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~• GEOTECH <br />October 9, 2003 <br />Michael Ripp <br />MVR Resources, Inc. <br />P.O. Box 54 <br />Delta, Colorado 81416 <br />Re: Corey Pit, Impacts to Adjacent Structures <br />Deaz Mr. Ripp: <br />Civil, Structural & Geotechnical Engineers <br />222 South Park Ave. Montrose, CO 81401 <br />(970) 249-6828 FAX (970) 249-0945 <br />Per your request, Buckhom Geotech Inc. has conducted an analysis of material strength <br />parameters and mining plans for the Corey Gravel Pit #3 located just west of Mexican Gulch, <br />south of LaSalle Road in Montrose County, Colorado. The mining plan provides for removal of <br />approximately 40 feet of gravel from within the Pit boundaries. <br />Adjacent structures in the form of wire fences aze located along the east and west lines of the <br />Corey Pit #3 property. The purpose of our analysis was to determine if the mining operation o_r <br />reclamation plan could adversely affect the adjacent fence structures. The fences on the west <br />side of the gravel pit aze owned by Tom Wazd & Emily Schneider and James & Rita Bean. The <br />fence on the east side is owned by Dan & Jacqueline Sherwood. <br />Our analysis included review of the mining and reclamation plans, inspecting the site, sampling <br />and testing the gravel material to be mined, and conducting a slope stability analysis. The slope <br />stability analysis utilized the STABLE computer program developed by the Civil Engineering <br />Department of Purdue University in cooperation with the Indiana State Highway Commission. <br />The attached lab sheets show the gradation of the gravelley soils and that the soils are non <br />plastic. Based on these test, the Unified Classification of the soil is GW. Typical properties for <br />GW soils include aMohr-Coulomb strength angle of 35 degrees and a strength intercept of zero. <br />A unit moist weight of 12S pounds per cubic feet was used for the gravel material. <br />The mining plan calls for mining to within 2S feet of the adjacent property lines using a high <br />wall technique that will expose up to 8001ineaz feet of near vertical wall having a maximum <br />height of 25 feet. As the mining progresses, the high wall will be reduced and backfilled to leave <br />a final slope of 3:1 (horizontal to vertical). <br />In our analysis, we ran a computer model of the natural slope of the edge of the mesa, the <br />proposed high wall, and the final slope configuration. The results show that the existing sidehill <br />slope of the mesa has a safety factor of 1.75 and the final 3:1 reclaimed slope will have a safety <br />factor of 2.14. The high wall section will stand in a near vertical section initially but will slowly <br />ravel, erode, and slough over time. Our computer analysis shows that, with mining no closer <br />Phan 25 feet from the fence lines, the factor of safety for a soil slide or slump that would impact <br />Corey Gravel Pit #3 <br />Project 2003.470 <br />Page 1 of 2 <br />