Can a tank be pumped when the ground is frozen?
Yes, if the lids can be located and opened. Snow on a marker is easy. A tank with no risers under 18 inches of frost is a different quote. If you know where the lids are, mark them before the first heavy snow. That one habit saves the extra locate fee.
What Michigan winter actually breaks
Not usually the concrete tank. It is frozen laterals, a pump that was never insulated, or a field that was already tired in October. Pumping a frozen-full tank stops the indoor backup. It does not thaw a field. After the thaw, if the yard weeps, read drain field problems.
Yale / St. Clair County
Call (810) 777-8732 and say it is winter and whether anyone can see the lids. Emergency indoor backup: emergency septic service. Do not run water “to keep pipes moving” into a tank that is already at the lid.