Semakau landfill

Here we look at a plant which has been making headlines since it opened in 1999. It was the world's first offshore landfill, and is now Singapore's only landfill. Taking up an area of 350 hectares and with a capacity which is expected to last until 2040, this environmentally friendly waste disposal plant is far from ordinary. There are even plans to turn it into an eco-park…BackgroundSingapore is a highly urbanized and industrialized small island nation with a land area of 697 km2 and a population of 4.2 million. When the rate of waste disposed by its citizens rose six-fold between 1970 and 2000, ambitious projects to curtail this growth were put in place. Singapore's National Environment Agency (NEA) formulated a range of strategies and programmes to achieve its objectives.One such project was the creation of the Semakau landfill – the world's first offshore landfill site. The landfill was created by reclaiming land between two small islands located eight kilometres off the coast of Singapore. The two islands of Pulau Sakeng and Pulau Semakau were previously home to small fishing villages, but nowadays are joined by a 7 km perimeter bund (embankment) which encloses part of the eastern sea area around them. The entire perimeter bund is lined with an impermeable membrane and waste is compacted within it.Semakau island was created entirely from the sea space at a cost of SIN$610 million (US$399 million). It has been in operation since 1 April 1999 and underscores Singapore's commitment to strike a balance between urban development and nature conservation. With a capacity of 63 million cubic metres, it is expected to meet Singapore's need for landfill space beyond the year 2040. Operated and maintained by NEA, Semakau landfill receives about 1400 tonnes of incineration ash and 600 tonnes of non-incinerable waste everyday. The landfill operation will eventually create an island made almost entirely of waste (towards the end when the landfill capacity is exhausted).Semakau landfill has been constructed with prudence and innovative engineering solutions to contain all wastes within the landfill area. The perimeter bund, lined with impermeable membrane, marine clay and rock layers, keeps the surrounding waters pollution-free, and any leachate generated within the site is treated in a dedicated leachate treatment plant.Great care has also been taken to ensure that the landfill is clean, free of odours and aesthetically scenic. As such, the marine ecosystem on and around Semakau landfill is well protected and flourishing.In July 2005, Semakau landfill was opened to members of public for recreational activities, since then, the island has gained popularity with nature lovers due to its rich biodiversity.Day-to-day operationsAt the Tuas Marine Transfer Station, incoming refuse vehicles are first weighed-in at the weighbridge before proceeding to the refuse reception hall. At the reception hall, refuse is directly discharged into specially built barges. A total of twenty discharge bays are available to ensure a quick turn-around time for the refuse collection vehicles. The tipping platform is designed to overhang into the barge so that refuse is tipped into the centre of the barge. Excavators are used to spread the refuse in the barge to ensure that it is optimally loaded.At the end of the day, the hatch covers of the fully loaded barges are closed before the boats are pushed by tugboats on a 25 km journey out to Semakau. This is to prevent refuse from being blown off by wind during the sea journey. The sea journey from Tuas Marine Transfer Station to Semakau Landfill takes about three hours and takes place at night to maximise the use of the marine vessels.On arrival at Semakau Landfill, the barges are berthed within an enclosed transfer building for the unloading operation. Large excavators with interchangeable and specially designed grabs are used to unload refuse from the barges. The excavators can either unload the refuse directly onto large 35-tonne payload off-road dump trucks or onto the tipping floor. Refuse on the tipping floor is scooped up by wheeled-loaders and loaded onto the dump trucks. The refuse then makes its final journey to the tipping site for disposal. A fully loaded barge is emptied within 6 hours.At the tipping site, refuse is discharged from the trucks and bulldozers and compactors are used to level and compact the refuse.Facts and figures about the site:LANDFILL DATALandfill area 350 hectareLandfill capacity 63 million m3EQUIPMENT DATARefuse transferBarges 6 units, each 3500 m3Tugs 3 unitsRefuse handlingSpreading excavators 2 unitsUnloading excavators 4 unitsWheel-loaders 3 unitsDump trucks 10 units, each 35-tonneLandfillingCompactors 4 unitsBulldozers 5 unitsThe future for Semakau landfillSemakau was, from its inception, a project designed to work in harmony with its surroundings and to protect the natural environment. It is therefore no surprise that Singapore's National Environment Agency (NEA) is looking into the feasibility of developing an eco-park there.In November 2008 the Minister for the Environment and Water Resources, Dr Yaacob Ibrahim made the announcement at the opening ceremony of a global conference on waste management: 'With this, we can create opportunities for research and development, as well as the application of clean technologies,' he said.NEA's CEO, Lee Yuen Hee, said that the agency has appointed two companies, RSP Architects and Jurong Consultants, to study how to transform a quarter of the island – some 90 hectares – into an eco-park. He said an eco-park on Semakau Landfill will provide numerous opportunities for both public and private companies to venture into new areas of technologies: 'The eco-park will help Singapore gain a competitive edge in driving the development of the critically important clean and green technologies. If implemented, the Semakau eco-park will become the centre for the test bedding of renewable and clean technologies, such as wind, solar, tidal power, fuel cells, desalination, renewable clean fuel, etc. in Singapore. The park will also house eco-friendly recreational and educational facilities powered by renewable energy. We envisage that the test-bedding systems would be able to generate enough energy and water to make Semakau a self-sustaining eco island.'In order for us to have these ideas planned properly, we have appointed two consultants to come up with a master plan on what can be done on the Semakau landfill. We will look at the ideas by the two consultants, extract the best ideas and integrate them into one master plan which we will implement once the final plan has been finalized.'The NEA is expected to make a decision on the building of the eco-park on Semakau landfill very soon.With help from Catherine Ong Associates, e-mail: soohow@catherineong.com; Christopher Chong and Felicia Song, e-mail: Christopher_CHONG@nea.gov.sg or Felicia_SONG@nea.gov.sgSee also:Waste Mining as a Total Solution