U Mole (a division of Vp plc, operating under the Groundforce banner) recently supplied a new Hammerhead HydroBurst HB80 pipe bursting system to Perco Engineering Services Ltd., which was used in the completion of a concrete sewer pipe renewal project in the village of Hemingford Abbots, Cambridgeshire, some three miles east of Huntingdon.

The 225-mm diameter pipeline, part of the network under the responsibility of Anglian Water, had become damaged, with collapses in a number of places along a 250-m long section. The brittle concrete pipe needed rehabilitation and Danaher & Walsh, term contractor for Anglian Water, called in Perco to recommend a solution.

After careful consideration of the options available, Perco’s engineers recommended replacing the existing pipe, which sat in generally compactable clay ground conditions, with a new, continuously welded, 250-mm OD SDR 17.6 MDPE pipe, using the pipe bursting technique.

Pipe bursting was selected as the most suitable technique because the existing sewer route ran up the middle of a narrow road. To have used more traditional open-cut techniques would have meant a significant increase in the potential for disturbance of the local residents and public in general. The project was undertaken in three stages between 2007 and early 2009.

In the first phase, Perco utilized a Miniburst system to create an opening through a collapse. The company’s 60-t Maxiburst rig was then deployed to burst out the old existing sewer pipe and replace it with new, continuously welded PE pipe over a length of 156 m, which included some 12 lateral connections.
The second phase of the work comprised a 96-m length, which had included seven laterals. This part of the work was undertaken in December 2008, also utilizing Perco’s 60-t bursting rig.

The third and final phase of the work comprised, a 65-m long section, with an additional seven laterals. This part of the project was undertaken in early 2009 using a new U Mole-supplied Hammerhead HydroBurst HB80, 80-t pullback capacity pipe bursting rig. This phase of the project took just one week to complete.
Throughout the works, across all three phases, the 250-mm SDR 17.6 MDPE pipe was provided to site by the pipe supplier in 12-m long sticks that were welded to the required replacement lengths onsite using a butt fusion welding system supplied by Fusion Provida.

Working as sub-contractor to Danaher & Walsh, Perco carried out the pipe bursting work, including the installation of the new PE pipe, as well as the stubs for the lateral connections along the route. Danaher & Walsh was responsible for preparation of the launch and reception pits and the re-connection of the laterals subsequent to the bursting operation. All three phases of the project were completed on time and on budget.
Commenting on the project for Danaher & Walsh, Dave Burkill, framework manager said, “By using the pipe bursting technique, this significantly reduced the disruption to the residents in this area and allowed us to maintain access to all properties during the project. By careful planning and consultation with all parties, the work was completed on time and to budget. We were pleased with the performance of the rig and all the site operatives.”

Perco director Nick Sheehan commented, “Working alongside Danahar and Walsh is always an enjoyable experience and their professionalism is always at the forefront of whatever they do. The new Hydroburst system worked well and we are pleased with the results achieved.”

U Mole sales director said, “Pipe bursting is becoming increasingly popular amongst pipeline contractors and clients across the country. The expansion of the Perco fleet to include a larger capacity unit is testament to this. The ability, when using such units, to replace deteriorated pipelines efficiently and cost effectively at minimal disruption to the local population and minimum disturbance to the local environment is gaining ever-increasing importance.”


The Hammerhead Hydroburst HB80 pipe bursting system has a compact design with a small overall machine footprint for reduced pit sizes. The 80-t pullback capacity rig utilizes a unique Upset rod design to eliminate jaw slippage and lightweight easy threaded rods which, with the built-in rod spinner, eases stringing and retrieval of the upset rod system. Pin joint tooling allows replacement pipe with expander to be assembled aboveground and then quickly connected to the bursting blades in the access pit. The HB80 is 2.08 m long x 0.83 m wide and 0.90 m deep and can operate out of an access pit as small as 3 m long x 1 m wide.

The Hydroburst HB80 rig has the capacity to burst pipes of up to 16 in. (400 mm) diameter on size for size replacement works and so is particularly useful on larger diameter cast iron trunk and transmission mains projects. With the Hammerhead Air Impactor system the unit can easily burst diameters in excess of 16 in. (400 mm) diameter.

Unique features of the new unit include:

  • Lightweight upset screwed rods (12.2 kg) for secure rod stringing both out and in
  • On-board burst head docking up to 12” (300 mm)
  • The Upset rod allows positive grip without the need for jaws
  • Auto rod spinner available as an option
  • Hydraulic rear stabilising foot
  • Fast rod stringing at around 18 seconds per meter

The new unit is also capable of bursting large diameter ductile iron pipes commonly found in the in the U.K. gas and water industries when used with Hammerhead Ductile Slitters.

Equipment Range

U Mole is the approved U.K. distributor for Earth Tool equipment and offers the company’s full range of products for trenchless installation and pipeline replacement for either sale or hire. These include: Active and standard head Hammerhead impact moles (earth piercing tools), Hammerhead ramming hammers, other Hydroburst rod-based, hydraulic pipe bursting systems and the Portaburst cable-based, hydraulic pipe burster range.

The company is also the representative for The Robbins Co. in respect of the Robbins SBU (Small Boring Unit) product line, including provision of all spares and consumables within the SBU range. The territory across that U Mole acts in this capacity includes: France, Belgium, Holland, Denmark, Sweden, Norway, United Kingdom and Eire.

U Mole also supplies a full and extensive range of trenchless and limited dig equipment including: MTS/Vac-Tron vacuum excavation systems, coring equipment for keyhole technology for use in the small footprint excavation of utilities and services with minimum disruption to the local area and minimum damage to the buried service. Also available are Pipe to Site coiled pipe trailers, Acuster plastic pipe fusion systems, Rotair compressors, Reed Tools and a complete range of accessories such as pipe Cobra flexible rodding, towing heads, cable socks, pipe pigs, swivels, breakaway connectors.

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