CAMERON HIGHLANDS - It has been one year since the Bertam Valley mud flood tragedy which took four lives and damaged almost 100 houses near Sungai Bertam.
While residents have returned to their daily routine, Tenaga Nasional Bhd (TNB) has been working to avoid a repetition of the Oct 23 incident.
Most significant is the dredging works carried out at the Ringlet Reservoir, created with the construction of the Sultan Abu Bakar dam.
TNB generation division senior general manager (asset management) Azman Talib said it would have removed about 750,000 cubic metres of sediment from the reservoir by year-end.
The reservoir has a 6.2 million-cubic-metre capacity. Unfortunately, two thirds of it is filled with silt, sand and rubbish, enough to cover 100 football fields stacked to the height of a double-storey house.
The things that are found in the two tonnes of solid waste retrieved from the reservoir each week include bottles and wooden items, electrical appliances, furniture, animal carcasses and plastic roofs.
"It is a very tedious and costly task. But we are concerned about the lives of Bertam Valley residents.
"We need to sustain our efforts until the main problem is resolved," Azman said, referring to land-clearing and farming activities upstream.
Noting that TNB would have spent RM40mil on dredging works this year alone, a huge sum compared to the total RM180mil spent so far since 2001, Azman explained that domestic and agriculture waste which ended up in the lake had increased by over 10 times compared to 50 years ago.
"In the 1960s, the amount of sediment in the lake was about 30,000 cubic metres per year.
"Right now, there is an estimated 300,000 to 500,000 cubic metres of sediment flowing into the lake yearly due to aggressive land-clearing activities," he said.
Recounting last year's tragedy, Azman said half of the intake opening had been blocked due to the increase of sediment in the reservoir, causing the water level at the dam to rise rapidly.
"There had also been exceptional heavy rain and flash floods at Ringlet town, further contributing to the water level at the reservoir.
"Water had to be released manually to avoid the spill gates from opening automatically at 3,513 feet.
"If that had happened, the damage would have been catastrophic," he added.
Azman said TNB had also lowered the reservoir's water operating level to 3,500 feet from 3,506 feet as a temporary measure.
He indicated it had become a standard practice to observe the weather forecast every hour.
TNB has erected signboards to warn of danger areas and installed four additional sirens within a 6km radius from the dam.
"There are warning lights to indicate the severity of the situation," he said.
Azman said rising water levels would also be communicated to the authorities and village committee members through text messages.
"A number of evacuation drills have been carried out to familiarise those in authority and also residents on what to do and where to go in the event water from the dam is to be released manually," he said.
He said TNB and TNB Research were also working on an early warning system for Ringlet Lake.
"This RM1.9mil system works by telling us the velocity and amount of water that flows into the lake.
"We would be able to predict any unusual water flow and give Bertam Valley folk ample warning in the event a manual release has to be carried out," Azman said.
The project is expected to be completed in November 2015.
Bertam Valley village chief Wong Fook Chai, 57, said they were happy with the additional sirens but he felt that TNB could put up more warning lights to caution those living deeper in the village.
"While we applaud TNB's efforts, we feel the state government should also curb land-clearing activities," he said, adding that the authorities should also deepen Sungai Bertam.