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and elevations should be considered with respect to the methods used in their establishment. The <br /> borings were drilled to depths indicated on Boring Logs in Appendix B. <br /> The two exploratory soil borings were drilled on July 26, 2004 using a truck-mounted CME-55 drill <br /> T rig. Hollow stem augers were used to drill the borings. The Standard Penetration (SPT) test <br /> method was used to obtain soil specimens and N values. The specimen is obtained by driving a <br /> split-barrel sampler 1.5 feet into the ground at the bottom of a boring according to ASTM D1586 <br /> (Penetration Test and Split-Barrel Sampling of Soil). The split-barrel sampling interval is <br /> designated SS on the Boring Logs in Appendix B with the associated N value. This value is the <br /> number of hammer blows required to drive -the split-barrel sampler 12 inches into the ground. <br /> "Grab" soil specimens indicatedon the Boring Logs were obtained from. auger cuttings. The <br /> specimens were labeled and sealed in glass jars for further review and classification in our soil <br /> laboratory by a geotechnical engineer. <br /> Boring Logs were prepared according to ASTM D2488 (Description of Soils: Visual and Manual <br /> - Procedure). Soil strata lines shown on the Boring Logs are approximate boundaries between <br /> different soil types.. Transition between soil.types may be gradual. <br /> SUBSURFACE CONDITIONS <br /> GEOLOGICAL CHARACTER <br /> The project site is in an area once covered by at least four major continental glacial ice sheets, <br /> each glaciation lasting over 100,000 years. These sheets developed between the late Pliocene <br /> Epoch 2.5 million years ago and the end of the Pleistocene Epoch 10,000 years ago. Global <br /> climate oscillations produced ice sheets between 200 feet and over one mile in thickness that <br /> flowed across the North American landscape. Rapid climate warming stopped advancements of <br /> ice sheets. The sheets stagnated and slowly melted away, depositing glacial sediment (glacial <br /> drift) upon the land. The most. recent major continental glaciation occurred during Wisconsinan <br /> age, following the Sangamon interglaciation period (warm climate) around.11000 years ago. <br /> During Wisconsinan age, maximum glacial cold and ice advancement occurred around 24,000 <br /> years ago. Regionally, this glacier stopped at Des Moines, Iowa around 16,000 years ago, <br /> retreating (melting) back to Minnesota by 12,500 years ago, and finally melting away completely in <br /> Minnesota around 9,000 years ago. <br /> Wisconsinan age glacial drift was deposited over older Pre-Wisconsinan glacial drift, which covers <br /> - bedrock. Glacial drift generally consists of glacial outwash and glacial till (ablation or basal types). <br /> Glacial outwash is deposited from glacial meltwater streams flowing from the glacial ice front. <br /> Grinding processes in a friction layer under the glacier cause rounded particles in glacial deposits. <br /> Glacial outwash deposits typically exhibit stratified bedding and sorted grain-sizes of sand and <br /> gravel caused by particles tumbling in flowing water. Coarser sand and gravel are deposited near <br /> the ice front, while finer silt and clay are deposited farther away from the ice front. In contrast, <br /> Allied Project 04049 3 July 27, 2004 <br />