On the fuzzy border between elves and dwarves North of the Vale, the dwarves built a refinery of significant scale. Though there was little to mine there, they considered it an important symbol of their claim on the area and, in fashion uncharacteristically reckless for even dwarves, disposed of their waste in the river downstream from where they drew their water. This waste poisoned the water for the elven village down the river on the opposite bank. The elven village was abandoned, but the refinery remained a while longer. It was abandoned only when the dwarves came under attack.
The refinery has since been reawakened by the gnomes.
This is the source of the poison the Citadel House adventurers were seeking when they first traveled up the East Confluence river. That they gained access to on a later visit when they first encountered the gnomes, that they stopped in on their way to Stalla Airgid, and where they delivered food in exchange for refined ore.
It is 29.4 miles up river from Confluence, where the eastern bank rises into a cliff. This cliff reaches as high as 50 feet above the water line at it’s highest point and does not return to the water line until 29.8 miles up river where a short section (0.1 mile) of rapids drops the water down nearly 40 feet to the lower level at which the cliff is 50’ above water, At the top of the rapids, the cliff rolls away into a gentle hill meeting the water’s edge. Six fountains in the cliff side spill a water/chemical solution into the river.
The fountains are 4”x4” square holes with a 3 inch overhanging lip. The lip has an elegant shape, but otherwise there is no adornment. Other hints as to the location of the refining facility include the water intake, a 1’ diameter stone pipe that is mostly underground, but opens at the high end in the bed of the river at the high point before the rapids. The other end is inside the facility, feeding a number of fountains and faucets. There are also two hidden doors. One is in the cliffside only a hundred feet after it begins to rise, 10 feet above the waterline (inches above the high water line), and the other is about a quarter mile away from the river to the east, shaped like a cellar hatch, purposefully hidden beneath brambles in the area.
The river door has a 60% chance of being barred from within, 30% chance of being open by mistake, and 10% chance one of the gnomes is out hunting. If unbarred because a gnome is outside, there is a 1% chance of a gnome entering and a 1% chance of a gnome leaving. The bar can be broken if a Strength check applied to the door beats 16. There is a chance of falling on a given attempt to force the door: any failed attempt under 5 results in falling back into the river unless a Dexterity save beats 16. Only one person can push at a time. If standing at the end of the ledge near the door, it can be noticed with a passive perception of 15. If searching at that spot, a perception check of 5 is sufficient.
The hatch door has an 80% chance of being barred from within, 15% chance of being open by mistake, 5% chance one of the gnomes is out hunting. If unbarred because a gnome is outside, there is a 1% chance of 1d6 gnomes entering and a 1% chance of a 1d4 gnomes leaving. The bar can hold up to 400 pounds in addition to the weight of the doors. This door is well hidden, requiring a passive perception of 20 to notice standing near it. If searching in the area, a perception check of 10 is sufficient.
The locked status of the doors changes only when a gnome leaves or enters. If no gnome is outside, then each hour there is a 1% chance of a gnome leaving. If a single gnome is outside either door, its likelihood of returning in a given hour is 10%.
Twenty or so (20+1d6) gnomes occupy the facility, mining ore and processing it, along with ore delivered from other mines. If they discover people outside of their facility, they will be cautious, but cordial and curious as they engage. Intruders found within their facility will be met with significantly more suspicion, but not immediately attacked. They will be expected to stand down and obey orders once the gnomes have informed them that they are trespassing. If aggression is initiated against the gnomes, they will retaliate quickly and without mercy.
Interested in dungeon design? Check out this playlist analyzing the dungeon design behind Durlag’s Tower in Baldur’s Gate.