Current through September 17, 2024
12-012.01
General Requirements: The well cavity of all water
wells to be decommissioned must be filled and sealed in accordance with the
appropriate procedure described below. Any licensed water well contractor
constructing a water well for any customer must as a part of the agreement
include the proper decommissioning of each water well and test hole constructed
to explore for ground water pursuant to the agreement. A landowner may only
decommission a driven sandpoint water well on land owned by him/her and used by
him/her for farming, ranching, or agricultural purposes or as his/her place of
abode. A well constructed after October 1, 1988, but not constructed according
to Title 178 NAC 12 must have a Declaratory Order prior to
decommissioning.
12-012.02
Preliminary Work: Prior to decommissioning a water
well, the depth of the well and the static water level must be measured and an
investigation must be made to determine the details of the well construction.
Potential sources of well construction details include:
1. The personal records of the
owner,
2. The contractor that
drilled the well,
3. The
registration forms on file with the Nebraska Department of Natural Resources,
available on its website,
4. Water
well contractors familiar with the area, and
5. Water well records on file with the
University of Nebraska-Lincoln Conservation and Survey Division, School of
Natural Resources.
12-012.03
Obstructions: Every effort must be made to remove
obstructions. If they cannot be removed, the well cavity must be filled with
approved fill material in accordance with 178 NAC 12-003.08B from the bottom of
the well to a point above the obstruction. If this is not possible, a 5-foot
non-slurry bentonite grout plug must be placed above the obstruction, or the
entire length of the water well from the obstruction to the surface must be
grouted.
12-012.04
Material Volume: The volume of material required to
decommission a water well can be determined using Table 3. Volumes for each
interval that is to be either filled or sealed must be calculated prior to
beginning. Materials used and calculated volumes must be consistent. If they
are not, (1) additional material must be added to replace lost volumes until
the interval is filled or sealed or (2) if material bridges in the well
(evidenced by calculated amount of filler/sealer being too much), operations
must stop until the bridge is removed by high pressure jetting, drilling, or
other methods.
12-012.05
Well Decommissioning Materials: Approved fill material
(178 NAC 12 003.08B, 12-012.05B) or grout material (178 NAC 12-012.05A) must be
used to decommission water wells. Grout seals must be used to prevent water
movement into or between water-bearing zones; approved fill material may be
used where grout seals are not necessary.
12-012.05A
Grout
Material: Grout material found in 178 NAC 12-003.06 can be used as
a seal in decommissioning water wells.
12-012.05B
Approved Fill Material
for Decommissioning to be used in water wells in intervals where
grout seals are not used or are not required must be disinfected sand, gravel,
or crushed stone except that native earth material may be used in large
diameter bored or dug wells because of the volume required. All fill material
must be free of potentially toxic chemical residue and trash such as leaves and
foreign materials. All fill material must be sized and introduced into the well
at a rate to avoid bridging.
12-012.06
Decontaminating: Disinfectant equivalent to at least
200 parts per million chlorine must be introduced into the well before any
material is placed into the well. The disinfectant can be in a liquid,
granular, or pellet form. This will also decontaminate the fill material placed
adjacent to the water-bearing zones. (See Table 1 for the amount of
disinfectant to use.)
12-012.07
Upper Plug: All cased water wells to be decommissioned
must have an upper plug to prevent surface and near-surface contaminants from
entering the well casing. Only non-slurry bentonite and sand cement grouts are
allowed in the upper plug. If the water well records indicate that a surface
seal was installed during construction, then any option below can be used. If a
surface seal was not installed or it is not known if a surface seal was
installed, then Option 1 or Option 3 must be used.
12-012.07A
Option 1
: Remove the top 3 feet of the well casing and grout the upper 5 feet of the
remaining casing. Install a 6-inch thick grout seal above the top of the casing
that extends a minimum of 1 foot past the walls of the original borehole and
extends at least 1 foot below the top of the cut-off casing. Backfill the
remainder of the hole with native soil mounded for settlement and proper
drainage. (See Figure 13)
12-012.07B
Option 2
: For all other wells not located in a structure and if the water well was
constructed with an annular surface seal, the water well casing may be left in
place. A 5-foot long grout plug must be placed in the casing within the top 10
feet. If the casing is going to remain above the concrete surface, a watertight
secure cover or cap must be installed on top of the casing. (See Figure
14)
12-012.07C
Option
3: If the water well is surrounded by concrete/asphalt that
extends 1 foot beyond the original borehole, and the casing is to be cut off
flush with the top of the concrete, then a 5 foot minimum grout plug must be
placed 10 feet below the concrete pad, and a minimum of 5 feet of concrete must
be installed above the grout plug and struck off level with the top of the
concrete. (See Figure 15)
12-012.08
Procedures for Specific
Well Types are set forth below and must be followed.
12-012.08A
Test
Holes must be sealed with a 5-foot grout plug placed at static
water level and/or confining layer. Approved fill material must be placed from
the 5 foot grout plug to the surface seal within the top 10 feet.
12-012.08B
Drilled, Bored, or Dug
Water Wells
1. Measure the
static water level and the total depth of the well.
2. If there is no water in the casing, place
a minimum 5 foot grout plug in the bottom as described in the Placement of
Grout section (178 NAC 12-003.07).
3. Use these measurements and the information
in Tables 3 and 4 to determine the volume of material to be used.
4. Fill the well cavity or casing with clean
disinfected sand, gravel, or grout up to 1 foot below the static water level.
a. If the static water level is less than 6
feet, refer to upper plug procedures for near-surface
decommissioning.
b. If the static
water level is greater than 6 feet, place a seal at least 5 feet thick on top
of the sand/gravel fill. (See Figure 16.)
5. Native earth is an acceptable
decommissioning fill material only for dug or bored wells that are two feet or
more in diameter because of the volume required. Place native earth material in
the excavated hole and mound over the well to accommodate future settling and
to divert surface water away from the well. (See Figure 17)
6. Fill the remainder of the well with clean
sand or gravel or grout up to 8 feet below the ground surface. At this point,
place a 5-foot non-slurry bentonite grout seal in the casing. (See Figure
17)
7. The remainder of the water
well must be decommissioned as described in the Plug Section. (See Figure
13)
12-012.08C
Driven Sandpoint Wells
1. Fill the entire casing with grout to the
top and cut off the casing 3 feet below the ground surface or water level.
Place a 6-inch grout seal 1 foot beyond the casing and backfill the remainder
of the hole with native soil mounded for settlement. (See Figure 18)
or
2. If the casing is pulled,
decommission like a test hole as described in 178 NAC 12-012.08A.
12-012.08D
Full Length
Grouted Wells must be decommissioned by pressure grouting the
inside of the screen and casing. (See Figure 19) The rest of the well must be
decommissioned as described in the Upper Plug Section, Option 1 or Option 3
only, as described in 178 NAC 12-012.07A and 12-012.07C.
12-012.08E
Multiple Aquifer
Wells: Water wells that obtained water from more than 1 water
bearing zone must have a seal between each zone if each water bearing zone is
separated by a confining layer. (See Figure 20) A grout seal not less than 5
feet in length must be placed adjacent to each confining layer and 5 feet of
grout must be placed at the static water level.
12-012.08F
Flowing Water
Wells: Decommissioning these wells requires the placement of neat
cement through a tremie line to stop the flow; otherwise, expandable plugs may
be installed in the casing (or bedrock if not cased) to stop the water flow.
12-012.08F1 If it is known where a confining
layer exists, the following procedure to install an intermediate seal (see
Figure 21) is required.
12-012.08F1a If,
during construction, the annular space was not grouted at the confining unit, a
plug must be set at the bottom of the confining layer and the casing must be
perforated a minimum of 3 feet, to allow pressure grouting of the annular space
with neat cement.
12-012.08F1b
Bentonite grout can be used above the confining layer if the flow has been
stopped. The rest of the well must be decommissioned as described in the Upper
Plug section, 178 NAC 12012.07.
12-012.08F2 The exact location of these wells
must be flagged for at least 1 year after decommissioning.
12-012.08G
Closed Loop Heat Pump
Wells must be decommissioned as follows:
1. Remove all heat transfer fluid from the
closed loop, and
2. Dig down to the
top of the borehole and cut off the loop pipe at least 6 feet below the
surface. Pump the remaining loop full of bentonite or cement slurry. The
remainder of the borehole is to be decommissioned as described in the Upper
Plug section 178 NAC 12-012.07.
12-012.09
Documentation: A record that includes the materials
used, the quantity of those materials, location of placement thereof, and mix
specifications, including the type and viscosity of bentonite grouts must be
maintained on every decommissioned water well, including test holes.
12-012.10
Reporting
Decommissioning: A notice of decommissioning for all water wells
except test holes must be submitted to the Director of the Department of
Natural Resources on the Notice of Decommissioning form supplied by the
Department of Natural Resources within 60 days of the decommissioning of the
water well as required in Neb. Rev. Stat. §
46-602 as follows:
1. The pump installation contractor or water
well contractor must submit written notice of the decommissioning of a water
well to the Department of Natural Resources.
2. If both a water well contractor and a pump
installation contractor are involved in the decommissioning of a water well,
the pump installation contractor must submit the notice of decommissioning to
the Department of Natural Resources.
3. If a landowner decommissions a driven
sandpoint water well on land owned by him/her and used by him/her for farming,
ranching, or agricultural purposes or as his/her place of abode, the landowner
must report the decommissioning to the Department of Natural
Resources.
