FLOOD04055

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Basin: Statewide
• Title: Systems and Materials to Prevent Floodwaters from Entering Buildings
• Date: 5/1/1985
• Prepared For: US Army Corps of Engineers
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

Test Results

77. As the water level was being raised to the I-ft head, underseepage

developed rapidly but stabilized in about 2-1/2 hr to 10 gal/min. There was

some movement of fines into the sump, but the water cleared up during the

night of 23 May 1984. The pump which was being used (Figure 63) ran for about

40 sec and then cut off for about 50 to 55 sec after the water level in the

sump had been pumped down to a set level. This cycle continued until the

raising of the water level around the house resumed at approximately 9:50 am

on 24 May 1984.

78. As the water level was being raised toward the 3-ft level, the

underseepage increased. At 11:00 am on 23 May 1984, the seepage level became

too high in the sump (the level setting for the pump cuton and cutoff was too

high). This development allowed the seepage water to rise excessively and

caused some water to seep under the garage door (Figure 64) which was the

lowest level of the house. The limits on the sump pump were changed, and the

water was kept at a lower elevation in the sump which decreased the rate of

seepage under the garage door.

79. There was a little seepage around the baseboards of some rooms

(Figure 65). After the test, the cause of this seepage was found to be a leak

at the lap of the fabric. The lap of the fabric was heat-treated but was not

sealed adequately, and a small leak at the lap caused water leakage behind the

seal and into the house.

80. In general, there was too much underseepage during this test. A

larger pump had to be put into the sump with the smaller pump. The large pump

pumped continuously and the smaller pump ran intermittently.

81. Also, the fabric was not placed deep enough in the ground to lower

underseepage to an acceptable level. The fabric was placed about 2 ft below

the ground without any knowledge of how this embedment would decrease the

underseepage. Onsite tests and tabular or graphical data should be used to

determine the depth of cutoff to control underseepage. For example, percola-

tion tests could be performed onsite, and the values could be used in graphi-

cal charts to determine the underseepage for various depths of fabric embed-

ment. From this analysis, a depth of fabric could be determined which would

control under seepage to a tolerable level. Such an analysis would also allow

the selection of a sump pump which could handle the underseepage.

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