HDD Fleurhof Soweto (Rock Drilling)

This project consisted of 1 crossing for a 180mm sewer line, the inverts for the tie-in points were fixed as the new manholes had already been erected and the open trenching pipeline was already installed. We established our Astec 40-45 HDD rig together with our Straightline Rock Eye air hammer.

We also completed the HDPE Butt-Welding for this line and because it was a sewer crossing, we removed the internal bead with our in-house engineered HDPE bead cutter.

Initially we attempted the crossing with an aggressive HDD head but kept hitting rock which deviated our HDD head, due to the fact this crossing was for a sewer line and we only had a fall of around 1 degree we advised the client that in order for us to have the best chance at successfully installing the new pipeline at the required level and without back falls we would need to conduct rock drilling.

We attempted to drill downstream however we came across issues with the level of the existing stormwater which ran perpendicular to the new line to be installed via Horizontal Directional Drilling (HDD).

We then moved to the opposite side of the crossing and drilled upstream. The ground was incredibly hard in some sections, however, we completed the crossing and managed to maintain our fall of 1 degree.

At the end of the pilot bore our Straightline Air Hammer sonde housing broke which led to our sonde breaking. Fortunately, we were just behind the storm-water pipeline and the client broke through to allow us to retrieve our equipment as well as push our drill string through in order for us to connect the back-hammer and launch the new pipeline.

Once the pilot bore was complete we connected our 300mm back hammer and completed the back ream, after the back ream was complete we pulled in the new HDPE pipe.