May - Dec 2009

May - December

Starting the project:

  • To form the basement area of over 1-ha, 80,000 cubic metres were excavated, involving 10,000 truckloads of material being removed from the site
  • Basement construction was through Belfast "sleech": a notoriously difficult mixture of sand, gravel and boulder clay, beside the River Lagan, at 8m below sea level
  • Over 1,000 secant piles covering a perimeter of approx 500 metres were used. Piles 600mm diameter to a depth of 18m were restrained by ground anchors
  • Over 1,000 bearing piles were used, 600mm diameter to a depth of 23m
  • Basement concrete slab was 1.1m deep and used over 2,500 tons of reinforcement steel
  • The first concrete pour covered almost 0.5-ha to a volume of 4,200m3.
  • It was the largest ever concrete pour on the island of Ireland: over 700 concrete truck deliveries; a truck load every 2 minutes for 24 hours, requiring eight concrete pumps
  • In total, over 10,000 m3 of low carbon concrete was used in the basement construction contributing to a CO2 saving of 1,296 tonnes. The same emissions saving would require taking 416 cars off the road for a year, or saving 408.3 years' electricity in the average home.


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