Definition - What does Foam Drilling mean?
Foam drilling is a method of drilling that uses a combination of a polymer foaming agent mixed with water and compressed air. It's more effective than mud drilling in some ways, and generally provides for more efficient removal of spoil. It's one of the drilling techniques available to trenchless operators.
Trenchlesspedia explains Foam Drilling
Perhaps the greatest advantage of foam drilling is its superior ability to clean the drill hole. It can capture and transport more cuttings than other methods of drilling. That's due in part to the lubricating properties of the foam. On the other hand, the foam can be annoying and difficult to deal with. It might be necessary to build pits or barriers to entrap and contain the foam, and a good stiff wind can carry it to unwanted areas.
The mixture of the foam is generally one liter of foam solution per 200-liter (45-gallon) barrel. One way to keep the drilling going continuously is to use two to three barrels. When the first barrel is used up, switch to the second one. Then while the second one is in use, you can re-mix the first barrel.
Using open-topped barrels along with a small-capacity pump may be the preferred method, but there are other foam pump types. The insertion of the foam can also be done with a piston pump or even a hand pump.