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Using sea sand in construction: Building a sustainable construction sector

By Uwin Lugoda

In an attempt to bring sustainability to Sri Lanka’s construction industry, Prime Minister Mahinda Rajapaksa recently requested that the use of sea sand be expedited by beginning processes at the Muthurajawela Sand Yard.

The acceleration of sea sand usage in construction projects comes after years of planning to replace river sand with its more sustainable alternative.

According to data from the Ministry of Environment, the annual national demand for sand from the construction industry is an estimated seven million cubic metres. However, this demand has resulted in a severe shortage of river sand in the last two years. This then led the Ministry to urge the construction industry to look at alternative building materials in order to reduce the use of sand in building and construction work.

The government has imposed several restrictions over the mining of river sand over the years, which in turn created a scarcity that consequently pushed up its prices in the market. In fact, during the last eight years, the price of river sand has doubled, making it almost unaffordable to the majority of the general public.

This is further emphasised by data from the Chamber of Construction Industry of Sri Lanka (CCISL), which shows that unlike other construction materials such as metal which have remained stagnant, river sand has continued to increase in price. As of now, a cube of river sand costs almost Rs. 18,000 due to its scarcity, mining approvals, and transportation costs.

Speaking to The Sunday Morning, Urban Development Authority (UDA) Media Representative Prasad Manju stated that the Prime Minister sped up the process of sea sand preparation from the Muthurajawela Sand Yard. He explained that the sand yard was initially used for the preparation of sea sand for construction, by washing, cleaning, and drying it.

“The Government’s decision to ban the mining of river sand is not only a sustainable solution for the construction industry, but it also prevents damage to our river beds and protects the environment. The Muthurajawela Sand Yard is being prepared to deliver sea sand as an alternative, for which it was inspected by State Minister of Coast Conservation and Low Land Development Mohan Priyadarshana de Silva,” said Manju.

Sea sand’s capability as a river sand alternative was further proved by engineers who ran tests on the remaining sea sand from the Katunayake-Colombo Expressway construction project. This sand, which has been rain-washed and sun-dried for years, showed a similar quality to river sand.

Manju stated that cabinet approval has been given to pump sea sand to the land from the ocean floor, via a pipeline that is around 16 km long. However, despite having been done three times, the pumping of sea sand came to an end in 2018.

He stated that the Sri Lanka Land Development Corporation (SLLDC) has informed the UDA that the current stocks of sea sand will meet the construction industry’s demand for the coming year.

This existing stock of sea sand at the Muthurajawela Sand Yard has been sectioned into two groups of washed and unwashed sand. Both types of sand are currently being sold at the sand yard and similar yards in Kelaniya, Nawala, Kirimandala Mawatha, and Attidiya.

“The records show that 75% of the sand being sold from these yards are unwashed, while the remaining 25% is washed sand,” he added.

Launched over 16 years ago, the Muthurajawela Sand Project has pumped over four million cubes of sand each year it was active. The sea sand in stock now is currently being supplied for the construction of the Central Expressway.

Sea sand is pumped to the yard through selected contractors and is stored in open-air sand dunes, inserted into the sand machine, washed, cleaned, selected, and dried. The project is also going to avoid the use of chemicals when washing the sand, by using cold water instead.

The 70-acre sea sand yard has also been the recipient of sustainability awards, which include the Green Label for sand by the Green Building Forum for eco-friendly products. According to the Marketing Division of the sand project, customers buying sea sand from these yards gain a profit of around Rs. 4,000 per cube of sand.

Manju stated that the Muthurajawela Sand Yard has previously greatly reduced the environmental impact caused by the mining of river sand. He explained that breaking down the market monopoly on river sand, by introducing this cheaper alternative, has helped save Sri Lanka’s riverbanks from erosion and collapse.

He further stated that several public and private institutions are currently obtaining sand for their construction needs from the yard, with one such example being Metallurgical Corporation of China Ltd. (MCC), which is using sea sand for the concrete work on the Colombo Outer Circular Highway.