Performance Evaluation of Vertical Wells for Landfill Leachate Recirculation

A vertical leachate recirculation system was evaluated for its potential to recirculate leachate into landfilled waste. Leachate was recirculated through eleven vertical wells installed at three different depths. The results of recirculation tests performed over a 6-month duration are presented in this paper. The results indicated that specific capacity of vertical wells decreased with well depth. The specific capacity per unit screen length of the vertical wells ranged from 1.2 x 10^–6 to 1.2 x 10^–5 m³/s-m². The mean specific capacity of lines installed at three different depths were significantly (p<0.025) different from each other and were in the following order: shallow well (depth ~6 to 8 m) > middle well (depth~12 to 16 m) > deep well (depth~18 m). A potential reason for lower specific capacity for deep wells is the lower hydraulic conductivity of the waste in deeper sections due to higher overburden pressure. While the data presented in this paper are based on preliminary injection tests and may not represent steady-state condition, the results provide important insight into the hydrodynamic behavior of bioreactors.