Water Well Standards

CHAPTER II. STANDARDS

Section 16. Special Provisions for Large Diameter Shallow Wells.

  1. Use as Community Water Supply Wells. Because shallow groundwaters are often of poor quality and because they are easily contaminated, the use of bored or dug wells, or wells less than 50 feet deep, to provide community water supplies shall be avoided (unless there is no other feasible means for obtaining water). When used for this purpose, these wells shall be located at least 250 feet from any underground sewage disposal facility.


  2. Bored Wells. All bored wells shall be cased with concrete pipe or steel casing whose joints are water-tight from 6 inches above the ground surface to the depths specified in Section 9, Subsection A. Except where corrugated steel pipe is used as casing, the minimum thickness of the surrounding concrete seal shall be 3 inches. Where corrugated steel pipe is employed, the joints are not watertight and a thicker annular seal (no less than 6 inches) shall be installed.


  3. Dug Wells. All dug wells shall be "curbed" with a watertight curbing extending from above the ground surface to the depths specified in Section 9, Subsection A. The curbing shall be of concrete poured-in-place or of casing (either precast concrete pipe or steel) surrounded on the outside by concrete.

    If the curbing is to be made of concrete, poured-in-place, it shall not be less than 6 inches thick. If precast concrete pipe or steel casing is used as part of the curbing, the space between the wall of the hole and the casing shall be filled with concrete to the depths specified in Section 9, Subsection A. The minimum thickness of the surrounding concrete shall be 3 inches.

  4. Casing Material. Either steel (including corrugated steel pipe) or concrete may be used for casing bored or dug wells. Corrugated aluminum pipe is not recommended for use as casing. Note 19


    1. 1. Steel used in the manufacture of casing for bored and dug wells should conform to the specifications for casing material described in Section 12. Minimum thickness of steel casing for bored and dug wells shall be:
      Diameter (inches) U.S. Standard Gage
      or Plate Tickness
      18
      24
      30
      36
      42
      48
      8 gage
      1/4 inch
      1/4 inch
      1/4 inch
      1/4 inch
      1/4 inch

      Corrugated steel pipe used as casing shall meet the specifications (including the latest revision) of ASTMNote 20 A444, "Standard Specification for Steel Sheet, Zinc Coated (Galvanized) by the HOT-DIP Process for Culverts and Under- drains". The minimum thickness of sheet used shall be 0.109 inch.

    2. Concrete casing can consist of either poured-in-place concrete or precast concrete pipe. Poured-in-place concrete should be sufficiently strong to withstand the earth and water pressures imposed on it during, as well as after, construction. It should be properly reinforced with steel to furnish tensile strength and to resist cracking, and it should be free from honeycombing or other defects likely to impair the ability of the concrete structure to remain watertight. Aggregate small enough to place without "bridging" should be used. Poured-in-place concrete shall be "Class A" (6 sacks of Portland cement per cubic yard) or "Class B" (5 sacks per cubic yard).

      Precast concrete pipe is usually composed of concrete rings from 1 to 6 feet in diameter and approximately 3 to 8 feet long. To serve satisfactorily as casing, these rings should be free of blemishes that would impair their strength or serviceability. Concrete pipe shall conform to the specifications listed in Section 12, Subsection A, Item 4.

  5. Covers. All bored and dug wells shall be provided with a structurally sound, watertight, cover made of concrete or steel.

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