by guest blogger Jamie Holter
Scenes like this made the news in January 2009
But something else was happening near Highway 202 between Fall City and Snoqualmie. Tokul Creek, swollen by the sheer volume of water, changed course and, rather than meandering nicely under Highway 202, it redirected itself and began to erode the riverbank, leaving the banks and the local road unstable.
Engineers are now concerned that heavy fall rain in 2010 will push more debris up against the old concrete piers that support a bridge that’s no longer there.
The debris plugs the water flow and it backs up eroding the bank which can lead to more damage.
During the first week of September, contractor crews from Amir Ahmadi’s Project office began work on a bridge scour repair job on Tokul Creek.
Over the next month, under emergency permits from the Department of Fish and Wildlife and the Army Corps of Engineers, dozens of workers will be on site to remove large amounts of wood and debris trapped near the bridge. They will remove the old concrete bridge piers and armor the new existing bridge piers with large rocks.
But it’s not that easy. You don’t just come in with bulldozers. Biologists are on site to trap and relocate fish. They use this porous curtain to let water pass through but not the fish.
This rainbow trout was one of the first caught and taken downstream.
Then we install something called an aqua dam, a large inflatable filled water to make the area downstream fish and water-free. Pipes installed in the area take the water around the aquadam to a place downstream and out of our work area.
Here is a wide shot of a full inflated aquadam. Isn’t it strange looking?
Over the next few days we will get to work removing debris and hauling in ecology blocks, large light-weight lego-looking type barriers to shore up the existing bridge piers.
Stay tuned and we will provide more about the progress of this project on SR 202.