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I -INTRODUCTION <br />Northern Colorado Constructors, Inc. (NCCI) currently operates the NCCI Pit #1 aggregate mine <br />located in the !Northeast'/. of Section 24, Township 2 North, Range 67 West, Sixth P.M. in Weld <br />County. The property is bounded by private property on the west and north, WCR 25 on the <br />east, and WCR 18 on the south. United States Highway 85 is approximately one half mile east <br />of the subject property. The mining operation will extract gravel reserves from locations adjacent <br />to man-made structures. The rules and regulations of the Division of Reclamation, Mining and <br />Safety (DRMS) require that any mining within a setback of 200 feet of a man-made structure <br />show through engineering analysis that the proposed mining will not cause damage to these <br />structures. The accepted method of demonstrating this is through a slope stability analysis. This <br />report contains an overview of the prior geotechnicai investigation results by Terracon and the <br />methodology used in the analysis of the mining slopes and their estimated affects on all man- <br />made structures. Recommendations regarding acceptable setbacks from man-made structures <br />have also been included. <br />II -OVERVIEW <br />NCCI plans to mine the property in one contiguous cell. The future use for this property is <br />expected to be a lined water storage reservoir. The mined slopes will be reclaimed with a 3h:1v <br />embankment constructed from clay shale and overburden. Concurrent reclamation is planned <br />such that the reclaimed embankment will be constructed as the mining progresses. The <br />reservoir cell will cover an estimated 55 surface acres when full. Actual surface area will depend <br />on the final configuration of the reservoir after reclamation is complete. <br />III - GEOTECHNICAL DATA <br />A preliminary geotechnical investigation and subsequent liner evaluation have been performed <br />by Terracon. J&T Consulting, Inc. (JT) estimated soil strength parameters based on the <br />information from the Terracon report and liner evaluation, which was provided to JT by NCCI, <br />and other stability analyses that have been performed on gravel mining operations along the <br />front range. Table 1 represents a summary of the soil strength parameters that were used in this <br />stability analysis. <br />Table 1 -Soil Proaerties <br />Description Max dry density <br />c Saturated Density <br />c Cohesion <br />s Internal Friction <br />An le <br />Overburden 110 131 150 22 <br />Sand and Gravel 110 131 0 35 <br />Weathered <br />Bedrock 125 141 100 18 <br />Stable Bedrock 125 141 2000 20 <br />NCCI Pit #1 <br />Slope Stability Malysis <br />Page 1 <br />