Drainage of Landfill Covers and Bottom Liners: Unsteady Case

The paper presents a simple model for estimating leakage through a compacted clay barrier for a single inflow event. This algebraic model yields estimates of leakage fraction that compare closely with those obtained by solving the governing partial differential equation numerically. The algebraic model exhibits negligible bias and a standard error of estimate of less than 20% over its range of applicability. In most practical cases, the leakage fraction for a single inflow event is largely determined by the value of a single dimensionless parameter termed the leakage number. This parameter accounts for the hydraulic conductivities of the drainage layer and barrier, the lateral drainage distance, the barrier slope, the drainage‐layer porosity, and the inflow volume. The effects of inflow duration and barrier thickness on leakage tend to be relatively minor. The practical application of the leakage model is illustrated in a design example.