PBS Construction Ltd recently undertook a project on Wakefield Road in Mapplewell, Barnsley, Yorkshire, UK where a new sewer outfall was required to service a newly built Lidl supermarket. The works involved the installation of approximately 180 m of Naylor Denlok DN150 jacking pipe to form a storm water outfall, whilst the foul sewer pipeline, being at a much shallower depth, was installed using traditional open cut techniques. Traffic management was put in place on what is an extremely busy route into Barnsley. The works were due to take approximately 7 to 8 weeks to complete.
Design
PBS Construction Ltd, as the main contractor, offered the ability to design and deliver efficient and cost-effective solutions and planned and delivered this project alongside its client, Lidl Stiftung & Co. KG. The pipejacking operation was subcontracted to Trenchless Solutions Ltd (TSL).
Ground conditions at the site of the pipejacking operation comprised stiff clay with pockets of Sandstone, so Trenchless Solutions Ltd opted to utilise the tried and tested Guided Auger Boring technique as it offered the ability to install the Naylor Denlok DN150 jacking pipe to the required line, level, and gradient, whilst having the capacity to handle the ground conditions very effectively. The ground investigation works were completed with investigation bore logs being compiled by a third party prior to work commencing both for planning stage and practical contracting. To complete the pipejacking works TSL utilised its Perforator PBA85V auger boring machine alongside a Perforator HS90 hydraulic Powerpack, Bentonite Pump and tank, and an OEN navigation unit (which utilises a camera for accuracy of the pilot bore installation that makes up the first stage of the installation). TSL claims to have the largest fleet of Perforator auger boring machines in the UK. In all the trenchless installations using the guided auger borer totalled some 180 m in length which were installed over four individual drives.
Challenges
The project had been planned over the course of approximately 12 months due to the impact the project would have on local traffic with the need for road lane closures and traffic management. Ultimately the installation works for the pipejacking were carried out using 12-hour shifts, 7 days a week as requested by PBS Construction, because the local council wished to minimise the impact on the local community as much as possible
Further to this, during the second drive, the TSL crew encountered an obstruction which turned out to be a huge lump of dense sandstone. During the pilot bore stage the crew repeatedly attempted to get passed the obstruction but it was not to be. The decision was made to excavate an isolated digdown to remove the obstruction. The construction of the works was also planned so that Lidl would still be able to operate, whilst PBS used the Lidl carpark for a site compound and residents would have access to the nearby public footpaths at all times. Traffic management was in place due to a single lane closure which was unavoidable. The project overall had an estimated construction cost of about £800,000 with the trenchless installations being approximately £100,000. Commenting on the project for PBS Construction a company director said: “One of the factors that led to Trenchless Solutions Ltd being chosen as the preferred supplier was the locality to the project which enabled them to deliver a first-class service and due to the expert advice received from them from the tender stage through to planning. I would like to take this opportunity to thank the whole team at Trenchless Solutions for their expert assistance throughout the planning of the works and implementation of the installation. The works went very well and were completed on time and within budget!”
www.trenchlesssolutions.co.uk
