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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Strength gain curves for the RCC cylinders are included in Appendix C. <br /> <br />Further detai 1 s on 1 aboratory soi 1 s test results for Barnes Meadow Dam are <br />included in Appendix C. <br /> <br />2.3 Seismic Risk Analysis <br /> <br />Accordi n9 to the Sei smi c Ri sk Map of the U. S. (A1 germi ssen 1969), the enti re <br />State of Colorado is within seismic risk Zone 1, signifying that the maximum <br />intensity earthquake to be expected is VI on the modified Mercalli scale. The <br />recommended horizontal acceleration to be used in Zone 1 for desi9n is 0.03g <br />to 0.07g. <br /> <br />The Preliminary Map of Young Faults in the U.S. by the USGS shows the Laramie <br />River Fault and the Spring Creek Fault system, located 30 miles to the west of <br />the reservoir in North Park, to be active since the late Cenozoic era (last 15 <br />mi 11 ion. years) . <br /> <br />"Earthquake Potenti al in Colorado," by Ki rkham and Rogers, recommends that all <br />of Colorado, wi th the excepti on of the northeast corner, be consi dered as <br />seismic risk Zone 2, since several historic events with a modified ~'ercalli <br />intensity of VII have occurred. The report divides the state into seismic <br />provinces. Barnes Meadow Reservoir is located in the Eastern Mountain <br />Province, where the authors recommend a horizontal acceleration of O.lq be <br />used for engineering design based on a maximum credible earthquake of <br />magnitude 6.0 to 6.75 on the Richter scale. The report identifies not only <br />the Laramie River Fault and Spring Creek Fault as potentially active, but also <br />an unnamed East-West trending fault, located approximately 10 miles northeast <br />of the dam. <br /> <br />MKE feels that the report's definition of a potentially active fault as <br />Neogene (last 25 million years) is excessively conservative. Standard <br />engi neeri ng practi ce woul d consi der movement si nce the 1 ate Pl ei stocene Epoch <br />(1.8 million years) or Holocene (500,000 years) to be potentially active. <br /> <br />1231 H <br /> <br />-55- <br />