- Permanent Link:
- DER's New G-1 Rule
- Subjects / Keywords:
- Travel time ( jstor )
Water tables ( jstor )
Environmental regulation ( jstor )
- Spatial Coverage:
- North America -- United States of America -- Florida
- DER's New G-1 Rule, Buddy Blain and Debby Locklair, January 2, 1987
- General Note:
- Box 7, Folder 1 ( Vail Conference 1987 - 1987 ), Item 51
- Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
- Source Institution:
- Levin College of Law, University of Florida
- Holding Location:
- Levin College of Law, University of Florida
- Rights Management:
- All applicable rights reserved by the source institution and holding location.
DER's New G-l Rule
By Buddy Blain and Debby Locklair
January 2, 1987
The newly adopted G-1 rule makes substantial changes to the
Department of Environmental Regulation's groundwater rules.
Changes to Chapters 17-3 and 17-4 F.A.C. have introduced criteria
that are not clear. The rule, when applied to specific areas,
may affect very substantial portions of Florida. The areas to
which this rule applies are called zones of protection. These
must first be mapped by the Department of Environmental
Regulation and then be presented to the Environmental Regulation
Commission for reclassification as G-l areas.
Determining areas eligible for G-l protection is a two step
Step One determine eligibility of the aquifer. To determine
the aquifer or aquifer segments which qualify for potential
reclassification to G-l aquifer --
a. The aquifer or aquifer segment under consideration must be
within the zones of protection of a major public community
drinking water supply well(s) or wellfield(s), and
b. Such well(s) or wellfield(s) must be withdrawing water
(1) from unconfined aquifers; or,
(2) from leaky confined aquifers.
"Leaky confined aquifer" is defined to mean an aquifer confined
from above by a formation(s) which allows groundwater to move
vertically from the water table to the top of the leaky confined
aquifer in five years or less.
The rule prescribes specific formulae for determination of
vertical travel time for leaky confinement as follows:
a. Vv = Kv Ah/nl
Vv = vertical velocity (feet/day).
Kv = vertical hydraulic conductivities of the
surficial aquifer and underlying confining
bed materials (feet/day).
Ah = head difference between water table in the
surficial aquifer and the potentiometric
surface of the producing aquifer (feet).
n = effective porosities of the surficial
aquifer and underlying confining bed
1 = distance from the water table to the top
of the producing aquifer (feet).
b. Tv = 1/Vv 365
Tv = vertical travel time (years).
1 = same as above.
Vv = same as above.
The two formulae can also be stated as:
Kv xAh 1
a. Vv = -x b. Tv x 36
They can be combined and stated as:
Tv= n x 1 x 365
Kv x Ah
If the hydraulic properties of a given area yield a vertical
travel time of 5 years or less from the water table to the top of
the aquifer in question then it may be eligible for protection
by the G-l rule. If the vertical travel time to the aquifer
exceeds 5 years, then it does not meet G-l criteria and zones of
protection for wells or wellfields do not need to be determined.
Step Two determine sizes of zones of protection. The second
step in the G-l eligibility process is to determine the sizes of
the zones of protection of each major public community drinking
water supply well or wellfield of an aquifer that has been
determined to be unconfined or leaky confined by the first step
in this process.
There will be two zones of protection for each well or wellfield.
The inner zone of protection is the area with 200 feet of the
well head. Since the radius of the inner zone of protection is
set at 200 feet it will encompass an area of 125,664 square feet
or 2.88 acres.
The outer zone of protection is determined by the horizontal 5
year travel time to the well head. The radius of the 5 year
travel time outer zone of protection is determined by the
r = 5 year travel time zone of protection radius
Q = permitted average daily flow from the well (cubic
feet per day).
T = travel time of five years (1825 days).
h = distance from the top of the producing aquifer to
the bottom of the hole (feet).
n = effective porosity.
The rule prescribes the following values for porosity for
representative Florida aquifers:
Sand and Gravel .20
However, the rule authorizes the department to use more site
specific values for "", "n", or "h" when available.
The inner and outer zones of protection will be specifically
mapped and delineated by the Department of Environmental
Regulation on a detailed map of a scale which clearly depicts the
applicable zones of protection. These are then submitted to the
Environmental Regulation Commission for reclassification to G-l
in accordance with the provisions of Chapter 120, F.S., DER's
rulemaking procedures in Chapter 17-102, F.A.C. and specific
procedures prescribed in the newly amended Rule 17-3.403.
The Commission will also consider:
c. water quality,
d. institutional (including local land
use, comprehensive plans),
e. public health,
g. and economic factors.
Calculating the vertical travel time from the water table to the
top of the aquifer at first glance appears to be relatively
straight forward. However, little discussion has been held on
this phase. Values for vertical hydraulic conductivity of the
surficial aquifer and the underlying confining bed material, and
the effective porosity of the underlying confining bed material
are not specified in this rule. Aquifer tests and well log
information may be required in order to determine values for
these parameters with some accuracy. Since these values may vary
significantly, as shown in the following table of "Hydraulic
SConductivity of Selected Rocks", site specific studies may be