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Introduction <br /> The following report presents the results of a slope stability analysis for a proposed open <br /> cut gravel extraction operations at the Varra Pitt 124 (Two Rivers) operations between <br /> Milliken and Evans, Colorado. This analysis was performed at the request of Varra <br /> Companies, Inc., (Varra). This report is being submitted in partial fulfillment of an OMLR 112 <br /> Mine Permit Application. <br /> Background Information <br /> The proposed gravel quarry is located in portions of sections 3 and 4 of Township 4 North, <br /> Range 66 West and sections 33 and 34, Township 5 North, Range 66 West of the 6tn <br /> principal meridian. The surrounding land use consists of agricultural, rural residential and <br /> natural gas and oil gathering operations. The proposed mine occupies an estimated 380 acres <br /> with an active extraction area of approximately 270 acres.The water table at the site is located <br /> in unconsolidated alluvial deposits with an average depth to water of approximately six feet <br /> below ground surface. Soil conditions generally consist of varying thicknesses of top soil <br /> underlain by sand and gravel deposits,which in turn are underlain by claystone and sandstone <br /> bedrock. Over the entire area the average saturated thickness of the sand and gravel deposits <br /> (prior to mining) is estimated at about 35 feet. It is our understanding that the sand and gravel <br /> will be dewatered during aggregate extraction.The site location is presented on Figure 1. <br /> Previous Investigations <br /> WesTest, Inc., (WesTest) conducted a sand and gravel study in January 2015. The study <br /> consisted of drilling 12 soil borings from ground surface to bedrock to determine the <br /> potential aggregate mass within the proposed mine boundary. Selected sand and gravel <br /> samples were obtained for grain size distribution determinations. The depth to bedrock over <br /> the site varied between 12 and 47 feet below ground surface.The geotechnical investigation is <br /> presented as Attachment A. <br /> Overview of Stability Analyses <br /> Soil strength testing for the sand and gravel deposits was performed as part of the WesTest <br /> study. Density testing was not performed on field samples and unit weights used by the <br /> Division of Reclamation and Mining Safety were used for bedrock and overburden clay. Unit <br /> weight values reported by Terracon Consultants, Inc., and WesTest were used for the sand <br /> and gravel deposits. <br />