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Rifle Gravel Pit#1 Project No.21-010R-C2 Garfield County,Colorado 4.0 SUMMARY RJ Engineering conducted a global stability evaluation where we believe proposed mining could impact existing structures. Based on our evaluation, the factor of safety for the final slope configuration is well above industry standards. Our analyses indicate that all permanent structures should not be damaged by proposed mining activities. We believe the slopes and mining as proposed should be stable and should not affect the existing permanent structures. The structures and minimum mining distance to maintain stability include: Permanent Structure Minimum Distance Actual Distance to to Mining Minin Last Chance Ditch Tailwater Channel NA NA Last Chance Ditch Irrigation Lateral NA NA Colorado River Floodplain NA NA Non-potable URSA Resources Water 100 feet 136.1 feet Lines (supply and return URSA Resources Gas Line 100 feet 120.7 feet CDOT CR 346 and Culverts 40 feet 276.6 feet CDOT 1-70 Westbound Traffic Lanes 100 feet 276.6 feet CDOT Wildlife Fencing 100 feet 223.3 feet I-70 Westbound ROW Private Fencing East NA NA Shidelerosa LLLP Private Fencing North 100 feet 106.9 feet Colorado River Ranch, LLC Private Fencing South 100 feet 112.6 feet Scott 5.0 LIMITATIONS This study was conducted in accordance with generally accepted geotechnical engineering practices in this area for use by the client for design purposes. The conclusions and recommendations submitted in this report are based upon the data obtained from exploratory test holes and field reconnaissance. The nature and extent of subsurface variations across the site may not become evident until excavation is performed. If during mining operations, conditions appear to be different from those described herein; this office should be advised at once so reevaluation of the analysis may be made. 5