ASDSO Dam Safety Toolbox

Drilling

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Drill Rig

(Image Source: Fadi Fayad Al Taoba)

"Test holes are drilled to obtain representative disturbed and undisturbed samples to:

  • "advance and clean holes to specific horizons for logging, sampling, and conducting tests;
  • "advance holes to bedrock to delineate rock surface;
  • "install piezometers and relief wells."[1]

"Disturbed samples are commonly obtained through the Standard Penetration Test (SPT), using a split-spoon sampler. Undisturbed samples are obtained by pushing or coring a tube into in situ soil materials. The most common undisturbed sampling method is the hydraulic pushing of a Shelby tube, which is referred to as a 'push-tube sample'."[1]

"Test holes may be augered by hand, or through powered drill rigs that are mounted on trucks mounted rig, all-terrain rig, all-terrain vehicles, tracks, or on a barge. Selection of drilling methods depends on:

  • "access (terrain roughness, space, and height limitations) and noise ordinance;
  • "types of tests or samples needed for the investigation and design needs;
  • "disposal of drilling fluids and cuttings (contaminated cuttings and groundwater may have to be handled as hazardous waste), lithology (soil type such as sand, clay, and boulders). rock type, and aquifer characteristics (depth to water)."[1]

Drilling Methods

Best Practices Resources

Technical Release 210-60: Earth Dams and Reservoirs, NRCS

Drilling and Invasive Activities at Dams and Levees (ER 1110-1-1807), USACE

National Engineering Handbook: Chapter 5 - Engineering Geology Logging, Sampling, and Testing, NRCS

National Engineering Handbook Chapter 2 - Engineering Geologic Investigations, NRCS

Design of Small Dams, USBR

Trainings

On-Demand Webinar: Drilling Plans and Hazard Evaluations for Dams and Levees

On-Demand Webinar: The Practical Use of Geophysics to Assess Dam and Levee Safety



Citations:



Revision ID: 7405
Revision Date: 07/21/2023