20. Where a groundwater withdrawal facility is plugged, the plugging must meet the following conditions:1° a material not likely to degrade the quality of the groundwater must be used;
2° the well casing must be exposed to a depth of at least 1 m below the surface of the ground;
3° the well casing must be cut off at the bottom of the excavation;
4° the portion of the casing open to the aquifer must be filled with clean sand;
5° the remaining portion of the casing must be filled with pure bentonite or a cement bentonite mix;
6° a concrete slab must be placed over the end of the casing;
7° the excavation must be filled using the soil initially excavated.
This section also applies to an observation well.