Having an observatory right in the path of Mount St. Helens’ 1980 eruption is a double-edged sword.
At Johnston Ridge — the very end of state Route 504, the “Spirit Lake Highway” — visitors can observe the near constant changes in the volcanic landscape. The ridge is accessible to all, too, making it the perfect for those who wish to “ooh” and “ahh” at the volcano’s crater.
On the other edge, the eruption wasn’t so long ago. Especially not on the geological time scale.
Challenges such as the May 14 debris slide at Coldwater Creek, are really “par for the course,” said U.S. Forest Service spokesperson Gala Miller in a recent interview.
Work to restore access to the upper reaches of the highway by Seattle-based construction company Scarsella Brothers, Inc. began at the site early this week. Public access won’t be restored to Johnston Ridge until the spring of 2024 (regardless, the road is closed throughout the winter every year).
Rather than restoring the bridge, crews have two culverts for the creek’s flow. Atop the metal tubes, they’re repurposing soil from the slide, refining it, and pouring enough dirt down to drive across, one vehicle at a time.
At first, the various agencies involved — USGS, the Forest Service, Washington State Department of Transportation (WSDOT), the Army Corps of Engineers and neighboring county responders — had a good guess for the slide’s cause. On Thursday morning at the slide, WSDOT project manager Paul Mason was definitive.
A winter of heavy snow covered the young, ashy soil abutting Coldwater Creek. When an early May heatwave melted the snow in record time, the oversaturated ground couldn’t keep its foothold. Around 9 p.m. on Sunday, May 14, debris from a hillside just upstream pummeled the highway and washed out an 85-foot bridge. The event lasted 30 minutes. With around 300,000 cubic yards of debris sliding downhill, it was enough to cause a blip on USGS seismometers.
For the non-engineer, Mason quantified the debris slide as 120 dump trucks of debris per minute.
“When this slide first came through, if you stepped in the wrong spot, you were sinking in a good 10 inches,” Mason said.
Nobody was harmed. Two of the seven total vehicles in the now-unreachable parking lot were rental cars, Mason said. One of the rental car drivers was “a gentleman from Europe,” he added, so the slide “definitely affected folks that were not necessarily local.”
WSDOT’s contract with Scarsella Brothers is around a half million dollars. For Chehalis WSDOT office-based Mason, that’s a drop in the bucket compared to costs for construction he’s seen on Interstate 5 around Fife and Tacoma.
WSDOT is footing the bill, he said, and the other agencies involved may help to reimburse it. With the culvert and “shoefly” detour — meaning, it’s off the normal line of the road — agencies will have a suite of options for the permanent fix, Mason said. Due to state and federal environmental policy act evaluations and other building regulations, Mason said, getting the go ahead for bridges and permanent roadways is a yearslong process. This work will ensure most repair options are viable when the time comes.
“There are so many question marks at this point,” Mason said. “(The permanent solution) is speculative at this point in time, but that’s the rationale.”
For the rest of this summer, public access at the National Volcanic Monument ends just a few miles before Johnston Ridge. Much of the monument’s most scenic visits are still open, including Coldwater Lake, the Hummocks Trail and the Ape Caves. The U.S. Forest Service announced in a news release on Thursday evening that Forest Road 99 is now open, which provides access to Windy Ridge from the north.
The Mount St. Helens Institute, at the Coldwater Science and Learning Center, is also hosting interpretive programs from the Forest Service along with its usual educational opportunities.
Plan a trip to the national monument at https://www.fs.usda.gov/visit/destination/mount-st-helens-national-volcanic-monument-0.
