2024-03-26_REVISION - M2016076 (2)

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INTRODUCTION Lupton Meadows Sand and Gravel proposes to mine the property located at 9999 Weld County Road 25, Fort Lupton, CO, approximately 1.75 miles north of Weld County Road 18, in the Northeast % of Section 13, Township 2 North Range 67 West, Sixth P.M., and the Northwest 1/4 of Section 18, Township 2 North, Range 66 West, Sixth P.M. in Weld County, Colorado. The property is bounded by the South Platte River on the east, is bisected by Weld County Road 25 which runs north/south through the property, and by private property on the north, south, and west. 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 200 foot setback 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 explanation of the assumptions used for the soil strength parameters and soil strata located at the proposed pit and the methodology used in the analysis of the mining slopes and their estimated affects on all man-made structures. Recommendations regarding acceptable setbacks from man-made structures have also been included. OVERVIEW The DRMS mining plan proposes that the property will be mined in 2 phases. The mining will occur at 3H:1 V slopes. Concurrent reclamation is planned such that the reclamation embankment will be constructed as the mining progresses. The reservoir cells will cover an estimated 100 surface acres when full. Actual surface area will depend on the final configuration of the reservoir cells after reclamation is complete. GEOTECHNICAL DATA J&T Consulting, Inc. (JT) estimated soil strength parameters based on other stability analyses that have been performed on gravel mining operations along the Colorado front range and from visual observations of soil strata in nearby gravel pits. Table 1 represents a summary of the soil strength parameters that were used in this stability analysis. Table 1 — Soil Properties Description Max dry Saturated Cohesion Internal density Density (psf) Friction (pcf) (pcf) Angle Overburden 110 131 150 22 Sand and Gravel 110 125 0 35 Weathered 125 141 100 18 Bedrock Stable Bedrock 125 141 2000 20 Slurry Wall 100 110 0 45 Lupton Meadows Sand and Gravel J&T Consultin Inc. Lupton Meadows Sand and Gravel Mine g, Slope Stability Analysis Page 1