Current through Register Vol. 49, No. 13, September 23, 2024
Subpart 1.
General construction; flowing well or boring.
A well or boring from which groundwater flows above the
established ground surface without pumping must be constructed to prevent
erosion of the aquifer and the confining layer. Casing must be installed into
the flowing aquifer to prevent water flowing up the outside of the casing. The
requirements in this part are in addition to other requirements of this
chapter.
Subp. 1a.
Low flow and low pressure.
A flowing well or boring that flows 70 gallons per minute or
less, and that has an artesian pressure ten pounds per square inch or less,
must be constructed by:
A. drilling a
bore hole larger than the casing into the flowing aquifer, installing casing
into the flowing aquifer, and grouting the annular space surrounding the casing
with neat-cement grout or cement-sand grout from the bottom of the casing to
the base of the pitless adapter or unit, or to the established ground surface
according to part 4725.3050;
B.
driving steel casing with welded or threaded and coupled joints into the
flowing aquifer; or
C. for a bored
geothermal heat exchanger, grouting the annular space surrounding the bored
geothermal heat exchanger piping with neat-cement grout or cement-sand grout
from the bottom of the bore hole to the established ground surface or upper
termination of the bored geothermal heat exchanger piping.
Subp. 2.
High flow, high pressure, or
special construction area.
A. A well or
boring, including a bored geothermal heat exchanger boring, must be constructed
according to the requirements in this subpart when:
(1) the artesian flow rate at the established
ground surface is greater than 70 gallons per minute;
(2) the artesian pressure at the established
ground surface exceeds ten pounds per square inch; or
(3) the commissioner designates an area where
the use of standard construction techniques have resulted in uncontrolled
flows, or where hydrogeologic conditions such as eroded or unstable confining
layers require special construction to successfully complete a well or boring
and confine the artesian pressure.
B. A well or boring meeting the criteria in
item A must be constructed by:
(1) installing
an outer steel casing into, but not through, the confining layer overlying the
flowing aquifer, except that the outer casing may terminate in a competent
bedrock above the confining layer. The outer steel casing is not required to
meet the material specifications for casing in part 4725.2350 if the casing is
of sufficient strength to withstand the structural load imposed by conditions
both inside and outside the well or boring. The casing must be installed by
drilling a bore hole a minimum of 3.0 inches larger, or 3.5 inches larger for
casings deeper than 100 feet and larger than 12 inches inside diameter, than
the outside diameter of the casing or couplings, whichever is larger, into the
confining layer overlying the flowing aquifer. The bore hole must not penetrate
the entire thickness of the confining layer. Steel casing must be installed
into the confining layer and neat-cement grout or cement-sand grout must be
pumped into the annular space surrounding the casing from the bottom of the
casing to the established ground surface or base of the pitless adapter or
unit;
(2) drilling a bore hole a
minimum of 3.0 inches larger, or 3.5 inches larger for casings deeper than 100
feet and larger than 12 inches inside diameter, than the outside diameter of
the inner casing or couplings through the confining layer into the flowing
aquifer;
(3) installing an inner
casing into the flowing aquifer in accordance with part 4725.2250, subpart 8;
and
(4) grouting the annular space
surrounding the inner casing with neat-cement grout or cement-sand grout from
the bottom of the casing to the established ground surface or base of the
pitless adapter or unit.
Grouting must comply with part 4725.3050.
Subp. 3. [Repealed, 33
SR 211]
Subp. 4.
Flow
control.
A flowing well or boring must be provided with flow control
capable of stopping all flow, consisting of a valved pipe connection,
watertight pump connection, specially designed pitless unit, or a receiving
tank set at an altitude corresponding to that of the artesian head.
Subp. 5.
Overflow
discharge.
A water discharge from a flowing well or boring that disposes
of water to the surface, a surface water body, sewer, or subsurface
must:
A. be protected with an air gap
according to UPC section 603.3.1 as incorporated in part 4714.0050;
B. have a valve or other mechanism as
required in subpart 4 capable of stopping all flow; and
C. have the outlet screened with a
noncorrosive mesh screen having openings of 1/16 inch or less.
Subp. 6.
Temporary wells and
borings.
Temporary wells and borings that flow, and are sealed within
30 days of the time construction begins, are not required to be constructed
according to this part, but must be constructed to prevent erosion of the
aquifer, drill hole, or surrounding property, and must be sealed to stop all
flow with neat-cement grout or cement-sand grout according to part
4725.3850.
Statutory Authority: 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
