No State Rule Book for Hazardous Land Development
Submitted by Lynne Vogel on Thu, 11/20/2008 - 8:13pm
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 little over two years ago a road-building crew caused a massive landslide on Eagles Nest Ridge in Haywood County. Luckily, no homes were in the path of what has been called a “A Whopper of a Slide.”
The August 31, 2006 landslide occurred in a 700-acre development, called Cascades, which was being built by Maurice Wilder of Clearwater, Florida. The subdivision plat shows that the 90 foot wide by 1300 foot long debris flow would have severely damaged or destroyed any structures that would have been built on Lot 107 in the development.
After the landslide Dennis Franklin, contractor for the project, notified county officials and instituted temporary measures to stabilize the area. Marc Pruett, Haywood County’s erosion control supervisor, said that without notification he probably would not have known about the slide since no homes or residents were in danger.
Maggie Valley engineer Kevin Alford, who investigated the slide for a Cascades property owner, said that the failed section of the road bed occurred because
The upper road was built out of shot material (from) where they had to blast the roadway in there. It got too heavy. The sliding material acted like a bulldozer, scouring the slope of almost all soil and vegetation. It wiped out a path down to bedrock. It was like an elliptical -shaped bulldozer. It is an amazing thing when you see that kind of material go down the mountain. When you get up in the mountains and start building roads, there are good ways to build roads and bad ways to build roads. 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 potential for slope failures. There is still more material up there, so it could happen again.
North Carolina Geological Survey’s Findings
Geologists investigating the landslide site found that the collapsed slope embankment was composed of highly unstable woody debris and graphitic-sulfidic bedrock fragments. Rain on this weak, improperly-constructed, roadbed probably precipitated the landslide.
During the course of their survey the geologists determined that the still standing ~ 300 foot long road embankment showed evidence of additional failures. They warned that if the fragile embankment is not properly stabilized, this land mass will pose a future threat to public safety. Recommendations to the developer included a professional investigation of the failed site in conjunction with extensive and expensive stabilization measures or removal of the remaining roadbed.
In their assessment report the NCGS reference other Western North Carolina landslides caused by contractors' use of graphitic-sulfidic road fill.
No State Rule Book for Hazardous Land Development
It is unknown whether Mr. Wilder followed the safety recommendations outlined by the North Carolina Geological Survey. Mr. Wilder, along with all other developers conducting business in the state, are left to their own best judgment on landslide remediation.
Interested parties should be aware of these pertinent facts:
1. Landslides and weak soils endanger most mountain construction sites in Western North Carolina.
2. Developers do not have to report landslides to the state or to their clients.
3. There are no independent safety experts on-site to monitor construction practices.
4. North Carolina does not provide any measure of regulation over hazardous land development even though the region was devastated by landslides in September 2004.
5. North Carolina does not require real estate land risk disclosure.
Wouldn't You Want to Know the Risks of Buying Real Estate in Haywood County?
Landslide hazard maps for Haywood County are scheduled to be released this year, yet commissioners have chosen not to share this relevant information.
Officials only acknowledge that there are "difficulties" such as steep slopes and water quality issues associated with mountain development. The fact is most of the county's developable land is extremely hazardous. Evidence proves that building sites are impaired by unstable soils, the threat of landslides and dangerous unsupervised construction practices.
Haywood County Commissioners and their Planning Board know that hazardous land development is a threat to public safety and homeowners' financial security. There is no reason for this information to be hidden from public view.
For a comprehensive look at landslide-triggered losses in Haywood County please read the following reports.
Gambling with the Unknown
Haywood County Landslide
Rain Triggers Mudslides in Two Western North Carolina Counties
Study brings bad news
Hunters Crossing Landslide...It's Still Moving
Building Homes Where Nature Didn't Intend Them to be Built.
Deadly Landslide in Maggie Valley
Western North Carolina Mudslides Damage Private Mountain Roads. Who is Responsible?
Mudslides and Landslides Affect Property Values in Western North Carolina
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The "Cascades"
an apt name for a development dedicated to sliding tops of mountains downhill!
Are there county or state building codes that would apply here?
Greetings from Haywood County
I'm neither a civil engineer nor soils scientist nor licensed geologist nor geotechnical engineer. But I do live in Haywood County, and occasionally stay in a Holiday Inn Express...
A few questions:
1. How much "developable land" is there in Haywood County, and what percentage of that is "extremely hazardous"?
2. How exactly does one define "extremely hazardous" without having access to the information that County Commissioners and the planning board have apparently refused to make public?
3. Is mountain development any more hazardous than coastal development, especially on barrier islands? Or more hazardous than development in the coastal flood plain (see Princeville or Tarboro)?
I certainly don't mean to dispute the idea that there should be requirements for significant oversight, geotechnical testing, and engineering analysis prior to development on some locations here in Haywood and other mountain counties (see Peek's Creek landslide in Macon County during the 500-year floods).
Problems not limited
While Ms. Vogel is not amiss in focusing on Haywood County, it should certainly be noted that the ill-fated September 2004 is unique in Western North Carolina in terms of rainfall amounts from the remnants of Hurricanes Frances and Ivan.
http://www.geology.enr.state.nc.us/Landslide%20web%20version/Geologic_ha...
I believe that the promulgation of landslide hazard maps produced by the State should be the responsibility of the State, not local governments. Furthermore, I believe that the state Building Code Council should incorporate steep slope development guidelines into the NC Building Code, including requirements for geotechnical testing and appropriate engineered stabilization measures where necessary for developments statewide.
"Extremely Hazardous"
I am sorry for the delay in responding to your questions. I hope that readers will find the following information helpful.
Haywood County Commissioners can best answer questions regarding the amount of “developable” mountain land that is classified as “extremely hazardous.” They have ready access to landslide studies, prior landslide events and soil surveys. If Haywood County government wished to publicize geologically hazardous areas they could easily provide this data on their GIS real property maps. Although this hazard mitigation/ public advisory system has not been adopted by Western North Carolina municipalities, it is being employed in other parts of the country. In the future all real property will be labeled for geologic hazards.
The landslide hazard maps published by the North Carolina Geological Survey for Macon (October 2006) and Watauga ( January 2008) show that most mountain slopes “developed” or “available for development” in these two counties are highly hazardous building locations. Red-colored sections on the maps designate areas of high probability that disturbance of the slope will trigger landslides. The maps also show a significant number of landslides and their deposits. These are classified as extremely dangerous construction sites.
It should be noted that in 1998 and again in 2004 the North Carolina Department of Emergency Management warned in their hazard rating reports that landslides were significant threats to lives and property in the following 21 western counties: Alleghany, Ashe, Avery, Buncombe, Burke, Caldwell, Cherokee, Clay, Graham, Haywood, Henderson, Jackson, McDowell, Macon, Madison, Mitchell, Surry, Swain, Transylvania, Watauga, and Yancey.
To your question of which is more hazardous, coastal or mountain development I think the issue can be best weighed by the possibility of financial loss.
Residents who live in or plan to buy property in flood-prone areas of the state are apprised of the risks and they can purchase insurance protection. Those who live or expect to buy real estate in Western North Carolina are not warned of landslide/soil instability hazards and they cannot obtain insurance coverage. Homeowners policies will not cover earth movement damage regardless of the cause.