Engineering a Nation's Waste Management

The tiny nation of Brunei appears from above to be a paradise, but even such tropical environments have waste to manage. And being Waste Management World, we wanted to find out just what’s been happening lately with Brunei’s three-phase waste management plan. Ben Messenger looks at progress of the new Sungai Paku engineered landfill site, being built to the toughest U.S. EPA standards. The Sungai Paku engineered landfill is to be built to tough U.S. Environmental Protection Agency standards Possibly best known for its natural resources such as oil and gas, Brunei boasts the highest living standards in the Islamic world. In 2005 its population stood at 370,000 but, with an average growth rate of just over 2.7%, by 2010 that figure had risen to 400,000. Combined with an average growth in GDP between 1999 and 2007 of 2.3%, and a surge in registered businesses from 2577 in 1998 up to 7240 a decade later, the implications for the waste industry are obvious – waste is a growing problem. To date the country has disposed of all of its waste at six landfill sites split across four districts: Brunei-Muara, Tutong, Belait and Temburong. However, the current generation of landfill sites in Brunei is aging, with no leachate treatment or gas collection systems. Clearly this situation is incompatible with the Brunei Economic Development Board’s (BEDB) aim of being a top 10 nation in terms of quality of life, with a dynamic and sustainable economy. Rehabilitation In a bid to tackle the gulf between where waste management in Brunei is, and where it would like it to be, two years ago the BEDB initiated a three-phase plan to deliver a first-class waste management system for the people of Brunei. Phase one of the plan has seen the rehabilitation of the Sungai Akar site from the Brunei-Muara district’s regional dump into the Sungai Akar Recreational Park. Dealing with some 129,000 of the nation’s 189,000 tonnes of waste per year, the Sungai Akar site had almost reached full capacity. Due to problems with leachate, drainage, insects, rodents and odour it was no longer considered an appropriate site for dealing with waste.The rehabilitation project – started in December 2008 and being carried out by local engineering and project management company Jurusy Perunding – is said to be going to plan, with the site split into two for development. Site A has been completed, with the waste having been covered by grass and a natural habitat. Site B remains a live landfill until a new ‘engineered landfill’ at Sungai Paku comes online next year. As part of the plans to turn the landfill into a municipal park, 35 gas vents and flare pipes have been constructed along with a subsoil pipe network leading to a leachate treatment plant. Here leachate and septic sludge will be broken down in several stages before being discharged into a natural water course. Once completed, the project will remain under maintenance to ensure that the leachate and gases are completely treated. Engineered landfill Phase two of the BEDB’s waste management plan has seen the start of construction work on a new ‘engineered landfill’. The contract for the Sungai Paku site, due for completion in early 2012, was awarded in July this year to a consortium consisting of ST Marine – the marine arm of Singapore-based ST Engineering – and its Brunei-based partner QAF Limited. The construction of a new engineered landfill comes as part of the Brunei Economic Development Board’s plans to make Brunei a top 10 country by living standard The S$66.5 million ($50 million) contract is part of the BEDB’s current National Development Plan, with a total budget of B$9.5 billion ($7.2 billion) for social and physical infrastructure to be spent by 2012. The award includes the design and construction of the landfill and waste transfer and logistics station, as well as three years’ operations and maintenance. The BEDB says the new Sungai Paku landfill will be constructed to the toughest U.S. EPA standards, and will cover an area of some 110 hectares including access roads. A 200m wide buffer zone will be planted with trees to minimise the environmental impact of the site, and double layer heavy duty liners are to be used. In addition, a daily cover of 150mm of inert material will be applied to reduce odour. The current design for the new landfill caters for a gravity flow leachate collection system. The captured leachate is first collected in an anaerobic tank for digestion and then pumped into an aeration tank for further treatment, before reaching the sedimentation tank to settle. Once through these stages, the leachate will enter a facultative lagoon before reaching settling zone, wetland and open-water stages. To deal with the 200m3 to 400m3 of gas produced by an average tonne of landfilled waste, a system of rubble gas columns will be constructed in the landfill prior to filling a particular area. The gas will be flared manually, and the gas collection system has also been designed with one eye on preventing a landfill fire. Landfill gas analysis, including methane detection, takes place onsite at regular intervals to prevent methane build-up. Waste transfer With 58% of Brunei’s total land area reserved for conservation, it was perhaps an obvious choice to locate the new landfill on the site of an abandoned quarry. However, along with all its topographical, social and political advantages, the new site also presents one major drawback - location. Situated in the Tutong district some distance from the capital, Bandar Seri Begawan, the new site will be fed via a waste transfer station at the old Sungai Akar site, which will consolidate and pack waste efficiently using large containerised vehicles. On completion, the BEDB plans to designate the Sungai Paku site as the regional landfill. The country’s existing landfills are earmarked for closure. Testing ground In addition to offering Brunei a sanitary, modern landfill in which to dispose of its waste for an estimated 25 years, the Sungai Paku site is also acting as a proving ground for further developments to the nation’s waste management systems. For example, an aerobic windrow composting facility capable of handling 20 tonnes of organic waste at a time is being test-bedded at the site with a view to expansion depending on results. The site will also house a septic sludge and restaurant grease treatment facility, with design and technology endorsed by Singapore’s Public Utilities Board. This is to help prevent operators discharging septic wastes into natural water courses, a practice recently found to have been taking place at the Sungai Akar site. In addition, the BEDB recently commissioned a feasibility study from IDOM Ingenieria Y Consultoria S.A., an independent Spanish engineering consultancy firm, to develop an integrated solid waste management system in Brunei. The study will look closely at the potential of waste to energy systems as Brunei moves into phase three of its waste management plan. Conclusion Like many countries both large and small, the waste management infrastructure in Brunei has dated, failing to keep pace with the aspirations of the people it serves. In the modern era it is no longer acceptable for mixed waste from households and businesses to be dumped unceremoniously in uncontained sites and left to pollute the ground, the air and the water. Brunei, however, is in the fortunate position of having both the political will and the financial stability to act swiftly and decisively. A plan has been formulated, funded and executed. The implementation of that plan may be yet to reach its final conclusion, but great leaps towards an efficient and sanitary waste management system have certainly been made. Despite a growing population that generates increasing amounts of rubbish, Brunei has set itself on a path to proactively managing its waste. This will be key if the country is to achieve its goal of ranking among the world’s top 10 nations in terms of living standard. More Waste Management World Articles Waste Management World Issue Archives