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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 Dam-All vegetable matter of every description, including roots to a depth of two feet, shall be removed from the entire area upon which the door will rest, together with boggy or unstable materials and deposited outside the toes of the dam. The banks of the stream channel shall be dressed to a slope of about lil_:1. A bonding trench, aa•ith sloping sides and a bottom width of not less than 5 feet and depth of 4 feet, Shall then be excavated beneath the center line of the dam the full length thereof, which trench shall be refilled with the most imper- vious materials available. The toundatium cf the dam shall then be lightly plowed lengthwise of the dam, to provide proper contact between the foundation and the dam embarkment. PlaeiDS of Dam Embankment^The materials shall be placed in the bonding trench and in the embankment o[ the dam in layers not exceeding ti inches in thickness, after which each layer shall be thoroughly compacted by a heavily loaded disc cultivator, a corrugated or sheep's foot roller, the treads of a caterpillar or trucks, or by livestock used in the construction. During [he construction period, the top of the embankment shall be maintained as a horizontal plane the full width and length thereof. and no side dumping of materials shall be permitted. The materials shall at 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 scones shall be incorporated in the dam. The upstream face of the dam shall be constructed with a slope not steeper than ? i,~:l, 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 feet in width. The upstream lavo-thirds of the dam shall be constructed of the most impervious 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 riprap, or~other suitable 7aterials when required. OatleO-Should the state engineer so require, there shall be located beneath the dam an outlet pipe not less than 8 inches in diameter, equipped avith a control valve attached rA the upstream end of the pipe, together with suitable mechanism for operating the valve. Such outlet pipe shall be provided with cutoff collars. The pipe shall be placed in a trench bottomed in stable formation, and shall be completely surrounded with well compacted impervious :materials. Splllway-For the protection of the dam, an adequate spillway shall be constructed around one or boat ends of the dam, of sufficient avidth to provide a capacity to carry the entire discharge from the drainage basin above the dam during periods of unusual runoff. The spillway shall be located in 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 requirements. The top of the dam at all points 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 of a mini- mum freeboard between the maximtun high water line and top of dam, of 2.3 feet, and maximum velocities of 3.5 feet ppr second of time. AREAS OF LOW RAINFALL INTENSITY AREAS OF HIGFI RAINFALL INTENSITY AREA OF :. °.QUIRED WIDTH OF AREA OF REQU•P:D WIOTM OF AREA OF REQUIREL WI:ITY C• Oa.A1NAGE BASIN SPILLWAT "W" AT DRAINAGE BASI N SPILLW AT "W" AT DRAINAGE BASIN SPILLWAY "W" AT ABOVE DAM NARROWEST POINT ABOVE DAM NARROWEST POINT ABOVF DAM NARROWEST POINT IN ACRES IN FEET IN ACRES IN FEET IN ACRES IN FEET YO 8 p0 8 100 76 40 9 40 9 /60 84 60 11 60 11 600 90 BO 14 80 18 Sb0 99 100 16 100 22 600 106 710 21 120 26 700 ll7 Teo Ys 14o ao coo lsa zzo s9 16o a/ 900 loo 260 73 180 a7 1000 150 300 35 200 ~ /7 1700 360 750 3e 2Y0 /8 1200 169 /00 /Y 240 60 1300 176 450 // 260 67 1400 18T 500 /i 260 57 1500 196 600 61 700 60 1600 E03 700 65 320 i3 1700 fl! 800 59 ]40 86 1800 219 900 a2 ]60 70 1900 2Yb 1000 66 380 7] 2000 Eii ALL AREAS EAST O'_•' THE CONTINENTAL DIVIDE BELOW .AN ELEVATION OF 7000 FEET, ARE CONSID- ERED AS BEING IN THE HIGH RAINFALL INTENSITY ZONE. The above spillway widths may be reduced at a point 50 fact below intake, by 25 per cent, where the spillway is located the full length thereof in hard clay or shale, and by 50 per cent when located in hard rock formations, i[ the elope or grade of the bottom a increased accordingly. The grade for clay and shale formations should be 0.30 toot per 100 feet, and for rock formations 0.00 foot per 100 feet. The avidth 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 lower end o[ the funnel section, toward the reservoir 1.0 foot in the dis[nnce of 50 feet, and the slope downstream should be 0.25 foot in a distance of 100 feet. Borrow Pits-Pits, from which materials are taken to build the dam, shall be cleared of all vegetable matt°r, and nn material shall be borro',ved within a distance of 50 feet o1 any part of the dam. Materials excavated from the spill- way, when suitable, may De used in building the dam.