Illinois Administrative Code
Title 77 - PUBLIC HEALTH
Part 920 - WATER WELL CONSTRUCTION CODE
Section 920.60 - Drilled Wells in Unconsolidated Formations
Current through Register Vol. 48, No. 12, March 22, 2024
a) General. Unconsolidated formations such as sand and gravel may extend to or near the ground surface. Generally, however, they lie below the ground surface at varying depths and are covered by an overburden of earth. The kind, nature and depth of the overburden are factors in determining how a well shall be constructed.
b) Unconsolidated Formations. When wells are constructed in unconsolidated formations, a casing shall be installed the entire depth of the formation. Wells constructed in unconsolidated formations shall have a minimum of 20 feet of permanent casing.
c) Gravel Pack Construction. When an oversized drill hole is constructed to permit the placement of a gravel pack around the well screen, the diameter of the drill hole shall be a minimum of 3 inches greater than the outer diameter of the casing or coupling, whichever is greater. The annular opening between the casing and drill hole shall be grouted in accordance with Section 920.90(h). If a permanent outer casing is installed, it shall extend to a depth of at least 20 feet and the annular opening between the drill hole and the outer casing shall be grouted in accordance with Section 920.90(h). The annular opening between inner and outer casings shall be sealed at the top of the casing. The seal shall be made in such a manner as to prevent water or contaminants from entering the annular space between the inner and outer casing. If plastic well casing is installed, it shall be installed as required in Section 920.90(g). (See Illustration C.)