Safe Slope Regulations Rejected in Western North Carolina

The landslide probability maps for Buncombe, Macon, and Watauga counties show stark landscapes: steep mountain terrain at certain risk of slope failures. Much of this land, if investigated for stability, would be classified as unsafe "no build" locations. Currently residential development on these hazardous mountain slopes is receiving no more oversight and regulation than a Florida flatland subdivision.

In 1998 the North Carolina Department of Emergency Management determined that the 21 county region known as Western North Carolina was at extreme risk for the possibility of landslides. This report should have prompted immediate legislative action requiring strict control over the development and sale of hazardous land. Instead the state relegated this serious responsibility to county and local governments. Today no regulating entity has established meaningful slope regulations. Safe slope regulations are simple and effective: They require regulation over all slope grades if there is any evidence that disturbance of the slope would trigger landslides.

Landslide maps accurately identify at risk mountain slopes; professionals are then required to determine the suitability and safety of a proposed development site. Landslide maps are universal in design and color markers.

The following steep slope regulations were proposed for the Town of Boone by the Boone Steep Slope Task Force and Trigon Engineering. The Boone Town Council allocated $20,000 for the creation of a regulatory geologic hazard map for the town and its extraterritorial jurisdiction. The Town of Boone is located in Watauga County.

Red Zone (High Geologic Hazard): Areas of high probability that disturbance of the slope will yield landslides affecting the subject property or surrounding properties. Red zone indicators:

[1] Slopes steeper than 50% with any of the following: Fault Zone cataclastic (broken) rocks; Pre-existing landslide deposits; Daylighting fracture sets; Daylighting sedimentary layers (bedding), or other planar structures; Thick soils (greater than 10 feet thick).
[2] Localized over-steepened slopes (greater than 67%) (over-steepened by natural processes or previous development).
[3] Zones of likely debris flow deposition.

Orange Zone (Moderate Geologic Hazard): Areas of moderate probability that disturbance of the slope will yield landslides affecting the subject property or surrounding properties. Orange zone indicators include:

[1] Slopes ranging between 15% and 50% with any of the following: Pre-existing landslide deposits; Daylighting fracture sets; Daylighting micaceous or clay rich soils; Thick soils (greater than 10 feet thick).
[2] Localized over-steepened slopes (greater than 67%) (over-steepened by natural processes or previous development) associated with other Orange Zone indicators.
[3] Zones of possible debris flow deposition.

Green Zone (Low Geologic Hazard): Areas of low probability that disturbance of the slope will yield landslides. Green zone indicators include:

[1] Slopes less than 15% and none of the following: Unstable or steep pre-existing landslide deposits; Zones of possible debris flow deposition.

The requirements for all properties within the Red and Orange Geologic Hazard zones shall be as follows:
[1] Plans for the development of any property must be accompanied by a site-specific geologic analysis of the portion of the site to be affected by the proposed development plan, paid for by the applicant, and conducted by a North Carolina licensed geologist, to determine whether that plan can be developed on the site without jeopardizing slope stability on the site itself and on properties surrounding the site.
[2] If the lot is determined to be safe for development but requires remedial measures to ensure slope stability, a North Carolina licensed engineer must develop and present a plan that will preserve slope stability during and after the completion of grading and construction for the site as well as for surrounding properties.

Postscript

On October 2, 2006 the Town of Boone finalized their steep slope bill. The new regulations did not include many of the original standards called for by the Task Force. The most important change in the recommendations was the elimination of the color coded regulatory hazard map that identified high, medium, and low risk development areas.

Jeff Templeton and his influential group, The Committee for Responsible Environmental Regulations, were instrumental in undermining the safeguards advocated by the Boone Task Force and Trigon Engineering. Mr. Templeton argued that if the regulations were enacted as proposed, the new measure would lower property values and increase building costs.

On the same day that the Boone Town Council passed its new slope ordinance, a state geology group issued a report that identified Watauga County as the most likely county in the western part of the state to experience hazardous landslides.