The Hanoi Urban Environment Company (Urenco) said the "green" technique learned from Taiwan will help Nam Son and Xuan Son landfills double their capacities without having to enlarge their space.

The company, also the operator of the two dumps in Hanoi's outskirts, said in its proposal that it will build walls rising 20 meters high around the landfills.

The walls will be made of soil. On the walls’ surface, which will be covered with nets, plants will be grown and inside those walls will be laid five layers of waterproof fabric and sand.

Built in 1999, the Nam Son landfill in Soc Son District is the biggest in the city, covering more than 157 hectares (390 acres). More than half of it has been filled up with trash.

Spreading 13.32 hectares, the Xuan Son landfill in Son Tay District was put into use in 2007 and over 5 hectares has been filled with trash.

Each day, Nam Son receives 5,000 tons of garbage, while Xuan Son gets 1,200 tons.

With their existing capacities, both landfills will not be able to take in trash by December, 2020, according to Urenco.

The proposed technique will allow them to double the capacity while saving land fund and the cost for site clearance, said Nguyen Huu Tien, Urenco’s CEO.

"Building mud walls with plants growing on them will prepare the first step to turn the landfills into parks once they are no longer in use, as has been done in Taiwan and several other places," he said.

Hanoi is also building a plant that burns trash to generate electricity.

The project is expected to start operation in 2021 with a designed capacity of 4,000 tons per day, which means it cannot deal with all the trash that is generated in the city.

In this scenario, the new technique will be a solution for handling the rest of the garbage, allowing the two landfills to take in trash for five more years, Urenco said.

The cost of building walls for the two landfills is estimated at VND1.64 trillion ($70.3 million).

Urenco will call for private investment and use its own budget for the project, and then the city will pay service fees depending on the amount of trash the walled landfills will take in.

In January this year, Hanoi decided to spend VND3.4 trillion ($147 million) for relocating households that live within a radius of 500 meters around the Soc Son landfill, following residents’ protests.

The protest saw residents gathering to block trucks from entering the landfill, saying Hanoi and Soc Son authorities had been slow to compensate and resettle those suffering harmful environmental impacts from the waste treatment complex. As a result, rubbish was uncollected and piled up in many districts.

At a meeting with locals in May, 2016, Hanoi authorities pledged that they would complete the plan to compensate and relocate residents out of the dump by the end of last year.

But as of early this year, nothing had changed, prompting the residents to step up their protests.

Authorities said that the resettlement and compensation process has now been completed.