Current through August 26, 2024
The following requirements apply to the abandonment of all
boreholes greater than 10 feet deep or which intersect a water table and all
groundwater monitoring wells. The department may require, by order or other
appropriate means, that any borehole or monitoring well be abandoned. The
department shall consider the following factors in determining whether a
borehole or monitoring well should be abandoned: purpose, location, groundwater
quality, age and condition of the well or borehole potential for groundwater
contamination and well or borehole construction.
(1) TIMELINES FOR ABANDONMENT.
(a) A borehole shall be abandoned within 3
working days after its use has been discontinued.
(b) Any permanent groundwater monitoring well
no longer being used to gather information on geologic or groundwater
properties shall be abandoned within 60 days after its use has been
discontinued.
(c) Any groundwater
monitoring well found by the department to be acting as a conduit for
groundwater contamination shall be abandoned within 15 working days after
written notification by the department.
(d) Any groundwater monitoring well
constructed after February 1, 1990 not meeting the requirements of this chapter
shall be abandoned and replaced with a monitoring well meeting the requirements
of this chapter or any department approval granted under this chapter within 60
days after installation of the noncomplying well or 15 days after written
notification by the department that the well is noncomplying.
(2) ABANDONMENT PROCEDURES.
(a)
Boreholes. Any borehole
intersecting the water table or greater than 10 feet deep, whose use has been
discontinued, shall be abandoned according to the requirements of par.
(d).
(b)
Monitoring wells -
impermeable annular space seals. A permanent groundwater monitoring
well known to be constructed with an impermeable annular space seal shall be
abandoned according to the requirements of par. (d) after the protective cover
pipe and ground surface seal have been removed and the well casing cut off at
least 30 inches below the ground surface. The well casing may be completely
removed during abandonment by pulling the well casing, overdrilling around the
casing and then pulling the well casing out of the ground or by drilling out
the well casing completely. If the well casing is to be removed, the well shall
be sealed as the casing is removed.
(c)
Monitoring wells - permeable
annular space seals and wells in waste areas. A groundwater monitoring
well not known to be constructed with an impermeable annular space seal or
located in an existing or planned future waste disposal or treatment area shall
be abandoned by removing the protective cover pipe and the ground surface seal
and then completely removing the well casing. The well casing shall be pulled
out of the ground as the well is filled according to the requirements of par.
(d).
(d)
Sealing
requirements. Boreholes and groundwater monitoring wells shall be
abandoned by complete filling with neat cement grout, bentonite-cement grout,
sand-cement grout, concrete or bentonite-sand slurry. When a tremie pipe is
used to place the sealing material, the procedures of s.
NR 141.10(2) shall be followed. A tremie
pipe shall be used to abandon groundwater wells and boreholes greater than 30
feet in depth or with standing water. Groundwater monitoring wells and
boreholes greater than 100 feet in depth shall be sealed with a tremie
pipe-pumped method. Bentonite may be used as a sealing material without the use
of a tremie pipe under the following conditions:
1. Bentonite granules may be used for
abandonment of boreholes and groundwater monitoring wells less than 25 feet
deep and when there is no standing water above the filter pack seal.
2. Bentonite chips no greater than 3/8 inch
in diameter or bentonite pellets may be used for abandonment of boreholes and
groundwater monitoring wells less than 50 feet deep and the depth of standing
water is less than 30 feet.
3.
Bentonite chips no greater than 3/8 inch in diameter or bentonite pellets may
be used for abandonment of boreholes and groundwater monitoring wells which are
greater than 4 inches in diameter and less than 250 feet deep and the depth of
standing water is less than 150 feet.
(3) SEALANT SETTLEMENT. Any settling of the
sealant material shall be topped off. Sealing material may be terminated 30
inches below the ground surface in agricultural areas to avoid interference
with agricultural activities. A native soil plug shall be placed on top of the
settled sealing material in such cases.
(4) ABANDONMENT DOCUMENTATION. All borehole
and permanent groundwater monitoring well abandonments shall be reported to the
department within 60 days of the abandonment on forms supplied by the
department. In addition to the information required on the form, the person
performing the abandonment shall report any decontamination procedures used
between borehole and well abandonments.
