18E.80.050 Buffer Requirements.
A. Determining Buffer Widths.
1. The buffer width shall be measured on a horizontal plane from a perpendicular line established at the edge of the active landslide hazard area limits (both from the top and toe of the slope). (See Figure 18E.80-6 in Chapter 18E.120 PCC.)
2. A buffer of undisturbed vegetation shall be required for an active landslide hazard area. The required buffer width is the greater amount of the following distances:
a. Fifty feet from all edges of the active landslide hazard area limits;
b. A distance of one-third the height of the slope if the regulated activity is at the top of the active landslide hazard area and a distance of one-half the height of the slope if the regulated activity is at the bottom of an active landslide hazard area, or the distance recommended by the geotechnical professional.
B. Modification of Buffer Widths. The Department may require a larger buffer width than the buffer distance, as determined in A. above, if any of the following are identified:
1. The adjacent land is susceptible to severe erosion and erosion control measures will not effectively prevent adverse impacts.
2. The area has a severe risk of slope failure or downslope stormwater drainage impacts.