By Sheldeen Joy Talavera, Reporter
METROPOLITAN Waterworks and Sewerage System (MWSS) and its concessionaires have finished a tunnel excavation as part of the Angat Water Transmission Improvement Project (AWTIP), paving the way for rehabilitating other tunnels, company officials said on Tuesday.
The 6.40-kilometer-long raw water conveyance tunnel is the fifth tunnel in Norzagaray, Bulacan. It will carry raw water supply of approximately 1,642 million liters per day (MLD) from Ipo Dam to the Bigte basin.
“The benefit of our Tunnel No. 5 is we will be able to increase delivery [of water] to La Mesa [Dam] and prevent leakages. That is one of the [issues] that we are addressing, to be able to recover leakages from old tunnels,” MWSS Administrator Leonor C. Cleofas told reporters in Filipino on Tuesday.
MWSS and its concessionaires, Maynilad Water Services, Inc. and Manila Water Co., Inc., led a ceremonial tunnel boring machine breakthrough for the AWTIP on Tuesday.
Maynilad and Manila Water equally shared the project cost of P3.17 billion.
The AWTIP will provide operational flexibility to the raw water transmission system during the maintenance or repair of the existing tunnels, especially Tunnel No. 1 that was constructed in 1939.
The project also aims to improve reliability, operational flexibility, and water security in the Umiray-Angat-Ipo-La Mesa raw water conveyance system.
The system is serving 90% of the 20 million population in the whole service area of MWSS, Ms. Cleofas said.
She said that once the tunnel boring machine is removed, there will be the construction of an intake structure to transport water from Ipo Dam to Bigte basin.
“We need to have redundancy and to meet the increasing demand of water in Metro Manila,” she added.
MWSS and its concessionaires selected China International Water and Electric Corp. as the project contractor and DOHWA Engineering Co., Ltd. as the consulting firm.
Patrick Lester N. Ty, chief regulator at the MWSS Regulatory Office, said that the project is already included in the rate-rebasing and will not cause additional charge in water bills.
In 2022, the MWSS board approved the implementation of higher rates on a staggered basis for five years starting in January 2023.
Mr. Ty said that the rehabilitation of Tunnel Nos. 1, 2, and 3 will begin once the reliability of Tunnel Nos. 4 and 5 have been determined.
“Of course, this is worth it… What if we would have a problem in one of our tunnels, we would need to fix that… Our tunnels are already more than 50 years, these need to be rehabilitated,” he said in Filipino.
The 6.3-kilometer Tunnel No. 4 was completed in 2020 and was able to carry 1,600 MLD of water into the delivery system.
WATER ALLOCATIONMs. Cleofas said that MWSS is requesting 52-cubic-meter-per-second (cms) water allocation for June 16 to June 30 from the National Water Resources Board (NWRB).
“We want to be assured that there will be no water interruption. But even if we would be given 50 [cms], there would be no water interruption,” she said.
The NWRB has approved the 51 cms water allocation for June 1 to June 15. MWSS normally draws 50 cms from Angat Dam.
“Because it’s already the rainy season, even though we would be given 50 [cms], if the water is too much, we are the one requesting not to release water from Angat because we want to save the water from Angat,” she said.
