On the far end of the AquaDam®, the roll of new inner plastic has been set up on rollers. Once the rope has been pulled through with the string line, the end of this roll will be tied onto the rope.

You can see the piece of rope being pulled through the AquaDam®. 

The string line is gently pulled until the rope can be grabbed. Then the end of the new plastic roll is tied on and pulled carefully through.  

In this instance, there was very little room to maneuver, so the rope could only be pulled about 20' before it had to be retied.

Pull, take up the slack, retie... Pull, take up the slack, retie...