Prediction of landfill leachate amount using HELP model Case study: Semnan landfill

The components in the leachate are often toxic with numerous heavy metals, from non-separated municipal solid waste. Hence, leachate treatment is a serious problem. In order to design leachate treatment and collection systems, estimate of quality and quantity of leachate is necessary. Hydrologic Evaluation of Landfill Performance (HELP) Model was used to estimate leachate generation in the lined landfill cells for a variety of conditions. The HELP program is a quasi-two-dimensional hydrologic model for conducting water balance analysis of landfills, cover systems, and other solid waste containment facilities. In this paper HELP program is used to predict leachate HELP model use weather, soil and design data to estimate leachate quantity. The meteorological data were obtained from semnan Atmospheric Data Centre. Soil mechanics examinations in the landfill area were used to achieve soil data. In addition, design parameters are base on Semnan landfill design specifications. Semnan landfill capacity is designed to accommodate the municipal solid wastes during the next 25 years. In this study result indicated that precipitation and evapotranspiration has the most influenced on leachate generation increase and decrease, respectively. 82% of annual precipitation isn’t percolated into Semnan landfill due to evapotranspiration. HELP Model simulations were indicated that the maximum and average value of leachate height above barrier layer is 36 and 3mm, respectively. Semnan landfill is designed under minimum standard condition. Therefore, low height of leachate generated is due to area weather. The precipitation amount is low while the evapotranspiration amount is high in this area. High evapotranspiration is due to high temperature and solar radiation in Semnan landfill area. High evapotranspiration in the landfill cap caused 14.2% of the precipitation to infiltrate into the wastes and became leachate.