Residents Advised to Rely on Their Own Judgment to Assess Safety

TThe one clear message from Monday’s hastily called 11 a.m. meeting between San Miguel County officials and Lawson Hill homeowners evacuated in the aftermath of a mud-and-debris slide that announced itself Saturday night, around 8 p.m., was this: There are no right answers.

“There is a great deal of water at the base of the headwall,” acknowledged Tom Griepentrog, an engineer with Buckhorn-Geotech, the civil, structural and geotechnical engineering firm with offices in Telluride, Montrose, Crested Butte, and Gunnison.

Griepentrog was there to report to the crowd of maybe three dozen various scenarios for the future, short-term and long-term.

Griepentrog sketched an approximation of what had caused debris to move down from the headwall to unnervingly close to ten or so homes at Lawson Hill, bringing a mosaic of mud, trees and rock in its wake.

A two-to-three inch crack in the snow at the top of the slope, he explained, could be interpreted to indicate either the “movement or depth” of the large amount of water that has accumulated there this year, thanks to heavy winter snows.

Reporting that he observed no “recharge basins or catchment areas” for the accumulated water, Griepentrog said: “Something happened that caused the [water] pressure to build up and the soil to become weak,” and until the soil is stabilized and the water “diminished,” activity on the slope, where the vegetation shifts from aspen to conifer to landscaping in yards as it descends, will continue.

At what rate it continues is the question of the moment, however, and, as Griepentrog observed: “There is so much snow, and it has got to go somewhere.”

But while water does flow in “historic patterns,” Griepentrog said, “some kind of change,” ranging from an increase in water volume to earth tremors, can change that history. And while “frost is a stabilizing presence,” as is the “network of vegetation” and even the “binding roots” below, water, when it wants to move, begins its downhill flow. And once that flow begins, and the water “hits a harder surface, it begins to flow laterally.”

That lateral flow explains residents’ reports of water gushing from the earth as if from industrial-strength showerheads over the weekend, accompanied by a cacophony of land and debris shifts, cracks and collisions, sounding, as San Miguel County Sheriff Bill Masters described it, “like the whole hillside was coming down.

“When 30,000 gallons gets released at once,” he said, “it sure makes a lot of noise.”

‘Landslide Scars’ Prevalent in the Mountains

In an ideal scenario, “ditches carry water,” Griepentrog told the crowd crammed into the county meeting room, most often depositing that water into existing drainage.

But with excess snows, and no ditches or other pathways for the resulting water, a debris flow like this on is “a naturally occurring event.”

This naturally occurring event can nonetheless cut new pathways and leave behind “landslide scars,” he explained, discernible to the careful observer, despite the fact that, then, “for the next 200 or 300 years, there’s no further movement.”

He reiterated: “With heavy snowpack and accumulation in certain areas,” the terrain tends to develop “a new configuration to accommodate it.”

As water moves downhill – albeit slowly, at ten to twenty feet a day – it creates an active erosion of the surface, which “will continue to migrate uphill,” Griepentrog said.

Containment efforts focus on trying “to funnel that runoff into historic drainage,” which in this case would be Skunk Creek, the body of water closest to the debris flow.

Asked what homeowners could expect if rainstorms gather, as is predicted, later this week, Griepentrog said: “That’s the worst-case scenario.

“May is the month with the most rain,” he added. “The whole thing adds up to a very serious, unstable condition, and the only way to go through it is to watch” for changes and “take appropriate actions.” Then, “as the water begins to recede, we can take more permanent actions.”

Right now, trees and debris on the shifting mountainside are the biggest point of concern. “There’s really not much you can do to hold it,” Griepentrog said, of the “considerable amount of material” teetering on the mountainside. “We can go in with a front loader and keep taking stuff out, but there’s really not much you can do to hold it.”

The most workable solution, until the soil composition becomes dry again, “is to cut [the debris] up in pieces and try to roll it down.”

“The biggest hazard here,” Masters weighed in, “are trees on the slope” that are at risk of being knocked over,” which could then gain enough momentum, in a debris flow, to “to knock homes off their foundations and break gaslines.”

But that’s a doomsday scenario, he hastened to add, and the likelier outcome is “two to three feet” of debris in yards and “you might get a new yard, but it’s not going to kill anyone in their homes.”

Lawson Hill homes are, Masters added, built with their “windows and doors fairly high off the ground,” and covering ground-floor windows with plywood is most likely adequate preparation.

For now.

“It’s still dangerous,” Masters said, telling evacuees to “rely on your judgment [to] decide if you want to be there or not.” He went on to estimate the Sunday morning water flow as clocking in at maybe “30 gallons a minute,” only to double in volume later in the day.

Mother Nature is coping, with already “two or three channels developing now,” reported Deputy Sheriff Brian Beckham, fresh from the scene; water is further being diverted through hastily dug ditches around residents’ homes.

The water, Beckham added, “comes out clear, looking “like old snowmelt.”

Bottom Line: ‘It Slid Out, and There’s Water’

Elk Meadows evacuee Tom Spitzer voiced his concern at Monday’s meeting that “we need to get” the still-draining surface water diverted to Skunk Creek and “we need help with that.

“We must stabilize the hill prior to monsoon season,” Spitzer emphasized.

But while emergency responders dug ditches and hauled sandbags to the threatened landscape, County Administrator Lynn Black emphasized, “our responsibility pretty much ends after the emergency ends.” The county will, she said, pick up the cost of monitoring the soil, for now, and offer help with “paperwork and grant funding.”

The U.S. Forest Service washes its hands of events like this one, she added, which it considers to be “an act of God,” as do insurance companies, observed Lawson resident Bill Ellison. “No Colorado policy covers earth movement or debris flow,” he said.

Homeowners and/or the homeowners association are likeliest to take the helm should the flow lead to mounting problems, Black suggested.

But weekend weather predictions, she said, “look gnarly,” and while power and gas, shut down as an emergency measure, was restored late Monday, additional work on the gas line – now marked with locaters for speedier access – will necessitate a ditch dug down to the main access point, about three or four feet underground.

For now, all that’s certain, said Griepentrog: “The only thing we can say is, it slid out, and there’s water.”

Meanwhile, the sandbags pile up, such precautions as inserting metal rods into the affected soil to be watched carefully for further signs of earth movement are discussed, and hazard areas are being marked, as the evacuees decide whether or not to move back into their homes.

“It’s still dangerous,” Masters emphasized. “You’ve got to rely on your judgment, and decide if you want to be there or not.” But as the debris flow revs up, and the earth shifts, he said, “Unless you’re a deep sleeper, you’re going to know it.”