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11111 <br />• flat and slopes gently down toward Boulder Creek which flows east toward the South <br />Platte River. <br />Approximately 10,000 years ago as the glaciers in the Front Range to the west <br />melted, streams from the melting deposited outwash (alluvial) sands and gravels over <br />the existing land surface. These materials were deposited in wide areas and filled <br />existing channels. As time continued, the flow of water diminished as the glaciers <br />melted and streams became more discrete and created preferred channels as the <br />water flowed down hill. These streams cut channels and then backfilled channels as <br />they meandered over the land surface. <br />The water runoff created wide, flattened U shaped valleys as it was collected <br />by tributaries to the streams. The streams cut down along preferred courses as they <br />collected surface water from the tributaries. The water flowing to the tributaries <br />eroded the alluvial sand and gravel deposits, thinning and in some places removing <br />them and the tributaries carried the alluvium to the streams. This activity left thicker <br />• layers of the alluvium along the active stream channels and thinner to no layers out <br />away from the streams along the edges of the stream valleys. Later the wind blew <br />finer materials, clays and silts and fine sands in layers over the alluvial sands and <br />gravels. <br />The result of the above process can be visualized by a large area of a <br />comparatively thin layer of fine soils over thinner layers to no layers of the alluvial <br />sands and gravels in random areal patterns underlain by the sedimentary bedrock <br />away from the streams. Toward the streams the layer of sands and gravels overlying <br />the bedrock are thicker. The alluvial sand and gravel layers were irregularly <br />connected, which permitted water entering the ground to reach the streams by way of <br />the alluvium layers. <br />In the vicinity of the Reservoir Complex the depth to bedrock varied from as <br />little as 2 feet several hundreds of feet away from Boulder Creek to more than 40 feet <br />under other areas of the complex. The depth to bedrock increased abruptly near the <br />south side of the location of Reservoir No. 2 and along the south side of Reservoir No. <br />3. The geotechnical report in Appendix B has in it figures showing the elevation <br />McLAUGHLIN WATER ENGINEERS, LTD. s <br />GOOSE HAVEN RESERVOIR COMPLEX EXPANSION <br />CTL I T PROJECT NO. FC04797.002-145