Section 178-12-005 - NON-POTABLE WELLS12-005.01Construction of a Non-Potable Well12-005.01A Driven sandpoint wells are permitted only for temporary use and must be decommissioned within 90 days of installation. They must meet the requirements specified in 178 NAC 12-003.12-005.01B Observation wells must be located as required in 178 NAC 12-003.01C item 1.12-005.02Casing a Non-Potable Well: A non-potable water well must be cased with unused watertight casing in the following manner: 12-005.02ACased wells with an outside diameter (OD) of 6-5/8 inches or less12-005.02A1 The top of the well must extend at least 12 inches above the grade of the land surface. The earth surrounding the well must slope away from the well and must be firmly tamped to prevent settling around the casing.12-005.02A2 Non-steel cased wells must be fitted with a watertight connection to 0.237 inch wall minimum steel casing or fitted inside a metal sleeve secured and cemented in the borehole through the frost zone. The annular space between the metal sleeve and the casing must be a minimum of 2 inches and must be filled with an approved grout (178 NAC 12-003.06) or annular fill (12-003.08B). (See Figures 6 and 7) 12-005.02A3Above Ground Protection for Observation Wells: Non-steel cased wells completed above ground must be enclosed with a 5-5/8 inch minimum metal casing/sleeve, buried a minimum of 2-1/2 feet below the ground surface, and covered with an overlapping, vandal-resistant secured metal cap.12-005.02BCased Wells with an OD Larger than 6-5/8 Inches12-005.02B1 The casing must extend a minimum of 6 inches above the grade of the land surface. (See Figure 8)12-005.02B2 The well must have a concrete pad a minimum of 40 inches by 40 inches by 8 inches thick. Prefabricated slabs are acceptable. The concrete must contact the entire circumference of the casing. (See Figure 8)12-005.02C The earth surrounding the well must slope away from the well and must be firmly tamped to prevent settling around the casing. (See Figure 8)12-005.02D Watertight steel casing must be a minimum of 0.188 inch wall thickness.12-005.02E Watertight non-steel casing must be manufactured expressly for well casing and must meet the following specific requirements: 1. Casing strength must not be less than 160 pounds per square inch or Standard Dimension Ratio (SDR) 26 for 8-5/8 inch or less OD casing. Casing strength must not be less than schedule 40 for casing larger than 8-5/8 inches OD; and2. Non-steel casing must bear the National Sanitation Foundation (NSF) 61 stamp of approval.12-005.02F Special Engineered (SE) plastic piping systems must meet the requirements of 178 NAC 12-005.02E item 2.12-005.02G Packaging of thread compounds, sealants, and lubricants must bear the NSF 61 stamp of approval.12-005.03Bored (Seep or Cistern) Wells must be constructed to the same minimum standards for non-potable wells with the following exceptions: (See Figure 3.)12-005.03A Casing may be concrete, tile, or other material approved in 178 NAC 12-003.04C;12-005.03B The annular space must be filled with gravel;12-005.03C Watertight casing is required and grout must be placed from 10 feet below the surface or the static water level, whichever is less, to the surface or the bottom of the pitless unit.12-005.04Open Hole Wells must be constructed to the same minimum standards for non-potable wells and in the following manner. (See Figure 4.)12-005.04A The casing must extend at least 2 feet into the open borehole. A seal must be created between the casing and the lower borehole to ensure that the annular fill material remains in the upper borehole. This can be accomplished by using a collar attached to the casing, a drive shoe, or other sealing device.12-005.04B A minimum 5 foot primary aquifer seal must be placed in the annular space directly above the collar, drive shoe, or other sealing device.12-005.04COpen Hole Wells in Multiple Aquifers must be constructed to the same minimum standards for non-potable wells and must comply with 178 NAC 12-005.04A and 12-005.04B. The screened section must be gravel packed. The area of gravel pack must extend both above and below the screen for a length equal to 2.5 times the diameter of the well. A minimum 5 foot primary aquifer seal must be placed directly above the gravel pack. (See Figure 5.)12-005.05Wells Located in the Arikaree Formation Subject to Subsidence must be constructed to the same minimum standards as non-potable wells with the following exceptions. (See Figure 9) 12-005.05A The borehole for the surface casing must allow for a uniform annular space of 4 inches or larger than the surface casing;12-005.05B A minimum 6 inch annular space must exist between the surface casing and the well casing to provide for gravel placement.12-005.05C The metal surface casing must be a minimum of 20 feet in length.12-005.05D A minimum of 5 feet of concrete must be placed between the borehole wall and the surface casing and allowed to set, encasing the bottom 5 feet of surface casing.12-005.05E A minimum layer of 5 feet of non-slurry bentonite must be placed between the borehole wall and the surface casing above the concrete, with an additional 5 feet of concrete placed on top of the non-slurry bentonite. The concrete must be set prior to drilling inside the surface casing.12-005.05F The metal gravel chute must be straight and a minimum of 6-5/8 inches OD. The top of the chute must extend a minimum of 6 inches above the concrete pad and be equipped with a vandal resistant, secure cover or cap. The bottom of the gravel chute must extend from the surface casing a minimum of 2 feet below grade. The gravel chute and the upper 5 feet of surface casing must be encased in concrete.12-005.05G The concrete pad must extend a minimum of 12 inches beyond the surface casing borehole and be a minimum of 5 feet by 5 feet which surrounds the gravel chute. The thickness must be a minimum of 12 inches above grade and an additional minimum of 12 inches below grade within the boreholes. 178 Neb. Admin. Code, ch. 12, § 005