The method for delineating wellhead protection areas should be consistent
with the State program, if there is one. If there is no State-prescribed
method, the method chosen should fit the level of detail required by the
hydrogeologic setting. Some of the methods suggested by EPA include
arbitrary fixed radius, calculated fixed radius, simplified variable
shapes, analytical method, numerical method, and hydrogeologic mapping
method. (See Chapter 3 above.) Verify if there is a specific method
that the EPA and your State environmental agency recommends. The
more comprehensive and detailed the method of delineation, the less
likelihood of legal challenges to the wellhead protection boundaries.
Delineating the wellhead protection areas separate from the aquifers may
be necessary even if the entire jurisdiction is found to be in the
zone of influence.
There is a significant distinction between aquifer protection areas and
wellhead protection areas in State statutes, administrative regulations,
and local ordinances. Aquifer protection areas have been traditionally
used for the past 15 to 20 years by communities to generally protect large
areas that have significant groundwater reserves. Wellhead protection
areas are only those portions of aquifers (and may contain nonaquifer areas
also) through which contaminants are likely to reach the wells.
If an arbitrary fixed radius is used to define the extent of a wellhead
protection area when a more detailed study is still in progress, include the
term "interim" in the designation. Make sure that the ordinance title, the
heading of this section, and maps reflect the interim designation.
- For wells serving more than five hundred (500) persons and located in
unconsolidated (sand and gravel) aquifers, the Wellhead Protection Area
(WHPA) consists of three (3) areas (WHPA 1, WHPA 2, and WHPA 3) which
are listed and their hydrologic characteristics described below:
- WHPA 1: WHPA 1 extends from the wellhead to the 200-day groundwater
Time-of-Travel boundary.
- WHPA 2: WHPA 2 extends from the outer boundary of WHPA 1 to the
1000-day Time-of-Travel boundary.
- WHPA 3: WHPA 3 extends from outer boundary of WHPA 2 to the
watershed's groundwater divide or Zone of contribution id delineated
based on technical criteria more stringent than watershed
determination.
[Town of Norway, Maine, Wellhead Protection Ordinance, Section C,
1993]
-
Communities that already have an aquifer protection ordinance may be
able to modify it to include a delineated wellhead protection area.
In this case, the community will need to consider if it has the ability and
the resources to use the more restrictive wellhead protection
management measures over the entire aquifer protection area or just within
the wellhead protection overlay zone. The same is true for communities with
numerous private wells and public drinking water wells. In this case,
the protection area will likely be larger than anticipated because of the
interaction between the pumping wells. In some parts of the country, the
wellhead protection area will be nearly as large as the aquifer protection
area, in which case it may make sense to use the more intensive wellhead
protection management measures over the entire area.
- Boundaries for the aquifer protection zones for the Aquifer Protection Overlay District are shown on published maps entitled "Wellhead Protection
Area Maps, Brookings County Shallow Aquifer Map" ...(and) are hereby
adopted by reference as part of this ordinance as if the maps
were fully described herein.
The shallow/surficial aquifer boundary was mapped using data from the south
Dakota Geological Survey and United States Geological Survey. The zone of
contribution was mapped using an analytical technique outlined in the
U.S. Environmental Protection Agency publication "Guidelines for Delineation
of Wellhead Protection Areas, June, 1987." The Aquifer Protection Overlay
District was divided into two zones.
[Brookings County, South Dakota, Zoning Ordinance, Section 1106, 1989]
Be certain to include a reference to procedures for amending the designation
of aquifer protection zone boundaries. Although the definition of wellhead
protection areas is inherently tied to knowing the exact location of wells,
a description of the process for expanding aquifer protection boundaries
should be included.
- The recharge protection areas may be modified from time to time based
on the recommendation of the technical advisory committee established in
subsection (d) of this article and the Water Resource Protection Area
map shall be revised accordingly; substantial changes in the Water
Resources Protection Area Map, based on the recommendation of the
technical advisory committee, shall be made by City Council by Ordinance.
[City of Newark, Delaware, Zoning Ordinance, Section 30-53.b(4),
1991]
Normally, zoning boundaries are made to coincide with parcel or site
boundaries. But, when a fixed radius method is used to delineate the
wellhead protection area, provisions to cover parcels that are only partly
in the district may be needed. This exception also applies when the
boundary of the protection area cuts a large parcel.
- In determining the location of properties within the zones depicted
on the zones of influence maps, the following rules shall apply:
- Properties located wholly within one (1) zone reflected on the
applicable zones of influence maps shall be governed by the
restrictions applicable to that Zone.
- Properties having parts lying within more than one (1) zone as
reflected on the applicable zones of influence maps shall be governed
by the restrictions applicable to the zone in which the part of the
property is located
- Where a travel-time contour which delineates the boundary between
two zones of influence passes through a building, the entire building
shall be considered to be in that zone in which more than fifty (50)
percent of the floor space of the building is situated as of
August 28, 1986.
[Broward County, Florida, General Ordinance, Section 27-381, 1984;
1989]