The protocol for the delineation of wellhead protection areas for public water supplies defines areas for protection and management of drinking water supply area on groundwater sources.  The delineation method is dependent upon several factors as outlined below.  The accompanying tables summarizes this information for wellhead protection areas.

Granular Aquifers
Granular aquifers whether confined or unconfined have a delineated WHPA-1, 2, and 3. The WHPA-1 will be based on a 180-day time of travel (TOT) or a 400’ fixed radius whichever is greater. WHPA-2 will be based on a 5-year time of travel.  WHPA-3 will be based on a 10-year time of travel or the Hydrologic Flow Boundaries whichever is geologically correct for the particular site.  These thresholds are based on using an acceptable model based on aquifer data and characteristics or calculated from known withdrawal values and generalized aquifer characteristics.

Karst Aquifers
Karst aquifers, whether confined or unconfined will have only a WHPA-1.  The WHPA-1 for the karst water supply will be delineated through geologic mapping trace studies, and will encompass the entire basin that supplies water to the well or spring.

Underground Mine Works
These systems are primarily found in the coal field region of eastern Kentucky.  Whether these aquifers are unconfined, semi-confined, or confined.  These aquifers will be delineated by only a WHPA-1 which will encompass the entire area which supplies water to the well(s) or spring.  The area will be determined by using underground mine boundary maps and geochemical data, if necessary, to determine the extent of the underground mine workings supplying water to the public water supply well or spring.

Fractured Aquifers
Fractured rock aquifers whether confined or unconfined will have a WHPA-1 that is 180-Day TOT or a 400' radius whichever is greater. The WHPA-2 is a 5-Year TOT with Hydrogeologic flow boundaries.  The WHPA-3 is the Hydrogeologic flow boundaries in porous flow conditions.

REFERENCES

U.S. Environmental Protection Agency: 1994, Ground Water and Wellhead Protection.  Handbook.  Office of Water, Washington, D.C., EPA/625/R-94/001.
U.S. Geological Survey.  1989. Basic Groundwater Hydrology, Water-Supply Paper 2220.
Freeze, R.A. and J.A. Cherry, 1979  Groundwater, Prentice-Hall Publishing Co., Englewood Cliffs, NY.
U.S. Geologic Survey, 1973.  Subsurface Geology and Ground-Water Resources of the Jackson Purchase Region, Kentucky, Water Supply Paper 1987