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<br />Altern~tive n <br />iroprovement Alternative #5 h a combination of Altern~tive .1 (Floodplain Man~gement) <br />and Alternative #2 (Channel Inpravements with full bdsin development and undetained <br />flows). Des"ignedchannel iClprovementsthroughthestudyreachwereconsideredfor <br />areas of hi9h damage potential based on the floodplain maps for the lOO-year full <br />development condition as presented in this report. Channel irnprovementswerede- <br />signed fQr the un<::etdined flow with candl importation. By designing for the un de- <br />dainedflovl, futureelimindtion'lfthesepondingdredscdnbeconsideredwithout <br />increasingfloodddmdgepotentidl downstream. <br /> <br />ESTIMATED CONSTRuCTiON COSTS <br />The e,timated costs of these improvement alternatives are based on contractor <br />construction prices, inc1 uding overhead and profit, as of ~lay 1geO, ~rith an E~IR <br />Construction Cost lndex of 292 {1967= 100). These prices are an aggregdte unit <br />price which includes the cost of excavation, materials and insta lldtionbackfi1l <br />and compaction requl red for inst~llation of these facil ities. <br /> <br />unit prices were obtained from cost data and construction bids in the Denver area. <br />(See Table 11 below) <br /> <br />The Fl()()d~la j" Management Al ternati ve was considered in Meas of low damage potential <br />or where channel irnprovementswereshO'Hnnottobecostbeneficial for that particu- <br />lararea. The provisions for Floodplain Management are discU5Sed in detail in <br />A1t,,rnative,01. Structural improvelllents for Alternative #5 are as follows: <br />Grou~ A - Channel improvements inlcude ben-liS placed upstream of the Coloraco <br />& Southern Rd il '"{)dd lIear Ti,::berl in.. Road. Irrprovern,'nts to the cul~ <br />vcrt ~t the Colorado & Southern R~i1ro~d crossing is required. <br />Gr(wp 5 - !II the down~tred'" port im. of the re~ch, from Stover Street to Colle~e <br />Avenue, no channel improvement, are justified. Ch,mnel improvements <br />upstreJmof College Avenut' include a grass-lined channel through the <br />mobile home p.lrk to convey the TOO-year flow. <br />Gro\lpC-Cnannel improvements for Alternative #5 include irq:>rover.1ents at all <br /><:~'\al crossings, d long with an improved culvert at Drake Road. <br />Flood proofing berm~ are required upstreJm of Drdkc ROJd dnd dO'iln- <br />str!'~", of the Pleasant '1all~y dnd lake Cana 1. Other improv€'ments <br />ir,clude dcaring vegctatio', in the chdnnel upstr'ealll Of Shield, <br />StrefCt dfldd 1"'Oild"'ay ran Jt a ariveway crossing dpproximHely 600' <br />~p~tp~a"1 Of Crake Ro~d. <br /> <br />T~hle 11 <br />UNlTCOSTS <br /> <br />Unit Price <br /> <br />Excdvdtion f(ir (iP';1l d'dnn,;l $ 3hubj~ Ydrd <br />Embankment , 2/cubicyard <br />fmbankrn<'nt (Importation plus man>rial) , 15cuhicyard <br />Seeding) ~2 ,OOO/am' <br /> Grass-lined channels <br />J'Jt.e) $8,50G/acre <br />Rockriprdp $ 40/cubic yard <br />Filter material $ 3D/cubic yard <br />Structural concrete I 300!cubic yard <br />Concrete forchanne1 lining S 300/cubic Ydrd <br />G~bions I ISO/cubic y~rd <br />^sphalt S 30/tDn <br /> <br />Final construction costs were (~lcualtcd using the ~nit prices in Table 1) ana the <br />d~tJ i 1 ed mdteri a 1 qUdnt i t iI'S c~ I cu I dted for I!~ch study reach. Un i t costs ~'ere cs- <br />ti:lIdt.ed IjSin~ co,,",on mat eriJ 1<; and const.ruct ion techr.iqtle<; to prod,lce till' draindge <br /> <br />-53- <br /> <br />_54_ <br />