SLOPE STABILITY ANALYSIS AND REMEDIATION TECHNIQUES FOR CREEK JUNCTION FAILURE SITE, MOUNT ROGERS NATIONAL RECREATIONAL AREA, VA

Debris from an unstable slope along the Virginia Creeper Trail and Appalachian Trail has given rise to concerns for public safety as well as maintenance costs for those at the Mount Rogers National Recreation Area near Marion, VA. The site is a heavily used area for outdoor enthusiasts, who commonly hike, mountain bike, fish, and/or ride horses along the converted Norfolk and Western railroad bed. The particular area of concern is known as Creek Junction, which is found outside of Konnarock, Virginia. A former road was closed off to vehicles and converted to a handicap fishing access where piers have been installed over the north bank of Whitetop Laurel Creek. Two piers have been constructed at the bottom of a slope where rock and sediment commonly build up on the Creeper trail as well as the handicap-access fishing trail located below. The location of the piers below the slope failure creates an additional risk. People spending more time at the site maximizes the time of exposure for falling debris, which may lead to serious injury or loss of life. The first step taken in the process of remediation is diagnosing the problem. A highly fractured diamictite makes up the unstable slope. This diamictite is a glaciogenic, non-volcanic conglomerate that is matrix- supported. It is unbedded and largely layered (from 3-30 meters). The failure slope contains various amounts of undulating fractures with three distinct orientations. A contributing factor to failure of the slope is the large amount of potassium feldspar making up the diamictite. Weathering of the potassium feldspar into clay creates a lower friction angle in the rock. This is especially prevalent where water flows into discontinuities, which results in an increase in failure potential. After gathering field data, the information was entered into RockPack III Beta software to display the orientations causing the failure. Once the mode of failure was determined, projections of falling rock were studied using Colorado Rockfall Simulation Program, version 4 (CRSP4). Potential remediation techniques include scaling, hazard-tree removal, rockwedge buttress, and/or drainage.