Two DVH 5/2 diversion valves are hooked up between the trailer pumps and the placing booms. "The diversion valves have been an added support of muscle within this system," Whitworth says. "They provide the flexibility to use either trailer pump with either placing boom, and provide cleanout routes. In addition, the valves can easily handle high pressures up to 1,885 psi without leaking."
After the trailer pumps and diversion valves, the concrete travels up to the two MX 43/47Z placing booms. It is then delivered to the tremie pipes that move it underwater to its final resting place underneath the precast concrete shells.
As of early January 2011, the concrete placing system had delivered 2,000 cubic yards of concrete for one precast shell. The system will deliver up to 5,000 cubic yards of concrete for each of the remaining pours and is estimated to be on site through 2015.
Putzmeister's Special Applications Business (SAB) helped decide what equipment would be best suited to deliver the tremie concrete. Equipment used for the placement process includes:
- Two freestanding MX 43/47Z-Meter placing booms mounted on two freestanding pin towers
- One 31-Meter placing boom
- Two BSA 2112 skid-mounted concrete trailer pumps
- One 40-Meter truck-mounted concrete boom pump
- Four Maxon Maxcrete IV 18-cubic yard (13.7m3) remix hoppers
- Two DVH 5/2 diversion valves