4725.2750 SCREENS; SCREEN LEADERS, RISERS, AND SUMPS.
If a screen is attached or connected to the casing, the connection must be made
by a threaded, solvent-welded, or welded joint, or by a nontoxic packer. Lead
packers must not be used. A screen riser or leader must not extend more than 21
feet above the screen. A screen sump must not extend more than ten feet below the
screen. The total combined-length of screen riser or leader, and screen sump must
not exceed 21 feet. A screen riser or leader, or screen sump must comply with the
confining layer requirements of part 4725.2020, subpart 1a. Multiple screens
separated by a screen riser, leader, or sump are not permitted.
“Screen” means a sieve or strainer-like device that serves as the intake portion of the well or boring.
“Screen risers/leaders or blank screens and screen sump” may also be referred to as blanks, risers, zeroslot screens, screen extensions, or leader pipes, and are pieces of pipe attached to the top or bottom of a
screen.
A screen is not required by rule. A well or boring may have an open hole or an “open bottom” in an
unconsolidated formation. However, not installing a screen in an unconsolidated formation may lead to
the well producing excessive amounts of sand, or sand heaving into the casing.
The rules do not contain standards for screen, screen riser/leader, or sump material, slot size, or screen
design. However, Minnesota Rules, part 4725.4650 requires a potable water-supply well to provide water
with less than 5 milligrams per liter (mg/L) sand and no more than 200 mg/L of silt and clay.
The installation of a screen and/or screen leader/riser inside an existing screen, screen leader/riser or open
bore hole (sometimes referred to as a channel pack screen) is not prohibited by rule. If alterations are
made to a well or boring that do not require a permit or notification, the contractor is urged to send in an
amended record; however it is not required.
The rules contain requirements for screen location.
Minnesota Rules, part 4725.2020, requires that a well or boring must not have open bore hole, gravel
pack, or screen extending through more than:
A. 10 feet of a confining layer, except for the Decorah or Glenwood formations;
B. 2 feet of the Decorah or Glenwood formations; and
C. 50 percent of the confining layer.
Minnesota Rules, part 4725.2850 prohibits gravel pack from extending: more than 10 feet above or below
a screen when a screen riser/leader or sump is not used; above the top of a screen riser or leader or below
the screen sump; or through more than 10 feet of an open hole.
Minnesota Rules, part 4725.3050 requires that if a bore hole extends more than 10 feet below the bottom
of a screen, the bore hole must be filled with grout from the bottom of the bore hole to within 10 feet or
less of the screen.
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One purpose of this rule is to prevent permeable materials (sand, gravel pack) from filling a bore hole
below the bottom of the screen. If a hole is drilled deeper than the interval in which the screen will be set,
the bore hole below the screen must be grouted. It is not permissible to allow the hole to collapse or fill
the hole with gavel pack.
“Filling” of the bore hole must be done in accordance with Minnesota Rules, part 4725.3850 which
requires grout to be pumped through a tremie pipe from the bottom of the hole upward.
Minnesota Rules, part 4725.3750 requires a property owner to have a defective part of a well or boring
repaired, including a screen.
A permit or notification is not required for installation or repair of a screen, or screen riser/leader and
sump in an existing well or boring (Minnesota Rules, part 4725.1837).
Lead packers or other lead components such as lead wool must not be used.
It is no longer required to attach a screen to a casing. If a connection is made, it must be with a threaded,
welded, or solvent-welded connection or a nontoxic packer. Rivets, screws, pins, splines, or other
mechanical fastening devices may not be used.
In some contamination cases, it may be necessary to monitor or remediate across the contact between an
unconsolidated formation and rock. This typically involves gasoline or other hydrocarbons floating on the
water surface which is near the drift/rock contact. Rules have been developed to allow a screen or open
hole in a monitoring well, remedial well or environmental bore hole to breech the contact in some cases.
For further information see Minnesota Rules, parts 4725.6050, 4725.6650, and 4725.7450.
STAT AUTH: MS s 103I.101; 103I.111; 103I.205; 103I.221; 103I.301; 103I.401;
103I.451; 103I.501; 103I.525; 103I.531; 103I.535; 103I.541; 103I.621; 144.05;
144.12; 144.383; 157.04; 157.08; 157.09; 157.13
HIST: 17 SR 2773; 33 SR 211
4725.2800 [Repealed, 17 SR 2773]
4725.2850 GRAVEL PACKS.
Gravel packs, filter sand, or stabilizer materials must be comprised of mineral
material or inert, non-toxic artificial materials, contain less than five percent
calcareous material, and must be graded, cleaned, and washed.
Gravel packs, filter sand, or stabilizer materials must not extend:
A. more than ten feet above the static water level;
B. more than ten feet above the top or below the bottom of the screen when a
screen riser or leader, or screen sump is not installed;
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C. above a screen riser or leader, or below a screen sump;
D. through a confining layer in violation of part 4725.2020, subpart 1a; or
E. through more than ten feet of open hole.
“Calcareous material” means soil or rock that contains lime, such as crushed limestone.
Gravel packs must be placed by methods that prevent bridging of the material, and allow verification of
placement.
Installation of temporary gravel packs must meet rule.
Minnesota Rules, part 4725.2020, requires that a well or boring must not have open bore hole, gravel
pack, or screen extending through more than:
A. 10 feet of a confining layer, except for the Decorah or Glenwood formations;
B. 2 feet of the Decorah or Glenwood formations; and
C. 50 percent of the confining layer.
Minnesota Rules, part 4725.4550, requires that a potable water-supply well must be cased to a depth of at
least 15 feet from the established ground surface. The top of a gravel pack must terminate at least 15 feet
below the established ground surface. Exempt are nonpotable water-supply wells, remedial wells,
monitoring wells and environmental bore holes.
In the case where no confining layer exists in the area of the sump, screen and riser or leader, and the
static water level of the formation being screened is above the top of the riser or leader pipe:
● If no sump is used below the screen, up to 21 feet of riser or leader pipe may be used above the
screen, and the screen and the entire length of the riser or leader pipe may be gravel packed.
● If 10 feet of sump is used below the screen, up to 11 feet of riser or leader pipe may be used above the
screen, and the screen, sump, and entire length of the riser or leader pipe may be gravel packed.
● If 5 feet of sump is used below the screen, up to 16 feet of riser or leader pipe may be used above the
screen, and the sump, screen and entire length of the riser or leader pipe may be gravel packed.
See Minnesota Rules, part 4725.2750 for sump, screen and riser or leader pipe allowable combinations.
A well or boring without a screen (open hole or open bottom), may only have gravel pack for a maximum
of 10 feet.
A gravel pack must not extend more than 10 feet inside a casing.
STAT AUTH: MS s 103I.101; 103I.111; 103I.205; 103I.221; 103I.301; 103I.401;
103I.451; 103I.501; 103I.525; 103I.531; 103I.535; 103I.541; 103I.621; 144.05;
144.12; 144.383; 157.04; 157.08; 157.09; 157.13
HIST: 17 SR 2773; 33 SR 211
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4725.2900 [Repealed, 17 SR 2773]
4725.2950 DRILLING FLUIDS.
Subpart 1. Water. Water used for drilling, development, hydrofracturing,
sealing, repair, or rehabilitation, other than water from the well or boring itself,
must:
A. come from a potable water system or from a well or boring of similar use
and construction;
“Potable water” means water which is safe for human consumption in that it is free from impurities in
amounts sufficient to cause disease or harmful physiological effects.
Water may be taken from a potable water system for use in drilling, development, hydrofracturing,
sealing, repair or rehabilitation any type of well or boring. Water may be taken from one type of well or
boring to drill another well or boring of the same type. For example, water may be taken from a domestic
water-supply well to drill another water-supply well, but water may not be taken from a monitoring well
to drill a water-supply well or remedial well.
Water may not be taken from a pond, lake, ditch, excavation, or other unsafe surface source. Besides
containing potentially harmful bacteria or viruses, surface water may contain nuisance organisms such as
iron bacteria.
B. contain a free chlorine residual at all times, except for monitoring wells and
remedial wells where chlorine will interfere with water quality analysis or
remediation; and
A free chlorine residual means that enough chlorine has been added to leave a measurable quantity of
chlorine in the water. Sufficient chlorine must be added to overcome the chlorine demand of the water.
Organics, iron, bacteria, scale, or other materials in the water, casing, or water system will “use up” the
chlorine (create a chlorine demand). Additional chlorine may be needed during the drilling process to
make up for the chlorine demand.
A monitoring well is exempt from the chlorine residual requirement by Minnesota Rules,
part 4725.6650. However, it is recommended that, where feasible, monitoring wells be disinfected to
prevent bacterial contamination, bacterial alteration of water chemistry, and bio-fouling.
Remedial wells may be constructed without chlorinated drilling water if the chlorine will interfere with
water quality analysis or if addition of the chlorine will adversely react with solvents or other chemicals
in the well. However, chlorine is recommended for the reasons noted above.
C. be conveyed and stored in clean, sanitary tanks and water lines.
It is required to use chlorinated water for drilling, development, and the other activities identified in
subpart 1.
It is not required to add chlorine to a mobile tank prior to transport. The chlorine may be added at the
jobsite just prior to use. However, addition of chlorine prior to transport will usually result in thorough
mixing and elimination of nuisance bacteria. If a granular chlorine product is placed into a steel tank
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without premixing, it may settle and result in corrosion of the tank. It is a good idea to pre-dissolve
granular chlorine in a bucket of potable water prior to addition to a steel tank.
Subp. 2. Drilling additives. Drilling additives, including bentonite, must meet the
requirements of ANSI/NSF Standard 60-2003e as determined by a person
accredited by the ANSI under ANSI Standard Z34.1-1993. A drilling additive is a
substance added to the air or water used in the fluid system of drilling a well or
boring.
Drilling additives include bentonite drilling muds, drilling mud conditioners, water conditioning
chemicals for drilling fluids and grouts such as soda ash, air-rotary foams, and lost circulation materials.
Drilling additives must meet the requirements of ANSI/NSF Standard 60. “NSF,” formerly known as the
National Sanitation Foundation, is an organization which both establishes standards, and tests and
certifies numerous products. “ANSI” refers to the American National Standards Institute. The ANSI
standard refers to accreditation of the testing laboratory. Any laboratory which is accredited by ANSI may
test products against the standard. At the present time, only NSF is actively testing drilling additives.
Two lists of currently approved drilling additives are included in the appendix. The first is a list of
ANSI/NSF Standard 60 certified drilling aids and sealants, and consists primarily of bentonite-based
products, but also includes NSF certified organic polymers, foaming agents, and cellulose-based products.
The second is a list of other products approved by the MDH for use as foaming agents, weighting
materials and lost circulation materials.
STAT AUTH: MS s 103I.101; 103I.111; 103I.205; 103I.221; 103I.301; 103I.401;
103I.451; 103I.501; 103I.525; 103I.531; 103I.535; 103I.541; 103I.621; 144.05;
144.12; 144.383; 157.04; 157.08; 157.09; 157.13
HIST: 17 SR 2773; 33 SR 211
4725.2975 DISPOSAL OF MATERIALS.
The disposal of drilling mud, cuttings, treatment chemicals, and discharged
water must be according to applicable state and local regulations. Drilling mud,
cuttings, and discharged water must not be disposed in a manner that creates a
health hazard. During test pumping, discharged water must be piped to a point of
overland drainage.
Municipalities have expressed concern about disposal of debris, cuttings, and grout in sanitary or storm
sewers. They have reported instances of sewer plugging and have indicated that contractors may be fined
and charged removal costs.
Drilling mud, cuttings, grouts, treatment chemicals, and discharge water should not be allowed to enter
surface water streams, rivers, ponds, lakes, or wetlands. Persons responsible for such discharges may be
subject to federal, state (i.e., MPCA, DNR) or local enforcement actions.
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Drilling mud, cuttings, treatment chemicals, or discharged water may contain contaminants such as PCBs
from older submersible pumps. Information concerning proper disposal of contaminated materials may be
obtained from the MPCA, Telephone Number – metro 651-296-6300 and outstate 800-657-3864 or their
Web site at www.pca.state.mn.us. Environmental releases must be reported to the Minnesota Duty Officer
at 651-649-5451 or 800-422-0798.
STAT AUTH: MS s 103I.101; 103I.221; 103I.301; 103I.621; 144.05; 144.12;
144.383; 157.04; 157.08; 157.09; 157.13
HIST: 17 SR 2773
4725.3000 [Repealed, 8 SR 1625]
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End
of
Screens, Drilling Fluids Section
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