Question

Write the sequence of following soil texture layers according to their increasing radius of influence in wells.
A. Fine to medium sand
B. Fine sand
C. Course gravel
D. Coarse sand
Choose the correct answer from the options given below:

• A. A, B, C, D
• B. A, C, B, D
• C. B, A, D, C
• D. C, B, A, D

Hint:

In well design, the gravel pack that surrounds the well screen acts as a filter. It is designed with layers that are progressively coarser as you move away from the well screen and towards the native aquifer material.

Answer 1

The Correct Option is C

Step 1: Interpret the question's intent.
The phrase "increasing radius of influence in wells" is unusual. A more permeable material allows a well's influence (drawdown) to spread further and faster, giving a larger radius of influence. Therefore, the question is likely asking to arrange the materials in order of increasing permeability. Alternatively, in the context of well design, it could refer to the arrangement of a gravel pack around the well screen, which is layered from fine to coarse as you move away from the screen. Let's assume the latter, as it's a common design sequence.
Step 2: Arrange the materials from finest to coarsest. The particle size determines the texture.
- Finest: B. Fine sand
- Next: A. Fine to medium sand
- Next: D. Coarse sand
- Coarsest: C. Coarse gravel
Step 3: Form the sequence.
The sequence arranged by increasing particle size (and thus permeability, and how they would be layered in a gravel pack outwards) is: B \(\rightarrow\) A \(\rightarrow\) D \(\rightarrow\) C.