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V 1-1+ The approximate cost of thIs alternatIve would be 5.0 mIll lDn dollar"s, plus about 1.4 mT1110n dollars for land costs. The tDtal CDst of 6.1+ mIllion dollars Is only an approxImate fIgure In relationshIp to the other alternatives and does not reflect t~3 various benefits and de- tailed cost consideratIons. LIned Channel Alternative. A dIstInct consideration Is the use Df hard- lIned channels that are more hydraulIca'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 already occurred. Thus the alterna'. tlve proposed Is a combInation of grass--llned, rock o'r gablon slde-- walled, and European-type, lIned channe'ls. Grass-l lne,d channels .,ould be placed In medIum densIty developed areels; rock or gablon sldE,walled 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,~d 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 I on-II ned channe Is woul d be used In the lIghter development In the mIddle of reach 3, the lower ha I f of reach 6 and the upper two th I rds clf reach 8. The rema I ndel" Df Lena Gulch would be Improved wIth grass li"ed channels to reduce the floodplaIn and make other land available for development. Also with thIs alternative culverts wT11 be replaced as In the grass-lined al ternatlve. The approximate capItal cost of this alternatIve would be 7.7 ml11i'on dollars 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 nDn-structural approach of removIng hazards and reducing damages In the exIstIng nood plaIn. I t also reduces the flood plaIn width where It Is excesslv"ly wide as the result of severe man-made changes. 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 Identify areas of non.. conformIng uses and Impose requl rements for flood proofing and future razing of existing structures, where possIble. In this way, recurring damages and hazards would be prevented ell" removed. As In the p,"evl'. 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 d,,- tailed 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.