OAR 690-210-0330: Unhydrated Bentonite

Unhydrated bentonite used in construction of casing seals for water supply wells shall be specifically designed for sealing wells and be within industry tolerances for dry western sodium bentonite. Bentonite shall be free of polymers that promote bacterial growth. Placement of the bentonite shall conform to the manufacturers specifications and result in a seal that is free of voids or bridges. Powdered bentonite and bentonite grout or slurry shall not be used as an annular seal material.