The AD&D Dungeon Masters Guide has mining rules on page 106. These rules are given in the context of siege warfare. The purpose of the mining is to undermine an enemy fortress or infiltrate into other underground workings.

The table on p.106 shows the cubic feet per laborer (and race of laborer) per eight-hour shift. It also gives how many workers can fit inside standard tunnel widths. Plus odds of encountering existing voids (caverns) and the inhabitants of such voids. Overall it’s pretty bare bones and requires a fair amount of calculation depending on what you want to do. In the tables below, I’ve calculated the amounts mined in a three-shift day for a standard ten-foot wide tunnel. This useful when wanting to quickly determine how far a crew can dig.

For example, a human crew of twelve digging in soft rock can make eleven feet of tunnel in one 24-hr period. This is a three shift day, so 36 total diggers required. For such a crew to cover the 100 yards under a castle wall would require 27 days (300/11=27.3).

However, wants to mine for resources? What about those dwarf mines rich in jewels and metals? The DMG is silent on the topic. Similarly, the DMG changes the frequency of encounters in civilized areas with roads. But no rules for building roads are given.

Here I’ve presented a simple method of mining, tying the riches found to various treasure types listed in the Monster Manual. Is it scientific? No. But it is simple, and you will be able to determine a regular income for a dwarf village. Note that by using the Monster Manual treasure types, miners will occasionally find magic items. Those with no romance in their souls may choose to eliminate finding buried magic items but remember, AD&D is a fantasy game. The whole point of any rule is to generate interesting scenarios. What could be more exciting than your dwarf miners coming upon a lost and powerful artifact? The things the best kept hidden being brought out into the world to sow chaos is inherently good gaming.

The roads presented here are very rough dirt roads. They meet the barest minimum of the definition of road. Any good DM will come up with maintenance costs and the destructive effects of weather. But at least it’s a method of building a quick and dirty road.

Note that the mining rules can also be used to figure the cost and time to build that mega-dungeon. For example, an 8.5″ x11″ piece of quarter inch graph paper at 10′ per quarter inch is 74,800 square feet. Three shifts of dwarf crew could quarry it in all in 1.9 years, humans could do it in 3.6 years. In my campaign, a tribe of mining dwarfs encountered a void and within that void was determined to be another tribe of mining dwarfs. This led to a protracted underground war/feud between these two tribes.

Let me know what you think. Was this approach helpful? How did you use it? What happened?