Approved Drilling Fluid Additives and Bentonite Grouts
Following is a partial list of requirements for drilling fluids and grouts used in wells and borings in Minnesota (complete requirements can be found in Minnesota Rules, Chapter 4725, Wells and Borings):
- Drilling fluid additives, including bentonite, must meet the requirements of ANSI/NSF Standard 60-2003e.
- Bentonite used for grout must meet ANSI/NSF Standard 60, or be a natural bentonite without additives.
- Grout must be mixed into a water slurry and pumped through a tremie pipe or the casing.
- Bentonite pellets, chips, and dry granular bentonite may be used only as an intermediate seal between a gravel pack and grout in any regulated well or boring. The layer of bentonite pellets, bentonite chips, or granular bentonite must not exceed 5 feet in thickness, must not extend into a confining layer, and must not extend more than 10 feet above the static water level.
The Minnesota Department of Health (MDH) has put together the following list of approved products:
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Contact the MDH Well Management Section
651-201-4600 or 800-383-9808
Minnesota Department of Health