Aquifer test methods to estimate transmissivity and well loss via a single pumping well
Date
2019
Authors
Roman, James Anthony, author
Sale, Tom C., advisor
Sterrett, Robert J., committee member
Ronayne, Michael J., committee member
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Abstract
Reducing the energy, environmental impacts, and costs required to produce groundwater from wells is emerging as a critical concern in the modern world. Establishing and maintaining pumping wells with minimal excess drawdown is thus important. Numerous methods have been devised to quantify the aquifer and well contributions of the total drawdown in a pumping well. The most common single-well methods involve step-drawdown test analyses that are inherently subjective and cumbersome. The limitations are overcome here using simple, analytical methods following the equations of Theis, Jacob, and Rorabaugh to estimate an aquifer's transmissivity and a well's well-loss parameters and excess drawdown due to well-loss effects. The major steps involve derivative analysis, solving systems of equations, and making elementary assumptions. The proposed methods analyze data from independent constant-rate tests at single pumping wells. In fact, Jacob's well-loss coefficient of 4.6x10-7 day2/m5 and 0.39x10-7 day2/m5 were estimated at a pumping well via Jacob's (1947) traditional step test analysis and the proposed method, respectively. The reduced subjectivity of the proposed method suggests it produced the more accurate estimate. The required energy and associated economic and environmental equivalences of pumping the well loss are then calculated to suggest when further development of a new well or the rehabilitation of a preexisting well is needed. The overall goal of this thesis is to advance the proposed methods for more straightforward and objective analyses of aquifer test data in academia and industry to promote the energy efficiency of groundwater production.
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Subject
single well
well loss
when to rehabilitate a well
transmissivity
aquifer test
well performance metric