The tiny Southeast Asian nation of Singapore annually disposes about 2.57 million tonnes (2.8 million tons) of solid waste, from a population of just 4.2 million people. Known for its draconian laws and strict enforcement in public cleanliness, the issue of garbage disposal is treated with equal ferocity. With a limited land area of only 697 sq. km (272 sq. miles), officials have tackled the challenging task of handling increasing refuse generation by developing a highly efficient disposal system.

The tropical island nation's solid waste disposal infrastructure currently comprises four waste-to-energy incineration plants and the offshore Pulau Semakau landfill. The strategy is to incinerate nearly all the rubbish, about 2.38 million tonnes or 92.7 percent of the refuse, while landfilling the remaining refuse.

Landfilled island

Shown above is the only break in the bund wall, which is at the southern tip of the island.

The Pulau Semakau landfill is a case study on sustainable development. Its unique approach to solid waste management demonstrates that economy does not necessarily come at the expense of ecology. Much effort and care was put into the design and operation of the landfill to protect the island's ecosystem, and maintain its biodiversity and aesthetics. The landfill has enough capacity to spread solid waste over an area equal to 840 football fields, piled three stories high, but it has preserved its diverse flora and fauna, and attracts visitors daily to its scenic landscape.

Construction of the landfill was started in 1995 to meet Singapore's need for waste management when the landfill on the mainland at Lorong Halus closed in 1999. It was the world's first manmade, offshore landfill created entirely from sea space. The unique landfill is situated among the islands, 8 km south of Singapore. The SG$610 million (about $431 million U.S.), the Pulau Semakau project is now Singapore's only landfill.

The landfill was formed by joining Pulau Semakau to another nearby island, Pulau Sakeng, with a 7-km perimeter bund comprising 4.5 million tonnes (5 million tons) of rock and 36 million tonnes of sand, in water depths ranging from 10 meters to 20 meters (66 feet). The bunds enclosed the sea area between the two islands, resulting in a 30-hectare (75 acres) offshore waste pond, covering an area of 3.5 sq. km, with a capacity of 63 million cu. meters. The large pond formed was divided into several small ponds, where tons of incinerated rubbish is now dumped each day.

Sustainability

Intended to be filled only with incinerated ash from the country's four incineration plants and incombustible refuse, the landfill, which began operations on April 1, 1999, is expected to last till 2040. However, government bodies, the Ministry of the Environment and Water Resources, and the National Environment Agency which manages the landfill, hopes this deadline will be extended through various waste minimization and resource conservation initiatives. Presently, about 1,400 tonnes of incineration ash and 600 tonnes of incombustible waste, such as construction and demolition waste, stabilized industrial sludge, and copper slag are disposed daily.

When it was first created, ecologists protested the destruction of mangroves and coral reefs that fringed the original islands. But environmental concerns were addressed right from the start. During construction, silt screens were installed to ensure that the corals and other marine life in the vicinity were not affected during the reclamation works. The landfill was lined with an impermeable membrane and marine clay to prevent leakages.

A leachate collection system diverts all leachate to a treatment plant. Regular water testing is carried out from a network of monitoring wells along the perimeter bund to ensure the integrity of the impermeable liners.

Another design feature is the built-in channels, which allow the flow of seawater into inactive cells, keeping the water fresh at all times.

Not another hole

Authorities also have painstakingly ensured that the island disposal site will not be operated like other dirty and smelly landfills in the region. The ash and incombustible waste intended for landfilling are first sent to a marine transfer station, which sits on a 7-hectare site on the western end of the main island of Singapore. These wastes are then transferred into barges, which are covered to prevent the ash from being blown into the air. The covered barges then make a 25-km sea journey to the landfill every night, where the waste is unloaded onto dump trucks for the final journey to the operating cells. Bulldozers and compactors are deployed to spread out and compact the waste.

Today, after years of operation, the replanted mangroves and remaining natural habitats on the island are flourishing. Birds nest on the closed cells, which are covered with a layer of soil, oblivious of the fact that it is made of rubbish. Fish can be seen swimming in and out of the lagoons, and marine life continues to thrive in the island's mangrove mudflats and western shorelines. Recently, as many as 66 bird species have been recorded there, including great-billed herons and Pacific reef egrets. Semakau's natural habitats have been so well preserved that it is now the only known location in Singapore where the seagrass, Syringodium isoetifolium, can be found.

To honor Semakau's reincarnation as a sanctuary of biodiversity, the government gave its backing for the island to become a center for recreational nature studies and biodiversity research. The landfill has since become an ecotourism destination, having received over a thousand visitors.

The eco-friendly landfill island of Semakau is but one in a list of environmental efforts by the Republic of Singapore, a country renowned for its fastidious cleanliness. Its efforts have encouraged neighboring countries like the Philippines to explore similar waste disposal solutions. Though economically less developed than Singapore, the Philippine Islands have implemented their own solutions. Southeast Asia's first biogas plant now stands at the Filipino Payatas dump at Quezon City, while the use of floating garbage landfills, like the ones used in Singapore, are also being considered for areas like Metro Manila.

These developments not only point toward a possible trend of government-mandate environmental action in Southeast Asia, but demonstrate that progress is not always a one-way process of environmental destruction. Therefore, environmental solutions can effectively be implemented by governments, in an environmentally-friendly and economically-viable way, be it in a developed or developing nation. PE