Rock Slope Failure in the Appalachian Valley and Ridge Province

In December 1983 a 300-ft high cut slope along the lower reservoir access road failed at the Bath County Pumped Storage Project site. Three different mechanisms of failure were exhibited in the slope: 1) block sliding along bedding planes, 2) block flexure toppling of beds with steep dips, and 3) secondary toppling. The failure initiated during an unusually wet autumn about five years after slope construction. The geologic conditions that contributed to the instability are common in the Appalachian Valley and Ridge province, tightly folded, thinly bedded siltstone and shale with polished and slickensided bedding planes.