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~BC'I'ION Xl The final b€nefit cost ratios indicated by the Phase A damage potential analysis compared with the Phase B estimated costs are tabulated below. SU~~RY AND CONCLUSIONS Sanderson Gulch The Major Drainageway Planning Report for Sanderson Gulch/Weir Gulch represents the culmination of an exhaustive study of the hydrological, hydraulic, economic, and environmental aspects of the gulches. TO the best of our knowledge, it represents the first attempt at a direct analysis of the damage reduction benefits derived from an urban drainago project of this magnitude in the Denver Metropolitan Region. Direct Damage Potential Reduction Benefits $ 880,000.00 l,206,OOO.00 Estimated Costs of Improvements Benefit/Cost Ratio 0.73 Weir Gulch The study represents the first direct involvement of the Urban Drainage and Flood Control District in master planning of inner- jurisdictional drainage problems. The gulches chosen for the study arc particularly applicable to the District's charge of dealing with inner-jurisdictional problems since they flow across the City and County of Denver, the City of Lakewood, and Jeffer~on County. In addition, ffidny of the problems being dealt with in the report developed while portions of the channel were still in Arapahoe County. It is imperative, for the total functioning of the system, that coordination of the system be assured between the City of Lakewood and the City of Denver. Many of the reservoirs whiCh provide flood protection to the City of Denver are located in either the City of Lakewood or JefferSOn County. Thc continued existence of these reservoirs is imperative to keep costs of improvements and damages due to flooding within acceptable limits. Direot Damage Potential Reduction Benefits $2,188,000.00 2,334,000.00 Estimated Costs of Improvements Benefit Cost Ratio .94 North Sanderson GUlch Direct Damage Potential Reduction Benefits $ 73,000.00 Estimated Costs of Improvcmemts 360,000.00 0.20 Benefit/C~st Rati~ To assure proper implementation of the master plan, it will be necessary for governmental agencies, possibly the Urban Drainaqe and Flood Control District or the local entities, to acquire ownership and/or agreements with the owner of existing reservoirs to assure their continuance. Only a few of the reservoirs are adequate for their location in developed areas. North Weir and South weir Gulch are not applicable to a benefit/cost analysis since there is no development in the basin and therefore little or no ~irPct d~mag0s may be ,,-ss'~m..,<i. North weir Gulch The hydrological investigations undertaken for the gulches represent a detailed study under both existing and projected development within the basin. Formal reservoir routings have been completed On all reservoirs under existing co~ditions and proposed conditions of improvement. Estimated Cost of Improvements 78,000.00 South Weir Gulch Estimated Cost of Improvements 80,000.00 The benefit/cost analysis allows true evaluation of the direct benefits received due to dimenished flood damage potential. I~ rcvic~ing thc benefit/cost ratios it must h~ r~m0mh0rpn th~t the benefits include only the direct reduction in flood damage potential due to direct property damage in bot~ the public and private sector. The figures do not include any of the intangible -124- -125-