Pump Tests Important Source of Well Data
Last December at the 2000 National Ground water Association (NGWA) convention, Pfannkuch, the NGWA's first McElhiney Distinguished lecturer, made comments about well construction in a speech entitled "Pump Tests for Practical People."
"Well construction is of great importance. Proper well construction provides a radius of flow of water toward the well and helps the area around the well provide water to the well," Pfannkuch explained. "The degree of penetration is also important, because if the aquifer is not penetrated all the way, there is more resistance to pumping and producing water."
Pfannkuch, whose background is in mining and petroleum engineering and hydrogeology, said population increases are contributing to severe water problems worldwide.
"When you look at the number of people added each year to the world's population, it becomes evident the per capita amount of water decreases every year. Seventeen countries in the Middle East and Africa are considered in water shortage areas and more will come in as the population rises," he said. "The only way to deal with the problem is to have sufficient ways of managing, protecting, allocating and distributing water."
One way to help ensure adequate water supply is through pump tests, which equate to performance tests, according to the professor.
"A pump test is a performance test, and performance tests involve stressing the system and looking at the response you get so you have some idea of performance characteristics of the system," Pfannkuch said. "It is similar to an EKG or stress test in humans to learn what's wrong with you. The purpose of these tests are to survey and analyze hydrogeology, check aquifer characteristics including storage, transmission capacity, and isolation capacity of the system, and determine how to improve capacity."
Pfannkuch said the tests could last hours or days to see reactions caused by surging or other techniques, or for multi-well or well recovery tests to determine hydrogeologic interconnections of wells.
He said contractors would likely be involved with pump tests for privately owned wells on farms or wells owned by municipalities or counties which are implementing wellhead protection programs for their system.
"For the contractor to find out who wants pump tests may involve some research," Pfannkuch explained. "Contamination and ground water protection has become more and more of a focus in industry. We are still testing aquifer performance but tests are extending more and more to non-aquifer areas to locate contamination and prohibit it from entering the aquifer."
He added that a pump test starts the moment a driller sticks a bit in the ground because you have to know the vertical distribution of water underground from the water table aquifer to deeper aquifers. The water table zone is the gateway for any contamination which might enter the aquifer, he said.
"There is no such thing as a totally impervious aquifer." explained Pfannkuch.
He also commented that drawdown and recovery times for wells undergoing pump tests should correspond with each other if the pump and well are operating properly.
Pfannkuch warned that it is important for anyone who runs pump tests to establish a reputation for running the test correctly, obtaining accurate data and properly interpreting it for clients who are paying for the tests.