‘Drill and Fill’ is a process similar to core aeration where soil and thatch are removed from the green to help relieve subsoil compaction and improve drainage and air exchange. With ‘Drill and Fill’ large diameter holes are drilled into the surface of the green to a depth of up to 10 inches deep. When the drill is removed it extracts a core of soil and thatch. The holes that are left are then pumped full of sand. These deeper sand filled columns allow water to pass through from the surface of the green more quickly which helps drainage and the overall health of the green.