2007-08-10_REVISION - M2001107 (4)

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