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<br />Mr. Andy Briscoe
<br />3 September 1969
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<br />Page 4
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<br />The Master Plan for lower Sunshine Gulch, begins south of l1apleton
<br />Avenue. From this point dOl-m, the existing channel is to be cleared
<br />of trees and debris that r.ligl1t be washed down the gulch during a major
<br />flood, Just upstream frarll the Farmers Oitch Siphon, eMbankments on
<br />both sides of the creek are to be constructed so that the flood "aters
<br />wi 11 be funneled over the FarMers Ditch Siphon, These embankments are
<br />to be Jand~capeJ in such a manner that they \.,';) ) cOf'form to the res i-
<br />dential landscaping of t'l-" area, ~eIOl-' the Farmer5 Ditch the c!annel
<br />is to be cleaned to approxi:;lately Statior. I:-i-JC. ;,t ~'1is poi....:, the
<br />artificial channel \.:111 start. The cIJannel, to be constructed from
<br />this point to the Pear] Street bridge, '\'Ji 11 cOi,~i:)~ of a r:lajor drainage-
<br />way, hd th terraces. T~le upper terrace I"; 11 DC gra,:>sed and Vii 11 be
<br />inundated or.ly during the larger runoff:,:>. The next IC)\'jer terrace, \'Jhich
<br />has a riprapped bottor'" \;j 11 carry tile floods ttlat arc expected to occur
<br />about once every 10 years. ~elo\J the second level is a 101.,-flo,; tricUe
<br />channel \'Jhicn ~'Ji 11 carry the more frequent Iy expecte~ flous of up to
<br />about 15 to 20 cfs. This levi-floll channEl ...ill also heir to flll"h sr.1all
<br />sediment loads dovm into Boulder Cree~. It is proroscd that tri', Im-!-fla"
<br />trickle channel \'Ji 1 J be constructed ~';it.il concrete, \""ith continui-:9 reinforc-
<br />ing to obviate sections of it being torr, out or damaged.
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<br />The existing Pearl Street culvert must be replaced uith a nev,' rlU1tirle
<br />barrel box culvert. The invert of the east barr-el is to be CV):,Lruc~ed
<br />a little )m',er than the h\::St barrei. T'li'.:> 1~ done to fence U:t;' ](}H
<br />flm'/s i'ito a snall cr-OS5 Se.CtiOl~ to keep tile ve\ocitic::. ~';:Jtl <:::d Cdrr'y
<br />the sedinent through the culvert. From Pearl Street to Carlyon boulevard,
<br />the drainagc\'Jay \'Ji I I con,:>ist of a hi~jl) velocity dlanncl. TI,i::. cf,CliHlel
<br />I-Ii 11 have concrete Ir/alls and a rirrapped ::JO::':O". The ':>;Ut;~ of t~le channel,
<br />It/hich ha.ve a 1 horizontal and 2 vertical slope, r~1(lY be lineJ "i~ll stone
<br />to improve the aesthetic::, of the channel. T:lis charHiel \-/; 11 be trcJ:1si-
<br />tioned in:o the existing Canyon iJoulevar\.. box ,.:ulv,'rts \{iici~ ')<lV(' the
<br />capacity to Cilrr'f the de~;9n flool... Frol:l (>nyon i~ojl':'vJrd to b()uldc~
<br />Creek, a steep, shallo\;: paved d,anllel \';'i 11 be cGn~;truc:ed.
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<br />Estimated Costs
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<br />The estimated costs of cr,nstructing the ':lori,s desc-jued ~l~1 lhe Haster
<br />Plan, have been co~pJted by estirating tho ouartities cf excavation,
<br />excavation disposal, (.u~vf'rt~;, drcps, channel lining, and r-e:aining
<br />~'Jalls. For the rur~o~~ 'Jf this let~er re-par:, nu attcnpt \"Jas ~-l.1de ~o
<br />estimate the cost of the right-of-vJay. The: righ:-'Jf-"Jay c::>st l'/as not
<br />included because it i~~ p1anned that a r:~ajor pari uf the vJurk \"j 11 lie
<br />on ci tY-OI,med righ:-of-Viay and that bet,!een Pearl ~trect ,lnd Canyon
<br />Boulevard the chalnel \,i'1 FollJw the exist ing al 'gnrlent. Til" lateral
<br />right-of-way cost can;1ot be estimated excc[)t by a qual ifieo appraiser
<br />familiar ~;ith flood problems.
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