C153629 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I can likely be produced from the alluvial material. Mr. Schrader's report (included in Appendix C-l) gives a number of suggestions on means of processing to improve the quality and gradation of the aggregate. C. Supplemental Materials Investigation Because of the uncertainties of the first aggregate and RCC trial mix test results, it was decided to expand on the investigation of aggre- gates. If the Rock Creek Valley aggregates could not provide adequate strength RCC, alternative sources in either the Colorado River Basin or the Yampa River Basin would have to be utilized. The importation of materials from these long distances would substantially increase the cost of a RCC dam at the Rock Creek site. During the summer of 1986, additional test pits were excavated in the Rock Creek Valley 1 to 2 miles upstream of the proposed dam axis. Bulk samples of the materials were taken and additional laboratory tests were made to verify the materials' suitability as RCC aggregate. In addition, a RCC trial mix program was carried out on the Rock Creek Valley materials as well as aggregates from a commercial gravel pit near Kremmling. The details of the supplemental materials investiga- tions is presented in Appendix C-2. The RCC trial mixes indicated lower than normal strengths for RCC with low cement content (100 lbs/cu. yd.). The mixes with fly ash also exhibited very slow strength gain. It was concluded that the Rock Creek Valley aggregates would provide an adequate supply and could be used to produce an acceptable RCC mix with cement contents in the range of 135 lbs/cu. yd. along with about 65 lbs/cu. yd. of fly ash. The higher cementitious material content than originally estimated results in higher cost estimates but substantially less than the cost if aggregate materials were imported. 3 - 13 6819W/5020W