Excavating a Tunnel Mine (CBD)

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Excavating a tunnel is hard work and time consuming. The rates for excavating by the various races follow. Rates are in cubic feet, per miner, per eight-hour day. 
 Mining Rates Table
 	Type of Rock	Type of Rock	Type of Rock
Race of Miner 	VerySoft 	Soft 	Hard
Gnoll, Halfling,Human 	75 	50 	25
Gnome, Kobold 	80 	60 	30
Goblin, Orc 	85 	65 	30
Dwarf, Hobgoblin 	90 	70 	35
Ogre 	150 	100 	50
Hill Giant 	250 	150 	75
Fire Giant, Frost Giant	300 	200 	100
Stone Giant 	500 	350 	175
A tunnel mine must follow the shifting vein of mineral through the earth. Such a path typically requires a tunnel 10 feet wide and 10 feet high.
When a miner discovers a vein, roll 1d10 and multiply by 10; this is the depth in feet needed to intersect the vein. Mining may now begin in earnest. To determine the path of the vein, roll 1d4 and consult the Mineral Vein Direction Table.
 Mineral Vein Direction Table
D4 Roll	Vein Runs
1 	North-South
2 	East-West
3 	Northeast-Southwest
4 	Northwest-Southeast
The vein always runs at least 20 feet in the direction indicated. After each 20-foot section is excavated, roll 1d10 and check the Vein Path Alteration Table to determine the new path of the vein.
 Vein Path Alteration Table
D10 Roll	Change
1-2 	Steep descent
3-4 	Shallow descent
5 	Curves right (10-60 degrees)
6 	Curves left (10-60 degrees)
7 	Continues straight/
8 	Shallow ascent*
9 	Steep ascent*
10 	Vein ends
: * If the mine starts on the surface, the first time this is rolled it is treated as descent rather than ascent.
Miners who wish to continue working the mine must follow the vein, even if it goes in a direction they do not wish to follow. If the path of the vein takes a course that makes it impossible to follow, such as emerging into thin air through a cliff face, that particular course of the mine has run out. If the vein ends in both directions, the mine is played out. This rule takes priority over the Duration of Mining Site rules.
In unusual circumstances, say a tunnel that ends at a cliff which overlooks a gorge, miners may try to pick up the vein again on the other side. The DM must decide how likely that vein is to continue, depending on the situation.
==Shoring a Tunnel==
A tunnel mine must be supported, or shored, with wood or stone pillars. Otherwise, sections of the tunnel will almost certainly cave in. Shoring can be done by characters with Mining, Carpentry, or Stonemasonry proficiencies.
Each 10-foot section of tunnel requires two side and one ceiling brace, each at least 1 foot thick. If the tunnel is 10 feet wide and 10 feet high, each brace uses 30 feet of bracing material. Each shoring brace requires four hours to build.
==Playing Out a Mine==
Mines contain finite amounts of mineral wealth. Sometimes, this amount is enough to keep miners busy for generations. More frequently the mine plays out after a period of intensive mining.
To determine the length of time a mine will produce before depletion, roll 1d100 at the start of the mining operation. The result is the number of weeks the mine can be worked. If the result was doubles (11, 22, 33, etc.), the mine has a much longer duration. Roll 1d100 again, the result is the additional number of months the mine will produce. Add this figure to the number of weeks set by the first roll. If the second roll is also doubles, roll 1d100 a third time, the result is the number of additional years the mine is will operate. Further doubles rolls are treated as tens of years, hundreds of years, and so on.
For the sake of convenience, treat each month as four weeks and each year as 48 weeks or 12 months when totalling up the mine's longevity. Please note that a "week" is the amount of work that one dwarf can perform in a week. If 12 dwarves are engaged in excavating a mine, 12 weeks of the mine's lifetime are used up for each week of operation.
If the mine is a placer mine, disregard any doubles rolls for the duration of the find. A placer mine is always depleted after 1d100 hours of work.
Category:The Complete Book of Dwarves