Yes, it's one of my favorite surveying memories. We had to repel down the canyon walls for Seven Oaks Dam near San Bernardino, California, setting slope stakes (among other things). There weren't many places to anchor ourselves at the top, so we often parked the truck sideways and anchored to the driveshaft. Fun times.
I also remember having to evacuate quickly during dynamite blasting, and they only gave us 20 minutes notice. In some cases, it was very difficult to get out in time.
Now that would be an adventure!
I've had the privilege of working a few places in my career that made me feel like who has it better than me? We monitored pier movement at the Black Hawk Bridge for several years. Don't think I'd call it a mega structure but it offered some unique challenges. This spot is one of the best kept secrets there is in my opinion. If you have time, this video explains it all. Black Hawk Br.
Have you surveyed any dams or other mega structures in your career?