KEY TO EXERCISE 12b

An unconfined alluvial aquifer with a hydraulic conductivity of 0.001 cm/s is 20 feet thick and is pumped at a rate of 9 gallons per minute. After steady state conditions are reached, a head of 15 feet above the aquifer base is measured in an observation well 10 feet from the pumping well. If the recharge rate due to precipitation is 12 inches per year, what is the steady state head in an observation well 20 feet from the pumping well?