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2. Structural Mitigation Mitigation practices can involve temporary or permanent structural measures such as sandbags, floodwalls, levees, channel improvements, elevation of property, and floodproofinglretrofitting. The descriptions below are very brief and are intended to provide an awareness of the alternatives available. There are numerous mitigation documents available, and the CWCB can provide further information and assistance to interested parties. The Colorado Office of Emergency Management and the Federal Emergency Management Agency have information and expertise in these areas as well. Temporary Measures Sandbags have long been used as a temporary flood control measure. The basic supplies required for an emergency sandbag levee are: . Sandbags (cloth or plastic) . Source of Sand . Polyethylene (Poly) . Heavy Equipment . Shovels, Wheelbarrows, and other hand tools . People Some general tips on how a sandbag levee should be created: . The sandbag levee requires careful and well-planned placement. . A properly filled sand bag is only half-full, and weighs about 40 pounds. . The open end of a filled sandbag should be folded over, not stitched or tied. . A key trench should be excavated to a depth of 4 to 6 inches and a width of 18 to 24 inches prior to placing any sandbags. . Poly should be placed in the trench and anchored with several sandbags. A sufficient width of the poly is placed on the water side of the levee. . Sandbags should be stacked in alternating rows, similar to the alternating joints of a brick wall. . Sandbags should be stacked in a pyramidal structure using a 3 to 1 ratio of the base width to the height. . The elevation of the levee should be maintained to the desired level of protection. . The poly sheeting will provide a water proof cap, once the levee has been built. . Sandbags are placed to secure the poly on top of the levee. . Levees should be kept at least 6 feet from foundation or basement walls. Figure 3 depicts a typical cross-section of a properly constructed sandbag levee. Flood Proofing Flood proofing is defined as "any combination of structural or non-structural changes or adjustments incorporated in the design, construction, or alteration of individual buildings or properties that will reduce flood damages." Simply stated, flood proofing includes any effort 20