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<br />which would minimize the seepage of the floodwaters. Since the test was per- <br /> <br />formed about 2 days after compaction of the backfill, the fill did not have <br /> <br /> <br />time to settle and reduce permeability. It is believed that the early testing <br /> <br /> <br />of the system caused the seepage to be more severe than would have occurred <br /> <br />with a better-compacted backfill. <br /> <br /> <br />72. The upper snaps (Figure 59) for attaching the protective fabric to <br /> <br /> <br />the house at the desired elevation were installed. The top elevation of the <br /> <br /> <br />protective sheathing should be the depth of flood protection plus 6 in. to <br /> <br /> <br />1 ft of freeboard to protect the house from waves caused by boats, wind, etc. <br /> <br /> <br />(As stated earlier, the maximum depth to which a house or a building should be <br /> <br /> <br />made resistant to floodwaters is approximately 3 ft.) <br /> <br />73. A backwater valve was installed in the sewage drain line to keep <br /> <br /> <br />the floodwaters from backing up into the house through the toilet and bathtub <br /> <br /> <br />by cutting the 4-in. pipe which drained water from the house and placing the <br /> <br />valve in the line. The valve was enclosed in a plastic standpipe with a <br /> <br /> <br />screw-on lid to provide easy access. <br /> <br /> <br />74. For the purpose of this test, plywood sheathing and wooden braces <br /> <br /> <br />were used to provide support for the protective fabric around the patio and <br /> <br /> <br />porch. These areas could be equipped with decorative railings of the desired <br /> <br /> <br />height which can serve as permanent support for the fabric. A temporary brace <br /> <br /> <br />can be installed at the time the system is to be used. Temporary bracing can <br /> <br /> <br />also be prepared for garage doors (which have excessive span) to support them <br /> <br /> <br />when a water load is acting on the door. <br /> <br />75. The fabric was raised from the permanent storage compartment and <br /> <br /> <br />attached to the house by permanently installed snaps. A levee had been built <br /> <br /> <br />around the house, and with the fabric in place the house was ready for <br /> <br /> <br />testing. <br /> <br />Testing <br /> <br />76. Water was pumped into the area between the house and the dike <br /> <br /> <br />(Figure 62). The water level was raised to a I-ft head on 23 May 1984 and was <br /> <br /> <br />held overnight. On 24 May 1984, the water level was raised to produce a 3-ft <br /> <br /> <br />head on the walls of the house which was held for approximately 24 hr. <br /> <br />23 <br />