Ashfall II: Under the Dome

From the introduction:

The workforce of Dryavis on Spume is growing restless. They are cooped up in a small mining town under a mercilessly sulphurous sky raining ash and who knows what else on them. There’s little distraction from the harsh conditions as the few hundred miners make up the entire population of the planet. And now the Pihrund Corporation is beginning to terminate long term contracts and bring in newcomers.