Muscat: Oman Environmental Services Holding Company “be’ah” has completed the closure of the first cell in the Al Multaqa Engineered Landfill in Al Amerat.
This landfill cell closure is the first of its kind in the region. Landfill cell closure is carried out when a cell reaches its full capacity. The process ensures long-term protection to environmental and human health from leachate, odour and gases.
be’ah carried out the final closure following international best practices wherein the process is rolled out in a phased manner. As a new cell is constructed the previous cell is closed using engineered capping and gas extraction systems.
The company stopped receiving waste and halted operations in the cell after it reached its capacity. It then proceeded to cap the cell by placing protective layers on top of the intermediate cover. The layers were then covered with soil and riprap.
The next step was gas extraction and flaring. Landfill gases consist mainly of CH4, a greenhouse gas that contributes significantly to global warming. To reduce the harmful impacts from emitted gases on the environment and public health, gases are extracted from closed landfills for either treatment or re-use. These gases are commonly re-used in electricity generation and are flared in case they cannot be reused.
Active extraction within the cell is also necessary to prevent the build-up of gas pressure. Gas is extracted using wells installed in the cell which are connected to pipes that deliver it to the flare system which has a capacity to burn off 2,000 m3/hr.
The system’s flare unit is specifically designed for the combustion of landfill gases and the generated quantity of the gas from the cell. be’ah has ensured that every component of this system – control, gas monitoring and calibration - meets industrial standards.
be’ah also ensured that the final cell cover was compliant with US-EPA design requirements. The company will continue environmental monitoring such as groundwater and vegetation checks in and around the closed landfill site for 30 years.
The post-closure phase of the decommissioned landfill includes long-term care to minimise its impact on the surrounding environment. Landfill cover material will be allowed to settle and regrade as necessary while cave-ins will be filled to prevent the accumulation of stagnant water.
Sites of decommissioned landfills have potential future uses like recreational parks, golf courses, playgrounds etc, depending on their shape and the terrain.