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<br /> <br />378-3 Pond <br />Geology. Sufficient soil and <br />foundation investigations shall be <br />made to determine the suitability <br />of the site for its intended <br />purpose. <br />Earth embankment. The minimum top <br />width for a dam is shown in table <br />1. If the embankment top is to be <br />used as a public road, the minimum <br />width shall be 16 ft. for one-way <br />traffic and 26 ft. for two-way <br />traffic. Guardrails or other <br />safety measures shall be used <br />where necessary and shall meet the <br />requirements of the responsible <br />road authority. <br />Table 1. Minimum top width for <br />dams <br />grained materials for the upstream <br />two-thirds of the dam and the <br />rocky soils on the dowri~Lreani <br />slope. <br />If needed to protect the slopes ~t <br />the dam, special measures, such as <br />berms, rock riprap, sand-gravel, <br />soil cement, or spacial <br />vegetation, shall ~e provided <br />(Technical Release 56 and 69). <br />The minimum elevation of the top <br />,~ of the settled embankment shall be <br />:'~wf.t',:..eabove the water surface in <br />tFte,,.reservoir .with,,.,the, emergency <br />.spi.llway flowing at' design depth. <br />The minimum difference in <br />elevation between the crest of the <br />emergency spillway and the settled <br />top of the dam shall be 4 feet. <br />--------------------------------- <br />Total height of Top width <br />embankment <br />--------------------------------- <br />ft. ft. <br />10 - 15 8 <br />15 = 20 10 <br />20 - 25 12 <br />--------------------------------- <br />*Total height is the difference <br />between the top of the dam and the <br />lowest point on the dam <br />centerline. <br />The combined upstream and <br />downstream side slopes of the <br />settled embankments shall not be <br />steeper than five horizontal to <br />one vertical, and the upstream <br />slope shall not be steeper than <br />2.5 horizontal to one vertical and <br />the downstream slope shall never <br />be steeper than 2 to 1. All <br />slopes must be designed to be <br />stable, even if flatter side <br />slopes are required. <br />When it becomes necessary to use <br />rocky soils for the embankment, <br />the dam shall be designed as a <br />"zoned fill," using the finer <br />The height of the dam shall be <br />increased by the amount needed to <br />insure that after settlement the <br />height of the dam equals or <br />exceeds the design height. This <br />increase shall not be less than 5 <br />percent, except where detailed <br />soil testing and laboratory <br />analyses show that a lesser amount <br />is adequate. <br />For dams other than livestock <br />water tanks and/or erosion <br />control, special plans and <br />specifications shall be prepared <br />~F?~t'h'e°"dTatiii~ i's''A'4e'r''10 `feet i n <br />ye.~i-o°a I "he'i`ghf'fnea`~li'red' 'a I ong the <br />ore.~ter~J;rne•~o'r-has^~Sa+~'sii'rface area <br />irri~ext~e's's'rbf 'tw~rifyetiacres.= The <br />pavans must be apptoUe'd Eby' the• <br />S;ta;be;Engineer of Colorado before <br />-construc~ti'oh ~starks.-, <br />SCS, Colorado, January 1989 <br />