Contractor goes back to school for trenchless training

U Mole provided specialist expertise and portable rope bursting equipment, which saved time and cost on a tricky sewer replacement job in Trowbridge. The equipment was used by Warrington-based drainage specialist Jet Rod to replace a 25m length of 4” diameter sewer pipe at Grove Primary School in Hazel Grove. The old sewer pipe was made of pitch-fibre that had collapsed and was partially blocked. Located at a depth of 2m, the sewer runs alongside a footpath at the rear of the school where access is restricted. To expose the old sewer pipe would have entailed the removal of path edging and fencing in order to dig a 25m-long trench. Construction plant delivery, spoil removal and backfill consolidation would have been difficult and disruptive since the only vehicle access was across the school’s playing field. A further complication was the presence of a large tree very close to the line of drainage which would have been destabilised by any excavation works. Although not experienced in trenchless techniques, Jet Rod realised that pipe bursting would be a less disruptive method, enabling the job to be done quickly and without compromising quality. Having received an enquiry from Jet Rod’s Mark Leatherland, U Mole prescribed one of their range of pipe-bursters This machine they chose used a special compacted wire rope to pull the bursting head through the old pipe, simultaneously splitting and expanding the old pipeline while towing the new pipe into position behind it. The small footprint pipe burster is designed to meet the need for a very compact machine to be operated in difficult access or restricted size locations such as sewer laterals. At Grove Primary, the only excavations required were two small 2m deep pits to provide access to either end of the pipeline. One served as a launch pit, from which the burster head and new pipe were fed into the sewer. In the other it was installed to winch the bursting head through. Because Jet Rod had never used this equipment before, U-Mole also provided handover training and full technical support throughout the contract, a service the company provides for all their equipment. As the burster made its way down the existing drain the new 125mm diameter pipe, comprising short MDPE plastic sections screwed together end-to-end, was pulled through behind it. Despite difficulties caused by one of the small excavations being heavily congested with other below-ground services, Jet Rod completed the work in only a week. The total cost of hiring the burster and the training provided by U Mole was a modest £1,000. “The work was completed successfully and the tree did not need to be disturbed” comments Jet Rod director Mark Leatherland. He adds: “It was a good learning process for our staff and has expanded the services that we can offer. The cost of the pipe bursting equipment and training was offset against the cost savings on the excavation, backfill and reinstatement work which was not required for most of the run”.