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STATE OF COLORADO DIVISION OF WATER RESOURCES •~ OFFICE OF STATE ENGINEER SPECIFICATIONS TO GOVERN THE CONSTRUCTION OF A LIVESTOCK WATER TANK • Preparation of Foundation far Daot-All vegetable matter of every description, including roots to a depth of two feet, shall be removed from the entire area upon which the dan] will rest, together with baggy or unstable materials and deposited outride the toes of the dam. The banks of the stream channel shall be dressed [o a slope of about 1'fz:l. A bonding trench, with sloping sides and a bottom width of not less than 5 feet and aepth o[ 4 feet, shall then be excavated beneath the center line of the dam the full length thereof, which trench shall De refilled with the most imper- vious materials available. The foundation of the dam shall then be lightly plowed lengthwise of the dam, to provide proper contact between the foundation and the dam embankment. Placias of Dam Embankment-The materials shall be placed in the bonding trench and in the embankment of the dam in layers not exceeding 6 inches in thickness, after which each layer shall be thoroughly compacted by a heavily loaded disc cultivator, a corrugated or sheep's toot roller, the treads of a caterpillar or trucks, or by livesmck used in the construction. During the construction period, the top o[ the embankment shall be maintained as a horizontal plane the full width and length thereof, and no side dumping o[ materials shall be permitted. The materials shall et all times contain sufficient moisture to provide proper compaction. Puddling of material with water shall not be permitted. No frozen material or large clods or stones shall be incorporated in the dam. The upstream face of the dam shall be constructetl with a slope not steeper than 2yz:1, and the downstream face on a slope not steeper than 2:1. The crest or top of the finished dam shall be not less than 8 fee[ in width. The upstream two-thirds of the dam shall be constructed of the most impervioLL6 materials, such as clay loam, or a mixture of clay and sand, and the downstream one-third of more pervious material, such as sand or gravel. The up- stream face of the dam shall be adequately protected against wave action by stone rlprep, or other suitable materials when required. Outlet-Should the state engineer so require, there shall be located beneath the dam an outlet pipe not less than 8 inches in diameter, equipped with a control valve attached to the upstream end of the pipe, together with suitable mechanism for operating the valve. Such outlet pipe shall be provided with cutoff coLars. The pipe shall be placed m a trench bottomed in stable formation, and shall be completely surrounded with well compacted impervious materials. Spillway-For the protection of the dam, an adequate spillway shall be constructed arotmd one or bolo ends of the dam, of sufficient width to provide a capacity to carry the entue discharge from the arainage basin aoove the dam during periods of unusual runoff. The spillway shall be located ]n stable formations not easily eroded, and shall extend to a point well downstream from the dam. The following table shall be used to determine the necessary width of spill- way to meet the above requiremenu. The top of the dam at all poinu shall be not less than 4 feet above the bottom of the spillway. The following table shows the widths of spillways for corresponding drainage areas with an allowance o1 a mini- mum freeboard between the maximum high water line and top of dam, of ^_.3 fee[, and maximum velocities of 3.5 feet per second of time. AREAS OF LOW RAINFALL INTENSITY AREAS OP HIGH RAINFALL INTENSITY AREA OF REQUIRED WIDTN OF AREA OF Rf OUIRED WIDTN Oi AREA OF REQUIRED WIDTN OF DRAINAGE BASIN SPILLWAY"W"AT DRAINAGE BASI N SPILLW AT"W"1T DRAINAGE BASIN SPILLWAY "W"Ar ABOVE DAM NARROWEST POINT ABOVE DAM NARROWEST POINT ABOVF DAM NARROWEST POINT IN ACRES IN F[ET IN ACRES IN FEET IN ACRES IN iE[T 20 H 2U 8 100 .6 f0 5 IG 9 1S0 8/ 60 11 fi0 11 500 9U 80 11 80 16 550 96 ]UO 1F 100 600 105 110 21 120 26 700 117 160 ^_5 140 JO 600 125 220 25 160 3/ 900 110 Y60 33 180 37 1000 lSi~ 300 15 200 17 1]00 160 350 36 ^_20 {6 12U0 169 100 12 240 50 :300 1:5 150 1/ 26D 5J ]{00 181 500 {6 250 5: !500 196 60~ 51 JOG 60 lF00 20J ;00 jj 320 fiJ I~00 212 E00 55 J10 66 IB00 215 900 62 360 70 1900 -- S 1000 6L J80 i3 2000 23 ALL AREAS EAST OF THE CONTINENTAL DIVIDE BELOW AN ELEVATION OF 7000 FEET, ARE CONSID- ERED AS BEING IN THE HIGH RAIN-Poll INTENSITY ZO.YE. The above spillway w•]dths map be reduced ai a point 50 feet below intake, by 25 per cent, where the spilltvap is located the full length thereof ir, hard clay or shale, and b>' S0 per cent when located in hard rock tormallons. ii the slope or graae of the bottom is increased accordingly. The grade Sor clay and shale formations should be 0.30 foot per . 100 feet, and for rock formations 0.90 foo: per 100 feet. The ia•idth of the entrance to the spillway must in all cases be ~ one-third wider than shown in the table. and the bottom should slope from the ]ox•er end of the funnel section, toward the reservoir 1.0 foo: in the distance of 50 feet, and the slope downstream should be 0.25 foot in a distance of 100 }ec;. Borrow Pies-Piss, from which materiels are taken to build the dam, shall be cleared of all vegetable matte:, and no material shall ~De borrowed within a distance o! SO feet of any part of the dam. I,laterials excavates from the spi'.;- way, when suitable, may be used in building the dam.