If the Murum Dam fails, the rushing water would cause the Bakun dam downstream to fail as well, resulting with rapid flooding of the entire Rajang River Basin, the Murum Dam environmental impact assessment (EIA) reportedly warned.

Sarawak Report citing the purported EIA report said the the chances of such a scenario is rare, but is classified as “high risk” because of the potentially catastrophic consequences.

“The results suggest that a cascading failure of both dams would be a catastrophic event for all communities downstream to the ocean.  The timing of the flood wave is affected by the Pelagus Rapids…

“Upstream of the rapids the flood peak would arrive approximately six to 12 hours from failure; downstream of the rapid the flood peak would arrive approximately 12 to 36 hours from failure.

“Inundation of the adjacent floodplains would continue for several days following the arrival of the flood wavefront,” the EIA report reportedly said.

The report classifies risk as either extreme, high, moderate, or low, depending on the likelihood of a scenario taking place and the severity of its consequences.

SEB: EIA report misrepresented

Meanwhile, a Sarawak Energy Bhd (SEB) spokesperson refuted Sarawak Report’s claims, saying that the online news portal had misrepresented the EIA report.

“Indeed the Sarawak Report’s misrepresentations about the Murum EIA confirm that (when) ignorance is combined with spite, you produce nonsense,” the spokesperson told Malaysiakini in response to queries about the article.

The spokesperson said the EIA report was meant to help identify the potential impact of the Murum Dam project so that SEB can develop and implement procedures in “all possible scenarios”.

According to the EIA, the floodwaters are predicted to cover up to 2,960 square kilometres, while Sibu will be facing floodwaters about 15 metres deep.

For comparison, the area the Federal Territory of Kuala Lumpur is 243 square kilometres, while Penang state is 1,664 square kilometres.

Sarawak Report claims that the EIA report was prepared by a Malaysian company Chemsain Konsultant Sdn Bhd in 2008, but by then tunnelling work for Murum Dam has already started.

The authors of the EIA report had said that the Bakun Dam - about 40 kilometres downstream from Murum Dam - is not designed to withstand the deluge expected from Murum Dam if it fails.

It is likely to suffer structural damage from the force of the rushing water, the EIA reportedly found, raising the possibility of a cascading failure.

“With that number of people living downstream you would expect a very high standard of safety in the design and in all aspects and operation planning.

“So the purpose of the [EIA] exercise is to identify how stringent you have to be... which is why you have to do these EIAs before and not after you charge ahead and build the dam,” Sarawak Report quoted British hydropower expert Phillip Williams as saying.

When asked about the authenticity of the EIA report that Sarawak Report released, the SEB spokesperson said it should be compared against Natural Resources and Environment Board’s (NREB) records for verification.

SEB also denied that construction on Murum Dam had begun before the EIA report was ready, since the construction work only began in early 2009.

It also denied Sarawak Report’s claims that the EIA report was kept secret.

On the contrary, the report is available from NREB’s resource centre in Kuching for public viewing since Murum Dam’s approval process was underway. The project was approved on Dec 3, 2008.

“The study was distributed by the NREB to all the members of the external review panel, ie Ministry of Public Utilities (MPU), Public Works Department (JKR), Resident and District Office (R&DO), etc to gain feedback before NREB’s final approval,” the spokesperson said.

Emergency plan
 
Meanwhile, the EIA predicts if Bakun Dam holds against the deluge of the Murum dam, then the effects of a Murum Dam failure would be small and confined within the Bakun Reservoir.

According to SEB, the area between the Murum and Bakun Dams are uninhabited.

The EIA also recommends that in order to mitigate the risk of cascading failure, the potential causes of a Murum Dam failure needs to be studied and avoided through design and construction methods.

If the risk at Murum Dam designed remains unacceptably high, then Bakun Dam’s structural integrity needs to be studied and strengthened, while an emergency action plan needs to be developed to warn and evacuate communities living downstream.

“Sarawak Report therefore questions SEB as to whether any of these three key recommendations in their own EIA report were ever carried out?

“If so, where is the Emergency Action Plan to rescue the people down river and why, six years after this report, has there been no public announcement of any form of Emergency Action Plan, even though Bakun is now full and Murum is being filled?” Sarawak Report asked.

In response, the SEB spokesperson said that emergency plans are already in place even before work began to fill the dam.

“The objective of the ERP is to have the line of communication (Murum-Bakun-government Agencies) ready in case of an emergency,” it said.

In addition, it said an independent expert panel regularly scrutinises Murum Dam to ensure that it meets international standards, whereas SEB is implementing a system to sure that the project is safe and reliable.

The spokesperson also pointed out that cascading dams build along a river is common throughout the world and Malaysia.

Other examples of cascading dams within Malaysia include the Perak River Hydroelectric scheme and Batang Hydroelectric Scheme in Perak, and the Sultan Mahmud Power Station and Hulu Terengganu Power Station in Terengganu.

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