MWSS’s initiatives to rehabilitate the transmission system-

The Metro Manila region is the main driver of economic and social development in the Philippines. Infrastructure investment and sustained development in the region is a policy focus for the country. However, secured water supply to Metro Manila has come to light as an area of concern. In 1997, to ensure better provisioning of services, the Philippine government and the Metropolitan Waterworks and Sewerage System (MWSS) contracted out the water supply services in Metro Manila. While Manila Water Company Incorporated (MWCI) was awarded the contract for the east zone distribution system, Maynilad Water Services Incorporated (MWSI) took over the west zone distribution system of Metro Manila. However, given the strategic and economic importance of secured water supply to the region, the MWSS retained the responsibility to source and transmit raw water to these two concessionaires. This has led to better supply coverage, more hours of service and lower levels of non-revenue water in the region.

However, fundamental issues continue to persist in this sector. The Angat transmission system, which is the main source of water supply to Metro Manila, is around 75 years old. The system is in poor condition and there are severe leakages in the existing tunnels. The metropolitan region, therefore, is highly vulnerable to water supply disruptions.

The Philippine Development Plan 2011-2016, focusing on sustained economic growth and infrastructure investments, identified the acute shortage of potable water as the primary urban challenge. In line with these issues, the Philippine Water Supply Sector Roadmap envisions adequate and sustained universal water supply coverage by 2025.

The Angat water transmission system

The Angat-Umiray transmission system was operationalised in 1968 to meet the municipal water supply needs of the MWSS service area. In addition, it also supplies water for the national irrigation area of 26,000 hectares called the Angat Maasim Rivers Irrigation System (AMRIS) and for hydropower generation.

The water transmission system consisting of the Umiray diversion and the Angat dam has a capacity of 4,000 million litres of water per day (mld). The Umiray diversion conveys water from the Umiray river to the Angat dam. The dam has a capacity of 850 million cubic metres (mcm) with an overflow level of 217 metres. It also has a watershed spanning over 62,000 hectares. The water released from the Angat dam is stored in two reregulation dams – the Ipo dam and the Bustos dam. While, the raw water supply under the MWSS comes from the Ipo dam, the Bustos dam supplies water for irrigation purposes. The Ipo dam has a capacity to store 5.9 mcm of water and an overflow level of 101 metres, which is sufficient to meet Metro Manila’s water needs for only two days. The Ipo dam also has 6,600 hectares of watershed land around it.

Currently, there are three tunnels that connect the Ipo dam to the Bicti basin interconnection structure at Bigte. These three tunnels transmit around 4,650 mld of water over a distance of about 6.4 km each. This water is further transmitted through six raw water aqueducts over about 16 km each, to reach either the La Mesa treatment plants or the La Mesa reservoir. The two La Mesa treatment plants, with 1,500 mld and 900 mld capacity respectively, connect to the MWSI service area in the west zone of Metro Manila. On the other hand, raw water from the La Mesa reservoir flows into the Balara treatment plants (with 600 mld and 1,130 mld capacities respectively), which connect to the east zone distribution system under the MWCI. Thus, water from the Angat dam is transmitted to Metro Manila and some areas of the Cavite and Rizal provinces, serving around 15 million people.

However, the transmission system faces a number of issues that have led to the sub-optimal utilisation of the system’s capacity. The existing tunnel system is inadequate to meet the structural requirements of Metro Manila. The older aqueducts lose nearly 10 per cent of the water inflow due to leakages.

Further, the transmission system is also inadequately equipped to meet the rising water requirements of Metro Manila. The region’s water demand is projected to increase to 50 cubic metres per second by 2025 and further to 70 cubic metres per second by 2035. However, while the granted water right for the Angat system is 54 cubic metres per second, the flow is less than 46 cubic metres per second 80 per cent of the time and about half the time, it is less than 40 cubic metres per second. Therefore, to meet the future water requirements of Metro Manila, there is an urgent need to restore the system’s full design capacity. However, to ensure that the rehabilitation of the system does not cause any disruption to the existing water supply to the region, the inspection and rehabilitation works will have to be undertaken in a phased manner.

Angat Water Transmission Improvement Project – Scope and funding

To address these issues, the MWSS had proposed the Angat Water Transmission Improvement Project (AWTIP). The approval from the National Economic and Development Authority (NEDA) board for the AWTIP was received in May 2014.

The scope of the project involves the construction of an intake structure at the Ipo reservoir and laying of a fourth parallel tunnel from Ipo to the Bicti basin. The proposed tunnel will be around 6.4 km in length with an inner diameter of 4 metres. The tunnel will have a design capacity of 19 cms. Further, the work also involves the construction of a new transition basin at Bigte. This new basin will be connected to the existing transition basin number three.

The immediate objective of the AWTIP is not focused on increasing the system capacity, but on allowing the rehabilitation of the existing tunnels and aqueducts. The proposed tunnel will provide operational flexibility to the transmission system and ensure sustained and secured water supply to Metro Manila while the rehabilitation work is being undertaken.

The MWSS will be the implementing agency for the project. NEDA and the Governance Commission for Government Owned or Controlled Operations will supervise the project work. Further, the operation and maintenance of the project will be undertaken by the MWCI and MWSI.

The total project investment is estimated at $134 million. The bulk of this investment will come in the form of a $123.3 million loan from the Asian Development Bank (92 per cent). The remaining investment of $10.7 billion (8 per cent) will be undertaken by the Philippines government.

Progress so far

As of now, only the tunnel construction work has been awarded (in May 2016) by the MWSS. Italy-based Cooperativa Muratori e Cementisiti di Ravenna Societa Cooperativa will be executing the tunnel design and construction work at an estimated cost of  PhP 3.29 billion. The work is likely to commence in January 2017. The MWSS is yet to announce the contracts for the remaining project works. The entire transmission improvement project is scheduled to be completed by December 2021.

Project outcomes

The new tunnel will help restore the Angat system to its full design capacity. It will facilitate the rehabilitation of the whole transmission system, which will mitigate the risk of a partial or total water supply loss to Metro Manila. It will also augment supply to the sixth aqueduct, which was added to the system in 2012. Further, it will also strengthen the entire system to meet the rising water demand in the future. Increased availability of water will also allow service providers to increase the number of piped connections.

The project includes a capacity building component to train the MWSS staff to improve their management and supervision skills.

Going forward

While several measures have been undertaken over the past few years to improve the Angat transmission system, there are still a number of issues to be addressed. Supply coverage services have not kept pace with the growing population and increasing urbanisation. Thus, the Angat system alone will not be sufficient to cater to the growing water needs of Metro Manila. Alternative water sources will have to be developed. Further, some areas of the region, such as those in southern Manila, still lack water supply provisions and continue to depend on groundwater for their daily needs. Steps need to be taken towards ensuring universal coverage of water supply and development of new waterbodies such as Laguana de Bay or those in Rizal, which could cater to the water needs of Metro Manila.