DEWATERING WELLS
4725.6150 DEWATERING WELL.
Subpart 1. Scope. This part applies to a dewatering well as defined in Minnesota
Statutes, section 103I.005, subdivision 4a. A dewatering well must be constructed,
repaired, maintained, and sealed in accordance with the general standards in
parts 4725.2010 to 4725.3875, and the requirements of this part. A dewatering
well must not be used for a purpose other than dewatering. A dewatering well is
exempt from the provisions in parts 4725.4050 to 4725.6050.
“Dewatering well” means a nonpotable well used to lower groundwater levels to allow for construction
or use of underground space. A dewatering well does not include:
● A well or dewatering well 25 feet or less in depth for temporary dewatering during construction;
● A well used to lower groundwater levels for control or removal or groundwater contamination; or
● A drain tile, perforated pipe, sump, or pit less than 10 feet deep, or less than 10 feet below the floor of
a basement.
A dewatering well may only be used for dewatering, and may not be used for other purposes including
potable supply, monitoring, remediation, irrigation, or other purposes.
Dewatering wells are not water-supply wells and are, therefore, not required to follow the isolation
distance setbacks, minimum depth, and other standards of Minnesota Rules, parts 4725.4050 to
4725.5650.
Minnesota Rules, part 4725.1825 contains the dewatering well notification requirements. Changes to
Minnesota Statutes, Chapter 103I, in 1994 eliminated the dewatering permit and in its place established a
notification.
Subp. 2. General construction requirements. A discharge from a dewatering
system must not connect to a potable water system.
The discharged water from a dewatering well must be disposed of and treated if necessary in accordance
with applicable state and local laws. The U.S. Corps of Engineers, MPCA and DNR should be consulted
about discharge to navigable or public waters. Local governments, including watershed districts, may
have jurisdiction over discharge, including discharge to sewers.
Water taken from a dewatering well may not be provided to any private or public water system.
Subp. 3. At-grade dewatering wells. A dewatering well cased and completed
at-grade must conform to part 4725.6850.
At-grade dewatering wells must conform to the at-grade monitoring well specifications.
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Subp. 4. Loss of potable supply. A licensee who installs a dewatering well that
causes the loss of an adequate private potable water supply must provide the
private well owner with a temporary supply of potable water during the operation
of the dewatering well. The supply must be adequate for drinking, cooking, and
other household uses. The commissioner may require the private well to be tested
to determine if a health risk exists before the licensee discontinues an alternate
water supply. The licensee must assure that the required testing is completed and
reported to the commissioner.
The notification requirements of Minnesota Rules, part 4725.1825 require the dewatering contractor to
indicate on the notification whether the dewatering project will affect potable wells.
The DNR should be contacted regarding well interference issues involving appropriation permits.
Subp. 5. Sealing. A dewatering well that is not in use must be sealed according
to this chapter.
The sealing procedures are detailed in Minnesota Rules, part 4725.3850.
Subp. 6. Exceptions. A dewatering well in an unconsolidated formation installed
for less than 18 months and less than 50 feet in depth may be constructed and
sealed in accordance with the conditions and exemptions in items A to E.
A. Casing is not required to meet the standards of parts 4725.2350 to part
46725.2650, if the casing is water tight, free of oil or other contaminants, and
withstands the forces exerted on it during installation and removal.
This allows the use of nonstandard casing. However, the contractor is responsible for failure of
substandard casing including remediation of contamination allowed by the casing, or removal and proper
grouting of collapsed casing.
B. The upper termination of the casing must be covered with a tamper-resistant
overlapping cover on the casing as specified in part 4725.2250, subpart 17. The
casing is not required to terminate at least 12 inches above the established ground
surface if the casing extends at least 12 inches above the working grade. The
working grade is the temporary elevation of the ground surface during a
construction project.
C. The gravel pack must not extend more than ten feet above the static water
level.
D. The annular space is not required to be grouted to depth of 50 feet in
accordance with part 4725.3050, subpart 3, if the annular space is filled with
cuttings taken from the bore hole.
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The annular space around the casing must be completely filled with grout or cuttings. The cuttings may be
shoveled into the space so as to prevent bridging.
E. At 18 months after construction or sooner, the well must be sealed according
to this chapter. A dewatering well installed for 18 months or less, not encountering
a confining layer, less than 50 feet in depth, completed in an unconsolidated
formation, and that is not flowing, may be sealed according to part 4725.7450,
subpart 4.
Minnesota Rules, part 4725.7450 allows sealing of certain environmental bore holes by removing the
casing and screen allowing the hole to collapse. Certain dewatering wells may also be allowed to
collapse only under the following conditions:
● The well must be less than 50 feet deep;
● The well must be completed only in an unconsolidated formation;
● The well must not encounter pollution; and
● The collapse must not be induced.
The remaining portion of the hole above the collapse must be grouted from the bottom to the top with
cement or bentonite grout.
Subp. 7. Special construction areas. The commissioner may require additional
construction standards in special well and boring construction areas as described
in part 4725.3650.
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; 144.122; 144.383; 157.04; 157.08; 157.09; 157.13
HIST: 17 SR 2773; 18 SR 1222; 33 SR 211
4725.6200 [Repealed, 17 SR 2773]
4725.6300 [Repealed, 17 SR 2773]
4725.6400 [Repealed, 17 SR 2773]
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End
of
Dewatering Wells Section
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