Question:medium

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:

Show 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.
Updated On: Feb 19, 2026
  • A, B, C, D
  • A, C, B, D
  • B, A, D, C
  • C, B, A, D
Show Solution

The Correct Option is C

Solution and Explanation

Step 1: Determine the question's intent.
The phrase "increasing radius of influence in wells" is atypical. Higher permeability in a material enables a well's drawdown to propagate further and more rapidly, resulting in a larger radius of influence. Consequently, the question likely requests an ordering of materials based on increasing permeability. Alternatively, within the context of well construction, this could refer to the layered arrangement of a gravel pack surrounding the well screen, which progresses from fine to coarse with increasing distance from the screen. The latter interpretation will be adopted, given its prevalence in design practices.
Step 2: Order the materials by particle size, from finest to coarsest.
Particle size correlates with texture.
- Finest: B. Fine sand
- Next: A. Fine to medium sand
- Next: D. Coarse sand
- Coarsest: C. Coarse gravel
Step 3: Construct the sequence.
The sequence, ordered by increasing particle size (and consequently, increasing permeability and outward layering in a gravel pack), is: B \(\rightarrow\) A \(\rightarrow\) D \(\rightarrow\) C.
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