Laserfiche WebLink
<br />Building Stones, 1916 Race Street, Philadelphia, Pennsylvania, 19103, (later <br />amendments, editions or subsequent publications not included). <br /> <br />5.7.9 The methods and procedures for determining minimum embankment slopes for dams <br />up to 50 feet high are outlined in the "Design of Small Dams," United States Department of <br />the Interior, Bureau of Reclamation, Third Edition, 1987, U.S. Government Printing Office, <br />Washington, D.C., 20402, (later amendments, editions or subsequent publications not <br />included). Dams over 50 feet are required to be evaluated using industry standard stability <br />analyses. <br /> <br />5.7.1 0 For earth dams, the minimum static stability factor of safety (FS) under steady state <br />seepage conditions is 1.5. The minimum FS for rapid drawdown is 1.2. Acceptable factors <br />of safety for dams other than earth embankments shall be determined in accordance with <br />Rule 5.7.7. <br /> <br />5.7.11 For earth dams, the seismic stability criteria shall be as follows: <br /> <br />5.7.11.1 All High Hazard dams and Large Significant Hazard dams shall be <br />designed to withstand the predicted earthquake loads, based upon an analysis of <br />potentially active faults, unless sufficient investigations indicate the faults do not <br />contribute to seismic loading of the dam. Accelerations shall be determined by <br />methods acceptable to the State Engineer. <br /> <br />5.7.11.2 For all High Hazard dams and Large Significant Hazard dams, the <br />minimum seismic stability analysis required shall be a pseudo-static analysis using <br />an appropriate pseudo-static load coefficient as defined in Rule 5.7.11.5 of not less <br />than 0.05. <br /> <br />5.7.11.3 All High Hazard dams and Large Significant Hazard dams that have <br />cohesionless materials in the embankment or foundation, shall be evaluated for <br />liquefaction potential. <br /> <br />5.7.11.4 For all High Hazard dams and Large Significant Hazard dams, pseudo- <br />static analysis shall be acceptable if all of the following conditions are satisfied: <br /> <br />1. The dam and foundation are not susceptible to liquefaction; <br /> <br />2. The dam is a well-built (densely eompacted) dam and predicted <br />peak bedrock accelerations are 0.2g or less, or the dam is constructed <br />of clay soils on a clay or rock foundation and predicted peak bedrock <br />accelerations are 0.35g or less; <br /> <br />3. The static factors of safety of the critical failure surfaces involving <br />the dam crest (other than the infinite slope case) are greater than 1.5; <br />and <br /> <br />20 <br />