A small pit is excavated at each end of the pipe that is being replaced, and a small section of the old pipe is broken out. A steel rod is pushed into the old main and then the rod is used to pull a cutting tool back through the pipe. The cutting tool breaks up the old pipe, and at the same time a new plastic pipe is pulled into place in the gap left by the old pipe. The replacement pipe provides similar or greater flow capacity as the original pipe. The technique is not suitable for all pipe materials.
Pipe bursting is more generally used in urban areas to reduce disruption for road users and reduce the costs of the road reinstatement. However, on a recent renewal scheme near Southwick pipe bursting was used to minimise our impact on the local environment. The bursting ‘rig’ is in the trench (shown in the photo below).
The rods having been pushed through the old main are being withdrawn. Behind the rods the cutting tool (the cone shaped tool in the photos below) is pulled through breaking the old cast iron pipe and at the same time the replacement pipe is pulled in behind. Generally the pipe is installed in approximately 100 metre lengths. The other end can be seen in the background across the field.
The picture below, was taken as pipe bursting is about to start in a woodland setting and shows the 100 metre pipe coil being introduced into the old pipe. The steel rods can just be seen in the bottom right of the picture. Pipe bursting in this situation minimises environmental damage.