Friday, January 9, 2015

WSDOT maintenance crews don’t leave it to beaver

By Justin Fujioka
The upstream side of the culvert was blocked using a
steel plate attached to the end of an articulated crane to
control the release of water and prevent a sudden flood,
which could have put our crews and properties
downstream of Bear Creek in danger.

A dam blocking an 80-foot-long culvert in Woodinville this week was enough to drive Ward and June Cleaver up the wall, and our maintenance crews simply couldn’t leave it to beaver.

The beaver constructed the dam in the center of the culvert that runs under SR 9, just north of SR 522, near Woodinville. No word if he received help from Whitey and Lumpy. The critter’s creation was so clever and well-built that it prevented a large amount of water from an upstream pond from getting through the culvert. This caused the water level of the pond to rise and that’s when we knew this was not just your average beaver dam. So our maintenance team went to work.

In order to safely clear the beaver dam, crews blocked the upstream side of the culvert to control the release of water to prevent a sudden flood, which could have put our crews in danger and affected properties downstream of Bear Creek. The culvert was blocked using a steel plate attached to the end of an articulated crane from a truck, which required the closure of the right lane of northbound SR 9, just north of SR 522.

On the downstream side of the culvert, crews used a grapple hook on the end of a rope attached to a chainsaw winch (basically a giant fishing rod) to grab small chucks of the beaver dam as they slowly broke down the structure.
Grapple hook used to remove small chucks of the beaver dam.

Brave and cold crewmembers walked the grapple hook into the five-foot-wide culvert and dug it into the debris. After safely walking back out of the culvert, the crew started up the chainsaw winch to pull out the grapple hook. Most of the time, it carried out nothing more than a handful of rubble.

Because the dam was estimated to have filled a fourth of the culvert, the process was like chipping away at concrete. Occasionally, the crew would lift the steel plate up to allow water to flow into the culvert with hopes that the force would clear more debris. After eight hours of hard work, the crew’s slow and meticulous approach allowed for the water to flush out the beaver dam.
A rope tied onto the grapple hook was
attached to a chainsaw winch to allow
our maintenance crew to move out of
the culvert and into safety before small
chucks of the beaver dam were removed.

Why was it necessary to remove the beaver dam? Good question. If we would have left the rodent’s dam intact it could have caused water to undermine and damage the highway above it (SR 9) and it could have created potentially damaging flooding downstream. In the past, our crews have removed or modified beaver dams near roadways, but never under one. If you’re interested in more info on when we remove beaver dams, check out this document.

So where’s the eager beaver? Hard to say. Some speculated it was hanging out with Wally and Eddie Haskell. More likely, when humans moved in, it moved on. Typically, we work closely with the Washington Department of Fish and Wildlife to make sure animals are relocated if necessary. In this case, the beaver wasn’t spotted near its dam. Those who frequent the area say they often see a beaver, but it’s usually hanging out in the pond upstream of the culvert. Wherever it is, we salute you and your engineering prowess, Mr. Beaver, but ask that in the future, you show off your skills in less potentially-hazardous spots.

View the video of the beaver dam inside the culvert and how our crews removed it.


Anonymous said...

Technically, an articulated crane rather than a "boom lift," but who's being picky?

Justin Fujioka said...

Yes, you are correct. Thank you.

Anonymous said...

Beavers are one of nature's best engineers. I hope this one has found a nice new home. In the future, if the furry engineer IS around, here's an option:

Toby Tyler Hilden said...

Enjoyed reading, thanks

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