Following hard on the heels of its 2014 success on the Medmerry managed realignment project on the Sussex coast, construction consortium Team Van Oord has completed another coastal protection scheme – once again with the help of Kijlstra precast units.
The £30m Broomhill Sands coastal defence project (near Rye, at the other end of the county from Medmerry) involves construction of a concrete wave wall and rock revetment along a 2.4km stretch of coast. The scheme is designed to improve the standard of protection from 1 in 5 to 1 in 200 years – including an allowance for climate change and changes in predicted tide levels.
The scheme involves recharging around 700m of shingle beach, the construction of eight new timber groynes to stabilise the beach and the construction of a 1,700m rock revetment and wave wall to the remainder of the frontage.
The contractor carrying out the work is Mackley, a member of the Team Van Oord consortium.
Technically quite different from Medmerry, this scheme nevertheless makes extensive use of Kijlstra’s precast panels as well as its CSO chambers and ancillary products.
The panels are a key component in the design of the concrete wave wall, explains Kijlstra’s project co-ordinator, Hendrik Jonker. “We have supplied precast concrete upstands to form the vertical part of the wall.”
Approximately 570 panels, each measuring 3m long, 1.2m high and tapering from 300mm to 250mm in thickness from the base to the top, were installed on an insitu cast base prepared by Mackley.
“Originally, the contractor wanted a completely precast solution but although we quoted for a full off-site design there was no real advantage and we actually advised an insitu base,” says Hendrik.
Though wave walls are traditionally insitu structures requiring costly and time-consuming formwork and steel placement, using factory-made precast units meant the wall was built in the shortest possible time – a major advantage on an exposed coastal site.
“Speed of installation has got to be key – it was the main reason for going precast,” says Tony Barnes, Mackley’s project manager. “We made rapid progress and installed an average of eight units per day throughout the project.”
The panels were all bespoke units, manufactured to specification at Kijlstra’s factory in Henlade, Somerset. They are among the first Kijlstra units to be built in the UK factory which only started production in January 2015.
Besides the wave wall, Kijlstra also supplied bespoke units for the construction of a number of maintenance access ramps at Broomhill Sands.
“Again, we built the top of the ramps insitu but used Kijlstra precast units for the bottom,” says Tony. “We were working 3m below tide level and using precast concrete allowed us to work between tides.
“We lifted the units into place during one low tide, then came back the next day to grout them in place. If we’d done it all insitu, we’d have had to install cofferdams around the ramps and that would have been very expensive and time-consuming.”
The project was due for handover in mid-January.
Note: This project has been named a finalist in two categories of the prestigious 2016 Constructing Excellence in London and South East Awards. For more information, click here.