We had our tank pumped, gracious time flies, almost a couple years back.
I added soil on top of the tank when I did the final grading of the house after it was built. I marked the access to the tank with large stones so when I had to pump the tank it would be easy...
What I did not know was that there was another access door to the solid's tank.

I had dug down six inches or so to find the access I knew about. When the pumper showed up, in a VERY nice, and VERY clean purple truck, he told me about the second tank. A dishonest pumper would have just pumped the liquid side, cleaned the filter and taken my money.
I knew where the pipe came out of the house so we knew where the other access would be. Sorta.
It was a good three feed down.

The pumper had a helper and the three of us took turns digging for the access.
The county ONLY required an extension on the tank that has the filter, no the side that has the solids. WHY they do this is beyond me.
We eventually dug out the access and the pumper installed a plastic extension so we would not have to repeat that nonsense again. I think my total bill was around $350 with something like $50-75 being the extension.
A fellow TBNer mention years ago that they pump their septic tank every Presidential election. Easy to remember to pump the poo at election time. The pumper's very nice purple pump truck had a sign on the top of the tank.
"Contents of tank smell like a politician's promises."
:laughing:
Later,
Dan