Civil engineering |
Lessons learned from emergency concrete repair
Paul Rigby, technical consultant at Saint-Gobain Weber, explores the complexities of dealing with emergency repairs and reflects on Weber’s own experiences of helping during crisis situations.
THE UK COASTLINE IS approximately 11,000 miles, making it one of the longest national coastlines in Europe. Sea defences stretch around almost half of this and the cost of maintaining hundreds of miles of sea walls, artificial beaches and breakwaters is more than £750 million a year. Climate change and the more extreme weather conditions the world is now facing can damage these defences to the point where life and property suddenly become endangered and maintenance teams have to act quickly. The oceans absorb 90% of the extra heat generated by human influence which means that because of global warming, the ocean is heating up and expanding. Even if we cut emissions, the Met Office says that sea levels will continue to rise until the year 2100. Since 1998, the UK has had six of the ten wettest years
on record, and with winters projected to get almost a third wetter by 2070, it’s unsurprising that we’re seeing an increasing number of reports of sea defences, dams, reservoirs, harbours and ports succumbing to the elements. We’ve dealt with many emergency repairs, but there
are two in recent years that highlight the importance of timely and routine maintenance of concrete structures in marine environments.
Whaley Bridge Dam The Whaley Bridge dam, originally built in 1831, holds
back 1.3 million tonnes of water from the Toddbrook reservoir. In August 2019, this small town in Derbyshire made national news when heavy rain partially dislodged the large concrete slabs that formed the spillway, which undermined the underlying structure of the dam wall. Around 1500 residents were evacuated while emergency crews pumped out water and an RAF helicopter dropped 400 tonnes of aggregate to help shore up the reservoir. These aggregate sacks were then secured in place with specialist grout. Fewer than 24 hours after an emergency order to supply materials to the Toddbrook Reservoir was placed by EPMS Supplies, more than 8600 bags of Weber’s technical mortar products were on site to help secure the dam.
Charlestown Harbour Just over 300 miles south of Whaley Bridge lies
Charlestown Harbour in St Austell, Cornwall. As a Grade II-listed harbour and UNESCO World Heritage Site, it provides breathtaking views and attracts thousands of visitors each year.
In December 2021, a landslide caused part of a cliff face in Charlestown to collapse. Concrete repairs specialist Gunite and Shotcrete Services were brought in to make the repairs on behalf of Alun Griffiths Civil Engineering & Construction. At the request of Gunite and
30 | March 2023 |
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Shotcrete Services, we supplied 6,000 bags of webercem spray DS to Charlestown within five days to help save the remaining cliff and make the area safe.
Lessons learned In both situations, it is incredibly fortunate that people,
the volume of materials and transport were all available to deal with the issue swiftly and that all of these separate teams pulled together to prevent a potentially devastating outcome – but let’s look at what else we have learned from being part of these projects…
Don’t underestimate routine maintenance When it comes to concrete structures – not just those in marine environments – we should adopt a “prevention is better than cure” approach. At Whaley Bridge there had been routine inspections; the Canal and River Trust (CRT), which owns the reservoir, had inspected the dam in the previous November and an independent engineer had also submitted a report to the CRT in April. The engineer asking for vegetation to be removed, and for joints and cracks to be repaired within 18 months, but unfortunately it would seem these works were not addressed quickly enough.
Utilise local manufacturing Weber were able to help so quickly because our regular involvement in major infrastructure projects demands large-scale manufacture in the UK. We have three plants meaning we were ready to deliver to both sites at short notice. In total we distributed 200 tonnes of grout from our manufacturing plant in Flitwick, Bedfordshire – to add to the 50 tonnes that were already at EPMS Supplies depots – to Whaley Bridge in Derbyshire. For Charlestown, we were able to supply all 6000 bags of product which then made the journey from Flitwick to arrive on-site ready for the repair works.
Supply chain relationships make a difference Having the products is one thing but getting them to site urgently requires a completely separate set of logistics. Nine lorries were required to transport all the materials from Flitwick to Whaley Bridge. The order was placed on Friday 2 August 2019, and by the end of that day 8640 bags of Weber Precision Grout were prepped and ready to leave site. A total of 11 members of staff helped, including two who came from our Telford plant to help load the lorries at 6.30am on a Saturday. All of the materials reached the dam just a few hours later. Once products are on site, the concrete repair specialists take over to deliver the works as efficiently as possible. In Charlestown, work was completed by two nozzlemen with two pumps over just one weekend. ●
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