Sensitivity analysis of landfill design using the HELP model

Abstract

The purpose of this study was to perform a sensitivity analysis of landfill design and construction using the Hydrologic Evaluation of Landfill Performance (HELP) model. The sensitivity analysis involved determining the magnitude of changes in a landfill water balance due to various alterations in landfill design. This was accomplished by designing 22 different landfills, using the HELP model to simulate 20 years of operation for each of the different configurations and then evaluating the resulting water balance output. A landfill configuration which allows leachate to migrate off-site can be detrimental to the environment. Therefore, the design of a landfill must try to eliminate the off-site migration of leachate. It was discovered that the best approach to eliminating the off-site migration of leachate from a landfill is to minimize the amount of liquid which enters the landfill. This project found that maximizing runoff by increasing the slope of the surface layer of the landfill was the most effective method of reducing the amount of liquid which entered the landfill system. It was found that the other design configurations had little overall effect on the water balance of the landfill. It was recommended that persons designing a landfill should utilize the maximum slope possible on the surface cover. This will limit the amount of liquid which enters the system which in turn limits the amount of leachate available for off-site migration.