The project involved a 76 metre length of HDPE pipe OD 160 mm installed using horizontal directional drilling (HDD)to leave a busy, central area undisturbed.

Kielce-based project contractor Ekobox Sp. z.o.o. specialises in installations of telecom power lines and road lighting, using trenchless pipe and cable laying techniques. The company has a history working with piercing tools and has recently complemented their fleet with the addition of the HDD machine; TERRA-JET (TJ) 4015 S.

Ekobox owner Mr Suchansky selected the premium TJ model, which is equipped with an air conditioned driver’s cabin, an MP3 player and an on-board computer with touch screen. The width of the operator’s cab allows the seat to rotate 180 degrees. Manufacturer TERRA AG says that the computer saves every metre of the bore as it prints out a bore protocol with all torques, pulling and thrust forces, and also the drilling fluid volume and pressures. The touch screen gives all the information the operator requires, says the company.

The drill operator drives and operates the HDD machine using two multifunctional joysticks installed in the left and right armrests of the operator’s seat, allowing control and smooth movement of the rig.

Article continues below…

The TERRA-JET 4015 S can drill directional bores up to 200 metres length and 460 mm diameter, depending on ground conditions. It is driven by a 62.5 kW (85 HP) powered diesel engine, which is ‘clean’ and fulfils the required ‘green’ emission regulations for some years to come.

Torque and pullback force are produced by separated hydraulic circuits allowing the maximum torque of 4,000 Nm (3,000 ft.lbs) and the maximum pullback force of 150 kN (15 tonnes, 33,000 lbs) to be used simultaneously under full load.

The drilling fluid volume is 90 litres per minute (23 gpm) at a maximum fluid pressure of 70 bars (1,000 psi). The drilling fluid volume may be optionally increased. The system which mixes the bentonite into the drilling fluid via an injector (Venturi hopper) is on board the HDD machine. This patent removes the need for an extra mixing system and a second engine.

The TERRA-JET 4015 S is equipped with a second generation Automatic Drilling and Backreaming System (ADBS). This patented ADBS automatically and within milliseconds adjusts the working speed of the drill to suit the ground conditions says the company. In soft ground the drill operates at maximum speed, in hard ground slowly, but always at the optimum speed.

Machinery in action

The 76 metre long pilot bore in the sandy clay was achieved with ease. The drill head could even be located underneath the reinforced concrete plates. Said the contractor.

After the pilot bore the drill head was replaced by a new back reamer 215 mm. TERRA has developed this new type of backreamer with tungsten carbide teeth, which can be replaced easily every time. This new backreamer has an integrated protection pipe for the swivel, which closes the space between the backreamer and the HDPE pipe. Therefore preventing stones from falling in front of the expander chuck and block the backreaming.

With the backreamer the HDPE pipe OD 160 mm (6.3 inch) was pulled in simultaneously, proving no problem for the rig.

Mr Suchansky said “The new design and concept makes the TERRA-JET Series S to one of the most productive HDD machines available.”