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Rifle Gravel Pit#1 Project No.21-010R-C2 <br /> Garfield County,Colorado <br /> 1.0 PROJECT INFORMATION <br /> 1.1 Purpose and Scope <br /> This report presents the results of our slope stability evaluation for the south side of the <br /> proposed Rifle Gravel Pit#1 in Garfield County, Colorado. The investigation consisted of field <br /> reconnaissance and review of existing exploratory drilling information for the subject site. We <br /> were requested to conduct this stability evaluation to address concerns that the mining <br /> operation would adversely affect the existing gas and water lines located in the ROW along the <br /> southern property line for the gravel pit. Our analysis was conducted to substantially address <br /> section 6.5 Geotechnical Stability Exhibit of the Division of Reclamation, Mining and Safety for <br /> Hard Rock, Metal, and Designated Mining Operations. <br /> 1.2 Site Conditions <br /> The subject site is located adjacent to County Road 346 about a mile east of the Mamm Creek <br /> Road intersection. The site is relatively flat with marshes and wetlands. The site is generally <br /> vegetated with shrubs, bushes and grasses. <br /> 2.0 SUBSURFACE INFORMATION <br /> HP Geotech previously conducted a subsurface investigation for the site under their project <br /> number 108 354A. Based on our review, Boring 3 is the nearest test hole to the southeast <br /> portion of the site where our analysis was performed. The test hole consisted of 7 feet of clay <br /> and silt over 20 feet of gravel underlain by claystone/siltstone bedrock to the maximum explored <br /> depth of 30 feet. The approximate elevations used in our analysis are presented in the table <br /> below. <br /> Subsurface Conditions Appx. <br /> for Boring 3 Elevation ft <br /> Ground Surface at Boring Location 5388 <br /> Gravel Surface 5381 <br /> Bedrock Surface 5361 <br /> Bottom of Boring 5358 <br /> 1 <br />