HDD Lenasia (Soft Ground)

This crossing consisted of a 25-meter 315mm HDPE sewer pipe that we needed to drill at a gradient of 0.2%, which is basically flat. Over a distance of 25 meters we had no room for deviation as the invert levels need to be accurate to tie into the pipeline further downstream.

We established our Astec 4045 HDD Rig. We also completed the HDPE Butt-Welding for this pipeline, the client further requested that we remove the internal bead on this pipeline which we done using our in-house engineered bead cutter.

The pilot hole took us half a day to complete, the levels were then double checked to ensure that we were at the required invert level. Once the pilot bore was approved we then commenced with the back reaming process which we completed in two stages, we then pulled in the new HDPE sewer pipeline.

We had a second 315mm crossing of approximately 20 meters, however, at the pipe level we came across large boulder formations which made maintaining the 0.2% gradient an impossibility, rather than waste time attempting the crossing we advised the client that the best solution would be to open trench this section.

Rock drilling would have been an impossibility as the boulders would throw off the air hammer and maintaining the gradient would be impossible. If the host pipe was to be used for water, we would have had no problem with the installation of the new HDPE pipe.