(1) The following special
sealing methods may be required in situations where different techniques are
necessary to protect aquifers.
(2) In drilled wells that
penetrate an aquifer overlain by clay or other unconsolidated deposits such as
sand and gravel in which significant (at least 6 feet thick) interbeds of clay
are present, the well casing may be terminated in such clay strata, provided
that the casing be sealed in substantially the same manner as is required in
the case of consolidated formations (see ARM 36.21.655 and Figure 3C at the end
of this subchapter) .