Just to show where I'm heading, here's the overview map for the entire first level, so far. This document is not a PDF, because it's going to be changed as the project continues. It's a "crude megalevel map" as described in Part V of the megadungeon training series. What to note right now is the way some regions are butting up against each other, but others are connected by lines representing tunnels. The tunnels leave room for expansion; the party could later find a map showing a secret door in the rail tunnel connecting the forge to the mines, for example, or the tunnel leading from the new mines can have simple codes indicating a reusable geomorph.
Next up are the new mines (FING-1); the map is done, just need to start stocking and preparing the key.