Sure enough, once I told Karsh that the mountain was clear enough for mining ore, he insisted that I go mine some. He wasn't actually pushy about it, instead offering me money to go mine as soon as possible. I turned his money down. I myself have a lot of projects I'd like him to work on soon, so getting him plenty of metal to work on those projects with means our goals are aligned for now. Plus, I'm sort of the central bank, money isn't actually valuable to me. Instead, I'm in charge of distributing money to goblins via jobs that would help the village, so I'm going to hire a few to help me ship ore back down to the village and process it in the rock crushers.
As such, I've spent the last twenty-eight days excavating ore. Part of that time I've had to actually develop a new rail line in the cave system, to help with moving ore out from the ever deepening shafts that I've made. I'm glad that there doesn't seem to be an end in sight for this vein of ore, because buying and shipping in metal would be a nightmare to have any reasonable amount of it. Plus high quality metal is currently our most valuable export ignoring the fact I can grow gigantic crystals.
When I made it back down to the village today, I was glad to see that Karsh had been hard at work refining the metal. There were still large piles of unprocessed ore, but there were also a whole lot of ingots in piles. Normally, tailings and slag from processing metal like this would be a pain to deal with, but with stone shaping they can be formed into blocks which we then dispose of by imbedding them in the road construction process.
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Karsh has learned a little more of the demon language while I've been gone, although it still remains very basic. I took some time to check in with him since I was gone nearly a month. His wife and kids miss a lot of the amenities from back in their homeland, but Karsh seems happy that he's finally getting to work with the metal that was the whole reason he moved his family here. We took the whole day conveying this sort of information back and forth using large lightstone slabs and charcoal to draw complex ideas to share.
Karsh had an interesting question which led us down an entire rabbit hole. The question was basically, "Why do you let the stream flood this much?" It is early spring now, which means that between the snow melt and frequent rain, the reservoir is slowly getting filled, leading to increased output flow. So I went and showed him the dam. Once we returned, he had a second question, "Why build it so big?"
That question intrigued me, and I asked him what alternative he'd propose. To which he did some basic drawings that conveyed an interesting idea. Rather than build a large dam, which has these complex mechanisms, the dwarves would put small loose rock dams at various points down valleys where streams would form during rainy seasons. This would slow the water down and prevent it from all flooding at once, leading to a more smoothed out river and stream cycle. This is apparently pretty common knowledge among dwarves, since their country is mostly mountains and hills.
I hadn't really thought of doing something like that. I went and built a huge engineering project, when I could have just been piling stones up in various places to accomplish a similar feat. I thanked him for the idea after that discussion, and decided to set out to track where the tributary streams form during the spring with the rain and melt.
I'll be missing out on the smallest streams, which likely only form at the very start of spring when all the mountain snow starts to melt, but I should be able to find plenty of small streams to demarcate in the valley higher up. Once I get a few of those marked, I'm going to make a few loose rock dams, and teach a few goblins how to make them, then pay them to keep making them along all the tributaries.
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With these dams, you can't just build one on a stream and be done with it. Each stream needs many dams placed every so often to continually slow the rate of water flow down the hill. If the stream is too large, or too rapid, it'll knock the dam down, but for small streams, the water loses momentum hitting the rocks. It then pools up behind the dam while it slowly drains between the rocks. That spreads out how long the water takes to reach the main stream, and by extension the ocean, and provides a much smoother volumetric flow in the main stream. It should also make the water cleaner as more fine particles drop out of the slow moving water.
The main dam can already handle a lot of water flow, but to add capacity to this dam requires a lot of excavation of stone. Something we sometimes need, but we can get a lot more bang for our buck labor-wise by just having some goblins build rock dams. As an added bonus, when we have goblins manually breaking rock in an attempt to get stone shaping, we would often have to spend some time doing our own stone shaping on the broken rock to make it into a shape that is more usable. Instead, the worst shape rocks can just be shipped up the roads to be used for making rock dams.
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For five days I followed our main stream upriver and drove two foot tall stone stakes into the ground wherever I found a tributary while it was sprinkling or raining. The work itself was pretty miserable since it was raining. I found 3 tributaries, and then followed those tributaries to find an additional 18 second-order tributaries.
A lot of them are a real pain to hike to, but there is a ready supply of stone nearby many of them, so a goblin with a decent pickaxe could probably break stone to make the rock dams. Otherwise, an individual with stone shaping will have to be used for some of the tributaries. In either case, I'm going to spend a few days making a few example rock dams so I can teach a few goblins how to make them.
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After five days I've cobbled together three example rock dams. One is quite large, and sits along one of the major tributaries of the stream. It took the longest to build, and required me to stone shape some materials because I ran out of easily accessible rocks in the nearby area. The second and third dam are in second-order tributaries, and each shows off a slightly different aspect of things to consider. One tributary had cut a fairly deep gash in the earth, and so that dam had to be first piled into the gash, then raised a bit above that into the surroundings. The other one I built just before a small section of steep elevation change, where it would be impossible to build a dam inside.
The idea is that each of these dams can help to explain an aspect of rock dam building, so that the goblins know what they're looking for. For now I'm holding off on building any rock dams on the main stream itself, since they'd either have to be built closer to it's source where the flow is much smaller which would mean a much longer hike for anyone working on that project, or would end up being very large and take a lot of stone and care in their construction.
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I took two days finding goblins who would be interested in some long term work, and after I found five who were interested enough in building the rock dams, I took them up the mountain to show them the ones I already made. I then took another four days making a few rock dams with them to make sure they understood what work they would be doing. I then showed them how often and where we want the dams.
I'll pay them slightly more than standard labor jobs, since they'll have to trek through the wilderness for a large portion of their work. I'll also check in on their work in a month to see how progress is coming. If they can complete between one and two dams a day, then we should have all of the tributaries mostly dammed by the end of the year. Then next year during the spring we'll check to see how all the dams are holding up, and whether we need to repair any, or change them.