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Channel running to mill  RSS feed

 
Woutah Maze
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Hi all,

about 300 meters from our house a little dam was built many many years ago and from there a little channel of about 1m wide (attached) runs alongside the hill and then comes down alongside/ underneath our house (restored water mill). Perfect for our plan to get a micro hydro installation installed which will completely remove the need to occasionally need to use a generator if it goes very cloudy for 3 days without wind (Portugal!).
We had to open up the dam some weeks ago as the channel (with an old irrigation tube) was leaking so much our fruit trees in the backyard were drowning.
So, we started looking at all possible solutions to get this (more or less) water tight. Budget over let's say 15 years is the main factor and so far the only feasible solution we found is to replace the old tube by a new one (ie http://www.plastiagro.pt/detalhe/2830/).
The downside is that these tubes don't last very long (especially if a medium sized rock falls on top of it) and it's not easy, not to say impossible, to replace a damaged part of the tube. As the channel runs alongside the backyard we also need some way to get some irrigation pipes connected to the channel. So we'd have to replace this every 3 or 4 years, tolerate some leaks and it's not the nicest looking solution.
Smartditch, a great product, but not even close to budget. At least a 0 too many in their price
Concrete canvas, sounds a brilliant solution. I made an enquiry for a quote, but I fear the price.
Concreting the channel, no machinery is possible and this could way so much the channel would need a looot of prep work
Half PVC tubes might sort of work, not ideal though as the channel has bends and is still quite expensive for a mediocre solution.

So here we go folks, any questions, let me know. I welcome your sensible suggestions

W
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The Channel
 
David Livingston
steward
Posts: 3674
Location: Anjou ,France
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What sort of soil are you on ? Any chance of using local clay?
Water mills have been on the go for thousands of years . What was used when the mill was built?
How about stone and cement ? You can make water proof cement

David
 
Woutah Maze
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Hi David,

the soil of the channel currently is quite clay-ish so that would indeed be the most permaculture-like solution. However... looking at it from a practical point of view this would require a lot of maintenance because of our lovely fellow creatures making holes and tunnels etc etc. Combined with the fact that we can't have our backyard being wet because of the fruit trees, we're looking for a more permanent solution.
In the past clay was indeed used, but back then there were 11 mills so a combined community effort to help each other out meant that this was feasible. I also have a nine-to-five job to take care of as the mill is not my source of income
Stone and cement sounds interesting. Any useful links for that by any chance? What would you think about the weight/ pressure this puts on the channel and possibility of earth movement causing cracks?

W
 
Denise Kersting
Posts: 87
Location: South Central PA
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cat fungi urban
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Hi! do you need to have your channel covered? I've seen pond liner that might be cheaper to use to create your penstock in a "stream-like" style than the tube you linked to. There is an option to use pvc, but it might be cost prohibitive, I enjoyed reading about this guy's setup: https://ludens.cl/paradise/turbine/turbine.html. If you could dam up and dry out your channel, you could build forms and pour concrete similar to making a pool. I would love to follow your setup, I wanted to do micro-hydro at our cabin, but I don't have the drop & run req'd on my land, and don't want to divert enough for a low head setup.
 
s. ayalp
Posts: 43
Location: istanbul - turkey
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dog greening the desert hugelkultur
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Why don't you use corrugated plastic pipes? Though there are many types of corrugated pipes, metal, one layer, two layers, thin plastic pipes for cable laying etc, the one that we (I am a civil Eng) generally use is two layered top-layered-stiff 12m pipes. When an unsightly (gray water) open channel water needs to be covered, we usually use corrugated plastic pipes. We also use them (larger ones of course) under roads, when the road passes over a small creek. First they serve as a framework while concrete is being poured (the water can be diverted already) and later on they remain for the main purpose. They don't need much maintenance (for your project it can easily last 25-30 years or even more).
Their main advantage is since they are prefabricated and come in large pieces (12m) they don't require much site preparation. You dig a channel, put some sand in the bottom layer, put the pipes make connections (a very easy process, with gaskets), backfill with fine material and move on.  Sand and fine material is to protect the pipe, so if there is not much traffic on the pipes I would say you don't have to use. Another advantages are, it has low friction coefficient, requires low maintenance and easy to make T or L connections.
The main disadvantage is an inherit one. When an open channel flow is put through pipes, to keep calculations etc simple, you have to keep the flow as an open channel flow, meaning the whole cross section of the pipe cannot be used by water, there should be some gap. So the pressure in the pipe cannot exceed 1 atm.  The pipe diameter can be larger than what you expect. What we do is that, we inspect the creek to see the largest flow mark, not the current one, calculate the required cross section area, and try to supply at least that area by pipes. In case of a large rain event and in case some of the area is blocked by sediments, branches etc, water can pass through without harming the structure.
Here is the link that might be useful
corrugated pipe-double
and a photo of the pipe type
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Woutah Maze
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Hi Denise,

incredible project that must have been what these guys did there in the jungle! Thank god our channel is already there
By now, we've more or less decided we'll either go with pipes, tubes or some sort of liner. Now to find the cheapest option which could be reliable for as many years as possible!
We already had a brief look at pond liners, but then forgot about it as we imagined some sort of closed tube/ half open PVCish channel would look much better - not thinking about cost of course. We are indeed now exploring channel liners again.
By the way, we don't have much head either, but still think one of the products by powerspout might be suitable for us!

@ s. ayalp. Would be a very good option indeed, but I'm afraid about the cost.. At certain places in the channel where often rocks fall down there are already some corrugated pipes but I believe those cost about 15 euros/ meter? That would be 4,500 euros just for the pipes.
Cheap for companies, governments etc. Not really for individuals if you're trying to get hydro just so you'd never have to use your generator anymore.
Prices like this keep bringing us back to the cheap plastic tubes which still look like the best option, even if you'd have to replace them every 3 years let's say. Having said that, the fact that i posted my question here on this forum, is because I'm hoping that someone still has a great alternative up their sleeve! ie a much, much, much cheaper version of the smart ditch

The amount of water going through the pipes itself shouldn't be a problem as we can regulate the water at the dam quite well.

W

ps: we had/ have some issues with our off-grid solar system recently, but I'll keep updating this thread.
 
Denise Kersting
Posts: 87
Location: South Central PA
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cat fungi urban
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If you are really industrious you could look into making bored wood piping: http://www.mswmag.com/blog/2014/10/wooden_pipe_a_trip_down_underground_memory_lane. Mentioned as more of a joke, however, it was used for a very long time. I'm not sure how much clay piping would cost, but there are several suppliers online that if you give your specs they will give you a quote. Although I do like the open channel idea, I think you could find good uses for the water that flowed by, though plants like watercress, and maybe pulling off enough for a small pond for water chestnuts and lotus. I think the powerspout might be a great solution for you, I did look at that option, but it wasn't really workable for my land. We thought about the Rife river pump, but it was too costly for our seasonal use cabin. Since it's just our cabin for camping, we really don't need much power anyway, but we do have a small solar panel to recharge a battery for pumping water up to the cabin.
 
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