The pounding rain that flooded the Puget Sound region Monday came during a perfect storm of factors that overwhelmed the capacity of the City of Edmonds’ stormwater system, Public Works and Utilities Director Phil Williams said Wednesday.
“This was the most serious and widespread urban flooding we have experienced for many years,” Williams said. “Some of our senior stormwater personnel say it was more intense than they can recall in the last 20+ years. We are still looking at the data to see if we can confirm that statistically.”
Capacities at two of the city’s pump stations were exceeded Monday night, including the new Beach Place stormwater pumping station located in the parking lot at the Edmonds Fishing Pier.
“It (the Beach Place station) performed well with both pumps being on continuously throughout this event and yet we still had significant flooding at Dayton and SR 104,” Williams said. “That flooding would have been significantly worse without the new pump station operating.” Anothe factor that contributed to Monday’s flooding? An 11.5-foot high tide just prior to storm, which causing the water level at the Edmonds Marsh to be at its highest during the peak rainfall period.
“Our drainage system actually did not fail anywhere in the city, it was simply overwhelmed,” Williams said. “No pipes or structures, embankments, or roads washed out or were plugged-up by any prior inadequate maintenance. They just could not keep up with the amount of water and sediment being generated by this intense storm event. You can design drainage systems using a reasonable worst case storm intensity but you can’t protect yourself from every possible event.”
Williams also said that most climatologists who have reviewed how the region will respond to longer-term climate trends have predicted the Pacific Northwest will experience more of its annual precipitation during the winter months and more of that coming in fewer, but more intense, storm events.
He added that the city’s planned Edmonds Marsh restoration project will extend the benefits of the city’s new pump station investment. The project includes construction of some berms on the east side of Highway 104 to limit the amount of water from Shellabarger Creek that can go north from the highway’s culverts to the Dayton storm system. It also calls for flap gates on the drains from the Harbor Square Business Complex “that would add to the benefits achieved with the pump station,” Williams said.
“We will likely pursue these sooner rather than later since the main stormwater-related marsh project — the daylighting of Willow Creek and Shellabarger Creek — may not happen now as soon as we had hoped,” Williams said. That project has had to wait for property ownership issues to be sorted out regarding the nearby Unocal site, which has been undergoing cleanup of contaminated soil.
— By Teresa Wippel
I have lived in this area for 41 years and have seen the flooding at SR-104 and Sunset many times. I don’t recall any storm with the wind as strong and the rain as heavy as what we experienced on Monday. Apparently the flooding would have been much worse without the new Beach Place installation. I’d be interested in knowing how generally many inches of rain caused the past flooding and how many inches we had on Monday. Hopefully the past flooding would have not happened had we had the Beach Place installation.
Hats off to the Public Works teams – I called about the manhole cover on 88th and Olympic View that looked like the fountain in downtown, and the crews were responsive and worked their tails off to get to all of the hotspots.
Thanks for the update, Phil. I wonder if the direction of the storm was significantly different.
Usually in any strong storm the windows on the south side of my house are battered with rain. This time it was the windows on the west side which were battered and significantly more than I remember in past storms. I hope we will find out the inches of rain which fell.
We moved to Edmonds in 2012 and in August 2013 there was a rain storm that was referenced as a 100 year occurrence. At least that was what was on the news and what the city referenced when we tried to recover some of the costs from the flooding that came from the street (600 block of Maple) into our driveway (7 inches deep on our garage door). The garage and downstairs flooded with damage costing us $10,000 to dry out, replace a foot of wallboard and replace carpet. This was street water flooding so not covered by homeowner’s insurance. There was significant flooding further down Dayton, etc. and there should be plenty of city records on that event. In fairness to the city they did put a new drain in front of my neighbor’s house on our side of the street about 9 months later which has helped tremendously. Not sure of the inches of rain in comparison but it certainly seemed worse to us than Monday.
On August 29th, 2013 we had a flood here on Aloha Way causing our finished basement to flood. Cost us $50,000 to fix. Uninsured because we don’t live in a flood zone. We had to have a new drain installed at the bottom of the driveway to the tune of $10,000. So far, so good.