Pipe-Ramming
We have long since successfully used our Goliath pipe-rammer to drive steel pipes up to 1.2m diameter under train stations, railway lines, motorways, stone culverts, high pressure gas mains and high voltage electricity cables, all in soft grounds such as clays, silts and gravels. This system is as simple as: excavate a launch pit typically 18m long; line up the open ended steel sleeve (typically a 914mm o.d. with 18mm wall) on the proposed tunnel line; connect a large compressor to the rammer which is installed into the back of the sleeve; allow the pneumatic driven piston (inside the rammer) drive the open-ended steel sleeve into the ground; remove rammer and weld on subsequent steel sleeves, reconnect rammer and repeat. Drive lengths of up to 80m have been achieved for 762mm o.d. sleeves. The system only displaces the soil in front of the 18mm wall of the steel pipe, therefore it is ideal where ground movement is critical. The soil swallowed by the pipe is only removed at the end of the drive. Therefore, an open-face is never created, thus eliminating the negative effects of dewatering between the shafts. The soil is then removed from the sleeve shaft-to-shaft by welding a steel plate to one end and pressurising the soil column until it emerges like a ‘syringe’. Correct lubrication of the inner sleeve/soil interface is essential. It is not possible to steer the sleeve once launched, however, when launched in lengths over 9m long it is similar to a driven pile in that it is difficult to deflect off-line once embedded in the soil correctly. The system has been used many times for graded sewers.

Horizontal Directional Drilling HDD
Directional Drilling of HPPE pipes up to 500mm in diameter, using our 15X and 15N drilling rigs, proves economical in the right ground. This process has great benefits when crossing motorways, railways, and rivers, with pressure mains or sewers. More recent developments with the tracking systems, such as the
Eclipse from DCI, can locate the pipe to within 15mm, at depths of up to 15m. This makes it a viable option to install sewer pipes. ‘Pam Directional’ from Saint Gobain is a ductile iron directional drill installed pipe. It gives the Client greater variety in his choice of pipe material for no-dig installations. The 15N HDD rig from Trenchless Technologies has many features built in to help ensure a quality product pipe on completion. The data logging system allows a summary of the pull pressures, torque on cutter-head and drill fluid quantities to be recorded. The operator can input the guide parameters for each string and therefore work within the limits of good practice. The permanent embedment conditions for the product pipe within an annulus of bentonite rich drill slurry ensures an optimum support condition for the performance of the pipe within the soil mass.