Case Study

Rising Sewer installation Dorset, Southern England

Contributing to critical infrastructure

Horizontal Directional Drilling
Contract No.
Ground Conditions
very hard compacted gravelly wet chalk


Installation of a rising main sewer

We carried out a recent project to install a new rising main sewer. Over 1000 metres of pipe was horizontally directionally drilled across fields and under a river in the beautiful Dorset countryside. The new main is required to replace a badly
corroded main to ensure that customer supplies are maintained. Following testing and commissioning of the new main the old main will be abandoned.

We used our Ditch Witch JT40AT drilling rig which had more than enough power to overcome the very hard compacted gravelly wet chalk ground. Part of the pipeline route was through a flood plain next to the river. In this section of the terrain was extremely wet and boggy making the task of getting the drilling fluid mixing system close to the rig a challenge. To resolve this we opted to remove the drilling tanks from our support lorry and mount them on a tractor
trailer to traverse the route alongside the drilling rig. The tractor trailer also came in handy in moving the rig from location to location as it was more manoeuvrable along the tight access roads in the area.

The installation was monitored using our Digitrak F5 Falcon walkover locating equipment to ensure accuracy of position. Using this equipment the axis of the drill line is plotted and can be used for 'as built' drawings. We used the target steer option allowing us to forward and reverse locate the drill head at long distance. This also negated the need to use a boat to get an overhead location point whilst drilling beneath the river. We were not alone on the project as our customer was also in attendance for the excavation, pipe supply, jointing and backfill operations.