City troubleshoots persistent sewer odors plaguing City Park area

A King County sewer line runs under 3rd Avenue South between the Woodway town line and Edmonds City Park. This line carries flows from Richmond Beach and while no Edmonds homes connect to it, noxious sewage gases often seep up through the vault covers, creating a neighborhood nuisance. Note that the vault cover is clearly marked as part of the Metro system.

It’s a problem that just won’t go away.

For years, residents living between City Park and the Woodway town line have been periodically assaulted by sewer odors rising through residential roof vents and vault covers along 3rd Avenue South.

While the city has taken measures to address this, residents in the area continue to report unpleasant sewage gas odors, and the city responds by working to address the issue.

“We continuously monitor this issue and we have taken several steps to mitigate it — some of those are effective, some not so much — so we are constantly investigating what is possible,” said Edmonds Public Works and Utilities Director Oscar Antillon.

My Edmonds News first reported on the problem in December 2020. At that time, the main culprit appeared to be fumes rising from a King County sewage line through vents in the vault covers along 3rd Avenue South. This line carries waste from King County – no Edmonds homes or businesses are connected. Plugging the vault cover vent holes appeared to afford some relief, but over time these plugs deteriorated and the problem would recur. King County is responsible for maintenance of this line, including periodic inspections and replacement of vault cover plugs as needed.

The vent hole plugs deteriorate over time and need to be replaced.

Our earlier report also noted a secondary source of odor originating from sewage pumped from Edmonds’ Lake Ballinger neighborhood east of Highway 99. While this flow originates from within the City of Edmonds, it travels to the Edmonds wastewater treatment plant through a King County line and is pushed by a King County-owned pumping station near Lake Ballinger. This second line also flows under 3rd Avenue and is connected to homes in the area. At the time of our report, city officials speculated that the pump could be over-pressurizing the line, causing sewage gases to backflow into residential sewage vent systems and be discharged — along with the odors — through rooftop vents.

To address the problem, the city installed a scrubbing station just inside City Park adjacent to the Pine Street/2nd Avenue South intersection. The facility employs a forced-air carbon filtration system designed to depressurize the air in the sewage line and scrub odors at the same time.

A second sewage line also running under 3rd Avenue carries waste from Edmonds homes (note that this vault cover does not identify it as part of the Metro system) in the Lake Ballinger area, which due to differences in elevation must be pumped under pressure. This line also connects to homes in the area, and the pressure is thought to cause sewage gases to periodically backflow into home venting systems and exit through roof vents bringing the odor with it.

While this affords some relief, the problem persists and the city continues efforts to address it.

“We believe that some of the issues are caused during peak flow from King County,” Antillon explained. “We are actively working with them to reduce any peak flows. Starting July 31, they plan to [level this out to] a steady flow, and we will be monitoring to see if that makes a difference.”

In addition, the city is increasing the capacity of the City Park odor scrubber by replacing the carbon filters and increasing the vent motor speed by 18%.

“We have met with numerous residents and explain the challenges with eliminating the odors,” Antillon said, adding the city has ongoing monitoring in place. “We encourage citizens to report these issues via our Fix It Edmonds App. This will help us track and monitor the issue,” he added.

— Story and photos by Larry Vogel

  1. This mess really stinks!
    It’s been going on for years and nobody wants to solve the issue! They keep trying all sorts of things and nothing works – my neighbors are getting tired of the run around! And the smell! Is it a health hazard for the little kids on the street? We are on 2nd Ave S and Elm St and that area seems to be the worst from what we’ve been told! Maybe limit what others can send our way! Maybe our plant can’t handle all the sewage! Come on city let’s get this fixed!

  2. Sorry Tom, can’t hear you. We’re too busy figuring out how to glorify 4th. Ave. up to the ECA to give Edmonds another tourist attraction. First things first, you know. Just wait your turn and keep those comments coming into our shiny new “Fix It Edmonds” App. Enough complaints and this stink baby will be fixed in no time, when we get time, that is.

    1. Your right Clinton – here we sit waiting our turn!
      The Fix-it app got back to me when i filed a request about the smell they told me to call the wastewater treatment plant and gave me the phone number – that isn’t a fix at all! So here we sit waiting our turn!

  3. Tom Schofield, I did a quick google of the hazards of the odor of raw sewage. As I’m sure you know, there are a number of health issues. I also found that raw sewage produces methane. I googled the cost of a methane gas detector. While the prices vary widely, it appears they can be purchased for around $100. Not professional quality, obviously. Should residents have to spend their money to resolve this issue? No. Since it isn’t being resolved, maybe residents getting readings, in their homes of the methane gas could be what attorneys would need for a class action lawsuit. If you and your neighbors have already been checking out this avenue, then just ignore my comment.

  4. The sewage plant on 2nd and Dayton has stunk for the 10 years that I have lived here. It’s not every day, but at least once or twice a week. You can smell it blocks away.

  5. Dawn, there are lots of things in this town that you can smell for blocks away. We had an opportunity to elect a Mayor with a track record of financial knowledge and banking expertise with contacts all over the region and a history of protecting the tax payers money as much as possible on Council. But; it looks like lots or us chose to drink the cool aid of public relations hype and following in the footsteps of all the great Mayors past (great in their own eyes at least). If these guys were such great managers, why have you been sniffing poop for the past 10 years? Nelson has only been the big Kahuna for four of those years you know. What has Mike R. got that these guys didn’t have or will he be more of the same ol’ stuff that we’ve gotten used to ? No specifics about what might be coming down really makes me nervous about him.

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