Our septic system needed to be upgraded, so we took the hottest weekend of the year (so far) to do it. My wife's dad and brother spent the day with me on Saturday digging large trenches to bury leach chambers. We redid all the plumbing. We plowed a new, larger garden and cut down some nuisance trees.
I've also learned about navigating the permitting stages with the health department. Good news is that I'll never need to do this again.