In Quezon City, one of the Philippines’ largest water supply infrastructures is being constructed. The 7.3 km long and 3.1 diameter tunnels and underground aqueduct will have a conveyance capacity of 1000 million liters per day, enabling the sequential temporary service suspension of the existing aqueducts. NovaBala Aqueduct 4 (NBAQ4) is the first tunnel to be constructed with a tunnel boring machine (TBM) in Metro Manila.
BAUER Foundations Philippines, Inc. was first commissioned to work on the design and construction of TBM launch shaft, through Secant Pile Wall comprising of 22 primary piles of 1000mm diameter and 22 secondary piles of 1200mm diameter all with a maximum depth of 47m. Bauer also carried out the construction of capping beam and bulk excavation to a depth of 45m, forming a 9m inner diameter. The piling works were completed with BG30 and BG14 drilling rigs, using extended double cut tools due to high strength concrete (50MPa).
Bauer was also awarded with the outlet shaft piling works, consisting of 20 primary piles of 1500mm diameter overcutting 20 secondary piles of 880mm diameter, all at a maximum depth of 29m. Construction was carried out using BG40, and drilling inclination system (DIS) was used on all piles to measure the verticality and ensure that each pile is within the design tolerance.