In which method of foam application is a bank of foam formed on the ground in front of the flammable liquid pool and pushed over the pool by the continued application of foam?

The roll-in method involves creating a bank of foam on the ground in front of the flammable liquid pool and then using the force of additional foam to push this bank over the surface of the burning liquid. This technique is effective because it ensures that the foam covers the surface of the liquid, effectively extinguishing the flames and preventing re-ignition. The foam acts as a barrier, preventing oxygen from reaching the burning fuel and smothering the fire.

In this method, firefighters typically create a thicker layer of foam that is more resilient to the heat and magnitude of the fire, enabling it to effectively protect against flammable vapors and isolate the burning material. The implementation of this technique is strategic as it utilizes gravity and surface tension to spread the foam evenly across the flammable liquid.

Other methods, such as bounce-off, rain-down, and subsurface injection, serve different purposes or are applied in different ways, and therefore do not involve the banks of foam being pushed over a pool in the same manner as the roll-in method. Each method has its specific scenarios where it is most effective, but for this particular question, the roll-in method is the one that correctly describes the process outlined.