APPENDIX C: MITIGATION ALTERNATIVES
• Modify the building (retrofit) so it can withstand the impacts of the hazard; and • Insure the property to provide financial relief after the damage occurs. Property protection measures are normally implemented by the property owner, although in many cases technical and financial assistance can be provided by a government agency. KEEPING THE HAZARD AWAY Generally, natural hazards do not damage vacant areas. As noted earlier, the major impact of hazards is to people and improved property. In some cases, properties can be modified so the hazard does not reach the damage-prone improvements. For example, a berm can be built to prevent floodwaters from reaching a house. FLOODING There are five common methods to keep a flood from reaching and damaging a building: • Erect a barrier between the building and the source of the flooding. • Move the building out of the flood-prone area. • Elevate the building above the flood level. • Demolish the building. • Replace the building with a new one that is elevated above the flood level. The latter three approaches are the most effective types to consider in the planning area. BARRIERS
A flood protection barrier can be built of dirt or soil (a "berm") or concrete or steel (a "floodwall"). Careful
design is needed so as not to create flooding or drainage problems on neighboring properties. Depending on how porous the ground is, if floodwaters will stay up for more than an hour or two, the design needs to account for leaks, seepage of water underneath, and rainwater that will fall inside the perimeter. This is usually done with a sump or drain to collect the internal groundwater and surface water and a pump and pipe to pump the internal drainage over the barrier. Barriers can only be built so high. They can be overtopped by a flood higher than expected. Barriers made of earth are susceptible to erosion from rain and floodwaters if not properly sloped, covered with grass, and properly maintained. RELOCATION Moving a building to higher ground is the surest and safest way to protect it from flooding. While almost any building can be moved, the cost increases for heavier structures, such as those with exterior brick and stone walls, and for large or irregularly shaped buildings. Relocation is also preferred for large lots that include buildable areas outside the floodplain or where the owner has a new flood-free lot (or portion of the existing lot) available.
WSP June 2024 Page C.6
Wake County, NC Multi-Jurisdictional Hazard Mitigation Plan
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