The work was undertaken for client The Barbican Traders Association. The project involved the replacement of a 4 inch (100 mm) diameter pitch fibre sewer pipe with a 100 m diameter HDPE pipe. The sewer is privately owned and serves the wastewater drainage requirements of several shops and businesses. The length of the drain was some 90 m. Due to various factors the drain was in need of replacement and Caradon District Council (CDC), after discussing the problem with the owners, proposed the use of open cut techniques should the Barbican Traders Association employ it to do the work. Had the project been undertaken in this way it would have required many of the businesses to close for a period of time with a significant loss of trade and income.

As the work was to be funded by the businesses served by the drain, the Barbican Traders Association sought an alternative solution which would enable the replacement to be completed more quickly and at less cost whilst keeping all the businesses open during the latter part of the Cornish summer tourist season. Ultimately pipe bursting was selected as the most viable option.

Over its length the 90 m, 4 inch diameter pipe ran along the back of many the shops served by it from the main sewer at the outfall end, under two footpaths, a 6 m wide road and through eight manholes. Although access was not impossible it was relatively difficult largely due to space limitations around the manholes. The type of shops and businesses affected by the work included a fish and chip shop, a hairdresser, a dog grooming parlour, a bakery, a supermarket and a post office, many of which required high water usage as part of their daily operation to maintain trade and therefore also needed adequate drainage at all times.

The work took place in early September 2005, over a period of about three weeks. Approximately one week was required to prepare the site for the bursting work, including breaking out of manhole benches etc; four days were needed for the actual bursting operations; and a further week was used for reinstatement works on the manholes and to clear the site.

The bursting operations used Charlton Drains’ recently purchased Hammerhead PB30, small footprint bursting unit, sourced through U Mole Ltd of Great Gransden, Cambridgeshire, Hammerhead’s Official European distributor.

All bursting work was completed through existing manholes with no extra access pits required for any part of the project, which meant even less disruption to the village and allowed the shops to remain open for business. The bursting operation was completed using several individual runs totalling four in all, with the shortest being 18 m and the longest being 34 m. The businesses were able to remain open throughout because the storage capacity of the laterals was sufficient to allow work to continue without fear of back flooding in the premises.

Bursting System

The PB30 compact pipe bursting system has been specifically designed for the replacement of small diameter sewers and laterals with minimum surface disruption and disturbance to the client. Producing up to 28 t of pullback using a special compact steel cable, the PB30 can be broken into several easily manageable components to ease transport/assembly in difficult access locations and even manholes.

The use of the compact cable together with the compact bursting heads with integral pipe towing head enables the PB30 to burst in-line bends up to and including 45o without problem. Hydraulic power can be provided by an independent power pack or even a backhoe on site.

Advantages of the system include reduced pit size if any when using existing manholes and therefore reduced surface disturbance, compact size - it can fit through a 750 mm wide doorway, the system breaks down into manageable sections, it can burst around 45o bends, it can achieve both size-for-size or up-size bursting and can be remote-controlled by the operator.

In Looe, the client was very pleased with the speedy and cost effective outcome of the project with many of the businesses affected by the work saying that they were not even aware that the work was going on. For the Barbican Traders Association Jane Wills said “The work was done in a professional way and the bursting option was an effective solution to our drainage problems, with minimum disruption to our businesses.”

Charlton Drains, just prior to the Looe project, also completed a pipebursting project at a school in Cheltenham for client Gloucester County Council. The work at the Sandford School in Severn Springs required the replacement of a 6 inch (150 mm) diameter pipe over 97 m to maintain the viability of the school’s drains.

In the near future Charlton Drains will also complete bursting works in Church Down for the Tewkesbury Borough Council where some 64 houses lay on a single pipeline that is in need of replacement.

Charlton Drains decided to purchase it own PB30 system because demand for the technology is on the increase and availability ‘on-hire’ was limited by the number the other contractors wishing to utilise the equipment. According to Rob Ranford, owner of Charlton Drains, “The system is extremely good for the non-disruptive work that is become increasingly requested by our clients. The Hammerhead PB30 system supplied by U Mole is very good kit and the back up service is excellent. It was only the limited availability ‘on-hire’ that made it difficult for us to operate without our own unit, so we bought one and can now offer more definite work dates and deadlines to our increasing client base.”

Availability

U Mole also offers for either sale or hire the full range of the Earth Tool Company’s products for trenchless installation and pipeline replacement including active and standard head Hammerhead impact moles (earth piercing tools), Hammerhead ramming hammers and Hydroburst rod-based, hydraulic pipe bursting systems.

U Mole also supplies the Vac-Tron range of vacuum excavation systems including skid mounted truck units, available in 500 to 7,500 litre capacities and trailer units available in 500, 750 and 1,100 litre capacities.

Acuster fusion equipment and a range of general No-Dig Accessories such as cable avoidance tools, Cobra flexible rodding, towing heads, cable socks, pipe pigs, swivels, breakaway connectors and Rotair compressors are also available. More recently, U Mole was also appointed as an approved UK distributor for the full range of Reed Tools.