Question

Four different soils are classified as CH, ML, SP, and SW, as per the Unified Soil Classification System. Which one of the following options correctly represents their arrangement in the decreasing order of hydraulic conductivity?

• A. SW, SP, ML, CH
• B. CH, ML, SP, SW
• C. SP, SW, CH, ML
• D. ML, SP, CH, SW

Hint:

In the Unified Soil Classification System, coarser soils like sand and gravel have higher hydraulic conductivity than finer soils like silt and clay.

Answer 1

The Correct Option is A

The hydraulic conductivity of soils generally follows the pattern: sand (SW) > sandy gravel (SP) > silt (ML) > clay (CH). This is because hydraulic conductivity is higher in coarser materials like sand and gravel, and lower in finer materials like silt and clay.

Step 1: Understanding Soil Classification.
- SW (sand and gravel) has the highest hydraulic conductivity. - SP (sand) is coarser than ML (silt) and has higher conductivity. - ML (silt) has lower hydraulic conductivity than SP. - CH (clay) has the lowest hydraulic conductivity due to its fine particles.

Step 2: Conclusion.
The correct order of hydraulic conductivity is: SW > SP > ML > CH.

Final Answer: \[ \boxed{\text{SW, SP, ML, CH}} \]