Torcross sea defence

Torcoss, United Kingdom

Year

2017

Duration

14 months

Cost

£2.4m

Location

United Kingdom

Project achievements

Solved the problem

Repaired the sea defence.

Environment benefitted

Ensured minimal waste and zero re-work

Used engineering skill

Ensured minimal waste and zero re-work

Repairs to sea defence to protect coastal community

The aim of the project was to identify the underlying issue with the existing sea defence in Torcross and rectify before the Winter 2016/17 storms. Funding was secured from the Flood Defence Grant in Aid (FDGiA) and the £2.4m project was completed within 14 months of the defence failure being identified.

Throughout the duration of the works, the Environment Agency (EA) and BMMJV worked to ensure effective community engagement and to minimise the impact on the local stakeholders.

They started by identifying a community representative, who helped them understand the concerns of affected residents and businesses.

During the design development stage, a survey was put to the community to give their opinions on various options for repair.

A public drop- in session was held to present the chosen design before submitting for planning approval. Regular newsletters, site public meetings and on-site Public Liaison Officer were used throughout the duration of the construction works, with the help of local MP and Slapton Line Partnership in sharing the messages.

Did you know …

Exposed and complex coastline with a recent history of rapidly changing beach levels with constrained access routes to the site, limiting the size of plant and materials
Risk of unexploded ordnance from Exercise Tiger
Environmentally sensitive site due to: Skerries Bank and Surrounds Marine Conservation Zone (MCZ); Slapton Ley National Nature Reserve (NNR) and Site of Specific Scientific Interest (SSSI)

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.