Introduction

Relief wells are commonly installed on the downstream side of an earth dam to control the seepage along the downstream face of the dam, as well as the pore-water pressures within the dam (i.e. levee). A key design requirement for problems of this type is the required well spacing.

The plan view option in SEEP/W can be used to explore the relative effect of well spacing on the seepage and pore-water pressures within the earth dam. The term ‘relative’ is used here because the plan view simulation is not a true three-dimensional analysis. The plan view analysis is ideally used to simulate the flow in confined aquifers; however, the relief well scenario in this example lends itself reasonably well to this type of analysis if a simplifying assumption is made that the levee acts as a confining unit and the foundation soils act as an ‘aquifer’. Consequently, the plan view simulation can provide some useful information at considerably less ‘cost’ in comparison to a true 3D analysis.

This example demonstrates how the SEEP/W plan view analysis can be used for this purpose.