When groundwater wells are drilled, the specific capacity of the well must be measured. Drillers must report this number to the state after a new well is installed. When measuring specific capacity, we look at the short-term discharge sustainable discharge in GPM, divided by the drawdown in feet, which will yield the discharge in (GPM/ft).
Well #12 yields 245 gpm at a drawdown rate of 95 ft. What is the specific capacity of Well #12?
First, we write out our formula for specific capacity:
SC= Flow (gpm) / drawdown (Ft)
We are given both of these numbers from the problem and are already in the correct units. Now, we plug in the numbers to the formula and solve.
SC= 245 gpm / 95 Ft
SC= 2.6 (gpm/ft)
To try a practice problem, be sure to check out Test Your Knowledge: How to Calculate the Specific Capacity of a Groundwater Well