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<br />Barrier design needs to account for leaks, seepage of water under the wall, and drainage of <br />rainwater that falls inside the barrier perimeter. A sump and/or drain tile is needed to collect <br />the internal ground and surface water. A pump and pipe are also needed to pump the internal <br />drainage over the wall as illustrated in Figures 2 and 9 on pages 4 and 22. <br /> <br />Aoodwalls, levees and berms can either surround the building (as in a ring levee) or connect <br />to high ground. Several communities have funded construction of berms or floodwalls that <br />run from high ground adjacent to one end of a house to high ground at the other end to <br />protect a below-grade patio or walkout basement (see Figures 9 and 13 on pages 22 and 28). <br /> <br />Cost: Minimal to $20,000+. The cost can range from practically nothing, as when the <br />homeowner regrades the yard or builds a berm with local fill, to $20,000 or more depending <br />on the complexity of the project and the materials used. Landscaping, backfilling and <br />building brick facades to match the structure can greatly increase costs. <br /> <br />2.3 Dry Flood Proofing <br /> <br />Sealing a building to ensure that floodwaters cannot get inside it is called dry flood proofing. <br />All areas below the flood protection level are made watertight. Walls are coated with a <br />waterproofing compound, or plastic sheeting is placed around the walls and covered. <br />Openings, such as doors, windows, sewer lines and vents, are closed -- temporarily, with <br />sandbags or removable closures, or permanently. <br /> <br />Figure 4. Dry Flood Proofing <br /> <br />One-way check valve <br /> <br /> <br />Flood proof walls <br /> <br />Maximum protection <br />level is lhree feet <br /> <br />Notfor buildings <br />with basements <br /> <br />Closures for openings <br /> <br />Accounrfor sewer backup <br /> <br />Dry flood proofing is only appropriate for buildings on slab foundations that are free of <br />cracks. Because most building walls and floors are not strong enough to withstand the <br />hydrostatic pressure from more than 3 feet of water, the design flood should be less than 3 <br />feet above the slab. The technique is not recommended for houses with floors below grade, <br />such as basements and garden apartments. because hydrostatic pressure can collapse the walls <br />or buckle the floor. <br /> <br />This technique is not as desirable as a barrier, which will keep floodwaters from reaching the <br />building. However. where there is not enough space on the lot for a barrier separate from the <br />building, dry flood proofing may be the only alternative. <br /> <br />Proper maintenance of materials used in dry flood proofing is a concern. Waterproofing <br />compounds can deteriorate over time, especially if they are exposed to sunlight. Removable <br /> <br />-5- <br />