Continuing through the Mine

The orcs keep the prisoners housed in room 11, where they can restrict their movement. They keep sentries posted at area 6 to keep them contained. When they take them to dig, they bring in extra guards, escort the prisoners to area 7 to gather their equipment, then lead them down to the next level at area 6.
[Interlude: this adventure arc is causing me stress... for at least the third time, I've thought of a useful magic item to give the NPCs to use... and discovered there isn't such an item in the game. And it feels like such an interesting item. I may have to delve into magic item creation, which I'm not entirely comfortable doing.] It would be an interesting twist if the orcs took the prisoners to various locations based on what they learn from a wand of mineral detection Granak obtained at some point...
The orcs take the miners down into the mine to root out the precious metals in the tunnels below. The miners, better attuned to the process than the orcs, keep leading the orcs away from the richest veins and the tunnels where they're trying to make their escape.
The miners have been breaking tools to stash pieces they can use while "resting" to cut a small tunnel down through the column in room 11 to a lower level. The Hardy brothers have also cut a tunnel down to the next level. Their plan is to connect with the other miners and find a way to cut their way out. It is slow going, especially with the miners only able to work with broken parts. The miners have slowly cut a narrow passage down through the column, and just recently broken through into a lower level. They had to dig down two levels before breaking through, which took them many months of hard labor. They had to go slowly to advance without being detected, as well as to dispose of the dirt excavated.
The orcs feel overconfident in their superiority, and believe they have the miners securely within their clutches. An interesting angle would be for the party to overpower the guards, then have Granak unleash a mass of orcs to rout them. The party could connect with the miners, and rush down through the mine to find the Hardys and search for an escape, with the orcs hounding them at every turn.