Typical Values of Permeability for Different Soils
The permeability or coefficient of permeability can be defined as the rate of flow of water through a unit cross-sectional area of the soil under a unit hydraulic gradient at a temperature of 
| Sl. No. | Different Types of Soil | Typical Value of Permeability |
| 1. | Gravel | 101 to 1 (100) |
| 2. | Coarse sand | 100 to 10-1 |
| 3. | Medium sand | 10-1 to 10-2 |
| 4. | Fine sand | 10-2 to 10-3 |
| 5. | Silty sand | 10-3 to 10-4 |
| 6. | Delhi silt | 7 X 10-5 |
| 7. | Boston blue clay | 6 X 10-7 |
| 8. | London clay | 1.5 X 10-9 |
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Factors Affecting Permeability
5 Empirical Formula for determination of the coefficient of Permeability