Tuesday, August 16, 2022

IMPROVING FLOOD PROTECTION

East Budleigh is a small village in East Devon, UK located about 2 miles (3.2 km) north of Budleigh Salterton. The village features a bypass culvert, constructed in the 1970s. The culvert is approximately 280 metres in length, of Armco construction, oval shaped, approximately 1,800 mm diameter and constructed from corrugated metal sheeting (with a concrete floor laid over it during the last 10 years).

The existing culvert was in a poor condition, with joints failing and large voids appearing in the material outside the culvert structure. These failures led to a small localised collapse in the road above during flooding in 2012 and there were concerns that in the future a larger collapse could occur, causing a failure in the highway surface.

It was decided that this culvert required structural strengthening due to minimal cover
to the busy road above, and to maintain flows through the culvert in storm conditions.
The Environment Agency utilised Atkins to design the culvert rehabilitation, with Kier
appointed at main contractor.

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Looking at the rehabilitation options and given that the location was a highly trafficked
residential area with minimum cover to the road, it was decided that lining with a
structural GRP segment lining system offered the best solution.

LINING OPERATIONS
Having investigated the various lining systems available, the Amiblu NC Line, noncircular GRP Structural Relining system was selected for the project. In total some 300
metres of Amiblu GRP NC Line Arch Shape liner, dimensions 2,360 mm wide x 1,350
mm high was required to complete the works.

Manufactured to WRC Type II standard, the structural, large dimension, non-circular
GRP prefabricated linings were manufactured in January 2022 at Amiblu’s Gdansk
factory in readiness to commence deliveries on 21 February. Specialist contractor
Matt Durbin Associates was awarded the contract to install the linings.

The culvert meandered with the local water course, and on inspection for the design
of the linings was found to include long radius bends. These were designed for in the
fabricated linings in the factory so that they would install without issue on site. Despite
the apparent loss of cross-section in the culvert the design and smooth internal finish
of the segment linings ensured that the flow capacity requirements for the culvert
would be met.

Given the small village size and the traffic management requirements for the
installation works, co-ordination with local residents and parish councils regarding the
large deliveries to site was essential and during the project worked extremely well.

Work commenced on site on 14 February with site preparation works. Deliveries of the Amiblu NC Line segments commenced on 21 February. Installation into the culvert commenced in March. In total, all installation and annulus grouting operations were
completed in just 8 weeks.

Client satisfaction for the project was high the Environment Agency commenting favourably on the works.

“From a client perspective, the GRP liner solution has provided a cost- and time-effective approach to prolonging the asset life. We were hopeful to avoid any requirement for open cut solutions to minimise the impact to the local community and meet delivery deadlines. We also needed to ensure that the flood risk standard of protection was not altered to upstream or downstream receptors. The structural GRP liner allowed for a bespoke unit to be installed which optimised the culvert capacity to retain the flow performance and extended the life for a minimum of 50 years. The outcome of improvements to the culvert have reduced flood risk to 27 residential properties, significantly reduced future maintenance costs and health and safety risks to the public.” said Daniel Gay, Project Manager for the Environment Agency.

For AECOM, Alexis Field, Project Director commented: “This has got to be the easiest project that I have been involved with, all credit to the team, Matt Durbin and Kier Group, for fantastic planning, proactive problem solving and having pride in their work.”

Matt Durbin, Managing Director of Matt Durbin Associates said: “It has been a pleasure as always working with Amiblu, great service and great products. We have developed strong partnerships with all involved to deliver this project and look forward to delivering more
like it in the future.”

Adrian Parker, Senior Project Manager for Kier commented: “This project is a great example of how accelerated delivery can be achieved under the Environment Agency’s Collaborative Delivery Framework. From identification of the scheme for fast tracking in June 2021, the scheme was on the ground in 22 February and complete by 22 June. MDA have done a great job and thanks also to Amiblu.”

In closing for lining manufacturer Amiblu, Leon Woods, Technical Sales Manager commented: “Whilst we have worked with Matt Durbin Associates on many occasions, to date (March 2022), this was Amiblu’s largest NC Line project in the UK and the first for the Environment Agency as the asset owner. The project required a great deal of collaboration between the MDA and Amiblu’s engineers to design the right solution, resulting in the creation of a bespoke profile for East Budleigh, manufactured to the optimum dimensions to accommodate anticipated flow rates and required capacity. We have been delighted with the positive feedback from all concerned.”

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