ARTESIAN LANDFILL LINER SYSTEM - OPTIMIZATION AND NUMERICAL-ANALYSIS

Conventional landfill design attempts to control the downward seepage of leachate by using low permeability liners. The rate of leachate see page into the underlying ground-water system can be controlled by decr easing the permeability of soil liners and/or by using synthetic membr anes to form an additional barrier to leachate migration. However, los s of leachate from conventional landfills is likely to occur due to th e inherent limitations of natural materials and the inevitable imperfe ctions of installing synthetic liners. The artesian landfill liner sys tem eliminates the downward seepage by reversing the direction of the hydraulic gradient so that seepage occurs into, and not out of, the la ndfill. A conceptual cost model incorporates the trade-offs between th e capital cost of constructing robust liners and the operational costs of supplying recharge water and treating additional leachate produced by the artesian hydraulics. In addition, a two-dimensional, transient finite-element flow model demonstrates that the reverse hydraulic gra dient limits the loss of leachate even if the integrity of the landfil l liner is imperfect or deteriorates over time.