In Malaysia, landfills are being filled up rapidly due to the current daily generation of approximately 30,000 tonnes of municipal solid waste. This situation creates the crucial need for improved landfilling practices, as sustainable landfilling technology is yet to be achieved. As such, it seeks to reconcile economic and environmental objectives including reduction of waste at source, reuse and recovery. A sanitary landfill that have leachate management through internal basin drainage and treatment, external drainage and surface water management, landfill gas management, and closure and restoration provisions is proposed to overcome this issue.

a) With an aid of diagram, propose a design of sanitary landfill. (2 marks)

b) Gases released from municipal waste landfills have the potential to cause odors problem in neighborhoods surrounding the landfill due to presence of methane and carbon dioxide (40% to 60%) and the remaining are nitrogen, ammonia, sulfides and various other gases. Analyze TWO contributing factors of the odor problem Support your answer with appropriate example and mechanism involved. ( 4 marks) 

c) A landfill liner is intended to be a low permeable barrier, which is laid down under engineered landfill sites to prevent migration of leachate, and its toxic constituents, into underlying aquifers or nearby rivers, causing spoiliation of the local water. However, all landfills will eventually fail and leak leachate into ground and surface water. Plastics are not inert. State-of-the-art plastic (HDPE) landfill liners (1/10 inch or 100 mils thick) and plastic pipes allow chemicals and gases to pass through their membranes, become brittle, swell, and breakdown. In extreme cases the liner may dissolve or tearing, cracking, or puncturing and the waste may react with the liner-causing degradation of the polymer or its additives. Comment on this statement and recommend possible liner system design to rectify this issues. (4 marks)