An aboveground storage tank has leaked flammable liquid into the surrounding diked containment area. A foam stream is directed against the side of the tank. Which foam application method does this describe?

The scenario described illustrates the bounce-off method of foam application. This method involves directing a foam stream towards the tank, which allows the foam to hit the tank surface and then "bounce off" into the flammable liquid area. The foam in this case creates a blanket over the liquid, effectively suppressing vapors and minimizing the risk of ignition.

In contrast, the other methods differ in their application techniques. The roll-in method focuses on the foam rolling over the surface of the liquid, allowing for more direct coverage. The rain-down method disperses foam from a height, letting it fall onto the liquid, while the pour-over method involves directly pouring foam onto the liquid surface. Each of these techniques is designed for specific situations and leveraging the characteristics of the foam to achieve maximum effectiveness in fire suppression and safety.