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USGS NAWQA Transport of Anthropogenic and Natural Contaminants to Supply Wells Study

Approach for Evaluating Potential for Multi-Aquifer Wells to Affect a Public-Supply Well

Protecting the area at land surface above a confined-aquifer zone of transport can help prevent an unidentified multi-aquifer well from shunting contaminated groundwater across the confining unit and affecting the public-supply well within a timeframe of interest. A simple way to gain insight into the potential for multi-aquifer wells to affect a confined-aquifer public-supply well is to estimate a zone of transport (ZOT) for the public-supply well within the confined aquifer and then evaluate the likelihood that a multi-aquifer well lies within that zone. For this purpose, the ZOT would be defined solely on the basis of confined-aquifer traveltimes—traveltimes through the unconfined aquifer and confining unit would not be considered. A zone of transport equation for confined aquifer-travel times and a calculation tool are given below.

ZOT Diagram

Zone of Transport (ZOT) tool

  • Q(ft3/days)
  • t(days)
  • theta
  • H(feet)
  • ZOT(miles2)

More information:
Johnson and others, 2011
USEPA, 1993
USGS Circular 1385 (Eberts & others), pg. 119-120

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Page Last Modified: Tuesday, 22-Sep-2015 14:33:51 EDT