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t5• Geology and Groundwater: As noted above, topographically the site forms <br /> ' the southwest bluff of the Cache la Poudre River. Actually, however, <br /> the site consists of an old alluvial terrace probably deposited during <br /> tthe much higher flows of the ancestral Poudre River during the Pleistocene <br /> or Ice Age. The stratigraphy at the site includes overburden varying in <br /> ' thickness from five to twenty feet , overlying 35 to 45 feet of gravel . <br /> ' This, in turn , overlies claystone bedrock of the Pierre Shale Formation <br /> of Cretaceous age. The overburden was largely deposited by a combination <br /> ' of stream deposition, slope wash, and eolian or wind action. The gravel <br /> itself was obviously deposited by a major stream because of its relatively <br /> ' coarse-grained nature. The gravel at the site has been used historically <br /> ' as base course beneath pavements. Both detailed testing and long <br /> experience have indicated that this material is very satisfactory for <br /> ' this use. More recently the Colorado Highway Department has tested <br /> aggregate from the site for suitability as aggregate in bituminous <br /> ' (asphaltic) concrete. The Colorado Highway Department has determined that <br /> ' aggregate produced from the site is suitable for use in paving mixes which <br /> meet that Department's rigid construction specifications. A report from <br /> ' the Colorado Department of Highways asphalt lab is included as Appendix 5 <br /> tThe water table at the site is approximately 25 feet below the ground <br /> surface resulting in a saturated gravel thickness of approximately 15 <br /> ' feet. The 13 test borings drilled at the site indicate that the direction <br /> ' of movement of the groundwater at the site is north or northeast. The <br /> groundwater at the site is of high quality. An analysis of groundwater <br /> ' from the site is included as Appendix 6 . Drawing 2 shows the <br /> ' -7- <br />