The aftermath of the Bertam Valley disaster in Cameron Highlands, last week - The Malaysian Insider pic, October 29, 2013.The rapid increase of the water level in a short period of time late Tuesday and early Wednesday last week was an exceptional situation for the Ringlet Reservoir, said TNB president and chief executive officer Datuk Seri Azman Mohd.
He said the unusually intense rain on October 22 and 23 had brought huge volumes of water to the lake, together with solid waste, debris and siltation from what was described as massive land clearing and farming activities upstream.
The rubbish clogged up the Bertam water intake, an outlet where water from the reservoir normally flows before entering the Bertam tunnel to underground power generation units.
Such accumulation of siltation and sediment had reduced the reservoir's holding capacity.
"As a result, for the first time in the history of the 50-year-old reservoir, water level surged at a rate of 1.96ft per hour, which was 13 times more than the normal monsoon rain condition," he said in a statement in Kuala Lumpur yesterday.
According to the statement, surplus water had to be discharged in stages from the Sultan Abu Bakar Dam to avert the dam's automatic full spillage through all four spillway gates that would have caused greater destruction to the occupants of Bertam Valley.
Four people were confirmed dead, following a flash flood when Sungai Bertam overflowed following the release of water from the dam on October 23.
About 80 houses and several cars were also destroyed in the Bertam Valley settlement areas.
The TNB statement explained that, by design, a spillway gate is a dam’s protective structure used to control the release of water from a dam into a downstream river.
Downstream areas should be clear of people and structures, it added.
Azman said given the challenge of these external factors, which were beyond TNB's control, it was impossible to give advance notice to immediately evacuate the water release pathway other than what had already been done in the circumstances.
"While we could and should be continually improving our standard operating procedures (SOP), given the circumstances, we seriously doubt whether any SOP can be fully effective in averting such a disaster," he said.
He also said that no one should have lived in the path of the dam’s water release and it becomes even more unpredictable when weather elements, together with the development activities, come into play.
"We're continually monitoring the situation and we experienced a rate of rise of water level of 1.2ft per hour from 4pm to 6pm yesterday. A sudden blockage of the power station's intake can trigger another catastrophe.
"People living in the area are still not out of the woods yet, as development activities that have caused the Bertam reservoir to lose its water holding capacity continue to gain momentum," he added.
"We don't think anybody can guarantee the safety of the people at the site given the present conditions. Thus, they should be kept out of harm’s way and vacate the area," he added. – Bernama
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