Level One

Looking at the map started for level one of the mine, rooms 7, 8, and 9 are down an old end of the mine, part of the original vein. With much of that section of the mine played out, it has been abandoned and left to nature. The tunnels are coated in a thick layer of dust beyond where the three rooms are, and this spot would be the perfect one for an old school crawl-type series of encounters. The rooms themselves have become a depository for junk - tools, broken carts, broken picks and shovels, support braces, etc. Room 7 is used for storing the tools the miners are using currently. The orcs lead them here each morning to get their tools, then lead them to the current dig site. They won't let them keep the tools overnight for fear of their escape or using them as weapons.
Room 8 is used to dump any newly broken equipment, with room 9 lost to the ages... and spiders. Room 9 is full of junk and coated in dust, none of which is easy to spot through the webs. They are everywhere, covering all of the cast off tools of the mining trade, and strung from every corner. In the dark corners are four giant spiders who use their web sense to drop on victims. Room 8 is starting to get covered in webs, and houses a swarm of spiders, which can attack separately or in support of the giant spiders in the next room.
Room 10 feels like it should open to a special sequence. Part of the older section of the mine, the passage off room 10 was being revisited by the Hardy brothers as a new direction to dig. They realized that while it showed no more signs of gold, there were rich veins of some minerals running through some sections of the tunnels, which they hoped to mine. That was just before Granak attacked the mine. Rigging a quick trap, the brothers were able to partially collapse the tunnels leading to room 10. Unfortunately, they inadvertently trapped themselves inside. Believing them to be dead, Granak had left them to take over the rest of the mine. Trapped between the orcs and a dead end shaft, the brothers began the task of trying to tunnel their way out. They quickly developed a system to use with the other miners to pass information back and forth. The prisoners let them know that Granak wished they had survived so he could steal ownership of the mine from them, and decided to continue playing dead until they could all escape and bring justice to bear on Granak and his orc tribe.
The prisoners smuggled food to them, and the brothers suggested they all try to tunnel down to the next level and find a way out of the mine together. I need to give this a little more thought, but I think it is a good direction to take...