This achievement is much easier than it sounds. When I first read it, I thought, "80 feet!?" but remember, the Charger is FAST and covers that kind of ground in a second or two.
With that said, all you need to do is line up a survivor so that your charge path won't lead you into a tree or a wall, or car or anything... Hard Rain has many open areas like streets, corn fields, open swamps... Charge a survivor and assuming you don't miss or hit anything, the achievement will pop. Good luck!