Description: EMAS Drilling, developed by Wolfgang Buchner in Bolivia combines jetting with a percussion action. Drilling mud (water mixed with clay or bentonite to a suitable density) is pumped down through the drill stem using a hand operated metallic version of the EMAS pump. The mud flows back up around the drill stem, carrying up the drill cuttings. Sand and small stones are decanted, and the drilling mud is recycled through the pump. When progress is difficult, due to particularly course sand or small pebbles, the technique is changed to a suction system.
A percussion action is performed by lifting and dropping the drill using a lever, mounted on a drilling tower. In addition, the drill stem is rotated in half-turns in both directions, enhancing the grinding action of the bit. The drilled diameter is about 2 inches and wells are cased with cheap 1½” (39 mm) PVC pipe to accommodate a 1¼” PVC piston pump although they can be reamed to a larger diameter.
Capability: EMAS drilling can penetrate loose soils, as well as consolidated materials and light rock but not hard rock or boulders. In coarse sands, progress may be slow, as sand may sink faster than it can be lifted out with the drilling fluid. In such conditions, a temporary switch is made to a sludging technique: an open-ended drill bit is installed, and a valve on top of the drill stem. The technique drills to 30m. The entire drill stem is metallic so deeper drilling becomes heavy and several operators are needed to operate the lever.
Equipment: An EMAS drilling rig, capable of drilling holes to a depth of 30m, can be built in Bolivia for about US$ 600 – 800 (including the tower, mud pump and all essential non-common tools to operate and maintain it). All non-standard components can be built locally in about any arc-welding workshop, using only materials found in ordinary hardware stores.
Locations: Primarily in Bolivia, but introduced in other Latin American, African and Asian countries.