Question: A pipe-pump assembly is being considered by a farmer for use in irrigating a field during summer. There is an underground water well that is 250 ft deep. The well is an open-hole type in which the free surface of water is about 8 ft below grade. To ensure that one of the pumps will operate for only a few hours per day, the farmer will fill a 2500-gallon tank in 4 hours, which will provide enough water for 2 days of farm operation. The tank cannot be more than 10 ft long and should come complete with valved piping connections whose locations will be specified by the farmer.
The tank can be located anywhere in the line that the farmer deems fit. Due to location of the field and well, a pump must be located no more than 600 ft from the well. The pipe will be connected to an existing irrigation system that is 750 ft from the well and is 10 ft long. The farmer's land is flat, from the well to the field. Design the main piping system to meet the water requirements of the farmer. Specify the maximum depth of the pipe inlet in the well for the purposes of installation by the farmer. Further Information: The design engineer may consider the use of a foot valve (a type of check valve), complete with a strainer at the inlet to the piping system. This will ensure that the pumps are properly primed, that is, completely filled with water before the start of pumping. Other alternatives are available.