APPCOR12482 - Laserfiche WebLink

Home Browse Search

STATE OF COLORADO DIVISION OF WATER RESOURCES OFFICE OF STATE ENGINEER SPECIFICATIONS TO GOVERN THE CONSTRUCTION OF A LIVESTOCK WATER TANK Preparation of Foundation Ior Dam-All vegetable matter of every destri ption, including roots to a depth of two feet, shall be removed from the entire area upon which the dant will rest, together with boggy or unstable materials and deposited oulsidq the toes o[ the dam. The banks of the stream channel shall be dressed to a slope of about 1'h:l. A bonding trench, with 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 oI the dam the full length thereof, which trench shall be refilled with the most imper- vious materials available. The foundation o[ the dam shall then be lightly plowed lengthwise of the dam, to provide proper contact between the foundation and the dam embankment. Placing of Dam Embankmenl^The materials shall be placed in the bonding trench and in the embankment of the dam in layers not exceeding fi 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 livestock used in the construction. During the 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 stones shall be incorporated in the dam. The upstream face o[ the dam shall be constructed witha slope not steeper than 2ilr:l, and the dgwnstream [ace 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 two-thirds of the dam shall be constructed of the most impervious materials, such as clay loam, or a mixture o[ clay and sand, and the downstream one-third of more pervious material, such as sand or gravel. The up- stream face of file dam shall be adequately protected against wave action by stone riprap,-or other suitable materials when required. Outlet-Should the state engineer so require. [here shall 6e 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 •.vith cutoif collars. The pipe shall be placed in a trench bottomed In stable formation, and shall be completely surrounded with well compacted impervious materials. Spillw'ar-For the protection of the dam, an adequate spillway shat! be constructed around one or both ends of the dam, o[ sufficient width 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 [he dam at aLL points shall be not less than 4 feet above the bottom of the soillway. The folfo5ving table shofvs the Svidths o[ spillways for corresponding drainage areas with an allOSVance of a mini- mum freeboard between the maximum high water line and top of dam, of 2.3 feet, and maximum velocities of 3.5 feet per second of time. AREAS OF LOLV RAINFALL INTENSITY A REAS OF HIGH RAINFALL INTENSITY 4REA Of REQUIR EO WIDTH OF AREA Of REQVIRED WIDTH OF AREA OF REQUI R[D WIDTH OF DRAINAGE BASIN SPILLWAY "W" AT DRAINAGE BASIN SPILLWAY "W" AT DRAINAGE BASIN SPI LLW AT "W" AT ABOVE DAM NARROWEST POINT ABOVE DAM NARROWEST POINT •BOVE DAM NARROWEST POINT IN ACRES IN FEET IN ACRES IN FEET IN ACRES IN FEET 2V S .0 S JOJ iG {0 9 {0 9 {i0 94 50 Il 60 11 i00 70 90 1{ SV l9 G60 7S 1Ufr 15 100 600 105 i10 7L 1_0 26 700 1IT 190 2S l{0 70 9G0 1"_7 220 27 l60 1{ 700 110 ^_GO 13 190 37 1000 liV J00 JS 200 41 L100 160 J50 79 220 16 1200 169 {00 {2 240 i0 1]00 178 {50 {i 260 iJ 1400 137 500 46 290 57 1500 196 600 51 J00 60 1600 203 700 i5 J20 63 1700 212 900 57 ]40 66 1900 Sl9 900 62 J60 70 1900 225 1000 66 19G 7J 2000 2]J ALL AREAS EAST OF 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 a[ a point 50 feet 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, if the slope or grade of the bottom is increased accordingly. The grade for clay and shale formations should be 0.30 foot per 100 feet, and for rock formations 0.90 toot per 100 feet. The width 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 of the funnel section, toward the reservoir 1.0 foot in the distance of 50 feet, and the slope downstream should be 025 foot in a distance o[ 100 feet. Borrow Pits-Pits, from which materiels are taken to build the dam, shall be cleared of all vegetable matter, and no material shall be borrowed within a distance of 50 feet of any part of the dam. Materials excavated from the spill- way, when suitable, may be used in building the dam.