Current through August 26, 2024
A well driller or well constructor shall construct wells
terminating in bedrock formations according to the requirements of s. NR 812.12
and the construction of wells in bedrock shall be completed to meet all of the
following requirements:
(1) MINIMUM
DIAMETER. The minimum diameter for bedrock wells is 6 inches.
(2) CASING DEPTH. Minimum casing depth shall
be measured from the ground surface. The following requirements apply to the
minimum casing depth in bedrock formations:
(a)
Sandstone. Wells
completed in sandstone bedrock shall have a minimum of 30 feet of
casing.
(b)
Crystalline
bedrock. Wells completed in crystalline igneous or metamorphic bedrock
shall have a minimum of 40 feet of casing.
(c)
Limestone or dolomite.
Wells completed in limestone or dolomite bedrock shall have a minimum casing
depth as follows:
1. Forty feet when the depth
to the top of limestone or dolomite is equal to or greater than 20 feet below
the ground surface.
2. Sixty feet
when the depth to the top of limestone or dolomite is less than 20 feet below
the ground surface.
(3) CASING MATERIAL AND INSTALLATION.
(a)
Material. Either steel
or thermoplastic well casing pipe meeting the requirements of s. NR 812.11 (6)
or (7) may be used as permanent casing for bedrock wells.
(b)
Centering. When well
casing is set within an upper enlarged drillhole, it shall be centered within
the drillhole to ensure an even annular space around the casing. When casing is
placed in an upper enlarged drillhole that extends more than 80 feet below
ground surface, a drive shoe or casing shoe shall be welded to the bottom of
the casing and the casing shall be driven to a firm seat. The department may
require, as a condition of an approval or in a special well casing area, that
the well casing pipe be centered in the drillhole using any of the following
methods:
1. A set of at least 3 centering
guides provided at every pipe joint within the bedrock to ensure an even
annular space around the well casing pipe. A minimum of 2 sets of 3 centering
guides shall be provided, one near the top of the bedrock and one at the bottom
of the string of well casing pipe.
2. A drive shoe or casing shoe welded or
threaded onto the bottom of the string of well casing pipe and, if the well
casing pipe extends more than 63 feet into the bedrock, at least one set of 3
centering guides provided on the casing pipe within the bedrock. If only one
set of guides is provided, it shall be installed within 5 feet of the top of
the bedrock.
(c)
Hung casing pipe prohibition. Casing shall be set to the
bottom of an upper enlarged drillhole unless the casing is installed in
compliance with the requirements of par. (d).
(d)
Screens. Screens may be
installed in loosely cemented sandstone wells. The requirements for screen
materials and installation of the screen specified in s. NR 812.13 (4) and the
requirements for gravel packs specified in s. NR 812.16 apply to drilled wells
in bedrock formations.
(e)
Thermoplastic casing use restricted. Thermoplastic casing may
only be placed in an upper enlarged drillhole and may not terminate in
crystalline bedrock or be driven or jetted into place.
(f)
Damaged or deformed thermoplastic
casing. A well using thermoplastic casing terminating in bedrock shall
be free of cracks and free of deformation and the inside diameter shall remain
within manufacturer's specifications after construction or reconstruction. A
failed well constructed with thermoplastic casing shall have the casing removed
or drilled out prior to filling and sealing.
(g)
Drilling tool use
restricted. Drilling tools such as drill bits or stabilizers may not
be placed in the thermoplastic well casing pipe nor may any drilling or
reconstruction occur after placement of the well casing pipe in the well. This
restriction does not prohibit the insertion of equipment for the development
and cleaning of wells.
(4) DRIVING OR ADVANCING CASING. A well
driller or well constructor may drive or mechanically advance steel casing from
the ground surface to the top of bedrock when the depth to the top of bedrock
is equal to the minimum casing depths under sub. (3) or deeper. When steel
casing is driven or mechanically advanced to the top of bedrock, it shall be
completed in accordance with all of the following:
(a)
Drive shoe. The casing
shall be equipped with a drive shoe or casing shoe meeting the requirements
specified in s. NR 812.11 (10).
(b)
Annular space sealing. Clay slurry, sodium bentonite slurry,
or granular bentonite shall be maintained around steel casing during
advancement using any of the following methods:
1. When casing is driven or advanced from the
ground surface, excavating a funnel-shaped depression around the casing to
create a reservoir, which shall be kept filled with dry granular bentonite. The
granular bentonite shall be kept dry at the surface during
advancement.
2. Filling a starter
drillhole or temporary outer casing with clay slurry or sodium bentonite slurry
and drill cuttings having a mud weight of at least 11 pounds per gallon, or
with dry granular bentonite, which shall be maintained around the outside of
the casing.
3. Constructing an
upper enlarged drillhole in accordance with sub. (5). The upper enlarged
drillhole shall be kept filled to within 10 feet of the ground surface with
clay slurry or sodium bentonite slurry and drill cuttings having a mud weight
of at least 11 pounds per gallon, or with dry granular bentonite which shall be
maintained around the outside of the casing.
(c)
Driving to a firm seat.
Steel casing shall be driven or advanced to a firm seat into the top of
bedrock.
(d)
Mechanically
holding down thermoplastic casing. For a well constructed with
thermoplastic casing, the casing may not be driven to a firm seat. However, the
casing may be held down mechanically within an upper enlarged borehole during
grouting to prevent the casing from floating.
(5) UPPER ENLARGED DRILLHOLE. When a well is
constructed with casing that extends 5 feet or more below the top of bedrock,
an upper enlarged drillhole shall be constructed to the depth the casing is
set. When a well driller or well constructor constructs an upper enlarged
drillhole for any reason, it shall be constructed in accordance with all of the
following:
(a)
Minimum
diameter. The minimum diameter of an upper enlarged drillhole shall
meet the following requirements:
1. The upper
enlarged drillhole shall be 4 inches greater than the nominal diameter of the
casing when coupled joints are used.
2. A well driller or well constructor may
reduce the diameter of an upper enlarged drillhole to 2 inches greater than the
nominal diameter of the casing when welded steel casing is used and the
required sealing material, according to the requirements of sub. (7), is placed
in the annular space between the upper enlarged drillhole and the well casing
pipe using a pressure grouting method according to the requirements of s. NR 812.20.
(b)
Method of keeping hole open. A well driller or well
constructor shall maintain an upper enlarged drillhole at full diameter during
drilling by any of the following methods:
1.
Keeping the drillhole filled up to within 10 feet of the ground surface with
drilling mud.
2. Circulating
bentonite drilling mud.
3. Setting
a temporary outer casing to the top of bedrock.
4. Circulating air, air and water, or
drilling foam when the drillhole is constructed through non-caving clay, silt,
or hardpan.
(c)
Minimum depth. The minimum depth of an upper enlarged
drillhole shall be one of the following:
1.
To the final depth that the well casing is set.
2. To the bottom of any clay formation, or 20
feet, whichever is less, when the casing is driven or advanced to the top of
bedrock in accordance with sub. (4) (b) 3.
3. For a well constructed using thermoplastic
casing, to a depth not more than 5 feet into the top of firm limestone,
dolomite, or shale.
(d)
Grouting. A well driller or well constructor shall grout an
upper enlarged drillhole according to the requirements specified in sub.
(7).
(6) LOWER
DRILLHOLE. A well driller or well constructor shall complete the drilling of a
lower drillhole in accordance with all of the following:
(a) The lower drillhole may not be
constructed prior to grouting an annular space unless the casing is first
driven to a firm seat in bedrock.
(b) Drill cuttings may not fill an open
annular space during the drilling of a lower drillhole, except when casing is
driven or advanced to the top of bedrock in accordance with sub. (4) (b)
3.
(c) Cement grout shall set for a
minimum of 12 hours prior to drilling a lower drillhole.
(7) GROUTING AND SEALING. A well driller or
well constructor shall seal annular spaces using one of the pressure grouting
methods specified in s. NR 812.20. Grouting material shall meet the
requirements specified in s. NR 812.11 (15). A flowing well shall be grouted
using the materials specified in s. NR 812.15. Potable high capacity wells
shall be grouted using the materials specified in s. NR 812.152. A well driller
or well constructor shall seal annular spaces with any of the following
materials:
(a) Sodium bentonite, sodium
bentonite-sand, or a mixture of clay slurry or bentonite drilling mud and
cuttings when the upper enlarged drillhole is less than or equal to 20 feet in
depth.
(b) Sodium bentonite, sodium
bentonite-sand, neat cement or bentonite-cement when the upper enlarged
drillhole extends less than 5 feet into the top of bedrock.
(c) Neat cement or bentonite-cement when the
upper enlarged drillhole extends 5 feet or more into the top of
bedrock.
(8) BENTONITE
CHIPS IN FRACTURED FORMATIONS. A well driller or well constructor may use
bentonite chips in an annular space when fractures, voids, or caverns are
encountered that prevent the flow of grout at the surface. When bentonite chips
are used by a well driller or well constructor to seal fractures in an annular
space, the chips shall be placed in accordance with all of the following:
(a) The upper enlarged drillhole shall be a
minimum of 4 inches larger than the nominal diameter of the permanent casing
and shall extend to the depth of any fractures, voids or caverns encountered
greater than 20 feet below the ground surface.
(b) The upper enlarged drillhole shall be
free of drilling mud or cuttings.
(c) Any bentonite chips placed below the
water table shall be screened and poured in a manner that prevents
bridging.
(d) Any bentonite chips
placed above the water table shall be hydrated using water meeting the
requirements specified in s. NR 812.11 (14).
(e) The volume of bentonite chips used shall
be limited to the minimum needed to resume grouting according to the
requirements specified in s. NR 812.20.
(f) The number of bags or volume of chips
used, the depth they were placed, and the reason they were needed shall be
noted on the well construction report.
(9) DUAL AQUIFER PROHIBITION. Wells may not
be constructed open to both an unconsolidated formation and a bedrock
formation.
(10) WELLS CONSTRUCTED
INTO THE MAQUOKETA SHALE. Wells constructed or reconstructed to withdraw water
from any of the aquifers beneath the Maquoketa Shale and the Niagara formations
in the eastern part of the state shall be cased and grouted into the Maquoketa
Shale formation except in areas designated by the department as special well
casing pipe depth areas. If a liner is used to case off the Niagara formation,
the Maquoketa Shale formation or both, it shall be installed and grouted in
place in accordance with s. NR 812.21.
