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INTRODUCTION <br /> This report presents results of a structural geology evaluation performed by engineers and <br /> geologists from LACHEL&Associates, Inc. (L&A), Golden, Colorado at the Mobile Premix, <br /> Specification Aggregate (Spec-Agg) Quarry. This evaluation included field observations, <br /> geological mapping and stereographic analysis of structural geology data. The quarry is <br /> located in the NW 1/4 of Section 15, Township 4 South, Range 70 West (see Figure 1), <br /> approximately 3 miles south of Golden, just off U.S. Route 40. This independent study was <br /> conducted at the request of Mobile Premix, a Western Mobile Company, owner of the <br /> quarry, as a requirement for State of Colorado Permit No. M-74-004. The purpose of the <br /> study was first, to evaluate current quarry wall conditions with respect to stability and <br /> second, to establish a baseline determination of structural geology features that affect the <br /> stability of the Spec-Agg Quarry. It is L&A's understanding that future annual observations <br /> and measurements will be compared with and added to this baseline in an effort to monitor <br /> ' the impact of structural features on the pit wall stability. <br /> , quarterly P Beginning in June 1996 uarterl inspections of the quarry were made by L&A in order <br /> Ato establish a basic understanding of the factors affecting the potential stability of the <br /> quarry walls. Observations with respect to geology, groundwater conditions, wall stability, <br /> bench heights, blasting patterns and reclamation activities were recorded. <br /> Further detailed geologic investigations were performed beginning on January 18, 1997, <br /> extending through February 3, 1997, and included extensive measurement of geologic <br /> structures affecting each of the four main walls of the quarry. <br /> Following these field exercises, the baseline data collected was evaluated <br /> stereographically in order to quantify the prominent structural features affecting wall <br /> stability. This stereographic analysis was also used to categorize the potential for rock <br /> slope failure mechanisms possible along each wall. <br /> 1 <br />