Reverse Flood Drilling

The reverse flood drilling method with rotary head is a straightforward and effective way to drill large-diameter deep holes, on land and off shore.  Because the hole remains flooded it is a very stable  method in unforgiving rock formations.

Compressed air is injected into the drill pipe below water level into an air chamber at the cutter head. As the air rises and expands within the drill pipe, the density in the internal liquid column is reduced.

The higher density of the water column outside the drill pipe causes the overburden and drill tailings to pass from the shaft, through the cutter head and rise up through the drill pipe. The tailings are lifted to the surface with the help of the rising air.

Construction Drilling utilizes a Wirth PBA 612 pile top drill rig when reverse flood drilling. We have been successful installing shafts from 50” to 78” in diameter, up to 300’ deep.

For large-diameter deep drilled shafts, we primarily use rotary bits as we find the rotary method to be the most stable, non-aggressive way to install drilled shafts. With the rotary head reverse flood method, no air is introduced to the rock formation.

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