For all intents and purposes you can bury a Monolithic Dome as deep as you want. Near the Rio Grande there is a 30 foot dome buried 28 feet underground. A heavily loaded dome tends to become like a cookie cutter, therefore, the footing must be wider to sustain the load. The structure itself needs a little more strengthening, too.
Advanced planning and engineering is necessary. A standard Monolithic Dome will handle earth bermed against it without any special consideration other than drainage. Any buried structure must be carefully drained and protected from water.