Product Profile: The HDD60 Hard Rock Hammer System

Recently, Mincon Inc., was given the opportunity to showcase its latest rock drilling technology in a project in Northern Ireland that involved extremely challenging geology. The Roanoke, Va.-based manufacturer used its HDD60 Hard Rock Hammer system for the project.

Mincon is a company with more than 34 years of manufacturing experience in rock drilling equipment and has over the last 10 years developed a complete range of Steerable Hard Rock Hammer Systems for trenchless drilling applications.

The current range of tools is capable of drilling pilot hole sizes from 3 ½-in. (89 mm) to 7 ½-in. (190 mm). With the industry’s only patented pull reaming hammer, reamed hole sizes in rock of up to 14 in. (356 mm) with excellent production rates are now possible.

Mincon product specialist Mike Nameth was invited to participate in commissioning a HDD60 Hard Rock Hammer system with P McCormack & Sons Ltd. Drilling of Maghera, County Derry, Northern Ireland. Present from P McCormack & Sons Ltd. Drilling were Martin McCormack, Fintan McCusker, Rob Vickers and Alan Bolton.

The equipment used on this project included an American Augers DD8 drill, a Mincon HDD60 Hard Rock Hammer System, a Mincon Hard Rock Support Station, a DCI Sonde and a 900-cfm X 350psi air compressor

The project involved the installation of high density polyethylene (HDPE) conduit along a utility right of way in Lanark, Scotland. The bore was 400 ft (122 m) in solid bedrock that had to follow the course of the road. The rock that was drilled was 25,000 to 30,000 psi (172 to 207 MPa) compressive strength. The entry angle for the HDD60 was 22 degrees and no disturbance to the integrity of the old handmade rock wall beside the entry point was allowed. The profile of the bore required drilling under a stream approximately 60 to 70 ft (18 to 21 m) from the start of the bore. Once the bore passed under the stream, the drilling was leveled out at a depth of 8 ft (2.5 m) at the bottom of the radius and a severe bend of almost 90 degrees was made to stay within the utility right of way while simultaneously climbing at up a hill at a 20 to 25 percent grade.

The production rates varied, depending on the formation from one to five minutes a foot. The Mincon HDD60 with a 6 ¼-in. (159-mm) slant faced bit steered efficiently at 2 to 3 percent in solid rock. The operating pressure in the Hammer averaged between 325 to 330 psi (22.4 to 22.8 Bar). The operators were impressed with the smoothness of operation of the HDD60 Hammer, due to the high frequency technology. Steering was also enhanced by the extremely fast cycle time of the piston in the Hammer. The vibration transmitted back through the drill string from the hammer action was so minimal that the auger stake downs were not required.

The Mincon support station provided the operator controls, which allowed for a steady stream of rock drill oil to be injected into the air supply and from there through the drill string and into the hammer. With the variable flow water pump a constant flow rate of water was pumped into the air supply to aid in flushing and stabilizing of the borehole and dust suppression.

While everyone agreed that the job conditions were extremely difficult and challenging due to the geology and the extreme amount of steering that was required in a short space, it was the combination of professional drilling contractors and the right tooling that proved successful. The Mincon HDD60 Hammer exited the bore at the required location and the total drilling time to complete the bore was approximately 12 hours.

The bore was extremely successful and company owner Greg McCormack purchased the system from Mincon’s United Kingdom and Ireland HDD Dealer T.A. Drilling in East Sussex. The tool has since been used on a number of other jobs with similarly successful results.

Frank Purcell is vice president of Mincon Inc., which is based in Roanoke, Va.