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K'077, ' , v ,,Ili ' . ^ Wt. , . <br />December 8, 2006 <br />Hart Environmental <br />P.O. Box 1303 <br />Boulder, Colorado 80306 <br />Attn: Mr. Michael Hart <br />Project: 06606 <br />Dear Mr. Hart: <br />At your request, and pursuant to the rules and regulations of the Colorado <br />Mined Land Reclamation Board (6.4.19 - Permanent Man-Made Structures), Mr. <br />Ed Glassgow, P.E., Scott, Cox & Associates, Inc. reviewed the existing geologic <br />data (boring logs) and conducted a field inspection of Ready Mixed Concrete <br />Company's proposed Holton Lakes Sand and Gravel Pit property in Weld <br />County, Colorado. The purpose of this inspection and data review was to <br />provide you with offset recommendations between areas proposed for <br />excavation and existing permanent man-made structures. Additionally, we note <br />South Plate River traverses the proposed pit area. Therefore, we are also <br />providing an opinion regarding offset from the river. <br />The available boring log documentation (a total of 26 borings completed at <br />scattered locations across the site) shows that the soils at this site consist of an <br />average of approximately 3.5 feet of overburden (consisting of topsoil, silty sand <br />and undifferentiated materials logged just as overburden) atop an average of <br />approximately 22.3 feet of sand and gravel (it is believed that the full gravel <br />section was penetrated in all of the borings). The groundwater table was not on <br />the boring logs that we reviewed. However, there is a drill hole summary <br />showing that the groundwater depth ranged from approximately 11 feet to <br />approximately 29 feet below the existing ground surface. The depth of the <br />borings ranged from approximately 20 feet to 32 feet. It appears that the borings <br />were terminated below the base of the lowest gravel layer, which would <br />typically be claystone bedrock in this area. Therefore, it is anticipated, from our <br />review of the boring logs that the pit depth could range from 20 feet to over 33 <br />feet. For the purposes of this report we will assume a maximum mined depth of <br />33 feet.