The Theis equation can be used to answer many questions that arise concerning the relation of the cone of depression to pumping stress. For example, a power plant in Louisiana relies on two wells to...

The Theis equation can be used to answer many questions that arise concerning the relation of the cone of depression to pumping stress. For example, a power plant in Louisiana relies on two wells to supply water for fire protection. The wells are approximately 1800 ft deep and together are capable of producing a sustained yield of 900 gal/min (˜173,000 ft 3 /day). As part of the licensing procedure for the plant, it is necessary to compute the effect of these wells on the nearest well completed in the same aquifer. A well survey was performed, and it was determined that the nearest well is 7500 ft away. To determine the effect of pumping the fire protection wells on the potentiometric level at the nearest well also completed in the aquifer, it was necessary to perform a controlled field experiment called an aquifer test to determine the transmissivity T and the coefficient of storage S of the pumped aquifer. The results of the aquifer test indicate that T equals 4680 ft 2 /day, and S equals 0.0007. For the purposes of making an overly conservative estimate of the effect of the pumping stress at the nearest well, it is assumed that the fire protection wells discharge at 900 gal/min for the entire 40-year design life of the power plant.