Question

Given below are two statements:
Statement I: In pumping test, the water level in the well is depressed to an amount equal to the safe working head for the subsoil.
Statement II: In the recuperation test, the water level in the well is depressed by an amount less than the safe working head for the subsoil.
In light of the above statements, choose the correct answer from the options given below:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Hint:

Remember:
- Pumping test $\rightarrow$ Constant drawdown, depressed to the maximum safe working head.
- Recuperation test $\rightarrow$ Variable drawdown, kept safely below the safe working head to ensure well stability during recovery.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Pumping tests and recuperation tests are used to determine the yield of open wells.
During these tests, water is removed to lower the water table inside the well, creating a hydraulic gradient that drives water from the surrounding aquifer into the well.
The safe working head is the maximum drawdown limit that avoids piping or boiling of the subsoil at the bottom of the well.

Step 2: Detailed Explanation:
Let us analyze both statements:
1. Statement I: In pumping test, the water level in the well is depressed to an amount equal to the safe working head for the subsoil.
This statement is correct.
In a pumping test (or constant-drawdown test), water is pumped out continuously at a rate that keeps the water level stable at a constant, pre-determined depth.
To find the maximum safe yield of the well, the water level is depressed to an amount equal to the safe working head.
This ensures the test measures the maximum sustainable rate of water entry under safe operating conditions.
Therefore, Statement I is true.
2. Statement II: In the recuperation test, the water level in the well is depressed by an amount less than the safe working head for the subsoil.
This statement is correct.
In a recuperation test, water is pumped out rapidly to lower the water level, and then pumping is stopped.
The rate at which the water level rises (recuperates) is measured over time to calculate the well's specific yield.
Because the water level is not held constant, the initial drawdown is kept safely below the maximum safe working head.
This prevents any structural damage or subsoil instability at the base of the well during the subsequent recovery phase.
Therefore, Statement II is true.

Step 3: Final Answer:
Both Statement I and Statement II are true because they accurately describe the target drawdown depths used during well yield tests.
Hence, the correct option is (A).