The Ditch Witch JT2720 All Terrain Rock Drilling System drilling 600 feet straight under Mission Gorge Boulevard in Santee, California.

A new break-through has emerged in the Directional Drilling business that eliminates the need for the cumbersome, and expensive "mud motor". The old technology had contractors for utility projects singing the blues; when the ground conditions were rock.

Trenchless technology, or underground boring technology, are terms used to describe methods for laying utility cables, or systems, with minimal disturbance to the surface of the ground. When the job called for the laying of fiber optics, for example, contractors had to rely upon conventional horizontal drilling methods, or specifically slant-faced drilling technology.

And this technology has not really changed in the last ten years. Traditional horizontal drilling methods are still a great way to drill in normal soil conditions. The determining factor in whether or not one can use this type of technology is whether or not one can statically push the drill face through the ground without using the rotating mechanical cutting action that is typically used when trying to drill straight. When this method cannot be used, a fluid driven mud motor is typically incorporated to perform the drilling function. Unfortunately, this method has proven to be a very expensive and cumbersome process. The procedure usually works fine for vertical drilling, where recovery of the drilling mud is relatively easy. But start drilling horizontally, and mud recovery becomes a big problem. The problem is not so much the drilling itself, as it is the recovery, filtering and pumping of the mud which powers the process. The filtering and pumping unit is enormous and expensive to operate, and the acquisition and operation of the mud motor itself is also an expensive proposition. When the process calls for the pumping of 150 to 300 gallons a minute in adverse conditions (hard soil, or rock), well, you can begin to get the picture. There are a few other ways to drill horizontally in rock hard conditions that donÕt require a mud motor. But these methods are slow, require a great deal of patience and skill, and are basically ineffective in very hard materials.

Pulling back a 12" reamer while installing multiple fiber optic conduits.

The Ditch Witch Corporation has recently developed a revolutionary process that eliminates the need for the mud motor, and the need for the expensive mud recycling system. The new process adds more horsepower to the drill bit, and thus increases the production rate. Paul Rogers, President of Ditch Witch of Southern California, explains the process: " Rather than turn a drill bit that is fluid driven, we turn a drill bit that is mechanically driven. The method employs a shaft within a shaft. There is a PTO shaft that runs down the inside of the drill pipe, which drives the drill bit, while the outside pipe delivers the mud which is still required to flush the cuttings out, and keep the electronic locating devices cool. The mud still needs to be run, but only five to ten gallons per minute during the drilling process. Obviously, this is a lot more cost effective than having to run about 250 gallons per minute, and at a slower production rate! This will now enable contractors to go in and drill solid rock areas with adverse drilling conditions such as cobble rock-which they couldnÕt do before." Ditch Witch has introduced two models of the 125 HP drilling rigs: the Ditch Witch JT2720 Mach 1-which employs the conventional drilling system; and the Ditch Witch JT2720 All Terrain-which incorporates the new rock drilling system.

San Diego, California is an ideal testing ground where these two systems can be compared to each other, side by side. Long known as one of the toughest places to install underground utilities, San Diego is often thought of by contractors as one big rock pile. Fortune would have a large fiber optic job coinciding with the emergence of this new technology. The first two rock drilling systems introduced by Ditch Witch are now operating at the site; as well as other, bigger rigs, that operate on the mud motor technology. "We are finding out very rapidly that mud motor technology is not nearly as efficient as the new All Terrain system", said Rogers.

(Left) Monte Downing of West Coast Pipeline evaluating the use of the new Ditch Witch JT2720 All Terrain Rock Drilling System.

West Coast Pipeline, owned by Monte Downing, specializes in directional drilling. They are evaluating the use of the new Ditch Witch machines by drilling under Mission Gorge Boulevard in Santee, California, and in the western suburbs of San Diego. The particular bore shown in the photographs is 600 feet straight through rock. The initial pilot hole is approximately 6 inches, pulling back a 12-inch reamer. They will be installing multiple fiber optic conduits behind the reamer. These new machines also offer additional refinements over the old technology, such as cruise control. The operator can actually set the pull-back, or drilling speed, and perform hands-off operation.

The reliability of this industry has always been solid. And technological advances such as this only help to augment the efficiency and cost-effectiveness of the world of trenchless technology. We all benefit when water, gas, electricity and telephone cables (fiber optics) can be installed faster and cheaper. This should also make technology like Internet access faster and more affordable as well.