they’re going to look like.”

Among those projects: an upgrade in the wastewater treatment plant’s system that converts wastewater solids into biosolids; and possible abandonment of a stormwater outfall that runs under Port of Anacortes property, although Buckenmeyer said the city could decide to keep that outfall for emergency use.

Councilman Matt Miller agreed with Walters.

“I’m hoping there might be some additional info that we can glean when we look at our overall — what we are doing in wastewater treatment, because it feels like there’s a bunch of different things going on. It’s kind of hard for us to keep track, and how much we’re spending on various design help is making us a little bit reluctant to make a motion at this point.”

Buckenmeyer pointed out, however, that the pump station is an integral element of the stormwater outfall project. “The outfall itself doesn’t do us any good without this part of it,” he said. “This is what does what we can to eliminate those [overflows]. This is what gets that stormwater into that outfall.”

Miller made the motion to approve the contract, seconded by Councilwoman Carolyn Moulton. The vote was unanimous.

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