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<br />-000176- <br /> <br />64 <br /> <br />estimated by the Geologicul Survey on the basis of [Pcovery of In'ound <br />WU1(>rsJ)res('ntly nonbeneficillllv consumed within the zone of influence <br />of the THin llnd laterals, htl.."ed on d{>signs pr{'IHlred bv the Bureau of <br />Hednmation. The drain yields were ('stimuted for 1\\:0 ground-water <br />condition~: tt low wllter-table condition throughout tlw Clospd Basin, <br />such IlS prenliled during the full of 1946; IlBd II high wlll('r-table con- <br />dition, such llS prcvuiled during the spring of 1947. <br />The following tubulution shows th(' yit'lds estimated as described <br />ubove !llld drain costs estimated on t.he basis of October 1952 prices: <br /> <br />Eslimatedannual yield in <br />Kre.f&etperyur <br />low-water Hirh-waler <br />Gravily sump drain Iab/e table <br /> <br />Annual cost per acre-loot <br />01 drain yield <br /> <br />Will'loutlaterals_n_____n_________u.....n____.... 6,600 14.100 <br />WitlllateraIL_________.....________nn __h_______ 15,500 33,300 <br /> <br />low-water <br />".. <br /> <br />High.water <br />table <br /> <br />'17 <br />112 <br /> <br />.. <br />.. <br /> <br />In light of the adverse findings with respect. to the probable qunlit.y <br />of the drain yields, it was concluded that furthl'r consideration of tl <br />grnvit.y drain along tlw general aligmnent. of the slimp wa~ not <br />warranted. <br /> <br />INTEHCEPTOR DRAll'O <br /> <br />As the studies summarized nboye hud established thl\t the ground <br />waters in the nreu just west of t.he ~loscll-I10()pCr irrigated lands were <br />of sntbfactofY quality under t.he compact provisions with respect to <br />sah'age of ClOSt'll Busin watprs, consideration was given to eonstruc- <br />tion of u gravity interceptordmin nlong the nlignment shown 1)Jl Dfaw- <br />ing 253-504-1759, for the dual purposes of making additional water <br />available for beueficiul consumpth'e lIse in Colorado Hud pnn"iding <br />drainage relief for the lunds in the ~Iosca-Hooper area. <br />It ,,;ns recognized that construction of a drnill ill this location <br />necessarily mllst be uccomplished in such II IUalllH'r us to insure <br />nguinst udvcrse effect u/)OJl existing irrigation on the nlluvin.1 fnu to <br />the wcst and in t.he .:\ oscn-Hoopef nrell to the ('ast. Also, it wa.'i <br />recognizf'd that the depth of pervious mntefiul underlying tht' eOI1- <br />templated alig-nment might. be of such mngnitude R.", 10 preducll' <br />nchicving the desirable cutoff of ground-wnt{,f fIo\\" t~) the enst. For <br />this reason, both a shnlIow and u deep dmin were inn>stigated. The <br />alignment selech'd W8..-'; rOllsidc.'rNI to e;.;.sentilllly skirt tilt' vI'ry pen.iolts <br />llllu\.ial fan to the wt'st. and to he of sufficient. distullce from the <br />western irrigllted llrefiS to insure against uti vef:-;C l'ffeet. on the slIb- <br />irrigation pmctices therein. <br />ComlHJtlltioIls of the probnbh' quantities of ground water that <br />might ){' rxpected to be n'eo\'rn'd hy both the shallow and deep <br />dmins along tlu' l~ontemplat('d nlignllwnt w('re mude using the formula <br />Q=0.OOl12 'I'lL, in which Q is th(' lllHount of wntl~r rN'o\'{'red in <br />Here-feet \H>r yenr, T the field co{'ffi('ient of trllllsmissibility in gallons <br />pef dny, the hydrnuJic gradient in fPl'l per mile at right tlllgl('s to <br />the drain. and L the length of the drain in miles. The field coefficient <br />