In Malaysia, Salini Impregilo is completing the 382 MW Ulu Jelai hydropower project, a plant that will help meet the growing demand for electricity at peak times and reduce carbon emissions.

The project, located in the hills of a tropical rainforest with about 4,000 mm of rainwater per year, is set to reduce CO2 equivalent emissions by some 250,387 tonnes annually by substituting conventional fossil fuel-powered generators with hydroelectric power during peak periods.

In addition to supporting the growth of renewable energy in Malaysia, we have also focused on improving the site’s environmental footprint and helping to make the area more resilient to climate change and extreme weather.

Our designers kept environmental issues front of mind, developing solutions to optimise the project’s environmental footprint, both during the construction phase and on an ongoing basis. For example, we have created and built an underground powerhouse, eliminating any landscape impacts and avoiding land degradation.

Additionally, through the project layout, we have improved the overall efficiency of electricity generation, making it among the most efficient in the country. According to a report by the United Nations, Ulu Jelai allows “high power output with a small reservoir size”. 


An unique project in Malaysia

The project is also unique in Malaysia due to the roller-compacted concrete (RCC) we used for the dam. This progressive engineering method means:

  • faster, large RCC dams can be completed up to two years more quickly than regular mass concrete dams;
  • project costs are lower, as RCC is 25 to 50% less expensive than conventional concrete;
  • less cement is consumed because leaner concrete mixtures can be used, helping to reduce environmental impacts upstream in the supply chain.

Finally, given that the area is exposed to soil stability risks due to tropical rainfall, we have taken action to prevent soil erosion and control sediments, drawing on comprehensive risk assessments to model impacts before, during and after construction.

In addition to paving all site roads with draining materials to ensure safe access in all weather, we have also focused on slope-cutting activities. Slopes are installed with a network of drainage channels that carry the rainwater in silt traps and check dams. This prevents sediments from being dispersed in the river basin.

Another example of innovation at Ulu Jelai is the use of ‘fibromat’, a biodegradable coconut sheet placed on the slope immediately after cutting and seeding activities. This technique protects the slope and safeguards the seed from water run-off. It also encourages the environment and local biodiversity to recover more rapidly. These measures allowed us to reduce soil erosion rates by 93% compared to the worst scenario, and by 97% in comparison with a pre-development scenario for the access road and the upstream control weir.