9
Digging down deeper than 1.5m below the footprint of the
old caravan park, the construction team had found alluvium deposits that meant a major fill operation was needed. With the River Axe and the sea nearby, the site needed to be 3.96m above sea level. To achieve that meant a fill operation that would involve shifting 300,000 cu m of sand onto the site. With the site partly surrounded by the sea on one side and a
tram line on the other, there is only one route into the site and a planning constraint of 40 lorry deliveries per day would have made the construction programme lengthy to say the least. Andy Demetriou, operations director at ISG’s UK Retail divi-
sion, explains: “The original plan for the site was to bring in truckloads of fill by road. This would have taken an estimated four years to complete and contributed to increased traffic on the local road infrastructure. ISG proposed an innovative dredged sand solution, which received overwhelming support as this would reduce the environmental impact of four years’ of truck movements in the locality. “ Instead of trucking in sand, which would also give the project
a massive carbon footprint, ISG proposed to bring in dredged sand from the sea and transport that material to site via a pipeline to raise up the base to the required level. “We had to get a separate planning consent to fill the site
because it was so different,” says Fletcher. ISG finally started work on site on January 24, 2011 and had to immediately break up the caravan bases. Because of the weakness of the land under- neath, these aggregates were used to create site roads. The pumping operation began in April with Westminster
Dredging recruited to carry out the job. The sand and aggregate was dredged out of a licensed undersea quarry known as a win- ning ground, 30m below the sea bottom in the Bristol Channel.
...continued overleaf
Above and left: The dredging gets under way
“It was going to be off the Isle of Wight but there was a prob-
lem with the materials so it was switched to the Bristol Channel,” adds Fletcher. “The sand and aggregate was dried out on the boat and then watered down then pumped ashore.” To deliver the sand and aggregates, ISG commissioned the
welding of a 3.6km long, 825mm diameter pipeline from a plant in Southampton. Around 1.5km of the pipeline rested on the seabed. The remainder snaked onto the land and through the town and this was the subject of particular concern for some locals, who were unhappy that the pipe bridge ISG proposed to install would be structurally sound and could collapse. ISG overcame this by building two temporary bridges. When
the pipeline came off the ship and ran up the beach, it ran past the town’s yacht club and over the pair of temporary bridge structures then through land owned by a third party.
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