Project achievements and benefits
The short tidal window working hours meant shifts could start as early as 6 am and finish as late as 10 pm. When setting these working hours BMMJV connected with the local stakeholders, explaining the long working hours, how noise and disruption would be minimised and the resultant reduction in the overall duration of the contract.
Residents were informed that reducing the overall duration of the contract protected their homes faster and reduced the risk of failure. The joint venture between Bam Nuttall and Mott MacDonald allowed for early contractor involvement within the design process. This proved particularly helpful in producing a solution that minimised the impact on the local residents.
Public access had to be maintained to the Site of Specific Scientific Interest (SSSI), public rights of way and the Tiger War Memorial.
The community was extremely grateful with the outcome of the project and complimentary throughout, with multiple residents and the local member of parliament providing very positive feedback about the works.
Project elements
Pressures for the EA to deliver a solution as quickly as possible to prevent failure of the defence was a priority for the whole team. Construction works got underway in November 2016, as soon as the planning permission and the Marine Management Organisation (MMO) license were in place and was completed at the end of March 2017. The short tidal window working hours were maximised to give the longest working hours.
Deliveries of materials were restricted to the high-water periods with the concrete arriving each day as the tides were dropping ensuring a pour could be achieved with each tide.
Production graphs of the concrete and piling works were maintained throughout to monitor production to ensure the works progressed as programmed and accurate predictions of works could be portrayed to the local stakeholders. To increase productivity, the construction was carried out using propriety shutters and prefabricated elements. This allowed assembly of the steelwork and shutters to be carried out outside the tidal window, making full use of the working day.
The concrete capping beam was poured using 4 sets of shutters. A set installed for the pour, a set being set up for the next pour, a set left in place for the curing process and a final set being stripped out and cleaned ready for the following day.
Having the rebar designed into prefabricated cages allowed BMMJV only to install the required amount of steel for the planned pour. Splice bars were added to join the next cage to ensure the steel was keept to the design requirement without leaving rebar installed which could get un-necessarily exposed to the elements.
BMMJV worked to ensure minimum waste and zero rework. Concrete supply was the factoring resource so both size and time of pour were critical. Utilising the structural concrete as blinding allowed BMMJV to always have full loads to site and ensured there were never short for a pour. The team working ahead of the pour would have the blinding level set so each pour could run into a blinding pour. This application of value engineering achieved a concrete waste of below 1%.
During piling works, some problems occurred due to higher rock levels being encountered than expected and plant issues. These issues were quickly resolved through good team communications on site and with the design team and client. The whole team was updated daily through photos of progress and beach levels on site, ensuring issues could be quickly resolved and progress reported during construction. BIM was used for document control.