WELL DRAWDOWN

The Drawdown of a Well is the amount the water level drops once pumping begins.

The water level in a well is 20 feet below the ground surface when the pump is not in operation. If the water level is 60 feet below the ground surface when the pump is in operation, what is the drawdown?

Drawdown, feet =Pumping Water Level, feet - Static Water Level, feet

Drawdown, feet = 60 feet - 20 feet

Drawdown, feet =40 feet

Example: The water level in a well when no water is being pumped is 45 feet below the ground surface. When the well pump is in operation the water level drops to 57 feet below the ground surface. What is the drawdown in feet?

Write down the formula.

Drawdown, feet =Pumping Water Level, feet- Static Water Level, feet

1. Make a table of the data.

Plug the data into the formula.

Do the arithmetic.

Pumping Water Level = 57 feet

Static Water Level = 45 feet

Drawdown, feet = 57 feet- 45 feet

Drawdown, feet = 12 feet

Practice Well Drawdown Calculations

1)The distance to the static water level is a well in 60 feet before energizing the pump.After pumping for a few minutes the dynamic water level drops to 90 ft. Calculate drawdown in the well, in feet.

a)30.0 feet

b)60.0 feet

c)90.0 feet

d)150.0 feet

2)Before pumping a well, the static water level is 15 feet below the ground surface. During pumping the water level is 45 feet below the ground surface. The drawdown is ________ feet.

a)15.0 feet

b)30.0 feet

c)45.0 feet

d)60.0 feet

3)The distance to the static water level is a well in 90 feet before energizing the pump.After pumping for a few minutes the dynamic water level drops to 122 feet. Calculate drawdown in the well, in feet.

a)32.0 feet

b)90.0 feet

c)122.0 feet

d)212.0 feet

4)The distance to the static water level is a well in 50 feet before energizing the pump.After pumping for a few minutes the dynamic water level drops to 82 ft. Calculate drawdown in the well, in feet.

a)32.0 feet

b)50.0 feet

c)82.0 feet

d)132.0 feet

5)Level of water in a well is 164 feet.After pumping continuously for 5 days, the level has dropped to 181 feet. What is the drawdown? (Show work for credit)

a)17 feet

b)164 feet

c)181 feet

d)345 feet

6)The static water level in a well is 84.5 feet. The pumping level is 104.2 feet. What is the drawdown?

7)A well is 250 feet deep. The level of water in a well is 164 feet.After pumping continuously for 5 days, the level has dropped to 181 feet. What is the drawdown?

a)17 feet

b)69 feet

c)86 feet

d)181 feet

8)The static level in the well is 79.12 feet and the drawdown is 26.08 feet. Calculate the pumping water level in the well.