Sorry for lack of action shots, I wasn't thinking about TBN when I was working.
We had a sewer blockage that my son and I were unable to get at from the toilet flange (toilet off) with a 50' 1/2" snake (turned by a drill - put the excess in 1/2" pvc pipe segments to keep it from coiling up outside of the pipe) so we had to call in a plumber; he got things flowing and reminded me that we should have our septic "serviced" every 3-5 years. Seems a bit often, but considering the last time there was any sort of service was probably 1998, I figured it was about time.
Septic co "located" the tank for me. Incorrectly, as it turns out; I gave them an approximate location (basically bingo for where I finally found it) but they said it was closer to the block wall there and 4'+ down so I got the 'hoe and started digging. Luckily, didn't damage the riser when I finally hit it at the end of that trench.
Then used a long piece of rebar to figure out what the orientation of the tank was and then I poked in the lawn with some shorter 3/8" rebar (with difficulty, rebar isn't the right thing for this obviously) and found the other lid.
After the tank got pumped (didn't smell nearly as bad as I'd guessed, though I wouldn't want to smell it all the time - probably part of the reason the guy smoked) I used the tractor to push the dirt back into the ditch and pack it down, and then grabbed a few bags of some topsoil from back by the barn (bags are reused, I didn't put chicken food on the lawn, though the lawn does grow goose food). Tank had a lot of crud as expected but wasn't anywhere near full of sludge. I'm not sure if my regular flushing of extra sourdough starter into the drain has helped or not
(the lawn isn't fancy though the ducks & geese I got at the beginning of summer have been working hard to fertilize it for the first time; it's mostly crab grass at this point which is fine by me, it takes very little to keep it going)