Explain two below ground drainage test?

1. Percolation Test: This test is used to determine the rate at which water drains through the soil in a specific area. A series of test holes are dug in the ground and filled with water. The rate at which the water drains into the soil is then measured over a specific period of time. This information is used to determine the suitability of the soil for drainage purposes, such as for the installation of a septic tank or soakaway system.

2. Infiltration Test: This test is used to determine the capacity of the soil to absorb water. A hole is dug in the ground and filled with water. The rate at which the water infiltrates into the soil is then measured over a specific period of time. This information is used to determine the capacity of the soil to absorb water and can help in designing drainage systems that are appropriate for the specific soil conditions.

1. Auger Hole Test

- Method:
- Dig auger holes to a depth of at least 1 m below the proposed drainage system.
- Fill the holes with water and observe the rate at which it infiltrates into the soil.
- Interpretation:
- High infiltration rates indicate good soil permeability and suitability for below-ground drainage.
- Low infiltration rates suggest poor soil permeability and the need for alternative drainage measures.

2. Percolation Test

- Method:
- Dig a hole approximately 30 cm deep and 30 cm wide.
- Fill the hole with water and allow it to soak into the soil.
- Refill the hole with water to a depth of 15 cm and record the time it takes for the water to drop by 5 cm.
- Interpretation:
- Fast percolation rates (less than 15 minutes) indicate good soil infiltration and suitability for below-ground drainage.
- Slow percolation rates (more than 30 minutes) indicate poor soil infiltration and the need for additional drainage measures.