Crews use diamonds to protect the environment

From ODOT-

When the I-5 Willamette River Bridge project is finished in 2014, we’ll see a beautiful pair of arched bridges, touching down in the river only once. That’s quite a contrast to the original bridge and its temporary replacement, which were supported by scores of concrete columns marching across the river.



This month, we began removing the last series of 21 columns from the temporary detour bridge. We’re doing this work carefully because we’re committed to protecting, preserving and enhancing the river environment during construction. In fact, we’re striving to keep all debris out of the river and will cut the columns off at the riverbed to remove any trace they ever existed.



It’s a big job. Each remaining column is demolished above the work bridge using big hydraulic hammers. The work bridge catches all the concrete and steel debris, which is recycled.



Crews then remove the work bridge surrounding each column. This allows them to use a special diamond-encrusted flexible wire saw to cut and remove each column in sections, all the way to the bottom of the river. Each cut section is lifted onto the bridge, where it is demolished and recycled.

Here's a close-up of the special wire saw. It's ultra-sharp, cuts clean and creates only a fine dust that eliminates any environmental impact to the river.

Cutting the columns below the waterline is a big improvement over earlier demolition methods, which required building an intrusive cofferdam to reroute the river, then demolishing columns directly on the riverbed’s mud. And it’s also safer for the environment and workers alike.

Here is the diamond saw removing columns on the original Willamette River Bridge two years ago. The smooth top surface shows where the saw previously cut through the concrete column and connecting wall. Workers stop the saw regularly so they can descend on ladders to drive big steel wedges into the cut to prevent binding.

ODOT and our contractor, Hamilton Construction, are committed to leaving the project site and local environment in better condition than before construction began.