The effect of a bench on leakage through a cover: A field and numerical assessment

Abstract

Field experiments are conducted to quantify the leakage through an 11-mm-diameter hole in the liner on slopes with and without a bench under waste cover conditions. Over 14 months, with a total precipitation of 947 mm, a 0.68 m bench on a 4H: 1V slope results in a 43-fold increase in leakage (from 6.5 L to 282 L) compared to the reference section without a bench. Substantial leakage is attributed to snowmelt occurring at low temperatures. 3D numerical modelling is conducted and shows good agreement with the measured leakage induced by both rainfall and snowmelt. Parametric studies are conducted to further analyze the impact of hole locations, slope length, and slope gradient on leakage. The validated numerical model is used to predict potential leakage in a real case scenario, which features benches formed by differential settlement observed after 3-year service as a landfill cover. This paper contributes to enhancing leakage prediction so as to optimize the design of slope and bench configurations in waste covers.