Filling in old septic hole, a shovel at a time

Last week, while wandering about the land, I noticed that someone had jumped down on the cement septic tank and removed one of the very heavy lids exposing a dark, black hole.
I finally managed to get the dang thing back in place enough so that nothing could fall in, and resolved to do something about it.
This week Stuart and I took our shovels over and began to fill it in...at least enough so that no one would probably be inclined to dig it up again.
Stuart, being way brave and not scared of dark black holes, looked into the tank before fitting the concrete lid tightly back in place...he said it appeared empty. He had worried that someone had hidden something in it. Brrrr, my imagination had conjured up a wild assortment of possiblities.
Now we have to get the entire mountain down on top of it, but Stuart thinks we need a tractor with a blade of bucket to do the job. My old hernia tells me the same!