I then planted those in around the septic cap. They include: one mature rhubarb (no we're not going to eat it, I bought it because it's pretty and the leaves are toxic), one stonecrop sedum (I have one that doesn't get eaten), one spiderwort (not yummy), one coreopsis (not yummy), one onion chive (repellent), one garlic chive (repellent), two butterfly weeds, a couple dozen marigolds of various colors in sizes from giant to dwarf, and eight Dusty Miller artemesias. I may or may not have forgotten a couple other things.
EDIT 4/14/17: Round 2, I dug up more wild chives and finished the border. I also watered everything in it. Much of the area around the septic cap is now full, although there's room to plant more things if I find other stuff I'm looking for. If not, no big deal, the other stuff will probably fill in eventually. I hope that at least some of this less-palatable planting will survive the wildlife.