Sunday, November 10, 2013

Angat Dam breaches 210 meters water level, but wont spill yet

By Dino Balabo
Angat Dam in Norzagaray, Bulacan.

MALOLOS CITY—Water elevation at the giant Angat Dam climbed by 2.65 meters in 24 hours breaching its spilling level of 210 meters above sea level (masl) due to rains brought by super typhoon Yolanda.

However, the National Power Corporation which manages the dam said they will not spill water yet; and added that 210 meters is “normal high water level during flood season.”

Records showed that water elevation at the Angat Dam climbed to 211.25 masl at 9AM yesterday, from 208.60 masl on Friday.

According to Engineer Rodolfo German, Angat Dam which supplies 97 percent of Metro manila’s potable water requirement can hold up to 217.4 masl.

German is the the general manager of the Angat River Hydroelectric Power Plant (ARHEPP) of the Napocor.

He stressed that they will only spill water if there is another typhoon coming towards dam and will bring more rains.

“Malaki pa ang factor of safety, but we can spill water anytime,” he said.

As of Saturday, he said there is no coming weather disturbance based on latest weather forecasts.

With regards to stability of structures of the 47 year old dam, German expressed confidence.

He also said that water inflow coming down Sierra Madre mountain is estimated at 568 cubic meter per seconds (cms) while outflow through their power tunnels that feeds water to Arhepp’s power turbines is only 61 cms.

German also estimated that water elevation at the dam will further climb to 214 masl in the next 24 hours.

For his part, Engineer Russel Rigor, head of the flood forecasting division of the Napocor explained that the 201 masl is not necessarily the spilling level.

He described it as the normal high water level.

With regards to the Umiray Angat Transbasin Tunnel (UATP), German and Rigor said they don’t know if it is still open.

German earlier said that it will be closed once water elevation at the Angat Dam reached 210 masl, but Rigor added that it is the responsibility of the Metropolitan Waterworks and Sewerage System.

The 13-Kilometer UATP divert water from Umiray River in Quezon Province to Angat Dam.

With regards to decision on spilling water in the Angat River, German admitted that when water elevation at the dam claimed to 210 masl, it is the Napocor’s decision.

He said that National Water Resource Board (NWRB) only makes decision on water release when elevation is below 210 masl.

As this develop, Bulacan Governor Wilhelmino Alvarado reiterate his call for preemptive water release of dams in the province including Angat Dam.

In his weekly broadcast aired over Radyo Bulacan on Saturday, the governor expressed apprehension on possible flooding in the province in case Angat Dam spill water.

“Hindi na natin dapat hintaying umapaw, pagkatapos ay biglaan silang magpapatapon ng malaking volume, tiyak na babahain na naman ang Hagonoy at Calumpit,” Alvarado said.

He also expressed concerned over the stability of the dam noting that President Aquino have allocated P5.7-Billion for its rehabilitation.

The said rehabilitation is mean to improve stability of Angat Dam in case of possible magnitude 7.2 earthquake that will be generated by the possible movement of the Marikina West Valley Faultline (MWVF).

But sources recently disclosed that the possible earthquake was used in justifying the rehabilitation of the dam whose main purpose is to increase its water holding capacity to meet the increasing needs of Metro Manila.