ARM 17.50.722. MONITORING WELL ABANDONMENT

(1) Abandoned borings, water supply wells and monitoring wells shall be completely sealed with grout or bentonite in order to prevent future contamination of ground water. The sealing materials used shall be continuous, physically and chemically stable, and have a hydraulic conductivity of less than 1 x 10 (2) All boreholes not completed as a monitoring well, piezometer, or water supply well must be abandoned immediately after drilling and completion of soil testing. (3) If any borehole is deeper than the well to be placed in it, the portions of the borehole below the well screen shall be sealed with bentonite pellets or a bentonite slurry. (4) All abandonment activities must be carried out in compliance with ARM 36.21.670 through 36.21.678 and ARM 36.21.810. -5 cm/sec.