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Unstable slabs of sandstone sit just above the mouth of the tunnel that carries the BBWA canal under the Rims.
Rich Clawson is convinced the city is going after the wrong rocks.
Rather than taking down the “Santa Claus Rock” that towers over Sixth Avenue North, Clawson said, the city should be worried about unstable rocks, just four blocks west of Santa Claus, that could fall and plug the tunnel that carries the BBWA irrigation canal through the Rims.
If that happens, said Clawson, an artist and builder who used to own property near the tunnel, “it could trigger a disaster.”
His concerns are shared by Allan Workman, superintendent of the Billings Bench Water Association.
“It could block my ditch and flood out the city of Billings,” Workman said. “If something does happen there,” he said a bit later, “it’s going to be catastrophic.”
“There” is just above North 14th Street, where the canal disappears into a concrete culvert that is the start of an 1,800-foot tunnel that carries the water through the Rims, under the valley through which Alkali Creek flows, then up to the bench where the water comes back to the surface and flows north toward Lake Elmo.
On the slope of the Rims directly above the tunnel entrance, there are two enormous, partly detached slabs of sandstone with a capstone on top, straddling the two slabs.
To the left of the rocks there are some rusty cables tethered to the face of the Rims on one side and to one of the giant slabs on the other. They apparently were installed to prevent some other unstable sandstone from sloughing off, and to secure the slab itself.
Gary Hoffman, the ditch rider responsible for maintaining the canal from its beginning near the Laurel water treatment plant on the Yellowstone River to the tunnel entrance, said those cables have been in place since at least 1989, when he went to work for the BBWA.
He said he hasn’t noticed any movement in the rocks since then, but the situation is definitely a concern.
Ed Kemmick/Last Best News
Steel cables were tethered to the Rims decades ago to prevent the rocks from falling into the ditch.
“I’ve thought about that over the years,” he said. “That looks like something that could come tumbling down and fall in the ditch.”
Workman said the rocks, besides being partly detached from the Rims, sit on top of steep, muddy slopes that have been eroding away for years. The sandstone itself is also weakened by harsh weather.
During this exceptionally wet winter, with numerous periods of freezing and thawing, Workman said, “it’s just kind of blown that sandstone stuff apart. … At some point, in my opinion, that rock is going to come down.”
His board of directors hasn’t talked about the potential problem in the past, Workman said, but he plans to bring it up when the board meets in late July.
“It’s one of those kind of things that makes us nervous, but I don’t know how you’d remove those with water in the ditch,” he said.
You could try to restrain any rocks or slabs intentionally brought down, he said, but it would be too risky. If a rock somehow fell in the ditch, the flooding would be intense. To completely stop the flow of water from the intake at Laurel to the tunnel would take about 12 hours, he said.
He said he will talk to the board about the possibility of removing the threatening rocks when the ditch is dry. The BBWA used to own the slope of the Rims above the tunnel, he said, but the city took ownership of it some years ago in exchange for asphalt work inside the tunnel.
Workman said he wasn’t sure whether the association would ask the city to help pay for the rock removal, though it would certainly welcome the help.
Jon Thompson, superintendent of parks for the Parks and Recreation Department, which manages the city-owned land from the top of the Rims down to their base, said the city did pay to remove a giant boulder that fell off the Rims a few years ago and destroyed a house. It also paid for the removal of unstable rock left on the Rims above the site.
But in that case the boulder was still shifting inside what remained of the house and the Rims above posed an imminent threat to the public. When the same company that did that work removed unstable rocks above homes on Shady Lane, he said, the City Council voted not to pay for the work, which was funded instead by the affected homeowners.
Ed Kemmick/Last Best News
Looking east from near the tunnel entrance, Santa Claus Rock, otherise known as the Sentinel, is visible four blocks away.
Meanwhile, the city is still planning to topple the Santa Claus Rock on Sunday morning. City engineer Debi Meling said the formation, which is 25 to 35 feet high and weighs an estimated 150 to 200 tons, will be pulled over backward with cables so that it comes to rest on the ledge on which it sits.
The city hired an engineering firm that concluded earlier this year that the formation was dangerously unstable. It sits right above Sixth Avenue North on top of very steep cliffs.
Clawson has been urging city officials to reconsider plans to take the formation down, saying it was one of seven rocks dubbed “the Sentinels” by the Crow Indians, who believed they guarded a burial ground atop the Rims.
Clawson said he was once told by a Crow historian that six of the Sentinels were lost in an earthquake that preceded — or heralded, in the view of the Crow — the smallpox epidemic of 1837.
That the one Sentinel remains standing shows how stable it is, Clawson said, while the loose slabs above the BBWA present a clearer threat to public safety.
Meling said that even if there is important cultural history attached to the formation, “it doesn’t mean we shouldn’t mitigate the hazard.” She said the city is making an effort to preserve what it can of that history by taking numerous photographs of the rock from a variety of locations.
Later, she said, the city will be working with historians to document whatever was known about the formation.
“It’s not like we’re going to rid the city of that history,” she said.
