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<br /> <br />sealed adequately, and a small leak at the lap caused water leakage behind the <br />seal and into the house. <br />In general, there was too much underseepage during this test. A larger <br />pump had to be put into the sump with the smaller pump. The large pump pumped <br />continuously and the smaller pump ran intermittently. <br />Also, the fabric was not placed deep enough in the ground to lower under- <br />seepage to an acceptable level. The fabric was placed about 2 ft below the <br />ground without any knowledge of how this embedment would decrease the under- <br />seepage. Onsite tests and tabular or graphical data should be used to deter- <br />mine the depth of cutoff to control underseepage. For example, percolation <br />tests could be performed onsite, and the values could be used in charts to <br />determine the underseepage for various depths of fabric embedment. From this <br />analysis, a depth of fabric could be determined which would control underseep- <br />age to a tolerable level. Such an analysis would also allow the selection of <br />a sump pump which could handle the underseepage. <br />Construction details must be considered carefully if any flood proofing <br />system is to work properly. For example, fabric laps must be very carefully <br />sealed, drains properly installed, and all construction adequately braced. <br />Merely sealing to the extent that it is believed the barrier will work is not <br />sufficient when attempting to make a barrier impermeable to a head of water. <br />If attention is not paid to these details and the possibility of a leak is <br />present, it is highly probable that a leak will occur. <br />The backwater valve worked well. It was found that it is important to <br />embed the pipe in the filter material such that fines are not leached away and <br />the filter will pass clear water easily. An appropriate filter cloth should <br />be used to cover the filter material to help in stopping the movement of fines <br />and to produce an effective filter. <br />No holes should be placed in the fabric by screws, nails, etc., when con- <br />necting the system to the house, since doing so produces a possibility for <br />leaks. <br /> <br /> <br />72 <br />