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SEO-WTR DIl! S TEL~303-945-5665 Sep 18 99 23:32 No .007 P.03 STATE OF COLORADO DNISION OF WATER RESOURCES OPFICE OF STATE ENGINEBR SPECIFICATIONS TO GOVERN TTfE CONSTRUCTION OP AN BAOSION CONTROL DAM Preparetlaa of Foundetlon Ear Dato-AII vegetable meaer of every descriptbn, 4tcluditt)i toots to a depth o[ two feet, shall be tetuoved ttou the torus area upon which the dam vt!!l rear. together with boggy or unstable materials and deporiued otuelde the tote of the dam. The benlat of the stremt channel shall be dressed to a elope of about 11:1. A euroff [rrureh, with sloping side and a bottom width of not ka than S feet and depth of a feet, shall then be excavated beneath the center 8ne of the dam die ftdl length thereof, which nerlelr shag be rsCllad with the most impelviorls materials available. The fotmdatlon of the dam shell then be lightly plowed lengthwise of the daa4 ro provide proper aoataet between thu foundation and the dam embanlanent. Placing of Dam Embenlaeeat-The materials sMll be pkted in dK cutoff ttmch and in the embadaneat of the dam in leyen not erroeditg 6 inches k thickntaa, after which each kyer shall be thoroughly oompeeted by a heavily Ioeded disc culdveror, a cotrlgated of sheep's foot tolls, t}:e lleadc of a caterpillar or tnleke, or Dy livestock used in the construction. Dttr{ng the mrntnretlon period, the Wp of the emhankroent shell be maulrained as a horirante] plane the full width and length [hereof, ettd no dde dumping of materials shell be permitted. The rmterials shall at all Hmes contain sufficient molsttrre ro provide proper eompecdon. Puddling of material with warn shall rat be permitted. No frorm tmterial r r large clods or atones shell be incorporeted k the dam. The ugtreem fete of die dam allall be cotstructed with a slope not creeper den 2 f: ], nd the downstream face on a elope not creeper than 2:1. The erect or tap of the finished dam slurp be rbt kss than 8 feet k width. 1'!te upstmatn two•thirds of the dam shall be constructed of the most impetviotu taeteriala, such as coy tiara, oT a idxnue of clay end s+nd. and the downstream one•rhud of [tan pervious materiel, such ec send or grevel. The upstneem face of the dam shall he adequately promerad aSainst wave action by stone riprap, or other suitable tMterials when required. Outkt•-There shall be located beneath the dam an urtgeted outlet pipe not less than 12 inches En dleraeur cad large etlnugh to drain widdrt rhlrtyavc hours any impoundment in excew of two acre-feet. Such outlet pipe shall be provided with cutoff mlkts. The pipe aball 6e plated >n a trench botromed in arable formation, and shall be completely surrounded with well compacted impetvbus meterie4, SpiJlwey-For the protection of the dam, en adequau sp111wey shall be constructed sround one or Doth ends of the dam, of su~dent width w yvvlde a capaciry to carry the entire disehsrge from the drainage basin above the dam during periods of unusual runoff. The spillway shall be located In spble fotmatlons nos easily eroded, and shall extend to a point well dorvnctresm from die dam. The following nbk shall be used to determine the necessary width of spillway ro meet the above requirements. Ttre top of the dam at ell poiner shall be nor lea then 4 feet shove the bottom of the spillway. The tollow(ng table shows the widths of epillweys for corresponding drelnage attar with an allowance of a mintmum freeboard between the maxunum high water line and [op of dam, of 2.3 tees, and maximum velocities of 3.5 feet per sernnd of time. AREAS OF LOW WUNiALL 1NtFlJSfiY MFRS OF HIGH MlNFALL 4NIEIr~/IY i MEe aF fxNN11oE WOM 1E~@/wOn1a>ialwAr ABOYE OYINA07i~ M'AT IWtrOMWrfOerrN AIFA6 uMM7aE a,1v1 AGUE [YW MIO~ n6aUa1~MVIM OF t#'LLMMt'M AT WFPCeI~r MFJ1a OMNiYiE aAaM A[OlE d~rNAO® im/®MimnaF NLwA'/1r AT IIMtba~t ~T PONE N g3FT P'OR M!@T m e b e eo0 N e0 11 e0 11 t100 b 00 1• b le 6p0 A 100 1e 1ao a rpo Im 1e0 r1 120 >• 100 117 1b b Ip 30 e00 Id nap ® la >• e00 Itl Zap 33 1ep 37 1000 to app 7e em U s0 1100 /rW 1a app 4r !W a 1300 1h ~p0 y !m 4/ 100 le7 pm b rep a lax I~ lee 2va ~o m 1T00 sl: em m a.o a 1e00 o e1s 227 ens 1 °00 S~eD A p lo 100p sa3 a op AL.. AREAS EAST OF 731fi CONTINENTAL DMDB BELOW AN ELEVATION OF 7000 FEET, ARP CONSWERED AS BHING IN THE HIGH ? V."rPA11 INTENSITY ZONE. 7lle above spWwey widths may be reduced et a point SO feet below fnteke, by 2S per cent, where the spillway b located the frill length thereof m hard clay or shale, and by 50 per cent when located In hard rock formatbns, if the slope or grade of the bottom is irraeeced eocordlogfy. TW grade for clay and shale formotiom should be 0.30 foot per 100 feet, and for rock fotmedom 0.90 foot per 100 feet. 73e width of the mham to the spillway must in all cases be one-third wider than Chown In the table, and the bottom should elope from the lower erd of the funnel seerb4 toward r11c reaervolr 1.0 foot in the dlatanee of SO feet, and the slope dowmtream should ire 0.25 foot in a dfsnnee of 100 fast. Borrow Pis-P(ts, from which n1a[erLtls are taken to build the dam, dull be cleared of ell vegetable metsa, and tYD iaaterid shell be borrowed within a dlatance of so feet of any part of the dam without approval. Materials excavated from die spillway, when slriteble, may be used is bvtldlag the dam.