Application Drilling Power Line Holes
Location Belgium
Hammer Challenger 125
Bit Conventional
Hole Size 22 inch (559 mm)
Depth or Length 6 feet (2 m)
Formation Overburden and Hard Limestone
Rig Type Stenuick Mast Mounted on a Back Hoe Arm


BEMCO S.A., a young and dynamic Belgium company, has conceived and is operating a railway wagon mounted drill rig for the realization of more than 1,000 catenary foundations. The project, which commenced in February 1996 is reportedly had considerable success and is an innovation in this field in Belgium.

As part of its modernization programme, the Société Nationale de Chemins de Fer Belge (SNCB) is carrying out the electrification of the Dinant-Betrix section 44 miles (70 km) long of the Athus-Meuse rail link. It crosses over the Devono-Carboniferous folded layers of the Dinant synclinorium and the anticlinal zone of the Ardennes.

The joint venture contractors commenced the catenary placement by traditional means of digging square foundations which required as much as 9 cubic yards (7 m³) of concrete.

The settlement of catenary by large diameter DTH hammer foundation drilling had never been used in Belgium before. As work had already commences, BEMCO, S.A. – based on considerable experience – achieved in the shortest time all conception and realization stages.

The convoy is composed of three wagons: the drilling rig, the compressors, the mobile workshops and the tanks. It meets the strictest SNCB requirements and is confirmed CE to work in the entire European Union.

BEMCO, S.A. chose a Numa 125 hammer as, in addition to offering high availability, the exceptional penetration rate of this hammer met all necessary performance requirements.

In order to limit daily traffic disturbances the railway utilization is reduced and workable time boils down to a few hours per day. Two Atlas Copco XRS 350 compressors supply air power to the Numa 125 for the drilling of 22″ (559 mm) diameter foundations to a mean depth of 8 feet (2.5 m). The drill rig is equipped with a Poclain Hydraulics rotary head whose hydraulic ability offers great working versatility, thanks too its low velocity torque.

At the present time, after more than 5,250 feet (1,600 m) in the most varied strata, the Numa 125 DTH hammer equipped with a 22″ (559 mm) bit has responded to all the expectations. Drilling has remained continuous throughout the project without incident of hammer and bit downtime.

The impact power of the piston – heavier than that of traditional hammers – combined with the BEMCO working method raised drilling efficiency to an exceptional level. The Société Nationale de Chemins de Fer Belge is reported to have been “astonished” by the results as well as by the quality of the job. It has decided for the rest of the work to push forward this new technique in view of its versatility, speed and cost-effectiveness.

This important and original project constitutes a new activity for BEMCO, S.A. This ambitious and innovative company has traditionally been involved in water well, environmental and geotechnical drilling. BEMCO is also about to commence an air RC geological sampling campaign.

Further details on this project and the company’s activities in general are obtainable from M. Jésus Subires, BEMCO S.A., Rue de la Station, 16 – b 5575 Gedinne, Belgium. Tel: (+32 61) 58 80 48. Fax: 58 71 75.

Written by Aime Michaux, Laurent Besohne and Jésus Subires.
Published in geoDrilling June 1997 Issue.