---
title: "Calcite significance for reservoir site"
subject: "Engineering Geology II"
chapter: 1
key: "semester_4/engineering_geology_ii:calcite-reservoir-significance"
source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/calcite-reservoir-significance
site: BCT Engineering
---

# Calcite significance for reservoir site

Engineering Geology II · Chapter 1: Introduction to Engineering Geology

- Asked in: 2075 Baisakh, 1 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/calcite-reservoir-significance
- Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-1

## Question

Mention the civil engineering significance of calcite with respect to reservoir site selection.

## Short answer

Calcite dissolves in acidic water, forming karst cavities and channels that can cause severe reservoir leakage and foundation instability. Reservoirs should avoid limestone areas or require costly grouting and treatment. However, calcite-rich limestone is useful for cement production.

## Answer

Calcite ($CaCO_3$) is the main mineral of limestone and marble. It is soft (hardness 3) and **soluble in water containing carbon dioxide**.

- Water slowly dissolves calcite along joints and bedding to form solution cavities, caves and karst channels.
- At a reservoir, these openings cause **heavy leakage and seepage** from the reservoir, loss of stored water and possible failure of the dam foundation.
- Sinkholes and collapse of cavities may endanger the dam and abutments.
- Therefore, reservoirs should be avoided in or near calcite-rich limestone (karst) areas, or the site needs extensive grouting, cut-off walls and treatment of cavities, which increases cost.
- On the positive side, calcite-rich limestone near the project is a source of cement raw material and aggregate.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Calcite is soluble in which type of water?
   A. Water containing carbon dioxide
   B. Pure dry air
   C. Oil
   D. Water containing sodium only
   Answer: A. Water with dissolved CO2 is slightly acidic and dissolves calcite. (Key point: Solubility)

2. What problem does calcite dissolution cause at a reservoir?
   A. Abrasion of turbines
   B. Heavy leakage through cavities and karst channels
   C. Swelling of the foundation
   D. Rock burst
   Answer: B. Solution cavities and karst channels cause leakage, loss of stored water and possible foundation failure. (Key point: Reservoir problem)

3. If a reservoir must be built in limestone, what is needed?
   A. Nothing, limestone is watertight
   B. Removal of the dam
   C. Extensive grouting, cut-off walls and treatment of cavities
   D. Only a thinner dam
   Answer: C. Grouting, cut-off walls and cavity treatment reduce leakage but increase cost; avoiding such areas is better. (Key point: Remedy)

## Related in Engineering Geology II

- [Geology in reservoir site selection](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Areservoir-site-selection) — Engineering Geology II, chapter 4
- [Geology in bridge site selection](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Abridge-site-selection) — Engineering Geology II, chapter 4, asked 6×
- [Geology in tunnel site selection](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Atunnel-site-selection) — Engineering Geology II, chapter 4, asked 4×
- [Geology in dam site selection](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Adam-site-selection) — Engineering Geology II, chapter 4
- [Scope of engineering geology in civil engineering](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Ascope-engineering-geology) — Engineering Geology II, chapter 1
- [Road, dam and foundation site geology](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Aroad-dam-building-bridge-foundation) — Engineering Geology II, chapter 4

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- [Engineering significance of rock-forming minerals](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aengineering-significance-of-rockforming-minerals) — Engineering Geology I, chapter 3, asked 3×
- [Site investigation for dam and reservoir](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Asite-investigation-for-dam-and) — Engineering Geology I, chapter 1, asked 2×
- [General river intake and site selection](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ageneral-river-intake) — Water Supply Engineering, chapter 5, asked 3×