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V 1-1+ The approximate cost of this alternatIve would be 5.0 mill lon dolla,-s, plus about 1.4 m111Jon dollars for land costs. The total cost of 6.1+ mIllion dollars is only an approxImate fIgure In relatIonship to the other alternatives and does not reflect t~a various benefits and de- tailed cost consideratIons. LIned Channel Alternative. A dIstInct consideration Is the use of hard- lined channels that are more hydraullca'lly effIcient so that channel rIght of way Is minimized. It Is ImmedIately apparent that this t,'ade off between channel construction and rlc;ht of way costs Is only va: Id In reaches where development has I'll ready occurred. Thus the alterna... tlve proposed Is a combination of grass..llned, rock o'r gablon side.. walled, and European-type, lined channe'ls. Grass-llne,d chann.als .lOuld be placed In medIum density developed are",s; rock or gablon sldllwalled channels In lIght resIdentIal areas to mInimize area taken In backyards and prevent slope erosion; and European..type, concrete-lIned chllnnels In the most heavily developed areas. The optImal combination of this approach ~'ould be concrete-lln'ld chan- nels In the presently heavily damaged areas of the trailer courts In reach 2 and I n the upper port I on of reach :3. and the heav 11 y deve loped areas of reaches 9 and 11 I n Wheat ridge.. Gab lon-II ned channe Is wo"l d be used In the lighter development In the mIddle of reach 3, the lower ha 1 f of reach 6 and the upper two th I rds c,f reach 8. The rema I nder of Lena Gulch would be Improved with grass ll"ed channels to reduce the floodplaIn and make other land available for development. Also with this alternatIve culverts will be replaced as In the grass-lined al ternatlve. The approximate capital cost of this alternatIve would be 7.7 mllli'on doliars with 0.8 mIllion dollars land cost to total 8.5 mill Ion dollars. The Intangible benefits would not be as hl9h as the grass-lined channels, but would be In the same range. Improved Flood Plain. This alternative fc~uses upon the non-structural approach of removing hazards and reducing damages In the existIng nood plaIn. I t also reduces the flood plain width where lt Is exce5sfvf~ly wide as the result of severe man-made dlanges. Undersized culvert capacitIes and near total constrictIons such as buildIngs that are built over the Gulch would be replaced ()r re~oved. One of the concepts of this alternative IS. to Identlfy areas of non.. conformfng uses and Impose requl rements for flood proofing and future razing of existIng structures, where possible. In this way, recurring damages and hazards wou 1 d be prevented (lr removed. A.s I n the p I-ev J... ously mentioned unImproved flood plaIn approach, no further develop- ment would be allowed In the flood plain. BesIdes flood Insur,9nce, professional assistance would be part of the plan to Implement a df~- taf1ed program and provIde educational mat'Hlal and guIdance for flood plaIn resIdents. This assistance could be coordinated by the Urban Drainage and Flood Control District.