(a) Wells shall be completed in accordance with the following specifications and in compliance with the local groundwater conservation district rules or incorporated city ordinances.
  (1) Siting Method. A well shall be located a minimum horizontal distance of one hundred fifty (150) feet from any concentrated sources of potential contamination such as, but not limited to, existing or proposed livestock or poultry yards, cemeteries, pesticide mixing/loading facilities, and privies, except in the case of monitoring, dewatering, piezometer, and recovery wells which may be located where necessity dictates. A well shall be located a minimum horizontal distance of one hundred (100) feet from an existing or proposed septic system absorption field, septic system spray area, a dry litter poultry facility and fifty (50) feet from any adjacent property line provided the well is located at the minimum horizontal distance from the sources of potential contamination.
  (2) A well shall be located a minimum horizontal distance of fifty (50) feet from any water-tight sewage and liquid-waste collection facility except in the case of monitoring, dewatering, piezometer, and recovery wells which may be located where necessity dictates.
  (3) A well shall be located at a site not generally subject to flooding; provided however, that if a well must be placed in a flood-prone area, it shall be completed with a watertight sanitary well seal, so as to maintain a junction between the casing and pump column, and a steel sleeve extending a minimum of thirty-six (36) inches above ground level and twenty-four (24) inches below the ground surface.
  (4) A driller is not required to adhere to the property line distance requirements if:
    (A) the well is located within a groundwater conservation district, and the district's rules regulate the spacing of wells;
    (B) the well is located on property that has restrictions regulating the spacing of wells and on-site sewage systems; or
    (C) public wastewater treatment is provided and utilized by the owner.
(b) Alternative siting methods:
  (1) Unless the well is drilled within the Edwards Aquifer, the distances given for separation of wells from sources of potential contamination in subsection (a)(1) may be decreased to a minimum of fifty (50) feet provided the well is cemented with positive displacement technique to a minimum of one hundred (100) feet to surface or the well is tremie pressure filled to the depth of one hundred (100) feet to the surface provided the annular space is three (3) inches larger than the outside diameter of the casing. For wells less than one hundred (100) feet deep, the cement slurry, bentonite grout, or bentonite column shall be placed to the top of the production zone. In areas of shallow, unconfined groundwater aquifers, the cement slurry, bentonite grout, or bentonite column need not be placed below the production zone. In areas of shallow, confined groundwater aquifers having artesian head, the cement slurry, bentonite grout, or bentonite column need not be placed below the top of the water-bearing strata.
  (2) A well that is cemented with positive displacement technique to a minimum of one hundred (100) feet to surface or a well that is tremie pressure filled to the depth of one hundred (100) feet to the surface (provided the annular space is three (3) inches larger than the outside diameter of the casing may encroach up to five (5) feet of the adjacent property line. For wells less than one hundred (100) feet deep, the cement slurry, bentonite grout, or bentonite column shall be placed to the top of the producing layer. In areas of shallow, unconfined groundwater aquifers having artesian head, the cement slurry, bentonite grout, or bentonite column need not be placed below the top of the water production zone.
(c) Drilling the well
  (1) All wells shall be completed so that aquifers or zones containing waters that differ in chemical quality are not allowed to commingle in the casing, borehole annulus or the filter pack and cause quality degradation of any aquifer or zone. When aquifers or zones of lesser quality are overlying the production aquifer or zone, the borehole annulus shall be pressure grouted with bentonite or cement from the top of the production zone back to the surface unless formations make total grouting impossible or impractical. In this case the entire borehole annulus which is groutable shall be grouted and sealed including proper surface annular grouting and completion.
  (2) The well casing shall be capped or completed in a manner that will prevent pollutants from entering the well.
  (3) Each licensee shall use potable water in drilling fluids.
  (4) Each licensed well driller drilling, deepening, or altering a well shall keep any drilling fluids, tailings, cuttings or spoils contained in such a manner so as to prevent spillage onto any property not under the jurisdiction or control of the well owner without the property owner's written consent.
  (5) Each licensed well driller drilling, deepening, or altering a well shall prevent the spillage of any drilling fluids, tailings, cuttings or spoils into any body of surface water.
  (6) A test well that is drilled for exploring for groundwater shall not be open at the surface or allowing water zones of different chemical qualities to commingle and must be completed or plugged within six (6) months of drilling.
  (7) Water wells located within public water supply system sanitary easements must be constructed to public well standards pursuant to 30 TAC Chapter 290.
(d) Casing the well
  (1) The driller casing a well shall install a watertight pipe, temporarily or permanently to maintain the hole sidewalls against caving, advance the borehole, and in conjunction with cementing and/or bentonite grouting, confine the groundwater to their respective aquifer or zone of origin, to prevent surface contaminant infiltration.
  (2) Only the following casing materials may be used for a water well:
    (A) Plastic casing--National Sanitation Foundation (WSF-WC) or American Society of Testing Material (ASTM) F-480 minimum SDR 26 approved water well casing;
    (B) Steel casing--New ASTM A-53Grade or better, and have a minimum weight and thickness of American National Standards Institute (ANSI) schedule 10; or
    (C) Fiberglass Casing--National Sanitation Foundation sixty-one (NSF-61) and American Society of Testing Material (ASTM) D2996 approved Filament Wound fiberglass casing (Glass-Fiber-Reinforced Thermosetting-Resin pipe.)
    (D) Monitoring wells may use other materials, such as flouropolymer (Teflon), glass fiber reinforced epoxy, or various stainless steel alloys;
(e) Annular Seal. The annular space to a minimum of ten (10) feet shall be three (3) inches larger in diameter than the outside diameter of the casing and filled from ground level to a depth of not less than ten (10) feet below the land surface or well head with cement slurry, bentonite grout, or eight (8) feet solid column of granular sodium bentonite topped with a two (2) foot cement atmospheric barrier, except in the case of monitoring, dewatering, piezometer, and recovery wells when the water to be monitored, recovered, or dewatered is located at a more shallow depth. In that situation, the cement slurry, or bentonite column shall only extend down to the level immediately above the monitoring, recovery or dewatering level.
(f) Surface Completion
  (1) In all wells where plastic casing is used, except when a steel or polyvinyl chloride (PVC) sleeve or pitless adapter, as described in subsection (g) is used, a concrete slab or sealing block shall be placed above the cement slurry around the well at the ground surface.
  (2) The slab or block shall extend laterally at least two (2) feet from the well in all directions and have a minimum thickness of four (4) inches and should be separated from the well casing by a plastic or mastic coating or sleeve to prevent bonding of the slab to the casing.
  (3) The surface of the slab shall be sloped to drain away from the well.
  (4) The top of the casing shall extend a minimum of twelve (12) inches above the land surface except in the case of monitoring wells when it is impractical or unreasonable to extend the casing above the ground. Monitoring wells shall be placed in a waterproof vault, the rim of which extends two (2) inches above the ground surface and a sloping cement slurry shall be placed a minimum of twelve (12) inches from the edge of the vault and two (2) feet below the base of the vault between the casing and the wall of the borehole to prevent surface pollutants from entering the monitoring well. The well casing shall have a locking cap that will prevent pollutants from entering the well. The annular space of the monitoring well shall be sealed with an impervious bentonite or similar material from the top of the interval to be tested to the cement slurry below the vault of the monitoring well.
Cont'd...
(5) The well casing of a temporary monitoring well shall have a locking cap and the annular space shall be sealed from zero (0) to one (1) foot below ground level with an impervious bentonite or similar material; and after forty-eight (48) hours, the well must be completed in accordance with this section or plugged in accordance with §76.104.
  (6) The annular space of a closed loop geothermal well used to circulate water or other fluids shall be backfilled to the total depth with impervious bentonite or similar material, closed loop injection well where there is no water or only one zone of water is encountered you may use sand, gravel or drill cuttings to back fill up to ten (10) feet from the surface. The top ten (10) feet shall be filled with impervious bentonite or similar materials and shall meet the standards pursuant to Texas Commission on Environmental Quality 30 TAC Chapter 331.
(g) Alternative Surface Completion. In wells where a steel or PVC sleeve is used:
  (1) The steel sleeve shall be a minimum of 3/16 inches in thickness and shall be a minimum of twenty-four (24) inches in length. The plastic sleeve shall be a minimum of Schedule 80 sun resistant or SDR 17 sun resistant and be twenty-four (24) inches in length, and either sleeve used shall extend twelve (12) inches into the cement, except when steel casing or a pitless adapter as described in paragraph (2) is used. The casing shall extend to a minimum of twelve (12) inches above the land surface, and the steel/plastic sleeve's inside diameter shall be two (2) inches larger in diameter than the outside diameter of the plastic casing being used and filled entirely with cement; or
  (2) A slab or block as described in subsection (f) is required above the cement slurry except when steel casing or a pitless adapter is used. Pitless adapters may be used in such wells, provided that:
    (A) the adapter is welded to the casing or fitted with another suitably effective seal;
    (B) the annular space between the borehole and the casing is filled with cement to a depth not less than twenty (20) feet below the adapter connection; and
    (C) in lieu of cement, the annular space may be filled with a solid column of granular sodium bentonite to a depth of not less than twenty (20) feet below the adapter connection.
(h) Unless waived in writing by the landowner, a new, repaired or reconditioned well or pump installation or repair on a well that is used to supply water for human consumption, shall be properly disinfected.

Source Note: The provisions of this §76.100 adopted to be effective September 15, 2014, 39 TexReg 7090; amended to be effective January 1, 2016, 40 TexReg 8756; amended to be effective April 1, 2018, 43 TexReg 1635