1. (a)

   1. (1) The casing shall be installed where the purpose of casing is to:

      1. (A) Seal off surface, near surface, or deeper contaminants; or
      2. (B) Retain the wall of the well in addition to repelling outside contaminants.
   2. (2) In selection of casing pipe, consideration shall be given to the strain to which the pipe will be subjected during construction and the corrosiveness of the water with which it comes in contact.
   3. (3) Used or reject pipe is not acceptable.
2. (b) Temporary (outer) casing. Casing intended for construction purposes only shall be of weight and design as necessary to be watertight and permit installation without distortion or rupture to the specified depth.
3. (c) Grouting guides. Protective casing that is to be grouted in the drill hole should have sufficient guides welded to the casing to permit the unobstructed flow and disposition of the thickness of grout specified.

4. (d) Screens.

   1. (1) Screen openings shall provide the maximum amount of open area consistent with the strength of screen and the grading of the water bearing formation or gravel pack.
   2. (2) The opening shall permit maximum transmitting ability without clogging or jamming.
5. (e) Joints. All casing pipe joints shall be watertight welded construction or threaded couplings.
6. (f) Upper terminal. The casing, well curb, or riser pipe shall be terminated at a height above ground surface consistent with the proposed plans for a pump house and pump installation but not less than eight inches (8”) above ground surface or twenty-four inches (24”) above maximum high-water level where flooding occurs.

7. (g) Steel casing for domestic, individual, and stock wells. Casing for domestic, individual, and stock wells of steel construction shall be as follows:

   1. (1) Minimum eleven-pound black steel pipe may be used in consolidated formations;
   2. (2) ASA galvanized standard weight Schedule 40 pipe, one inch (1”) ID to four inches (4”) ID pipe size and weight are covered in 17 CAR § 11-1001 et seq.; and
   3. (3) 4.090-inch ID galvanized pipe, nine and one-half-pound (Schedule 30), may be used on a statewide basis with the following provision that any failure of this weight pipe within a five-year period be replaced by the contractor at no cost to the landowner.

8. (h) PVC casing.

   1. (1) Effective January 1, 1989, PVC plastic casing may be used provided the PVC pipe is manufactured as water well casing and is permanently marked as well casing.
   2. (2) The casing shall be made to ASTM F480.
   3. (3) The contractor shall be responsible to ensure that the PVC wall thickness shall be sufficient to withstand both the formation and hydrostatic pressures imposed on the casing during its installation and development.

   4. (4) PVC casing shall be used only when:

      1. (A) Construction practices will allow the bore hole to remain open during casing installation; and
      2. (B) The casing can be lowered freely without driving.

9. (i) Fiberglass casing.

   1. (1) Fiberglass reinforced plastic well casing, tested in accordance with ASTM D1180 (ASTM International), may be used where judged desirable by the contractor and approved by the customer, in consolidated and unconsolidated formations.
   2. (2) Each coupling shall form a watertight seal.
   3. (3) Pipe having a minimum bursting pressure of six hundred sixty pounds per square inch (660 psi) may be used.

10. (j) Casing of industrial and irrigation wells.

    1. (1) General.

       1. (A) All casing, including steel, shall be strong enough to resist the forces imposed during installation and other forces that can be expected after installation.
       2. (B) It shall be the contractor's responsibility to see that all casing used in industrial and irrigation wells will not collapse.
       3. (C) Any material used in construction of industrial and irrigation wells that collapses or breaks within five (5) years shall be renewed with a material strong enough to withstand the stress or pressure without charge to the customer.

    2. (2) PVC casing.

       1. (A) PVC 160 PSI NSF or stronger material classification may be used in construction of industrial and irrigation wells, where judged desirable by the contractor and approved by the customer in unconsolidated formations.
       2. (B) All pipes shall be permanently marked under a method suitable to the NSF.
       3. (C) Plastic pipe must be made of new, not reclaimed material.

    3. (3) Joints.

       1. (A) The joints of all casing shall be watertight and plumb and in alignment.
       2. (B) All casing shall be installed to:

11. (i) Seal off water-bearing formations that contain undesirable water (such as saline); and

    1. (ii) Prevent water from the surface entering the fresh water aquifer so as not to contaminate them.

       1. (C) Each joint of PVC pipe shall have a minimum of four (4) screws or rivets in the coupling.

12. (k) Casing in consolidated formations.

    1. (1)

       1. (A) Metal or plastic casing shall extend a minimum of one foot (1’) into solid bedrock or slate in a cement or bentonite seal at least one inch (1”) thick from rock upward for five feet (5’).
       2. (B) In wells where consolidated formations, such as bedrock or slate, occur as a definable unit, the casing shall be set into the consolidated formation and sealed below all crevices that would normally release water of inferior quality into the well.
       3. (C) Plastic casing may be used to case through overburden in consolidated formations, providing the casing meets the requirements for the depth being cased.

    2. (2) Rock below creviced formation.

       1. (A) The diameter of the drill hole through the creviced formation shall be a minimum of two inches (2”) greater than the diameter of the casing.
       2. (B) If an outer casing is left in place in the earth mantle, the annular opening around that casing shall be sealed as outlined in subsection (l) of this section.

       3. (C)

          1. (i) All wells constructed in consolidated formations shall be cased a minimum of ten feet (10’) from ground surface or one foot (1’) minimum into the consolidated formation.
          2. (ii) Note.
13. (a) (a) Ten feet (10’) from ground surface or one foot (1’) minimum into the consolidated formation means that wells must be cased at least ten feet (10’).

14. (b) (b) Wells will never have less than five feet (5’) of cement or bentonite grout in the annulus.

    1. (c) (c) Wells must also be cased at least one foot (1’) into consolidated formations.

       1. (d) (d) Minimum of one foot (1’) into consolidated rock means that many times even though the formation is consolidated, ground water, at a particular depth, would be undesirable and additional casing and grout to a depth greater than one foot (1’) into consolidated formation is required.
       2. (D) All casing left permanently installed in consolidated formations shall be grouted with the appropriate materials, as outlined in 17 CAR § 11-506, from the bottom of the casing upward five feet (5’).
       3. (E) Where a desirable water bearing formation underlies a crevice or undesirable water bearing formation, the overlaying formation should be completely grout sealed and watertight.

       4. (F) Drilling construction should extend into the desired formation.

          1. (l)

    2. (1) Casing in unconsolidated formations.

       1. (A) Unconsolidated formations such as sand and gravel may extend to or near the ground surface.
       2. (B) Generally, however, they lie below the ground surface at varying depths and are covered by an overburden of earth.
       3. (C) The kind, nature, and depth of the overburden are factors in determining how a well shall be constructed.
       4. (D) Wells constructed in unconsolidated formations shall have a permanent casing installed in which the casing or screen shall extend the complete length of the drill hole.
       5. (E) A minimum of the upper ten feet (10’) shall be filled with grout after the casing is in place.

    3. (2) Gravel wall construction.

       1. (A) When an oversized drill hole is constructed to permit the placement of a gravel wall around the well screen or perforated casing, the annular opening between the casing and the drill hole shall be sealed in the top twenty feet (20’) with concrete, cement, or bentonite grout.

       2. (B)

          1. (i) If a permanent outer casing is installed:
15. (a) (a) It shall extend to a depth of at least twenty feet (20’), depending on the formations present; and

16. (b) (b) The annular opening between the drill hole and the outer casing shall be sealed as provided for in subdivision (l)(1) of this section.

    1. (ii) The annular opening between inner and outer casings shall be filled with concrete, cement, or bentonite grout in the upper twenty feet (20’).

Codification Notes: "PVC" means polyvinyl chloride. "ID" means inside diameter. "PSI" means pounds per square inch.