British seaside piers are as synonymous with holidaymakers as sticks of rock and Worthing Pier is no exception. Designed by Sir Robert Rawlinson, Worthing Pier was the thirteenth pier to be built in England at a cost of £6,500 by the Worthing Pier Company.
The first pile for its construction was driven into the seabed back in 1861 and has survived, not without damage, numerous storms and a fire as well as a 120-foot hole blown into its decking to hinder any potential enemy invasion during WWII. Little wonder then, this majestic and elegant Grade II listed tourist attraction is in need of constant maintenance and Worthing Borough Council is currently undertaking such a task.
Phase I of the project required essential maintenance to the timber framed landing stage that surrounds the end of the pier. Special strength testing had revealed that some of the piles had deteriorated, due to wear from the constant movement of the seabed material at beach level and needed replacing.
Paine Manwaring Green Ltd (PMG) who had been maintaining the pier for over 30 years, were awarded the contract to dismantle part of the landing stage, extract and replace piles and then reassemble the timber bracing and walkway. PMG had no piling capability, so called upon Aarsleff, who have vast experience of the marine environment, having previously installed thousands of timber piles for new groynes on Eastbourne Beach, for advice and assistance.
Aarsleff visited the site and made a number of recommendations, such as proposing that seven piles be removed and replaced; four in the back row and three front rakers, to ensure that the piles were installed square to the existing grid pattern and to gain access for its Banut 700 piling rig. The proposals were accepted by Worthing Borough Council’s engineers, and PMG awarded the piling contract to install the new 12m long Greenheart piles worth £20,000, to Aarsleff.
The existing piles were first removed by PMG, work which could only be undertaken during an approximate 1-hour window coinciding with the extremes of the low tides. Aarsleff had to track the rig back and forth 300m from the shore to the pier head at each low tide. Working at beach level on a navvy mat working platform, Aarsleff planned to install one pile during each consecutive low tide to a depth of between 3.5m to 4m into the underlying chalk. Aarsleff started work at the back row of the vertical 300mm square section piles and completed the first pile within the tight time frame.
However, the beach subsequently proved strong enough to support the piling rig without the working platform, thus enabling Aarsleff’s site team to complete the three remaining vertical piles on the next low tide and the three 239mm square section front row piles, sloping at 8.5°, on the following tide. As a result, the job was completed nearly 60% ahead of schedule.
PMG works director Alistair Ktori said, “Aarsleff has been absolutely fantastic, brilliant, I can’t fault them. There was only one week where the low tides would allow us to work on the beach and install the piles. Aarsleff didn’t need the working platform as the beach was able to support their rig and they completed the piling in just three tides, instead of the seven predicted. The line of the installed piles couldn’t be better and will help us when we come to reassembling all the additional timber bracing. Aarsleff has been extremely helpful right from the start of us contacting them from our search on Google. We saw on their website that Aarsleff had been involved with other marine piling projects. Aarsleff was also recommended to us, as they had successfully installed about 6000 greenheart piles for new groynes on the beach just along the coast at Eastbourne in the 1990s. There are some more piles to be replaced here on the southwest corner of the landing stage and if Aarsleff’s price is okay we would anticipate they could also install those.”
Phase II of the project was awarded to Aarsleff by KD Engineering (UK) Ltd following its success on phase I and its work with PMG. Specifically, the works on the pier are on-going with rotten and degraded piles being replaced as required and the pier being modernised over time. For this phase of the project 8 piles needed to be replaced, which like previous works, would not be without challenges due to the tight tidal time frame available for pile installation.
In fact, the tidal working window was 1.5 – 2 hours and a spring tide was essential to ensure that the sea retreated sufficiently to allow the Junttan PM20 rig to work. In addition enabling works, such as setting out of pile positions and the transportation of piles etc., also had to be planned around the low tide window. Even the wind, which would cause the tide to stay in longer, has to be planned for and carefully factored into the work schedule.
Specifically 8 Greenheart timber piles were installed to replace the 8 piles that were rotten due to age and general age-related wear and tear. Works were completed over two tides, some 75% ahead of the 8 tides that works were originally programmed for.
Alistair Ktori, Managing Director, KD Engineering said, “Once again, Aarsleff exceeded our expectations with professionalism and efficiency. We first worked with Aarsleff back in April 2010 and the project went very smoothly and without problems. This time, with the added knowledge of what we were doing, the work was completed in a quarter of the time allowed. We look forward to working with Aarsleff and their crew again in the near future.
The project was a huge success for Aarsleff, who subsequently received a number of enquiries, such as from the Hastings Pier Charity, who were keen to exploit the company’s knowledge and expertise on these types of projects.
Client: Worthing Borough Council
Main Contractor: Phase I – Paine Manwaring Green Limited, Phase II – KD Engineering
Piling Contractor: Aarsleff Ground Engineering Ltd
Construction Date: April 2010 & March 2014
Scope of Works: Phase I: 4, 300mm square section Greenheart timber piles and 3, 350mm square section Greenheart timber piles, Phase II: 5, 300mm square section Greenheart timber piles and 3, 350mm square section Greenheart timber piles
Equipment: Banut 700Download Case Study