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very high persistence. No other obvious cracking above the recent ground event release was <br /> observed on foot or by drone. Photos 2 and 3 highlight the upper two beds of limestone that sit <br /> on the more massive limestone below. The slide plane for the ground event occurred along <br /> bedding at these two upper beds. <br /> Two thin interbeds of laminar bedded, shaley mudstone bound the upper two limestone beds. <br /> The observed thin interbed of laminar bedded, shaley mudstone creates a potential failure <br /> plane of lesser cohesion and fiction angle than the limestone. In addition, significant icicles had <br /> formed primarily at the basal contact of the upper limestone to the mudstone interbed. <br /> However, it is somewhat unclear if the water was draining out along this basal contact, or if <br /> seepage down the face of the limestone was dripping and causing the icicles, or most likely <br /> both. <br /> A more detailed description and modeling of the January 18 ground event will be completed <br /> under separate cover but is mentioned here because the modeling of the ground event on the <br /> West Face was used as a back-analysis to determine appropriate input parameters for the <br /> stability modeling of the East Face. <br /> April 14, 2023-Site Reconnaissance <br /> A site mapping program was performed to collect structure data on the East Face, evaluate the <br /> strength parameters of the interbed and overall geologic/rock mass conditions and stability of <br /> the south-facing slope. During the field reconnaissance, the bedrock conditions were evaluated <br /> and classified by visual examination of surficial deposits and outcrops. Bedrock joints, structure, <br /> fractures and weathering were assessed and classified, and the geometry of discontinuities (dip <br /> and dip direction) were measured with a Brunton compass. Structure measurements made <br /> during the April reconnaissance are provided in Appendix B and were supplemented with <br /> previous mapping for modeling. Measurements were made of rock mass discontinuities along <br /> the entirety of the slope to evaluate the range and variability of discontinuity geometry and <br /> character. The collected datasets are believed to be representative of the exposed rock mass. <br /> Exposed outcrops were characterized using the Hoek-Brown rock mass classification system to <br /> assess in-situ strength properties (Hoek, 20002).Joint surface conditions, such as continuity, <br /> spacing, aperture, infilling, roughness, seepage, and a rating of significance were characterized, <br /> and collated on data tables. The degree of roughness and larger-scale waviness of joint surfaces <br /> was evaluated using the Joint Roughness Coefficient (JRC) methodology of Barton (19773). <br /> Digital photos were taken to document rock identification, typical and atypical rock conditions, <br /> locations of measurements, zones of localized weakness, and/or locations of geologic interest. <br /> Field measurements, mapping control, and feature location were recorded using a hand-held <br /> Global Positioning System (GPS) unit (GarminTm60 Cx), with typical degree of positional <br /> uncertainty of+/-9 feet (as calculated by the GPS device). <br /> z Hoek, E., 2000, Practical rock engineering: on-line document, rocscience.com <br /> 3 Barton, N.R. and Choubey, V., 1977, The shear strength of rock joints in theory and practice: Rock Mechanics, Vol. <br /> 10(1-2), pp. 1-54. <br /> Page. 3 <br /> 535 16th STREET,SUITE 620 1 DENVER,CO 80202 1 (303)732-3692 1 WWW.KILDUFFUNDERGROUND.COM <br />