Saving trees one GRUNDOBURST at a time

25.08.23 - A stunning park in south London is a peaceful haven for thousands of visitors in a busy residential area. With a lake, extensive grounds, a historic Palladian villa and a children’s splash area, Danson Park in Bexleyheath has a long and interesting heritage dating back to the 1700s and is a much-appreciated focal point for the local community. Thames Water recently contracted with Cappagh Construction Ltd of Wimbledon to upgrade an ageing sewer pipe in the park and - thanks to trenchless technology techniques – this was achieved with minimal disruption to the beautiful surroundings.

The former 300mm clay pipe had previously been repaired by relining, but after persistent blockages, Thames Water decided to invest in a larger capacity pipeline manufactured from modern PE materials, with an outer size of 355mm. Cappagh, a company well versed in trenchless methods of pipe installation, recommended a static bursting solution to insert the larger pipe through the existing void beneath the surface, displacing the existing pipe in the process. This method would avoid the need to dig a large, open trench which would not only spoil the surface of the ground, but would require trees to be felled to make way for the pipe. The size of the job precluded the use of the Cappagh’s own GRUNDOBURST 400G, so the company approached TRACTO UK with a view to hiring a larger unit. A GRUNDOBURST 800G was able to provide the required pulling power for the significant upsize of pipe along the required distance. The compact unit was lowered into a very small launch pit ensuring minimal disturbance of the ground. A ladder-rod system ensured fast, light and safe work for the operators, whilst the large range of TRACTO accessories ensured the right tooling could be selected to complete the job reliably and quickly. In fact, the first section of the pull of 100m was completed in under 5 hours.

Local MP, Sir David Evennet, accompanied by local politicians, council members and representatives from the ‘Friends of Danson Park’ visited the job on the day to see the pipe bursting in process. Delighted by the use of the innovative technology, which helped to preserve the mature trees above the sewer pipeline, he personally thanked the teams from Thames Water and Cappagh for ‘saving the park’.

The second and final pull of 78m was concluded quickly and successfully a few days later.

Jamie Muldoon, Thames Valley Area Manager for Cappagh Construction Ltd, was delighted with the end result; “By using the more powerful GRUNDOBURST 800G, we were able to complete this job very quickly and with very little detriment to Danson Park. During the installation the public was able to continue to use the park and most had no idea that major work was taking place underfoot only metres away. That’s the beauty of this technology – everything can safely carry on around it.”

Jess Ferncombe was the Cappagh Health & Safety point of contact for the duration of the project and oversaw the whole job. As the great granddaughter of the company founder, Jess has been working in the business for many years and has overseen many projects; “Using trenchless technology is great from a H&S perspective as there are just two small pits to cordon off from the public. The TRACTO products have been designed with safety in-built, so as long as they are operated correctly, we can be confident there will be no issues. As TRACTO has provided all our training, our operators are very well versed in the technology.”

From Thames Water’s perspective, the new installation will mean the blockage issues will be a thing of the past and the new pipe will have a very long lifespan. A regional spokesman attended the pipe burst and was exceptionally pleased with the outcome; “This pipe renewal will last for approximately 100 years. Installed with little damage to the locality, bursting is pretty much the most sustainable method of renovation and we are increasingly looking at this type of technology going forwards. This has been a highly successful job that will ensure the effective working of the sewer pipeline under Danson Park for many years.”

Roger Wahl, Managing Director of TRACTO UK, was also present for the first pull. Having paid witness to similar jobs, Roger knows first-hand the benefits of bursting techniques and how the technology can be used to preserve the environment whilst installing the necessary infrastructure for modern life. He was delighted at the speech of the MP who publicly demonstrated his support for the pipe bursting process; “The comments from Sir David Evenett have been so positive for the trenchless technology sector. He recognised that the pipe burst on this job pretty much saved the park and the mature trees that would have been felled without the ability to drill underground.”