Sanitary Sewer Manhole Invert Elevations

when you're following everyone's advice, use a 6" mirror to light the manhole interior. it will light it up like day, assuming the sun is out.

Agreed. That method is better than any light I have seen.

Ditto here, had a 2 meter GPS rod with a framing square bolted to it. If it was deeper than that, we just screwed another section to it. It was much easier to wash off and didn't contaminate the level rod or the prism pole. I also kept a spray bottle with bleach and water to sanitize it before it went back in the truck.

I will admit to using it with RTK for inverts, only had a few times I actually had to put the dish down in the hole. You just have to take the shot really fast......;-)