As one of the first steps in the retrofitting process, workers removed the existing concrete floor. .
As one of the first steps in the retrofitting process, workers removed the existing concrete floor.
Workers install one of the steel casings for the cement support piling. The pipes in the foreground were part of the dewatering system that reduced the effects of hydrostatic water pressure. Pumps were also installed to prevent water from seeping into the excavation site.
During the first stage of excavation, workers removed 23,744 cubic yards of dirt reaching 5-ft deep. The walls were reinforced as the depth increased.
Dewatering pumps are shown here behind the 3- by 10- by 9.5-ft oak beams that were used for wall reinforcement.
To provide angled support, tiebacks (0.6-in. diameter cables) were installed in 60-ft deep, 12-in. diameter holes which were then filed with cement.
The second stage of excavation. cables) were installed in 60-ft deep, 12-in. diameter holes which were then filed with cement.
Once excavation was complete, workers installed 689 tons of steel rods to reinforce the floor. Drain pipes within the steel mesh relieve hydrostatic pressure. Cement was poured through the steel to reinforce the floor.
The NBL's water proofing system consists of polyethylene sheeting, protection board and water barrier layers.
Some 645 tons of steel rods reinforce the pool walls. Wall forms were put into place to form the lower concrete walls of the pool.
Workers poured concrete for the upper 20 ft of the wall in sections using braced wall forms and steel reinforcing rods.
CONSTRUCTION STATISTICS schedule.
3" x 10" x 9' oak timbers1,782 timbers total
Steel tie wire
641,088 cu ft23,744 cu yards
Floor: 689 tons (1.378 million lb)Walls: 645 tons (1.29 million lb)
6 ft thick5,300 cu yards10,303 tons (20.606 million lb)530 concrete truck loads
5-ft thick below ground2.5-ft thick above ground3,500 cu yards6,979 tons350 concrete truck loads
6.2 million gallons25,823 tons (51.646 million lb)Filtered at 5,400 gal/minuteHeated to 86 degrees F