Greetings Will and Joshua,
Good old Michigan winters!
I don’t change methods in the winter except to be aware that the dirt removed for the lid access will freeze. Often, It’s nearly impossible to shovel back in the hole.
My past methods were to carry a spud to pry/remove the lids.
After damaging a couple, I’ve learned to use a shovel only and occasionally a large chisel and hammer to tap around the access lid.
I’ve since made a sincere effort to remove the access lids and if they don’t budge, don’t beat on them.
If there’s no success in getting into the tank, I state it in the report and give a discount on the septic inspection portion of the fee to the client.
After locating and digging for an hour plus, some compensation is still necessary.