The Umiray River contributes about 20 – 30% of the raw water for Metro Manila. The diversion facilities which was constructed under the Umiray-Angat Transbasin Project (UATP) became operational on June 2000. The intake facilities is located at Umiray, General Nakar, Quezon, while the outlet facilities is located in Macua, Dona Remedios Trinidad, Bulacan. The water from Umiray River to Macua River is conveyed through a 13 km tunnel (4.30 m. diameter) across Sierra Madre mountains.
On November 29, 2004, typhoon “Winnie” has caused severe damages to our Umiray-Angat Transbasin Tunnel and its facilities resulting to the complete stoppage of operation particularly the conveyance of raw water from the Umiray River to the Angat Reservoir thru Macua River.
A. Immediate Works (Phase 1):
Due to the clogging of the tunnel, the flow of raw water from the Umiray River to the Macua River was completely stopped resulting to a decrease in the volume of raw water available at Angat Reservoir and would mean a water shortage come dry season supplemented by the forecasted occurrence of El Nino by July 2005. To mitigate this water shortage, urgent works were done only to let the raw water flow again through the tunnel which is considered as Phase 1 of the rehabilitation works. Thus, MWSS together with its Concessionaires immediately undertook the following activities
B. Permanent Works (Phase2):
Since the immediate works done is only for the purpose of allowing the flow of raw water again into the tunnel, a permanent rehabilitation works has to be done to strengthen the stability of the structures to withstand future flood and typhoons. A Consultant was hired therefore to study and evaluate the existing structure including the hydrological component, and to undertake the detailed design for the complete rehabilitation works.