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A.LC. <br />fl(((ed Independent Consultar+[s - CranJ Junc/ear, /nc. <br />303 North Avenue <br />P.O. Box 41049 <br />Grand Junction, GO 84504 <br />97D -244-8703 <br />Fax - 970-243-2681 <br />Slope Stability Study <br />Permanent Man-Made Structure Protection <br />prepared 6y: Chris Steven Russell, PG, PE <br />Proposed D Road Gravel Pit <br />Operated by Ephemeral Resources, LLC <br />Grand Junction, Colorado <br />March 10, 2002 <br />Introduction with Summary of Findings <br />This office has conducted a geotechnical investigation and slope stabilty study for <br />the referenced location upon the request of Ephemeral Resources, LLC. <br />Ephemeral Resources, LLC proposes to extract gravel from a 104 acres site <br />located south of D Road at 29 '/z Road. Ten boreholes were drilled to the top of the <br />Mancos Shale at this location. As a result of this drilling, the soil boundaries were <br />delineated and the typical soil properties examined. The typical soil profile is as <br />follows: <br />0'- 10' Siltv Clay: brownish grey, moist to very moist with moderate plasticity. <br />10' - 30' River Cobble: 12" and smaller rounded to subrounded hard rock in <br />sandy matrix. Water table typically slighty below top of this layer. <br />Below 30' Mancos Shale Formation <br />Analysis of the site's underlying Quaternary alluvium shows that the limits of the <br />mining operation should lay from 2 times to 1.5 times the depth of excavation from <br />all permanent man made structures that, when damaged, may compromise safety <br />or cause hardship. Public utilities and roads are an example of this type of <br />structure. Other permanent man made structures that, when damaged, will not <br />compromise safety or cause hardship should be setback a horizontal distance <br />equal to the depth of mining. This study found that the proposed setbacks found <br />in the current plan are acceptable with exception of the northwestern boundary. <br />The 30' setbacks in that area should be widened to 35'. <br />