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Wall is DOT’s cure for landslides

11:37 am November 4th, 2013

By Pat Jenkins
The Dispatch
Landslides will still happen,
but they shouldn’t be a problem
any more for people traveling
on State Route 7 in the Alder Canyon
area now that a permanent containment
wall has been built.
That’s the word from state Department
of Transportation (DOT)
officials following the earlier-thanexpected
completion of the wall
made from pilings and timbers at a
cost of nearly $1 million.
Rocks and other debris that
tumbled from a hillside onto the
two-lane highway periodically in
recent years threatened the safety
of motorists and caused temporary
closures. After a lengthy study by
DOT geotechnical engineers, including
electronic monitoring and
tests of the slope, officials designed
a wall and hired Scarsella Brothers,
a Kent-based company, to build it.
While the hillside remains unstable,
its castoffs should stay behind
the new barrier, officials said.
“The slides won’t stop, but the
wall can hold back a large amount of
debris,” said Jan Deffenbacher, the
project engineer for DOT. When it’s
time to remove a buildup of rocks
and earth, highway workers will be
able to remove sections of the wall
to get to the stuff and haul it away.
A five-mile stretch of highway
near La Grande was closed early in July for what DOT expected would
be a five-month construction project.
But a long, dry summer enabled
Scarsella and its sub-contractors to
finish the work and reopen the
highway Oct. 5, nearly two months
ahead of schedule – much to the delight
of drivers who no longer had
to take detours on their commutes
or on trips to Mount Rainier National
Park.
The early completion “caught us
by surprise,” said Deffenbacher. He
noted that workers boring through
the rocky terrain with massive drills
to create holes for the steel piling
supporting the wall finished “faster
than we thought. We weren’t expecting
that, because we knew the
work would be a challenge.”
Part of the challenge was the
safety of crews working beneath a
hillside with a history of not staying
put. Using electronic monitoring
devices placed in the slope, DOT
engineers could remotely keep track
of any shifting and whether the potential
for slides was increasing.
“It was definitely a hazard,” Deffenbacher
said. “There was always
a chance of debris coming down.
There were regular safety meetings
for the workers to remind them of
precautions. But we got through
it with no injuries or serious incidents.”
Among other work, 30 support
piles were sunk up to 12 feet deep.
The contract for the total project
was for $950,000.
Last May, after one of the last
slides, 300 cubic yards of rocks and
debris were removed from the highway.
With those days apparently
over, drivers once again are cruising
through the stretch of highway that
has a speed limit of 50. The only
time they could do that during the
summer was one weekend in August
and one weekend in September,
when the highway was opened
temporarily to accommodate heavy
traffic for the Morton Loggers Jubilee
and the Labor Day holiday,
respectively.
A spokeswoman said DOT
thanks motorists, businesses and
residents affected by the closure and
along the detour route “for their
patience and tolerance” during the
closure.

The retaining wall on State Route 7 near La Grande was finished about two months earlier than expected. (DOT/courtesy photo)

The retaining wall on State Route 7 near La Grande was finished about two months earlier than expected. (DOT/courtesy photo)

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