The project
An exclusive housing development in Bedworth, Warwickshire, comprising 2, 3 and 4-bedroom homes in a semi-rural landscape just 10 minutes’ drive from the town centre.
The development is on the site of a former coalmine and much of the site consists of made ground. In addition, two disused pit shafts (up to 300m deep) are located on the site.
Although these shafts had been capped following closure of the pit, the reinforced concrete caps were considered inadequate and the developer decided to have them removed and replaced with new, more stable RC caps.
The existing shaft caps were cast onto a layer of made ground and specialist contractor L Healy Ltd was employed to remove these and replace them with stronger RC caps sitting on the deeper natural bedrock instead of the less stable made ground.
Challenge
Healy’s task involved creating two sheet-piled cofferdams, one over each of the pit shafts. The steel sheet piles needed to penetrate to a depth of 9m to engage the bedrock.
Wayne Healy, owner of L Healy Ltd, decided to install the sheet piles himself rather than sub-contract this work to a piling specialist.
Instead of employing a third party, complete with plant and operatives, Healy could use its own excavator and personnel which were already on-site. This achieved cost savings and more efficient use of resources. All that was required was to hire-in a boom-mounted vibrating piling hammer.
In November 2022, ahead of commencing the contract, Healy contacted Piletec and area manager Jade Walker agreed to supply a ICE8SG Side-Grip Piling Hammer maintaining contact with Healy in anticipation of the contract start date.
Due to the variable nature of the made ground, it was not possible to predict the ease or difficulty of the piling operation. In this event, Healy hit refusal limits (refusal limit is defined when the penetration or extraction rate is greater than 5 minutes per 250mm) with the Side-Grip Piling Hammer.
Solution
When pile refusal is encountered, this usually means that a larger, more powerful hammer is required to overcome the resistance.
Anticipating this possibility, Piletec area manager Jade Walker had maintained regular contact with Wayne Healy, ensuring that when a problem arose, she was prepared to offer a solution.
“Often, what happens is that when there is a problem like this, the client seeks advice from a specialist piling contractor – who will try to persuade them to let them do the work. But I had let Wayne know right at the outset that we could offer an alternative solution,” she explains.
The solution was the ICE1223B Piling Hammer, one of the most powerful hammers in Europe. Although many piling specialists do operate equipment of this size, Piletec is the only company in the UK that offers this Piling Hammer for hire.
Piletec off-hired the Side-Grip Piling Hammer and supplied the ICE1223B Piling Hammer to Healy which proceeded to install the two cofferdams with no further difficulty.
Piletec’s self-delivery solution offers an efficient and cost-effective alternative to employing a sheet piling contractor for a project of this type.
The ICE piling hammers are simple to use – though Piletec does offer equipment familiarisation where needed – and any competent excavator operator can work, even with the large ICE1223B Piling Hammer, with total confidence.
The two excavations measured 12m x 12m x 9m deep and Healy installed approximately 86 steel sheet piles into each one over a period of about six weeks.
“We chose Piletec after looking at the alternatives and checking out the market,” says Wayne Healy. “This was two years ago, before we were even on-site. But Jade kept in touch with us and when we finally got the go-ahead, everything was ready. Piletec provided excellent service and when we encountered problems with pile refusal, they were ready to provide a suitable solution.
The ICE1223B Piling Hammer is back on site now – this time, extracting the sheets from the completed and back-filled excavations.