![]() In this case, the pumping data collected will result in an overestimation of the yield of the well. Once these features in the bedrock that store and transmit the ground water are drained, they can take a long time to refill/recharge, resulting in low recovery rates. This discrepancy is more often the case in bedrock aquifers, where the water pumped comes from storage of the ground water in cracks, or fractures or weathered bedding planes in the bedrock. If the recovery rate or amount is not close to the drawdown rate or amount, then there are either well- or aquifer-related factors that will result in an incorrect well yield estimation. If the amount of drawdown is roughly equal to the amount of recovery, then the data collected is representative of the aquifer conditions surrounding the well and the data can be used to confidently estimate the well yield. One key outcome of the pumping test is to determine if the well recovers after one hour to within roughly 95 per cent of the drawdown measured after pumping for one hour. The water pumped from the well must be discharged far enough away from the well so as to not cause recirculation back into the well and thereby influence the pumping and recovery water levels.īoth the pumping, or drawdown water levels, and recovery water levels reveal critical information about the operation of the well. The drop tube helps ensure that the electronic water level tape or datalogger doesn’t get caught up in the wires for the submersible pump, or set off from water cascading into the well in open bedrock holes. Water levels are most accurately measured in the well using an electronic water level meter / tape, or datalogger lowered inside of a temporarily installed one-inch (1”) or two-inch (2”) PVC tube with a slotted well screen at its base, referred to as a “drop tube.” The drop tube, as shown in the photo, typically terminates at a depth lower than the depth that the water will be drawn down, which is commonly close to the top of the pump. The main point is that the pumping rate remains constant throughout the well yield test. The constant rate can be regulated in a number of ways, from measuring and timing a specific volume of the pumped ground water into a pail, to using an in-line flow meter. This activity can be performed by a Class 1 or 4 Licensed Well Technician. Table 1: Well Yield Testing Table from Water Well Record.Īccording to the Wells Regulation, the well must be pumped for a minimum period of one hour using a pump that has been installed in the well, while maintaining a constant pumping rate. The content for this paper comes from a course for Certified Well Technicians offered by Fleming College referred to as Continuing Education Course GEOL 69, Well Logging and Testing Fundamentals, and presents two methods to assist well technicians when completing the boxes in the Well Record form relating to the Recommended pump rate and Well Production sections. Another reason is related to the level of experience, expertise and training received by the well technician over their career. For example, due to more recent privacy policies, well owner names are no longer made available to the public. ![]() ![]() Water well records date back to the early 1900s and over the past 100 years, the information contained in the water well records has varied considerably, for various reasons. This source of “big data” contains information about the location, type of well, depth, construction materials/drilling method, geologic materials encountered, driller’s (well contractor and technician) name, water quality, response to pumping and estimated yield of the individual well that is recorded. In order to provide assistance to well technicians completing the well record for a domestic well, this article presents a practical approach for the analysis of the results of well yield testing data collected as part of the well construction activities of a domestic well.Īccording to the Ontario Ministry of Environment, Conservation and Parks (MECP), there are roughly 780,000 water well records in the publicly available digital water well record database.
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