A disadvantage of using cable tool drilling for monitoring wells is what?

• A. Excessive water production
• B. Possible problems in controlling heaving sands
• C. Lack of stability in solid bedrock
• D. High energy consumption

Answer: (B)

The main idea here is understanding how cable tool drilling behaves in unconsolidated, sandy formations and why that matters for monitoring wells. The hammering action and the way cuttings are circulated can disturb loose sands, causing them to move or “heave.” When sands heave, the borehole can become unstable, making it hard to keep the hole open, to place and seal the casing and screen properly, and to obtain representative water samples. This instability is a well-known limitation of cable tool methods in sands, so controlling heaving sands is the core disadvantage in this context.

Other options aren’t as specific to this drilling method. Excessive water production is a function of the aquifer and well design, not a inherent drawback of cable tool drilling. Difficulties with bedrock stability can occur in some situations, but solid bedrock itself isn’t the typical, defining problem for monitoring wells drilled by cable tools. And while energy use matters, it isn’t the standout drawback when considering performance in sandy formations.