Dam Seepage Models - Tools, Rules & Guidance (From a Regulatory Perspective)

Engineers often propose a seepage model as part of a dam evaluation. However, the goal of a seepage model is often not well-defined, and the model output is nothing more than an expensive, colorful picture in an appendix without much insight into the dam. Nonetheless, seepage modeling can be the secret to understanding gradients and flow through a dam providing the information needed to guide future actions. So, what things should regulators and dam owners consider when reviewing an engineering proposal that involves a seepage model? What should engineers consider when proposing a seepage model to a dam owner/regulator? What options do regulatory agencies have when they believe a seepage model will assist them with a regulatory decision?
This paper will discuss the following:
1. Rules of thumb and guidance to help with the decision of whether to pursue a seepage model.
2. Cautions and advice to avoid the modelling effort from becoming an expensive time sink.
3. A basic seepage modeling software program that the Montana Dept. of Natural Resources and Conservation has found to be an excellent cost-effective aid for the state dam safety regulator.