akmaster:
You said..."the specs call for a 0.3% slope TOWARDS the manhole.."
Based on that sentence, it sounds like this project was designed by a Lic Design Professional, and hopefully reviewed and approved by an AHJ.
That said, is the .3% slope spec'd for the duct bank, or the grade surrounding the manhole?
I have not seen any spec that stated any slope for duct banks. There is a grading spec which slopes the grade away from the hole to reduce (not prevent) runoff.
BTW, manhole covers are usually not bonded, a few jobs called for the ring to be bonded. If you think about this, the ring is cast in the concrete, which is buried in the earth!
