Terra’s New Manhole HDD Drill With Rod Lift

June 2010 Vol. 65 No. 6

TERRA AG has developed a manhole HDD drill that is able to undertake directional bores from manhole to manhole and from manhole to all near-by homes. At 2.5-feet depth, telephone cables can be laid; water lines at 4-inch depth, and gas or power lines at 5 feet.

The TERRA MINI-JET MJS 1600 makes directional bores in lengths up to 165 feet with a minimum turning radius of 50 feet. The directional bore can be reamed up to 12 inches, even in hard ground. The drill is equipped with a torque of 1,200 foot/pounds and thrust and pull back forces of 6 tons, 13,200 pounds.

The MJS 1600 can drill from manholes with an internal diameter of 3.3 feet and can fit through manhole entrances of just 25 inches. For smaller entrances, remove the manhole cover frame. The drill operation is controlled from the surface where the operator along with the control station, rod magazine and rod lift are positioned. Entering the manhole during drilling and back reaming work is not required. The operator inserts a new drill rod into the rod lift, which transfers it down into the manhole and positions it in the drilling machine. The new drill rod is screwed into the last drill rod. Inductive sensors make this operation possible even where the operator does not have a view into the manhole. The rod lift may also be positioned at an angle over the drilling machine where the manhole entrance is not located directly on top of the drilling machine.

Drilling and back reaming takes place with bentonite drilling fluid pressure of 0-800 psi and drilling fluid volumes of 0-9 gpm.