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1 - INTRODUCTION 1.1 Concept of Floodproofing Floodproofing is a composite body of techniques and approaches for preventing flood damage to the structure and contents of buildings in flood hazard areas. Examples of flood. proofing include the placement of levees, dikes, or walls around individual structures; water. tight closures for windows, doors and other openings; wall reinforcement to resist lateral pressure and debris flow; elevation of building on pilings or fill; use of membranes; paint or other substances to reduce water seepage into buildings; installation of check valves at sewer and utility locations to prevent entrance of flood waters, Floods are a major concern of Colorado's natural resources management activities, Despite the effort of federal, state, and local agencies to reduce flood damages through major flood control projects, the amount of flood damage that occurs each year is still increasing. Annual. Iy, between 10 and 20 floods larger than a 25-year magnitude and an average annual flood damage in the amount of $14,000,000 occur somewhere in Colorado. Over the past 90 years, over 350 lives have been lost and total property damage has exceeded 1.6 billion dollars. In Colorado, the amount of flood damages covered by flood insurance claims was $162,745 in 1981 and $1,134,189 in 1982. Since the enactment of federal legislation in the late 60's and early 70's, local communities have been made aware of flood plain management needs and requirements. Flood plain management entails a wide range of measures to optimize the use of lands within designated flood plains to reach an ultimate goal of flood damage reduction. These measures of conven. tional flood control works include dams and reservoirs, levees and flood walls, and channel improvements and diversions. Nonconventional methods include zoning, building codes, sub. division regulations, and designated floodways and encroachment limits. However, flood plain management does not attempt to eliminate development in flood plain areas, but rather, it encourages wise flood plain development to lessen the adverse effects of floods, Floodproofing measures are only a small part of a good flood plain management program. Floodproofing measures are instigated through development regulations and building codes. Floodproofing is the technique of building new structures on flood plains (or modifying exist. ing structures) in such a way that the structures are, by their design and composition, affor- ded protection against floodwater and floating debris, Thus, floodproofing enables development in low-hazard areas of the flood plain where moderate flooding with low stage, low velocity, and short duration is experienced; when co""ctive flood protection is not feas- ible; where structures essential to activities dependent on riverine locations n"ed some degree of protection; where a higher degree of protection than that provided by a flood- control project is desired; and for a reduction of flood insurance premiums, A decision to use a particular floodproofing method to reduce flood damages must be based on the characteristics of the individual structure. It is important to understand that these techniques are not a guaranteed solution, but rather their success depends on how they relate to the structural condition of a building, local soil characteristics, and the type of flooding that will occur. 1.1 Classification of Floodproofing Classification of floodproofing includes both classification of specific flood proofing measures and classification of flood proofed structures as a whole. Specific floodproofing m'~asures are classified based on the steps required to implement them, Floodproofed structures are classified based on the degree of protection provided.