Drilling at Embankment Dams

Drilling into, in close proximity to, or through dams and their foundations may pose a significant risk to the structures. Damage created by hydraulic fracturing during the drilling process (use of inappropriate drilling methods), improper in-situ sampling techniques, and/or unacceptable methods of completing (backfilling) borings can open seepage paths which could create conditions conducive to internal erosion (piping) and ultimately dam failure.

The primary purpose of this document is to provide guidance for drilling in and near embankment dams and their foundations. Of special emphasis is the prevention of damage to the embankment, structures, and their foundations from hydraulic fracturing, heave, erosion, filter/drain contamination, or other mechanisms during drilling-related activities. These guidelines are appropriate for FERC-regulated embankment dams or other earthen water retaining structures (levee, canal embankment, etc.) – any earthen structure that’s responsible for holding back water or serves to provide direct support to the feature or element that is holding back the water, including its foundation. The guidelines set forth the requirements of a Drilling Program Plan (DPP) for any exploration drilling, instrument installation, or remediation drilling (including grouting) work to occur on an embankment dam, in proximity of the dam in which the drilling methods could pose a risk to the dam, or the dam’s foundation and abutments.

Guidelines For Drilling In And Near Embankment Dams and Their Foundations