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Wellhead Protection Plan
Section 1. Wellhead Protection Area Map
The following map shows the WHPA for
Norfolk
’s West Well Field. It was drawn originally by the Nebraska
Department of Environmental Quality in 2001. The delineation
takes into account such factors as well pumping history, geologic
logs and local hydrogeology of the area, based on available data
that was collected from irrigation, domestic and public supply
wells.
The Nebraska Department of
Environmental Quality WhAEM Computer model was used to generate and
delineate the map limits. The model was run in April 2005, and
included all of the current pumps and pumping rate data for the
City’s West Well Field as of that date. A protection threshold
was established using the 20-year time-of-travel (TOT) radius, which
is the estimated distance from which groundwater contaminants could
be drawn into the given PWS well(s) if present well pumping rates
were continued for 20 years. Also included are TOT radii at 10
years, 2 years, 1.5 years, 1 year, and 180 days. These TOT
thresholds are useful in calculating the amount of time it would
take pollution to reach a public water supply well and contaminate
the drinking water supply if a surface spill would occur in the
WHPA.
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