Current through Register Vol. 44, No. 14, April 6, 2022
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******** This is piece 1. -- It begins at character 1 of table line 1. ********
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Water-bearing Overlying Material Minimum Oversize Drillhole for
Formation Casing Grout, Diameter1
length
or
Depth1
1. Sand or gravel Unconsolidated 19' None required
caving material; minimum;
sand or sand and but 5'
gravel below
pumping
level 3
2. Sand or gravel Clay, hardpan, till, 5' below Casing size plus 2" if
silt, or similar pumping pressure placement of
material to depth level 3 grout is used, Casing
of more than 15' size plus 4" if
gravity placement of
grout is used. 4,5,6
3. Sand or gravel Clay, hardpan, till, 5' below Casing size plus 2" if
silt, or similar pumping pressure placement of
material level 4 grout is used, Casing
containing layers size plus 4" if
of sand or gravel gravity placement of
within 15' of grout is used. 4,5,6
ground surface
4. Creviced, Unconsolidated Through Non required
shattered or caving material, caving
otherwise chiefly sand or overbur-
fractured shale, sand and gravel to den
limestone, a depth of 19' or
igneous, more.
metamorphic or
similar rock
types or
sandstone
5. Creviced, Clay, hardpan, till, Through o- Casing size plus 2" if
shattered or shale, or similar verburd- pressure placement of
otherwise material to a en grout is used, Casing
fractured shale, depth of 19' or size plus 4" if
limestone, more gravity placement of
igneous, grout is used. 4,5,6
metamorphic or
similar rock
types or
sandstone
6. Creviced, Unconsolidated 19' Casing size plus 2" if
shattered or materials to a minimum pressure placement of
otherwise depth of less than grout is used, Casing
fractured shale, 19' size plus 4" if
limestone, gravity placement of
igneous, grout is used.4,6
metamorphic or
similar rock
types or
sandstone
1...+...10....+...20....+...30....+...40....+...50....+...60....+...70....+....
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Casing and Grout Placement1 Cased
Portion
Grouting not required 2"
minimum
Upper drillhole shall be kept at least 2"
one-third filled with clay slurry while minimum
driving permanent casing; after casing
is in the permanent position, annular
space shall be filled with grout 5
Annular space around casing shall be 2"
filed with grout minimum
Casing shall be firmly seated in rock. 6"
Grouting not required minimum
Casing shall be firmly seated in rock. 6"
Annular space around casing shall be minimum
grouted.
Casing shall be firmly seated in rock. 6"
Annular space around casing shall be minimum
grouted.
80..+...90....+....0....+...10....+...20....+...30....+
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Well Diameter
Uncased Well Screen
Portion Diameter2
(where
applicable)
Does not 2" minimum
apply
Does not 2" minimum
apply
Does not 2" minimum
apply
6" prefer- Does not
red apply
6" prefer- Does not
red apply
6" prefer- Does not
red apply
135.......+...50....+...60
Notes for Table 2:
1 In the case of a flowing artesian well, attempts should be
made to install and seal the well in a manner that protects the artesian
aquifer, prevents erosion of overlying geologic materials, and confines the
flow to within the well casing, giving due consideration to practicality, cost,
and safety.
2 These diameters shall also be applicable in circumstances
where the use of perforated casing is deemed practicable. Well points commonly
designated on the trade as 11/4" pipe shall be considered as being 2" nominal
diameter well screens for purposes of these regulations.
3 As used in this Table, the term "pumping level" shall refer
to the lowest elevation of the water in a well during pumping, determined to
the best knowledge of the water well contractor taking into consideration usual
seasonal fluctuations and drawdown.
4 Pressure placement includes methods of grout placement
using pumps and tremie tubes or using grout displacement through the casing, or
otherwise from the bottom up around the casing, with one or more drillable
plugs. When pressure placement is used with a borehole diameter of only 2"
greater than the casing diameter, casing shall be assembled without couplings
unless installed per the "Casing and Grout Placement" technique described on
Line "2" of this Table. Gravity placement includes any method that relies on
gravity to draw grout, either dry or as a slurry, down into the annular space
between the casing and borehole or between an inner casing and outer
casing.
5 For wells constructed by cable tool, hollow rod, jetting,
or other drilling method where the permanent casing is driven, and where
neither temporary casing nor an oversize borehole are used, dry driven grout
methods using granular bentonite may be used. These methods use continuous
feeding of granular bentonite into a starter hole or continuous mounding around
the casing as the casing is driven. Collar flared joints or weld beads
extending beyond the outside diameter of the permanent casing shall be used
with sufficient spacing to ensure that the grout seal is continuous and extends
downward into the saturated zone (i.e., beneath the water table).
6 The oversized borehole for grout placement should be as
deep as necessary, based upon local hydrogeologic conditions and potential
contaminant sources, to prevent contamination from entering the well. Grout
should be placed along the full length of casing, particularly where the
presence of non-caving unconsolidated materials, coarse gravel, or creviced,
shattered, or fractured rock may result in pathways of contamination to a well
water system. Where this is not feasible because of practicality, cost or
safety, grout shall be placed at least to a minimum depth of 19 feet. See also
Note 1 to Table 1.
