178 Neb. Admin. Code, ch. 12, § 012

Current through September 17, 2024

Section 178-12-012 - WATER WELL DECOMMISSIONING

12-012.01General 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.

12-012.02Preliminary 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.

12-012.03Obstructions: 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.

12-012.04Material 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.

12-012.05Well 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.

12-012.05AGrout Material: Grout material found in 178 NAC 12-003.06 can be used as a seal in decommissioning water wells.

12-012.05BApproved 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.

12-012.06Decontaminating: 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.)

12-012.07Upper 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.

12-012.07AOption 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)

12-012.07BOption 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)

12-012.07COption 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)

12-012.08Procedures for Specific Well Types are set forth below and must be followed.

12-012.08ATest 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.

12-012.08BDrilled, 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)

12-012.08CDriven 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.

12-012.08DFull 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.

12-012.08EMultiple 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.

12-012.08FFlowing 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.

12-012.08GClosed 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.

12-012.09Documentation: 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.

12-012.10Reporting 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.

178 Neb. Admin. Code, ch. 12, § 012