One of the world’s largest hazardous waste management facilities: Sohar Industrial Waste Handling and Treatment Facility (IWHTF)

The Sohar Industrial Waste Handling and Treatment Facility (IWHTF) is one of the world’s largest hazardous waste management facilities. The facility includes three landfill sites, which will provide 18 million m³ of void space on the 50-hectare complex, developed according to a 30-year master plan. One landfill is for hazardous waste with two composite liners, another for non-hazardous waste with a single composite liner, and the third for inert waste. The earthworks for the development platform involved moving approximately 400,000m³ of soils to create a national, integrated hazardous waste management facility for Oman.

TerraConsult, now Ayesa, was appointed as the lead landfill design engineer for the Sohar IWHTF. Our primary role was to prepare the 30-year master plan, provide detailed designs, and offer construction support for three new landfill cells.  The brief for this Design & Build contract included tender support, site investigations, environmental monitoring, hydrogeological studies, facility master planning, earthworks design, landfill design, geosynthetics design, surface water management design, site-based construction support (including Construction Quality Assurance – CQA), and preparation of the operations, environmental monitoring, and closure plans. Ayesa provided the detailed design for the first cells on each of the three landfills and supervised their construction.

The facility’s hazardous waste landfill incorporated a double composite engineered containment lining system with eight geosynthetic layers, including two sets of HDPE/GCL, drainage, and protective geotextiles. This complex system ensures robust containment and leachate management. The Class II landfill was constructed with a single composite lining system and a separate evaporation pond. Ayesa’s expertise ensured the implementation of these advanced systems, reducing the need for future maintenance and repairs, and providing a reliable waste management solution for Oman.