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.
Johnson and others, 2011
USGS Circular 1385 (Eberts & others), pg. 119-120