The Novaliches-Balara Aqueduct 4 (NBAQ4) project in the Philippines recently marked a key milestone with the completion of its tunnelling work. Manila Water Company announced that the TBM has broken through at the La Mesa reservoir.

In a separate statement, Hong-Kong based Chun Wo Construction Holdings Company Limited, one of the contractors working on the NBAQ4, said this achievement is an important step for the company as it is the first project for Chun Wo in the Philippines and is part of the strategy of tapping into the Southeast Asian market.

Chun Wo has participated as part of the Novabala JV Corp (NBJVC), which also includes First Balfour (Philippines) and CMC di Ravenna (Italy). In August 2017, the JV signed the design-and-build contract for the project – a collaboration among Manila Water, Metropolitan Waterworks and Sewerage System (MWSS), NBJVC, and Arup.

The NBAQ4 is one of the largest water supply infrastructure projects ever undertaken by Manila Water, and is the first in Metro Manila to employ a tunnel boring machine (TBM). This new aqueduct is expected to improve the reliability and security of the raw water transmission system in the eastern region of Metro Manila.

Boyd Merrett, acting CEO of Chun Wo said, “We are proud to contribute to the construction of the water conveyance network in Manila through leveraging our experience in tunnelling and complex engineering projects. In view of local constraints, which include traffic congestion and relatively limited construction techniques available, we explored different construction methods from the commencement of the NBAQ4 design and build contract with Manila Water back in 2017.

“We subsequently developed innovative solutions with use of a specially designed earth pressure balance (EPB) TBM that features a double articulated shield to navigate 80-m radius curves, and development of a special precast ring design. We look forward to the completion of the NBAQ4 project, which shall improve the reliability and long-term water supply to the most densely populated areas of Metro Manila.”

The NBAQ4 is part of Manila Water’s improvement and expansion initiatives. It encompasses the East Zone concession area and is in coordination with the MWSS. The project involves the construction of a new intake facility at the La Mesa reservoir – a 7.3-km underground aqueduct passing under Commonwealth Avenue, and an outlet facility at the Balara Water Treatment Plant.

When completed in 2022, the new aqueduct will be capable of delivering an additional 1,000 mil l/day to the existing water treatment plants, ensuring the reliability and security of the raw water transmission system in Metro Manila.

Image: Chun Wo

Note: Below is the video of the TBM breakthrough by Manila Water.