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Mining Evaluation lfercacon <br />Ingleside Quarry Highway 287, Larimer County, Colorado <br />` Terracon Project No. 20035106 <br />Page 3 <br />Park, Colorado, many miles from the quarry site. The earthquake probably occurred at a <br />depth of 20 to 25 km and had a maximum MMI of VII and an earthquake magnitude of <br />6.2+/-ML. Non or only minor surface movement occurred during this event. The source of <br />this 1882 earthquake has not been determined to date. Based on our study the seismicity <br />of the area should not adversely effect the quarrying operations or the final slope <br />configuration of the reclaimed quarry. <br />The interbedded sandstone and limestone comprising the ridge or hogback in which the <br />quarry is located along with the additional area to be developed has a measured strike of <br />approximately north-south to N10° to N20°W and dips of between 10° to 25°E. The <br />average strike of the bedrock is N10° to N15°W with a dip of 20°E. The bedrock is slightly <br />weathered and moderately jointed. Two major joint sets were observed and measured: <br />one parallel to the strike of the Formation is approximately N5° to N15°W with dips of 45° <br />to near vertical and one perpendicular to the strike of the bedrock formation with a strike of <br />N70° to N85°E with dips of 80°SE to near vertical. Several minor joint sets were observed <br />and measured. These include orientations of N40° to N60°E with near vertical dips and <br />N25° to N60°W dips of 63°SW to near vertical. The location of the bedding and joint <br />measurements are shown on the Geologic map included as Figure 1 and are summarized <br />in Table 1 of this letter. The joint faces are non- weathered to slightly weathered, tight to <br />slightly open and rough. Some mineralization was noted on some of the joint surfaces. <br />Joint spacing varies from less than a foot to several feet. Some minor seepage was noted <br />through jointing in the rock along the quarry face at the time of the site observations. A <br />small highly weathered moist sandstone lens one half to 2 feet thick was noted at the base <br />of the headwall in the center of the quarry. <br />Based on our field observations and measurements and our evaluation of the site, it is our <br />opinion quarrying the remainder of the majority of the bedrock exposed at the site is <br />feasible. Temporary near vertical slopes may be maintained with proper safety precautions <br />during the mining operations. Temporary headwalls of approximately 50 feet constructed <br />near vertical should be temporarily stable. Mining may be sequenced in any of several <br />desired ways. Initially mining above the existing headwall should be carefully planned for <br />safety reasons. Anchoring drilling equipment or berming the slope directly above the <br />headwall will be required. Mining in strips to the south will allow for separation of <br />sandstone and limestone beds for production and crushing. <br />It is our understanding the ridge line at the top of the quarry is to be preserved to protect <br />views of residents to the west. It is recommended a horizontal distance of 50 feet east of <br />the top of the ridge be permanently preserved to protect the integrity of the ridge line. Final <br />quarry slopes should be benched for stability and reclamation considerations. It is <br />recommended that maximum bench heights of 25 feet and minimum bench widths of 20 <br />feet be constructed. The excavated walls should be constructed on '/. to 1 slopes. Some <br />