Ridgeway’s Filter Unit Rockbags have been successfully used by a team from the Environment Agency, VolkerStevin, Boskalis Westminster and Atkins (VBA) for the Croston FAS Scheme. They provided a £9.4 million integrated flood risk management scheme working together with Chorley Council, Lancashire County Council and United Utilities. In June 2017 the scheme was completed and reduced the risk of flooding to 347 residential households and 91 commercial properties in the Croston Area.

Ridgeway in collaboration with Japanese partner Sumitomo Corporation Europe provided over 1000 Kyowa Filter Unit Rockbags for this scheme. These were used on the inlet and outlet of the control structure in the storage basin to stabilise the banks.

The Kyowa Filter Unit Rockbags were easy to fill, lift and place by an excavator, covering areas rapidly. They can be placed onto uneven ground and be used to fill gaps were necessary. The stone in the Kyowa Filter Unit Rockbags easily silts over and was very well established after just 6 months at Croston.

Kyowa Filter Unit Rockbags can be easily repositioned which makes them ideal for temporary works. In August 2016 the Croston area experienced very heavy rainfall. As a result, water levels in the river Yarrow rose significantly and the construction site was in danger of flooding. With the use of visqueen sheet wrapped around some of the Kyowa Filter Unit Rockbags they were able to form a bund in less than an hour. As well as protecting earthworks, this also reduced the risk of flooding to Croston, as the control gates of the new dam were not fully operational at this time.
Richard Birchall, Project Manager, VBA JV Ltd.
Team: Environment Agency, VBA JS Ltd.

After considering the use of Kyowa Filter Unit Rockbags on other projects, TEAM2100 decided to use them in temporary works to support a failing wall on the River Thames. TEAM2100 is a collaborative team from the Environment Agency, CH2M and Balfour Beatty. This programme will deliver the first 10 years of capital investment in the tidal flood defences as recommended by the Environment Agency’s 100-year Thames Estuary 2100 (TE2100) plan to manage increasing tidal flood risk.

The team identified a tidal flood wall in London as having been undermined because the foreshore level had lowered. This undermining caused a significant move to the structure which presented not only a flood risk but a health and safety risk to the public and a nearby residential building.

Temporary works were required to support the failing wall while a permanent solution could be put in place. The temporary works consisted of a 5.5m stone fill embankment lined out with Ridgeway’s Kyowa Filter Unit Rockbags for scour protection. This formed a platform on which 12 modified shipping containers (filled with a combination of loose aggregate, void filler and concrete) were arranged to the required height. They used marine working platforms located outside the exclusion zone to undertake the works and placed materials by a combination of crane lifts and long reach excavator. Finally props and grout bags were installed to fill the gap between the containers and wall ready to take the load from the falling wall. The design began over the 2016 Christmas period, construction started in January and the embankment was completed in February 2017, installing and filling the containers was early march. The connection to the failing wall was made in mid-March and works completed at the end of March with the failing wall supported.
Eileen Chio, Communications Lead CH2M, TEAM2100.
Team: Environment Agency, CH2M and Balfour Beatty.

Ridgeway have established some significant signature projects with the Kyowa Filter Unit Rockbags in the UK, Europe and closer to home with the Environment Agency, framework contractors, councils and local developers.



To find out more on Ridgeway’s Kyowa Filter Unit Rockbags system contact us today at either Belfast +44 (0) 28 90454599 or Ashbourne +353 (0) 802 7173, email or visit