Figure 3 represents the most difficult installation scenario, such as a flowing stream where ropes must be used. The onsite conditions can change quickly in live streams because water depths will change from one side of the AquaDam® to the other. This difference in pressure will make the AquaDam® move downstream unless head pressure is maintained inside the AquaDam® during all phases of the installation. An AquaDam® that is unrolled too quickly and is not allowed to inflate above the level of the surrounding water will move downstream with the water flow. The workers on the bank slowly let the ropes out to allow the AquaDam® to unroll when inside water pressure and mass is achieved. Unroll 2-3 feet at a time, then wait for head pressure to build again, repeating this process until the AquaDam® is fully unrolled (see the Eagle River installation in Vail, CO). Timing is everything. Do not get in a hurry! Let your pumps work! A requirement of using ropes is that the AquaDam® must be installed in a straight line. Head pressure must be maintained inside the AquaDam® to prevent it from moving. Ropes tend to move to the outside of the unrolling AquaDam®. The worker at the end of the unrolling AquaDam® adjusts the ropes and keeps them in the center by slackening and moving one rope at a time while the other ropes maintain the necessary inside pressure to keep the AquaDam® from moving downstream. On site rock that needs to be moved to assure a good seal should always be moved to the downstream side and used for support.
Figure 4. A cross section of a large AquaDam® being installed in flowing water, illustrating the location of the berm, pumps, ropes, laborers and the inside water head pressure, compared to the outside water levels.
Once the ropes are manned, the pumps are primed, and the AquaDam® is aimed in the proper direction (at a right angle to the starting point on the bank), the pumps can be turned on and the inflation process can begin. Figure 5 shows a picture of restraining ropes used during installation of a large AquaDam® in a fast moving river. The small diversion channel in this project demands that a large AquaDam® be used despite the low water level, because of the anticipated increase in water depth (above 6 feet). The AquaDam® should be unrolled at a rate of about 1 to 3 feet every time the ropes are slipped and maintain a 12-24 inch (or greater) head of water pressure inside the AquaDam® ,compared to the upstream water depth, which will be increasing. Each foot of installed AquaDam® requires 2 feet of additional rope. The AquaDam® has to overcome imbalances of water head displacements happening in the river during the installation process. Only experienced installation personnel should attempt to install large AquaDams® in moving water. Smaller AquaDams® can be installed more easily and require less expertise.
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