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D. Sites of Special Geologic Interest(G.1.d.) <br /> There are no known or suspected sites of special geologic interest(e.g., fossil beds)at <br /> this site. No features of special geologic interest are anticipated to occur because the <br /> site is located within an extensive outcrop of Precambrian metamorphic rocks that are <br /> prevalent in the Front Range from west of Colorado Springs north to west of Fort <br /> Collins. <br /> E. Geologic Hazards (G.1.e and G.1.1) • <br /> According to Section 48: G-H of the Jefferson County Zoning,a Geologic Hazard <br /> Overlay District has been established to address four(4)types of geologic hazards: <br /> slope failure complexes, landslide areas, rockfall areas and subsidence areas. <br /> Geologic Hazard Overlay District Zoning Maps have been created to help regulate <br /> development in areas susceptible to these geologic hazards. <br /> The Elk Creek Quarry is located in an area well outside (south and west of) any <br /> existing Geologic Hazard Overlay District Zoning Maps. Therefore, any concerns <br /> about geologic hazards at the site would address unzoned or other geologic hazards. <br /> There is no evidence at the site of slope failure, landslide areas or subsidence. <br /> Rockfall areas exist as part of the active mining operation within areas that will be <br /> completely mined out before establishing final benches and highwalls. <br /> Earthquakes,seismic shaking and liquefaction are not considered to be geologic <br /> hazards at the site. The potential for radon gas in this part of the County is beyond <br /> the scope of this geologic report and site radioactivity potential is addressed by Elk <br /> Creek in another part of the rezoning application. <br /> F. Slope Stability(G.1.g) <br /> In order to provide an updated evaluation of slope stability at the site, Brierley <br /> performed structural geologic mapping of rock mass discontinuities exposed at the <br /> site, and made generalized stability analyses based on these data. Bedrock exposures <br /> at the site primarily reveal foliation jointing subparallel to metamorphic <br /> compositional layering. The foliation strikes northwest and dips from shallow to <br /> moderately steeply to the northeast, generally into the hillside that is being mined. <br /> Secondary joints that are steeply dipping to subvertical also occur. Finally, tertiary <br /> joints exist that dip northwest to southwest, or generally out of the hillside that is <br /> being mined. The foliation joints are persistent across the site. The subvertical joints <br /> are persistent for up to 10 to 25 ft. The tertiary joints that daylight in the cut slopes <br /> are only persistent on the scale of several feet based on the exposures to date. <br /> The joint mapping data is summarized in both spreadsheet and stereonet format in <br /> Attachment C and the following average joint data are interpreted from these <br /> mapping data: <br /> JC 00172 <br /> Peterson/Elk Creek <br />