Seite - 111 - in Book of Full Papers - Symposium Hydro Engineering

cutting shears could greatly affect the continuity of rock materials. Exploration locations were added to investigate the continuity of similar rock materials. In the days after the Emergency Spillway flows, between February 10 and 12, 2017, water was observed to be seeping immediately downstream from the Emergency Spillway structure through fractures in the rock with very little head. This led to questions of the efficacy and integrity of the original grout curtain beneath the Emergency Spillway. Exploration locations were added on both sides of the Emergency Spillway to investigate the rock conditions and the hydraulic conductivity of the rock formation. Figure 5 - Photo of the scour hole and channel forming to the left of the FCO Spillway chute illustrating the geology left behind by erosion and scour. Five drill rigs are visible in the FCO Spillway chute and one on the right side of the chute). In erosion gullies created by the flowing water, interpretations based on new reconnaissance-level geologic mapping suggested some larger shears might project back towards the FCO Spillway chute, resulting in unfavorable conditions. These features needed to be explored in detail to assess the overall stability and foundation conditions for the new replacement spillway chute. A series of rock-core borings was added to identify and delineate the continuity of these shears, with inclinometers installed to monitor the stability of the slopes in critical areas. The examples above are representative of the types of geologic features targeted to investigate the geology of the site. These types of features were explored primarily by drilling borings with further information derived from the 111