DECREASING
CONCENTRATIONS WITH INCREASED PUMPAGE
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By
the earthDr!
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When
a recovery well is initially pumped, one of three things can be observed
with respect to water quality over time or changing pumping rate.
Assume, that a single pumping well has been located so that it is screened along the long-axis of the plume where higher contaminant concentrations generally can be found. As the ground-water pumping rate is increased, as indicated by this next figure, the water that is produced by any of these depicted wells, while still originating from the upgradient direction, is coming from greater and greater lateral or vertical distances from the pumping well. Since these wells are constructed along the long-axis of the In examples on preceding webpages of this website, plume splitting was introduced as well as partial capture of the plume. Plume splitting can be achieved by the pumping of a single well or by the pumping of multiple wells oriented perpendicular to non-pumping, ground-water flow direction. Provided that there is water in storage of the formation and the permeability is sufficient, increasing widths and depths of capture can be achieved by simply increasing the pumping rate of a single recovery well. Although, a well can yield sufficient water to achieve the needed width and depth of capture, often times the contaminant concentrations are decreased due to diluting the plume with clean ground-water originating from upgradient locations both laterally and at increasing depths within the water table or confined system. Other times, a well does not have the capacity to yield a sufficient volume of water to achieve the necessary width or depth of capture, but increased rates of pumpage still result in decreasing contaminant concentrations. If either, yield or decreasing contaminant concentrations are a limitation, then it is often necessary to install multiple recovery wells oriented perpendicular to non-pumping, ground-water flow conditions. |
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earthDr@earthDRx.org |
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