A strategy in developing standards for liner of municipal solid waste landfills in Iran

The difference in climatic conditions across the country and low investment capacity in waste management systems makes it unrealistic to establish the same prescribed design for the bottom liner of municipal solid waste landfills. In this paper, a semi-performance-based approach for the proper design of liners in these landfills has been proposed. This approach has been used in the development of the technical evaluation guidelines and environmental criteria for municipal and hazardous waste landfills. Therefore, different climatic and hydrogeological conditions were considered. The rate of leachate infiltration into leachate collection system in different climates corresponding to high, medium and low precipitation was calculated using the HELP model and considered as a representative parameter of climatic conditions. The rate of waste deposition, which indicates the size of landfill, was introduced as the length of landfill along groundwater direction. Groundwater velocity, hydraulic conductivity and thickness of the aquitard were used as hydrogeological parameters. The resulting scenarios (324 scenarios) were defined in POLLUTE v7 and the chloride migration in five liner options were modeled. The results show that as the landfill is larger and the hydraulic conductivity of the aquitard is higher, the maximum contaminant concentration in the aquifer and the required time period to reach the maximum concentration will increase and decrease, respectively, by reducing the different layers of the liner system and decreasing groundwater velocity. Finally, the optimum liner for all climatic and hydrogeological conditions is proposed based on modeling results.