Rock work rumbles on in Spearfish Canyon

By Kevin Woster, Journal staff | Thursday, January 17, 2008

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State highway officials expect to have U.S. Highway 14A in Spearfish Canyon open to limited vehicle travel Thursday, Jan. 17, as work continues to remove dangerous rocks on the canyon wall near Bridal Veil Falls.

Steve Palmer, project engineer for the state Department of Transportation, said late Wednesday afternoon that crews were loading rocks broken loose by explosive blasts on Saturday and expected to allow traffic through the canyon sometime early in the evening.

Crews will continue drilling on the rock formation Thursday in preparation for further blasts. But traffic will be allowed to pass the barriers for a few minutes each hour during breaks in the work.

"We're trying to get back to our original game plan, which was to let traffic through at the top of the hour," Palmer said. "We're at a point where hopefully we can begin that sometime tomorrow," he said Wednesday.

Updates are available online at www.sddot.com, by calling 641-5446 or tuning your radio to AM 1670.

Palmer is hesitant to make long-range predictions because the rock-removal project has turned out to be more complicated than expected. Originally, DOT officials hoped to allow traffic through each hour during brief breaks in work on the rocks. The plan called for the road to be closed for longer periods to allow explosive charges to be set off and rocks to be removed.

The plan was to close the road completely last Thursday, Jan. 10, during more blasting operations but reopen it that evening. Then, there would be periodic closures for other blasts but hourly traffic flow most days.

Instead, however, Highway 14A has been closed since Jan. 10 at both ends of the canyon. Traffic into the upper parts of the canyon above Bridal Veil Falls is allowed by way of U.S. Highway 85.

A contract crew from Colorado set off two explosive blasts Tuesday, the second of which "moved a lot of material," Palmer said. The crew is drilling today in preparation for more blasts in the coming days.

Although the project has proven more difficult than expected, the contract bid was for about two weeks of work for $90,000.

"We're not really overrunning yet," Palmer said.

But he couldn't say how long the project would take or how many more disruptions in traffic flow through the canyon there might be. Although DOT periodically hires crews for smaller rock-removal projects in the canyon, they rarely involved explosives and haven't been so complicated.

Less-troublesome rock formations are identified by highway-maintenance crews as they clean up periodic rock-slide debris in the canyon. If overhanging rocks are serious enough, DOT then hires a private crew to go up and pry them off.

The current project came after a warning from a geology professor at South Dakota School of Mines & Technology, who noticed splits in the rock during a field trip above the canyon wall. The crew is trying to remove three "large features" up on the wall but has struggled with the first one since Jan. 10.

"On the first shot, we assumed everything was going to come down," Palmer said. "Well, much to our surprise, it was still standing there."

It took drilling and several blasts to recognize a "key holding the rock in shape" that wasn't visible before the blasting began, Palmer said. Crews are getting close to dislodging that key and hope to move onto the other targeted rock formations next, he said.

Palmer said he understands why people might wonder how a part of the wall that was considered a rock-slide threat could prove to be so sturdy.

"We ask ourselves the same question," he said. "Believe me, we've had a lot of discussion while we've been standing up there."

Palmer wouldn't try to predict when the job might be finished.

"I wish it hadn't happened this way. But once you're into it, you're committed," he said. "You've got to finish the job."

Palmer said the crews plan to drill extensively into the rock today and possibly on Friday, then "bring it down with one shot" of explosives.

He expects on-the-hour travel to continue Friday, and throughout the project, except during blast periods.

Contact Kevin Woster at 394-8413 or kevin.woster@rapidcityjournal.com