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Master Drainageway Planning StudiEiS Communit'l officials may wisll to quantify their flood and drainage problems and seek long-term approaches to them. In a master drainageway plan or a feasibility study, an analysis is performed which evaluates structural and non- structural improvement plans to mitigate or alleviate flood hazard problems and resultant damages. These studies can be performed simultaneously with a detailed floOdplain information study, or they can be performed indepen- dently. In many cases the studies will include designs and plan layouts. This type of worl< program will include the same tasks as required for a detailed floodplain information study willl some additions. Base Mapping and Field Surveys Ground elevations should be established for all street intersections as a basis for determining water depths at thasH intersections. Hydrolo~lic Methods The 2- anc 5-year flood discharges should be computed, TI1ese values are required in determining baseline flood damages and designing storm drainage faGilities. In addition to the stated hydrologic methods, the Rational Method, based on the equation Q.= CIA. can be used for small drainages of two square miles or less, Hydraulic Determinatiflns Computer modeling may not be practical for street and gutter storm drainage rcutings. Floodpl~lin Delineations No additicnal requirements. Floodways Delineaticns of floodways may not be a study task in this type of stu<Jy. Problem and Damage Assessments Street drainage and flood related problems will have fa be analyzed and prioritized. Damages due to flooding are estimated to establish a "baseline" condition for the study area. Those conditions define what is likely 1:0 happen if no improvements are implemented. Flood damage cate!IOrh.s applicable for damage analysis Damage to public faCilities Structural damage Conten1 damage Damage to stored goods InventolY loss or damage DamagE! to livestock Erosion Cleanup and removal of debris Interruption of traffic or services Missed work General inconvenienC!3 Loss of business income Loss of salos taxes Loss of salaries to employees Patient evacuation an,j emer- gency services Plan Formulation Following the determination of the drainage and flood problems, a plan-of- improvements can be formulated for each study area. The drainage and/or flood contl'Ol plans are developed for a selected frequency of protection. An array of allernative plans is formulated. Each plan is directed toward meeting any or all of the stated objectives of a contract or work program. Plan-of- improvement alternatives include structural alternatives, non-structural alter- natives. or a combination to addmss floodplain probiem~i, and the following street anc drainage project alternatives to address storm drainage problesm: 1) assuring adequacy of natural detention and conveyance of water, 2) using streets for conveying storm water, 3) main':aining drainage capacity of paved streets and gutters, 4) assuring ease of maintenance and access, 5) making use of available right-of-way, 6) controlling erosion, 7) assuring pubiic safely, 23