A recurring landslide has closed a main north-south road in the Gifford Pinchot National Forest.
Forest Service officials said Forest Road 25 will remain closed at Benham Creek for the winter season while they contemplate a permanent repair. The road is normally closed during the winter because of snowfall.
They closed it early this year because of the threat of a landslide sloughing off Strawberry Mountain.
“The amount of material that appears to be poised to move is … concerning,” said Ron Freeman, public services director for the Vancouver-based Gifford Pinchot.
The Forest Service also is closing the Wakepish Sno-Park, which is at the junction of Forest Road 25 and Forest Road 99 and is the main connection to the Windy Ridge viewpoint northeast of Mount St. Helens. The closure on Forest Road 25 is about five miles north of the junction to Windy Ridge.
The slide threatens a temporary one-lane bridge installed earlier this year.
Forest Service officials installed that bridge after discovering a massive landslide over the winter had taken out a permanent two-lane bridge installed for $1 million only 13 years ago — following a yet another landslide near Benham Creek. In 1996, a landslide associated with widespread flooding in the Northwest wiped out a smaller culvert that carried the creek under the road.
“The whole mountainside is in a slip zone there,” Freeman said.
Freeman said the Federal Highway Administration will underwrite the repair, as it has before, by tapping an emergency fund for federally owned roads. Rather than building another bridge, Freeman said engineers are weighing the possibility of a concrete-lined boxed culvert.
“It would be a lot cheaper to repair and get the road reopened again,” he said.
The alternative would be a large bridge high enough to span the valley. Freeman termed such a span the “bungee-jump alternative” because it would soar across the treetops.
