47.5 MB - The Whole Building Design Guide

2.2.1.1 Benefits/Costs: Determining AcceptableRiskMany decisions that are made with respect toExtreme hurricane storm surge flooding critical facilities are, in part, based on a determinationof acceptable risk. Risk includesmay be a very low-probability event, butthe flood water depths and waves may the potential losses associated with a hazard.be much more severe than the conditions Ideally, risk is defined in terms of expectedof the base flood shown on the FIRMs. probability and frequency of the hazard occurring,the people and property exposed,The potential impacts on a critical facilitymust be carefully considered in order to and the potential consequences. Choosingmake an informed decision regardinga site that is affected by flooding is a decisionto accept some degree of risk. Althoughacceptable risk and potential damage. Ifpossible, it is always best to avoid locating the flood-prone land may have a lower initialcritical facilities in areas subject to extreme cost, the incremental costs of construction,storm surge flooding.plus the likely increased costs of maintenance,repair, and replacement, may besignificant. Another cost of locating a criticalfacility in a flood-prone area is related to access problems if roadsand driveways are impassable. Although the building may be elevatedand protected, if access is restricted periodically, then theuse of the facility is affected.The building owner and the design team can influence the degreeof risk (e.g., the frequency with which flooding may affect thesite). They control it through the selection of the site design andthe building design measures. Fundamentally, this process is a balancingof the benefits of an acceptable level of disaster resistancewith the costs of achieving that degree of protection. With respectto mitigation of future hazard events:m Benefits are characterized and measured as future damagesavoided if the mitigation measures (including avoiding floodhazard areas) are implemented.m Costs are the costs associated with implementing measures toeliminate or reduce exposure to hazards.Section 2.2.2 describes damage and losses that are incurred bybuildings exposed to flooding. Direct damage includes damage tophysical property, including the site, the building, building materials,utilities, and building contents. Indirect damage that is not2-38 MAKING CRITICAL FACILITIES SAFE FROM Flooding