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4 f / INTRODUCTTON Connell Resources proposes [o construct a water storage reservoir from a sand and gravel pit known as the Timnath Connell Pit. The Timnath Connell Pit is located in Lazimer County, Colorado at the northeast comer of the intersection of I-25 and County Road 36. The proposed mining operation will extract gravel reserves from the property in some locations that are adjacent to man-made structures. The rules and regulations of the Division of Minerals and Geology require that any mining within a 200 foot setback of a man-made structure show through 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 a stability analysis of the mining highwall and the embankment that is proposed for lining the reservoir. The report also provides a general overview of the reservoir, the proposed embankment design, geotechnical results, and methodology, and conclusions and recommendations for construction of the reservoir. OVERVIEW The Division of Minerals and Geology mining plan, exhibit C, proposes that the property be mined in 4 phases. The reclamation plan, Exhibits E and F, proposes future use as a water storage reservoir. Concurrent reclamation is planned in that the reservoir lining will be constructed as the mining progresses. The reservoir will cover an estimated 140 surface acres when full and have a storage capacity of approximately 2000 acre-feet. Actual surface areas and storage capacity will depend on the final configuration of the - reservoir after reclamation is complete. The proposed reservoir will be constructed in the Valley Fill Aquifer. This a shallow ` alluvium stratum that varies in thickness up to a depth of approximately 16' for the proposed site. Underlying the alluvium is a relatively impermeable layer of blue/gray siltstone/claystone, called the Pierre Formation. The bore log information (see attached) for this site shows that weathered bedrock (siltstone/claystone) was encountered at depths ranging from 11.5 feet to 15 feet across the site. This will serve as the foundation of the reservoir and will also provide some material for embankment construction. GEOTECHNICAL TESTING In order to evaluate the slope stability of the proposed embankment, geotechnical investigations were performed to obtain the soil types and classifications for the onsite materials. Soil strength properties were estimated based on typical values for similar materials in this region. Table 1 represents a summazy of the results that were used in the stability analysis.