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I I. I I I I I I I I I I I I I I I I I 52 SECTION VIII EST I MATED COSTS Major drainage channels are relatively costly in an urban area because of right-of-way, bridges and culverts, special structures, and in some places, retaining walls where the channel must be designed narrow, Many of these costs can be attributable to other urban systems such as streets and traffic, recreation and open space, and land development. The cost estimate brings all costs together in the total figure, however, the financing strategy should differentiate between the incremental costs when developing funding sources. The estimated cost of constructing the works described by the master plans has been computed by estimating the quantities of excavation, excavation disposal, bridges, culverts, drops, channel lining, irri- gation ditch crossings, right-of-way, and appurtenant works. Unit prices used in computing the cost estimate are based upon anti- cipated current competitive bidding. A standard allowance for this type of work of 30 per cent was added to account for contingencies, administrative costs, legal costs, financing, and engineering. The master plan type cost estimates are presented for each of the drain- ageways on the following pages. These estimates are suitable for plan- ning at this time, but it must be realized that the cost estimates must be up-dated as the planning and engineerIng progresses in order to reflect changing conditions (including additional channel and flood plain en- croachment) and as more detail is developed in the preliminary and final design stages. The costs of bridges and culverts within the City have been estimated on the basis of all structures meeting the City standards for width of road- way and sidewalks, Streets have been classified according to the City's most recent plan for street development. The master plan drawings show the structures meeting the present pavement needs because the fInal loca- tion of pavement centerllnes is not known at this time. For those bridges and culverts outside the City limIts, i.e., in the County, the cost esti- mates are based upon meeting the requirements of the existing roadways. This was based on the assumption that It would be imprudent to install structures for wider roadways which might not be built for many years in the future. For reference purposes the primary lIst of construction unit prices which have been used for estimating the project cost are given in Table VII I-I. The cost of minor removals, replacement of seepage Ii nes, reestablishing small headgates, handlIng ditch laterals, and miscellaneous construction items has been reflected In unit prices, land costs, and in some cases, the units themselves. The summary of estimated costs for the project, including construction and right-of-way, is given In Table Vii 1-2.