![]() The discharge pressure does not vary by more than 5 psi.įor well yields less than 4 gallons/minute, the yield test shall continue by valving down the discharge to the approximate well yield determined in step (4) and recording the flow rate and pressure every 15 minutes until six hours have passed from the commencement of the test.The water level is determined to have dropped no greater than 200 feet through the duration of the test or 3) The test must provide, as a minimum, for continuous pumping for at least 24 hours at the design pumping rate or until stabilized drawdown has continued.The well yield is determined by dividing the average discharge (in gallons) by the average interval (in minutes) between each time the pump was shut off.įor recovery rates of 4 gallons/minute or greater, testing may be terminated after three hours if: Record the time and repeat this process at least three times to determine the recovery rate (well yield). Wait a set period of time (15 minutes) turn the pump back on and measure the discharge of the water until the water level is drawn down to the pump intake again. If the water level is drawn down to the pump intake turn the pump off and record the time.Time, flow rate, and pressure readings must be recorded every 15 minutes. The pump should be turned on and the manifold valve opened completely.The testing manifold must be connected so that the pumping switch mechanism is bypassed.The contractor performing the test shall provide a testing manifold consisting of an inlet for connection to the pressure line from the well and a tee with a pressure gauge graduated with intervals of at least 2 pounds per square inch (psi) and capable of measuring up to 200 psi.That procedure has the advantage that the well flow rate recorded is not affected by other problems such as a piping error or clogged water pipes or a defective well pump or water pressure tank. Yield tests for existing wells in which a submersible pump has been installed and connected to a water distribution system may be performed in accordance with the following procedure: A true well flow test, well recovery test, or well draw-down test requires special equipment and locating, opening, and pumping right at the well. This number may differ from the well yield results produced at the time of drilling, as the bottleneck will have been eliminated. ![]() The last 5-gallon reading is determined to be the "well flow" or "yield" for that well.īecause water runs through the bottlenecks of the well pump and pressure tank, 10-12 gallons per minute is usually the best result for the test. Water is run from the well in five-gallon intervals. Although it accommodates several different pump designs, wastewater pumps were a major focus. In February 2011, I wrote an article on my Field Test Calculator. For best results, water should be taken directly from the pressure tank whenever possible. In 2010, this column discussed unbalanced radial thrust and how the wide vane impellers used in wastewater pumps are extremely vulnerable to the damage it can cause. ![]()
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