Monday, August 16, 2010

Haywood County Mountain Real Estate: The Cascades Subdivision Landslide

Haywood County, North Carolina Landslide Map

Unpublished Haywood County Stability Index Hazard Map.
Risk models show that 49% of Haywood County land is unstable.

Haywood County, North Carolina Real Estate: Hazardous-Land Disclosure

Realtors are currently not obliged to disclose that Haywood County is one of twenty-one Western North Carolina counties designated landslide-hazardous by Federal Emergency Management Agency officials.

As the following article details, the decision to buy mountain real estate should be carefully considered. Although not discussed in The Mountaineer report, the financial risks are significant: Landslide insurance is not purchasable and homeowners' associations are responsible for its private roads.

The Cascades Subdivision Landslide

Photo 1-View looking up the track of the August 31, 2006 embankment failure-debris flow from the development road near lot 107.

Photo 2-View looking downslope at the debris deposit and damage to lot 107
Photo 3-View of cracks in embankment extending northeast from the head scarp of the August 31, 2006 embankment failure-debris flow
Photos compliments of the North Carolina Geological Survey
"A Whopper of a Slide"—Jeff Schmerker
The Mountaineer September 12, 2006

Breathtaking. That's the word Marc Pruett, the county's erosion control supervisor, is using to describe a landslide which occurred late last Thursday on a steep mountainside high above Maggie Valley.

Several orders of magnitude larger than anything in recent memory, the slide, in an under-construction 700 acre subdivision tentatively called The Cascades, might be one of the largest slides ever to occur in the county as a result of development activity.

The slide measures 125 across and runs for about 1,300 linear feet, or about 650 vertical feet.

The development is owned by Maurice Wilder of Clearwater, Fla. Wilder, who flew over the site on Friday, may have been the first to actually find it, said James Guy, the project manager. Though the slide was not witnessed, workers at the site say it occurred after very heavy rain on Thursday which dumped more than 6 inches in about 12 hours. The slide occurred at the temporary end of Summit Road and took out soil, rocks, tons of mud, leaving a massive debris pile far down the mountain where the slope lessens a bit.

"If people could come around with me for a week they'd be surprised to see what's going on in these mountains," Pruett said on a tour of the slide. "This one is a stunner."

Though unusual for its size, the slide is also unusual for another reason, Pruett said: the crews blasting the rock and digging into the hillsides here, led by contractor Dennis Franklin, followed all the rules when it comes to slope development. Franklin holds a license for doing excavation work.

"Dennis is the finest grading contractor I've run across," Pruett said.

Despite that, the slide sheds light on the issues behind the county's ongoing effort to enact a landslide development ordinance.

Though it might not have prevented the slide, measures in the ordinance would have offered an extra level of protection on the mountainside. An on-site engineer or soil tester might have alerted workers that the slope was susceptible to failure, Pruett said.

"It might not have prevented it," Pruett said. "The slope development ordinance is not a fix-all, but it does offer a higher level of standards."

Normally, said Franklin, the development's roads are resting on bedrock, but this particular piece of road was constructed wider than normal to serve as a temporary parking spot for equipment. It was this area that began tumbling down the hillside, gathering momentum and ended up taking out hundreds of trees plus tons of dirt. Franklin, who brought the matter to the attention of county officials, have already seeded the slope with grass seed and erected silt barrier fences. Pruett said he might not have found out about the slide otherwise since there were no houses in its path and no residents in the area being developed.

An engineer who analyzed the slide for one of the development's property owners said the construction of the road bed at the starting zone was the cause of the disaster.

Maggie Valley engineer Kevin Alford said the road bed in that areas was made from crushed rock which was formed from blasting.

"The upper road was built out of shot material (from) where they had to blast the roadway in there," he said. "It got too much water in it and got too heavy." The sliding material acted like a bulldozer, said Alford, scouring the slope of almost all vegetation. "It wiped out a path down to the bedrock," he said. "It was like an elliptical-shaped bulldozer. It's an amazing thing when you see that kind of material go down the mountain."

The material that came to a rest at the foot of the slope was a "molten mess glob of liquefied soil, rock, trees, brush, everything."

Alford said better planning when it came to building roads might have prevented the problem.

"When you get up in the mountains and start building roads, there are good ways to build roads and bad ways to build roads," he said. "In a situation like that I think it would have been reasonable to do subterranean work to find out what was there. When you have a large amount of uncompacted rock fill that gets a lot of water in it, you have the potential for slope failures. There is still more material up there, so it could happen again."

No comments: