Digging into the Deschutes River in Bend
三月 05, 2014
Bend BulletinBy Dylan J. Darling
An excavator crawled through the water of the Deschutes River in Bend on Tuesday, just north of the Colorado Avenue Bridge. The big yellow tractor pulled up samples of river rock to help planners understand what they’re starting with as they design safe passage around the Colorado Dam.
“We just had to go out and see what was is in the river and this was the best way to do it,” said Brian Hudspeth, construction manager for the Bend Park & Recreation District.
Results from the sampling will be used by planners as they design a new, safer way to pass over the Colorado Bridge. The $7 million-plus safe-passage project is among park projects around town partially funded by a $29 million bond approved by voters in November 2012. A new footbridge and a whitewater play area would be part of the safe-passage project.
The Bend Paddle Trail Alliance is still raising funds for the $900,000 it has committed to the project. So far the all-volunteer group has brought in more than $600,000, said Jayson Bowerman, a board member the group.
If permitting goes as planned, he said, riverside work could start in July and in-water work could start in September, with the whitewater play area opening in June 2015.
The holes dug by the excavator Tuesday were similar to “test pits,” he said, which engineers use at planned construction sites to understand what’s in the ground where they plan to build.
“People dig them all the time on the land,” Hudspeth said. “It is just different when you do them on the water.”
He said the sampling was done Tuesday because irrigation districts were pulling water from the river upstream of the Colorado Avenue Bridge for stock runs, lowering the river level.
The excavator dug five holes in the riverbed, going down 5 feet deep each time, said Shane Cochran, staff geologist at the Wallace Group, a Bend-based environmental engineering firm. Cochran and Mark Herbert, principal geotechnical engineer for the company, both wore waders and life jackets and were out in the chilly river with the excavator.
They pulled the samples — each enough to fill a 5-gallon bucket — from the excavator’s scoop and lugged them to the shore.
Park district workers helped move the samples to their truck and the excavator, driven by Jeff Taylor of Bend-based Taylor Northwest, refilled the holes in the riverbed.
The samples will be examined at a lab, but Herbert did say they were surprised to see how large some of the rocks were deep in the holes. Fine, sandy rocks down deep could lead to erosion when larger rocks are placed on top of them.
“We were basically looking for coarse stuff or fine stuff — to see what there really is,” Cochran said.
A draft report with results from the sampling should be done next week, he said.
The Wallace Group drilled core samples around the same section of river in November, also looking to see what was under the riverbed. They found basalt bedrock 40-50 feet below the bottom of the river, and although the core samples revealed what kind of rock is between the bedrock and river, Hudspeth said they didn’t show what size the material was.
“The drilling didn’t tell us everything we needed to know,” he said.
Before the excavator, or “trackhoe,” went into the river, it was power washed and its hydraulic fluid was replaced with vegetable oil, said Todd Taylor, president and CEO of Taylor Northwest.
“So it is about a $1,500 prep job,” he said.
The sight of the excavator moving through the river Tuesday caused joggers, dog walkers and other passersby to stop and see what was happening in the Deschutes.
“I thought maybe they took a wrong turn,” said Bret Graham, 54, of Bend.
Graham, owner of the Bend Tour Company, was out riding a Segways with Dustin Riley, 39, of Bend.
Emily Fridae, a pilates instructor at Peach Pilates, stopped her walk with a friend to check out the in-water work.
“We were just trying to figure out how it got in,” she said.
The machinery had eased into the river from a low spot on the western riverbank, just north of the Colorado Avenue Bridge.
— Reporter: 541-617-7812, email@example.com
Editor’s note: This story has been corrected. In the original version, the compass direction in relation to the Colorado Avenue Bridge was incorrect.
The Bulletin regrets the error.
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