Wells shall be grouted and sealed in accordance with
subsection 62-532.500(3),
F.A.C., (2-16-12), and this section, to protect the water resource from
degradation caused by movement of waters along the well annulus either from the
surface to the aquifer or between aquifers, and to prevent loss of artesian
pressure in artesian aquifers. Subsection
62-532.500(3),
F.A.C., (2-16-12) is incorporated by reference in subsection
40D-3.037(1),
F.A.C.
(1) All wells that are
constructed in a manner which creates an annular space between the casing and
the naturally occurring geologic formations shall be grouted and sealed in
accordance with the methodologies listed in subsection
62-532.500(3),
F.A.C., and this section. The use of lead packers for this purpose is
prohibited.
(2) Grouting and
sealing of water wells shall be accomplished in the following manner using neat
cement or bentonite grouts unless otherwise granted a variance by the District.
The slurry grout mixture shall be introduced into the annulus space from bottom
to top; the casing seat shall be clean allowing the casing to set at the total
depth bored in a hole reasonably free of drill cuttings; the manufacturer's
mixing instructions shall be followed and any polymers added to bentonite
slurry mixes must be approved by the District prior to use.
(a) Grouting and Sealing Using Neat Cement
Grout.
1. Composition of neat cement grout
shall consist of 5.2 to 5.5 gallons of water per cubic foot or 94-pound sack of
Portland cement or a mixture of 6.0 gallons of water per sack of Portland
cement with 3 to 7.5 pounds of Bentonite not to exceed eight percent by
weight.
2. The minimum set time for
grouting of casing using neat cement grout before drilling operations may
continue is twelve hours. The minimum set time for grouting of casing with
Portland cement and two percent calcium chloride by weight as an accelerator
will vary with depth and are listed in Table 1 below.
|
TABLE 1 INITIAL SET TIMES FOR SPECIFIED DEPTH RANGES
WHEN 2% CALCIUM
CHLORIDE IS MIXED BY WEIGHT WITH PORTLAND
CEMENT
|
|
Depth (in feet)
|
Set Time (in hours)
|
|
0-200
|
|
|
201-400
|
4
|
|
201-400
|
3.5
|
|
401-600
|
3
|
|
601-800
|
2
|
|
801 & greater
|
1
|
(b) Grouting and Sealing Using Bentonite
Grouts.
1. A Bentonite grout shall consist of
a high solid sodium montmorillonite. The grout shall yield solids ranging from
20 to 30 percent, with a minimum density equal to or greater than 9.4 pounds
per gallon, and a permeability of approximately 1 x
10-7 centimeters per second or less.
2. Bentonite slurry grout used for sealing
purposes is restricted to wells with an outside diameter of five inches or less
in diameter nominal size. A formation packer or a five foot neat cement plug
must be installed at the casing seat and an upper ten feet of neat cement is
required to prevent deterioration of or damage to the bentonite seal.
3. Bentonite grout used for abandonment
purposes is not restricted by well size but cannot be used to abandon a dry
well and cannot be placed any higher in the well than the height of the static
water level. Any unsealed remainder above the height of the static water level
must be filled with neat cement. At a minimum, an upper ten feet of neat cement
is required to prevent deterioration of or damage to the bentonite
seal.
4. Only Bentonite grout
approved by the National Sanitation Foundation is allowed on public supply
wells or in any identified contamination areas. If artesian flow conditions
occur, a neat cement plug shall be installed to stop the flow prior to the use
of Bentonite grout. Use of Bentonite grout shall not be allowed in contaminated
wells when the contaminants will prevent an adequate seal, or in wells with
water quality concentrations exceeding 10, 000 milligrams per liter total
dissolved solids.
(3) For wells constructed by driving well
casing, dry bentonite with an average mesh size between 4 and 20 U.S. standard
sieve size or grain size between 5mm and .85mm must be added to the continuous
casing string at land surface at the beginning and during construction of the
well.
Notes
Fla. Admin.
Code Ann. R. 40D-3.517
Rulemaking Authority 373.044, 373.113, 373.171, 373.309,
373.337 FS. Law Implemented
373.306,
373.308,
373.309
FS.
New 7-1-90, Amended
9-30-91, 12-31-92, 12-12-11, Amended by
Florida
Register Volume 41, Number 126, June 30, 2015 effective
7/12/2015.
New 7-1-90, Amended 9-30-91, 12-31-92, 12-12-11,
7-12-15.
