Watch out for basement flooding

Stormwater surge may back up sewers

Stormwater surge may back up sewers

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• Topics: Bellingham,

There are flood advisories brewing for the snow melt that will be caused by the coming rain.  See the weather advisories at the UofW Weather page for the most recent reports from the U.S. Weather Service.

The last time a weather situation like this occurred in Bellingham was in January 2009, and the City of Bellingham Public Works Department was asleep at the switch.  Basements flooded all over town with sewage backing up through drains.  All homeowners insurance coverage has specific exclusion clauses against sewer backups, and the city hid their negligent incompetence behind sovereign immunity.  The result was that over a dozen homeowners had to eat thousands of dollars of damages.
 
What happens is,  the snow acts like a sponge.  The heavy rainfall saturates the sponge-like snow.  When the snow finally melts, several hours of rainfall is released in very short period of time.  This creates storm flows at levels usually only seen in extraordinarily heavy rainfalls.
 
In many places, the city storm sewers are above the sanitary sewers, and when the storm sewers are overloaded, the excess water gets channeled into the sanitary sewers.  The high flow rates increase the water pressure in the sanitary sewers so the raw sewage surges out of basement floor drains, showers, sinks, and toilets.
 
The city has diversion valves that will vent the excess raw sewage into Bellingham Bay.  In 2009, they delayed for approximately six hours before dumping the excess by opening the valves.  The result of this pointless delay was that many citizens stored tens of thousands of gallons of the city’s raw sewage at great personal expense and damage.
 
My own investigations found that basements in the York and Alderwood neighborhoods were flooded last time.  Because of the silence by the city and the lack of professional reporting by the newspaper, the full extent of the sewage flooding in 2009 was never ascertained.
 
Cliff Mass’ weather blog is here.  

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About Paul deArmond

Closed Account • Member since May 29, 2009

Paul de Armond was a writer, reporter and research analyst. He is the recipient of the Whatcom Human Rights Task Force 2001 Human Rights Award. In the 1990s, he and Jay [...]

Comments by Readers

Paul deArmond

Jan 20, 2012

USWS forecasts are pushing the rain back until late today.  Me may dodge this one.

The chart John posted is an extremely rare weather event: snow, rain, freezing rain and sleet all happening at once!  The height of the bar is the probability, not the intensity.

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Paul deArmond

Jan 20, 2012

Flood watches and warning are now upgraded for Friday afternoon and Saturday morning.

UofW watches and warnings:
http://www.atmos.washington.edu/data/warning_report.WWA.html

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John Servais

Jan 20, 2012

A bit of an update here on Friday morning.  NOAA had predicted rain for this morning with the temperature in the high 30s and going for 45 by this afternoon - with massive melting and back to normal streets and sidewalks. 

What has delayed all this is the jet stream is just north of us and blocking the big low pressure and rain from getting to us.  The jet stream is predicted to dip south of us this afternoon and the temperature will rise.  Exactly when this happens is virtually impossible for NOAA to predict.  Indeed, their 12 hour forecast of rain by 4 am this morning is now replaced with rain by 4 pm this afternoon - a very big busted forecast.

Now, I’m not beating up NOAA - before someone starts telling me I’m being mean.  Even Cliff Mass has noted that the forecasters have really blown it over the past few days.  This weather pattern is very weird and rare - and forecast models just don’t work well for times like this.  And I know just a bit about all this as I served in the Air Force Weather Service - albeit years ago, but I’ve enjoyed the technical aspects of weather all my life.

So, that said - we could start getting sleet or freezing rain anytime from noon today to 10 pm tonight and it could last 20 minutes or 3 hours - depending on how fast the jet stream allows the low pressure and warm front to move in.  For new residents, you will know it is happening when the breeze suddenly springs up from the south east and is slightly warmer.  You will see snow start to fall off thin branches. 

Today could be the slipperiest day of the week with sleet, or the warm front could come in fast with rain and we could go from ice to easily drivable slush in one hour.  But today should be the last day of this snow and ice.

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John Watts

Jan 20, 2012

Paul seems a little harsh on the ‘City’, although John softens it somewhat by recognizing weather forecasts are problematic at best.
A Crosscut article touches on this subject: http://kplu.org/post/fast-melt-could-pose-environmental-challenges

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Paul deArmond

Jan 21, 2012

John, I took $6,000 out of pocket worth of damage and lost 15 years of research archives in the 2009 floods.  When I’m being harsh, you won’t have any doubt about my tone and the proper adjective won’t be “little.”

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