Q107: Desirable characteristics of gravel pack in a tube well construction... - Groundwater Development, Wells and Pumps - Soil and Water Conservation Engineering- ICAR JRF/SRF 2024 | Agrigyan

• Specifications for Tubewell Gravel Packs:
• Desirable Physical Properties:
• Must be clean, washed, and free from silt, clay, and organic matter.
• Rounded to sub-rounded particles (well-rounded gravel ensures high, uniform pore volume).
• Hard, durable, and chemically insoluble siliceous gravel (quartzite with $\lt 5\%$ calcareous matter).
• Uniformity: Must be uniformly graded (uniformity coefficient $C_u = d_{60}/d_{10} \lt 2.0 - 2.5$) rather than well-graded, because well-graded mixtures allow smaller grains to pack between larger particles, drastically reducing gravel pack permeability.
• Conclusion: It should not be well graded (Option 4).

Correct option: (4) It should not be well graded