2003-11-07_REVISION - M1984041 - Laserfiche WebLink

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STATE OF COLORADO DNISION OF WATER RESOURCES OFFICE OF STATE ENG]NEER SPEC~ICATIONS TO GOVERN 7HE CONSTRUCTION OF AN EROSION CONTROL DAM Prepmation of Formdadaa fa Dam-All vegetable matter of ~Y desetiption, including rood m a depth of two feet, shall be removed from the more area upon which the dam will test, together with boggy or uascable materials and deposited outside the toes of the dam. 'the beaks of the stream cha»rrd shall be dressed ro a slope of about 1 }:1. A cutoff treneb„ with sloping miles and a bottom width of not less than S feet and depth of 4 feet, shall then be excavated berreath the ante line of the dam the full length theteo~ which trwch shall be refilled with the mast impervious materiels available The foutrdetion of the dam shall then be lightly plowed lengthwise of the dam, ro Provide Proper contact between the foundation and the dam embanlmmt. Plscrrg of Dam F~bml®mt The materials shall be placed in the cutoff [reach and in the embaal®ent of the dam is layers sot exceeding 6 inches in thielatess, after which each layer shall be thoroughly mmpaeted by a heavily loaded disc cultivator. a oortugated or sheep's foot collet, the treads of a mterpillar or uvclq or by Evestock teed is the constrtlctioa During the eonstrttetioa period, the top of the embanl®ent shall be maiataincd as a horizontal plane the full width and length thereof; and m side dumpitrg of materials shall be permitted. The materials shall at ell times contain sufEdeat moisttue to provide proper compaction. Puddling of maoQial with water shag not be permitted. No frorm material or large clods or stones shell be incorporated in the dam. The upstream face of the dam shall be Doastrveted with s dope not steeper than 2i:1, and the downstream face on a slope cwt steeper that[ 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 m~~+„*.~.t of the most imperviow materials, such as clay loam, of a mirture of clay aad sand, and the downstream ate-thud of more petviotss material, strh as sand or gravel. The upstream face of the dam shall be adegmtely Pmnected against wave action by stone riprap, or other stdtable materials when required. chafer-Thee dull be located beneath the dam as vogated outlet pipe not less than 12 i~hes is diameter and large eaovgh to drain within chitty-sa hours arty impotmdmmt in excess of two aae-feet. Such outlet pipe shall be provided with turns Dollars. 'fhe pipe shall be placed is a treorh bottomed in stable formatioq atld shall be completely surrounded with well compacted impervious materials. Spllwaff-Pot the protection of the dam, as adaluaare spillway shall be coamucoed around oae or both ends of the dam, of suffidmt width to provide a capadty to carry the entire discharge from the drainage basin above the dam dutiag periods of unusual rtmoff. The spillway shall be kxa[ed io arable formations not easily eroded, and shall attend to a point well downstream fiom the dam. The following table shall be used m determine the ctaeessary width of spillway to meet the above requirements. 73e top of the dam at all points shall be not less than 4 feet above the bottom of the spillway. T'he following table shows the widths of spillways for corresponding drainage areas with as allowaaoe of a rniaimvm freeboard betsvem the nmldmum high water line and top of dam, of 23 feet, and marimum velodties of 3S feet per second of time. AREAS (7F LAW RNIVFALL lARENSRY AfiFAS (>F fffGff RAINFALL Q1(IFJ11fS!!lY ar~loFavlw~aetv~sel ~ratltnaFaPerwa s7FwoFawsl~tcw~1 7®t~wmltaF a~woFawslrra:ea~1 1~as~wannaF attweONINfQ® wATWeiOW®rP0N1N AaOYEtsaeNAG~ e171sstrwATMNiON~T aeovE[yacNACl~ ~atsetvwATtwsow~r fi£r IVelt Mii£r IORNiiffT e .o s a • an k ao t1 eD 11 coo e0 m t~ ao to eeo es ten is ten a em 1m 1n t, 120 to 7m 1t7 ten a 1b b em to m zo ten x em to too m 1eo a tom tso aoo x ten a 11m ten 0e0 Y ?70 b 1200 faD em ex to so tOm t7e ee0 M 300 m 1100 1A em b 2e0 37 1700 tee em -' 0/ 300 00 rem Al ]00 e8 sal e0 1100 tit 000 ee 310 m rem Rte am ex Oeo 70 /son m 1000 BB 0e0 77 a700 ?31 ALL AREAS EAST' OF THE CONTINENTAL DNIDE BELOW AN ELEVATION OF 7000 FEET, AAE CONSIDERED AS BEING IlV THE HIGH RAINFALL IN7ENS17Y ZONE. The above spillway widths maybe reduced at a point 50 feet below istake, by 25 percent, where the spillway is located the full length thereof in hard clay or shale, aad by 50 per ceat when locaad is hazel cock formations, if the dope or grade of the bottom is its aocardingly. The grade for clay and shale fotrnatioas shook! be 0.30 foot per 100 feet' and for rock formations 0.90 foot per 100 feet. The width of the eatracrs to the spillway must in ell cases be one-third wider than shows in the mble, and the bottom should elope from the krwc end of the funnel semaa, toward the resecwu 1.0 foot in the dismtlre of SO feet, and the slope dowrtream should be 0?S foot is a distance of 300 feel Bonow Pets-Pits, from which taatetials ate taken to bm7d the dam. shag be cleated of all vegetable matoet. e~ no material shall be borrowed within a dismace of 50 feet of arty part of the dam without approval. Materials excavated fiom the spillway, when suitable, troy be used in bufldatg the dam.