The thing to get right
If the well serves an escape window, the cover has to come off from inside.
The well exists so a person can climb out of the basement and then out of the well. A cover screwed, bolted or latched from above turns that well into a lid. Someone in a smoke-filled room, in the dark, possibly a child, has to be able to push it off without a tool and without knowing a trick.
We are not going to hang a code section on that sentence, because we could not read the clause on a source we trust, and this site does not cite what it has not verified. Take it as plain reasoning instead, and put the question to your building department directly: they will tell you how they want a cover fastened over an egress well, and their answer is the one that counts.
