Current through Reg. 50, No. 13; March 28, 2025
(a) Siting and
setback. All wells shall be located at least 10 feet from adjacent property
lines and sewer lines, and at least 25 feet from potential sources of
contamination that include but are not limited to septic tanks/fields,
livestock pens, or material storage facilities.
(b) Surface completion. Water well drillers
drilling a shallow closed-loop geothermal injection well shall place a concrete
slab or sealing block above the cement slurry around the well.
(1) The slab or block shall extend at least
two feet from the well in all directions and have a thickness of at least four
inches. The slab or block shall be separated from the well casing by a plastic
or mastic coating or sleeve to prevent bonding of the slab to the
casing.
(2) The surface of the slab
shall be sloped so that liquid drains away from the well.
(3) A pitless adapter may be used if:
(A) the adapter is welded to the casing or
fitted with another equally effective seal; and
(B) the annular space between the borehole
and the casing is filled with cement to a depth not less than 20 feet below the
adapter connection.
(c) Commingling prohibited. All shallow
closed-loop geothermal injection wells shall be completed so that aquifers or
zones containing waters that are known to differ significantly in chemical
quality are not allowed to commingle and cause degradation of any aquifer
containing fresh water.
(d)
Drilling and completion requirements.
(1)
Casing. Temporary casing may be installed to prevent overburden cave-in prior
to the installation of tubing material and grouting of shallow closed-loop
geothermal injection wells. If temporary casing is not installed, the
completion of well construction should proceed as soon as possible upon
completion of the borehole. If temporary casing is installed, it shall comply
with the following requirements:
(A) Steel
well casing wall thickness shall be dependent on casing length and shall be
determined using American Petroleum Institute (API) or American Water Works
Association (AWWA) standards but in no circumstance shall have less than
a.233-inch wall thickness.
(B)
Plastic well casing or screen shall not be driven. Plastic well casing shall
meet the requirements specified in the ASTM Standard F480, Standard
Specification for Thermoplastic Well Casing Pipe and Couplings Made in Standard
Dimension Ratios (SDR) as amended and supplemented. Plastic casing shall also
meet the American National Standards Institute (ANSI) standards for "Plastic
Piping System Components and Related Materials."
(C) If the use of a steel or polyvinyl
chloride (PVC) sleeve is necessary to prevent possible damage to the casing,
the steel sleeve shall be a minimum of 3/16 inches in thickness and the PVC
sleeve shall be a minimum of ASTM D1785 Schedule 80 sun-resistant and 24 inches
in length. Any sleeve shall extend 12 inches into the cement slurry.
(D) Shallow closed-loop geothermal injection
wells are not required to be cased into bedrock.
(2) The water well driller shall backfill the
annular space of a shallow closed-loop geothermal injection well from the
surface to the total depth with grouting material in a manner that meets or
exceeds good engineering practices and the gest current available technology.
Grouting materials consist of a combination of bentonite, cement, thermally
enhanced material, or a combination of such materials. In instances where
boreholes will not support a grouting slurry, grouting alternatives, such as
solid bentonite chip material may be used. Any other material used to backfill
the annular space of a shallow-closed loop geothermal injection well must be
approved by the Director.
(3) Where
no groundwater or only one zone of groundwater is encountered during drilling,
grouting alternatives may be used to backfill up to 30 feet from the surface
The water well driller shall fill the top 30 feet with grouting or grouting
alternatives that have been approved by the Director.
(4) At all times during the progress of work,
the driller shall provide protection to prevent tampering with the well or
introduction of foreign materials into the well.
(5) Borehole diameter shall, at a minimum,
allow for the insertion of a pipe sized to ensure all concrete is properly
located, distributed, and cured based on the overall design and operation of
the shallow closed-loop geothermal injection well. Loop tubing shall be
installed for the purpose of filling the annulus between the tubing and the
borehole with sand and grout material.
(6) No section of the annulus between the
heat exchange loop and borehole wall shall remain open after completion of the
well.
(7) For heat exchange loop
material and connection requirements, the applicable American Society for
Testing and Materials (ASTM) standards for the polyethylene (PE) pipe material
shall be used. The heat exchange loop shall not be forced into the borehole or
past an obstruction in such a manner that the structural integrity of the
tubing may be compromised. This includes but is not limited to instances of
cave-in, bedrock dislodgement, partial blockage, or overburden.
(8) All heat exchange loop pipe connections
to be placed in the borehole shall be connected by heat-fusion, electrofusion,
or a similar joints process. In addition to heat fusion or electrofusion
joints, non-metallic mechanical stab-type insert fittings shall meet applicable
ASTM standards.
(9) Wells that use
a plastic loop require the placement of a high solids bentonite slurry grout
with at least 20 percent solids by weight for any depth interval of the boring
that is in a confining or semi-confining layer containing significant silt
and/or clay.
(10) If copper tubing
is used for heat exchange applications, all below grade copper connections
shall be joined by brazing using a filler material with a high melting
temperature such as a material with 15% silver content or
equivalent.
(e) Heat
Transfer Fluids.
(1) Potable water, food
grade propylene glycol, and USP-grade propylene glycol are the only antifreeze
additives a water well driller may use for shallow closed-loop geothermal
injection wells.
(2) Any deviation
from the approved antifreeze additives requires an individual
permit.