Lateral movement of an AquaDam® during installation occurs when there is insufficient water mass inside the AquaDam® to overcome the difference in water pressure on the upstream side of the AquaDam® (compared to the downstream side, which will always be less). The difference in water depth must be compensated for by the amount of pressure inside the AquaDam® during and after installation. Water levels will rise rapidly during installation and should be monitored continuously by the crew in the water. Sometimes lateral movement is hard to detect, but usually the following are indications:
a. Visual lateral movement of the AquaDam® is the best indicator of movement.
b. The seams on the AquaDam® are straight for some distance but appear bent in the middle.
c. The AquaDam® is no longer pointed in the direction originally taken.
If lateral movement begins to take place or evidence of rolling can be detected, then steps should be taken to correct it. A 6-12 inch change in water level could wipe out all of the installed AquaDams® if the proper amount of head pressure is not kept inside. One step that can be taken to prevent lateral movement is to increase the internal water volume that creates the internal pressure. Fill material can be placed directly on the downstream side in small amounts, allowing the AquaDam® to rest on it. All rocks moved for seepage control should be used to shore it up during installation. Often, fill material has to be excavated from the channel. This is placed behind the AquaDam® for storage, and allows the AquaDam® to rest on it so that more water depth can be controlled than what our User's Guide suggests.
AquaDams® should always be filled with the maximum amount of water possible. Always fill your AquaDams® to their recommended height.
Other solutions to moving or sliding are to install a smaller AquaDam® directly behind the main AquaDam® on the dewatered side. In standing water, stop dewatering and allow the bodies of water on either side of the AquaDam® to equalize.
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