WATER MINE (not yours?)

Rtrak · Post: # 185784Post **Rtrak** » Mon Feb 01, 2010 1:05 pm

Hi folks, I'm quite new here so if I've got this in the wrong place give me a gentle nudge! I'm based in central Portugal where I'm busy sympathetically renovating an old granite farmhouse (assisted by unsympathetic local builders). Over here, as well as conventional boreholes or wells, ground water is extracted from mines. I get a lot of questions about these as they don't seen common elsewhere so I thought I'd expand a little. 0K, time to put on the kettle or switch topic!

The granite rock here is relatively soft, in the past this was excavated using hand tools to initially form a roughly horizontal passage about 400mm wide and 1700mm high, little niches were cut in the walls every so often to hold candles. I can't find out how they decided on the location of the entrance, possibly witchcraft or other ancient art, maybe whoever predicted water had to carry on digging themselves if none was found. Some of these passages are over 100m long, the longest I have is 73m. I guess once they'd gone 50m and found nothing it was a difficult decision whether to carry on or abandon it and start somewhere else. When water was located, they dug back letting the water flow toward the entrance before building a dam wall incorporating a tap to contain and distribute the water.

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When using mine water there are a few considerations to bear in mind. Light must be excluded to prevent weeds growing but access must be maintained for clearing etc. Bats, watersnakes, salamanders and other water life need to be relocated and sediment needs to be removed. There weren't any bats in the one I chose (there were however, mosquitoes - ouch!) so I netted the entrance to prevent bat ingress. I've arranged for a local approved contractor to clean the mine out before sealing and fitting an access door when my work is complete.

Having given the matter of water for the house some thought, I decided on a plan of action. Make a hole through the top of a mine about 150mm diameter 2m deep near the house. Install a permanent sheathing pipe through which a flexible collection pipe with non return valve and rough filter will enter the water. An electric pump with pressure regulater / vessel will sit atop the sheathing pipe in a insulated enclosure which will house a sediment filter. The feed pipes will then exit the enclosure in a trough 35m long and 750mm deep and feed into the house terminating in a stop/drain cock.

I identified the starting point for the hole using sophisticated scientific satellite techniques borrowed from NASA (isn't eveything these days?). No, in reality, as the water is currently 750mm deep (my wellies 400mm high) I opted for the established 'lining it up by eye' technique, I won't bore ( no pun intended) you with the technicalities as it's familiar to all.

Work started two weeks ago, I started with a hammer and chisel then drove a section of scaffold tube into the ground with a sledge hammer, the stone and powdered stone sticks in the end of the tube and exits when the tube is knocked against a stone. Adding a small amount of water helps this process. My various lengths of scaffold tube were modified with an angle grinder to form castelations at the business end like a real rock drill. By the way, the other (sledge hammer) ends were beginning to look like a peeled bananas as work progressed. 6 hours work 1.2m progress, 800mm to go.

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One week later I resumed, 4 hours later I broke through, right on the side of the mine!

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Ho hum, another 150mm over and I should be right on target!

Just a few tips if considering similar projects.
1. Don't put your glasses in a pocket where gravel accumulates.
2. Don't let your spare glasses fall down the hole unnoticed.

If there's any interest I'll add to this as work progresses!

Post: # 185851Post **MKG** » Mon Feb 01, 2010 11:09 pm

Well, I'm completely fascinated - keep those reports coming, please!

Mike

Millymollymandy · Tue Feb 02, 2010 7:11 am

Fascinated yes, bit confused as very technically challenged.

Why don't you just put a pipe down into the hole (the fancy whitewashed one) that's already there and pump it out?

Do keep updating as this is interesting and very different!

Rtrak · Post: # 206056Post **Rtrak** » Sat Aug 21, 2010 4:05 pm

Hi folks, sorry I've not updated, I damaged my spine somehow (probably over ambitious working, I'm 52 not 22!) and lost the feeling in 3 fingers of my right hand, it's just returning a little now but typing can still be inaccurate, absolutely infuriating!

I decided to junk the idea of using my 'hole in the ground' to extract the water. I decided it may be beneficial to increase the capacity of the mine by creating a new dam wall in the mouth. I built the wall by pouring concrete into polythene sacks so that the water wouldn't dilute it before it set. When I reached water level I incorporated a pipe to allow the water to pass through it. I then built the wall a further 600mm (2 ft) higher in concrete pinned into the rock with steel bars. I plugged the hole in the pipe and went off to do something else. A couple of days later I went over to the mine and saw water coming over the top of the wall - fantastic! I estimate I'm now storing about 50,000 litres of water, it's now mid august and no problems. There were a few 'weeps' around the wall, my partner's hair seems capable of blocking most pipes but instead I poured cement in the water this has worked fine and I now have no 'weeps'. I installed another weep pipe and built the wall a little higher so that I could mount the pump there. While I was doing this I noticed a small bird's nest in the roof of the mine, after I installed the pump I saw it was inhabited so I put a tarpaulin over the pump and left the bird to it. I also installed a ramp in the mine so the salamanders and lizards could get out and over the wall into the adjoining pond - the snakes prefer to go through the weep pipe much to the interest of our cats.

Next move is to install an access walkway so I can walk to the pump instead of walking through the pond or draining it. I'm also covering the top of the wingwalls with concrete beams so I can get the rotavator to the veg patch without acrobatics.

Thanks for your interest, I'll post some photo's if anyone's interested. I'm going to post soon about the birds that made a nest in our bedroom wall (internal) then laid their eggs!

Sat Aug 21, 2010 4:46 pm

I was going to ask you about the nest in the photo - same birds?

Rtrak · Post: # 206072Post **Rtrak** » Sat Aug 21, 2010 7:16 pm

No, the watermine bird was very small, I looked-in it looked out then flew away. I finished what I was doing then left well alne for a few weeks. I saw the bird fly in and out again so I knew it was OK. Ideally the mine should be sealed from light but I opted for the tarpaulin as a compromise.

Our house was a shell with new roof and floors but little else, not rendered inside or anything with holes left by the old beams etc unfilled. I ordered new windows and doors and continued working away. I then noticed a birds nest in our bedroom in one of the holes where a purlin used to sit. As I was working on the ensuite bathroom I saw the bird but only fleetingly. My partner noticed the four little eggs (guess us men don't notice anything!). When the windows and doors were installed we asked showed the fitters eggs and asked them to be quiet. We stayed in our caravan instead of moving into the house where we left the window open and checked the eggs periodically. One day I checked them and they weren't there, my partner checked and could see 4 tiny birds! They were fed regularly by both parents, Elaine had to return to the UK for a week. I was again working in the ensuite and looked into the bedroom where our Jack Russell bitch Daisy was looking puzzled, I checked and also witnessed the 'test flights' around our bedroom. Elaine returned that afternoon but the birds had flown! Quite rare I would have thought that all four should survive also quite moving. For a few weeks afterwards we found birds flying in the house, entering through the open windows or skylights. We caught them and popped them outside again, they didn't struggle when we picked them up either, maybe they had come to trust us, maybe it's like a Waly Disney story? I've attached a photo of the chicks, tricky to take because we didn't want to scare them or the parents.

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Millymollymandy · Sun Aug 22, 2010 5:26 am

Ahhhhhh lovely story and photo! Would like to see photos of what you have done with your water mine.

pumpy · Post: # 206402Post **pumpy** » Tue Aug 24, 2010 10:47 pm

Sorry, but i'm totally confused ( and i've been drilling bore-holes for a few years)..... there's no such thing as "soft granite". All aquafer water is "mined", and sometimes it can be "artesian", where-by it hits a pocket of impervious rock, creating a build-up of pressure, then once you drill into it, you release the pressure so the water naturally comes to the surface.... ( it's a law of physics). I don't under-stand this stuff about bags of concrete, etc....... i'm intrigued!

eccentricemma · Fri Aug 27, 2010 12:16 pm

this is a very interesting post about water mines, im very interested as i also live in Central Portugal (we must have some friends in common somewhere) and take water from a mine but it's all a bit of a mystery to me other than putting the tubo in and taking the water out!

also, do you use a filter to purify the water/have you had your water tested?

Rtrak · Post: # 226979Post **Rtrak** » Thu Mar 24, 2011 1:42 pm

Sorry for the delay in responding folks, don't often check in. Pumpy - regarding the granite, the granite retaining part of our forested area is 'soft' in that it can be scraped away easily by hand and is washed away by rainwater. The granite the house is made of is harder, meaning that tools are requires to shape it and that it doesn't readily wash away with the rain. I'll post some photo's. The concrete wall was necessary to both raise the level of water in the mine and to separate the mine from the 'pond' area, again I'll post some photo's with an update showing the cover, footway, pump and filter.

Rtrak · Post: # 226991Post **Rtrak** » Thu Mar 24, 2011 4:08 pm

I've taken some photo's now for an update on the water mine situation, also the granite situation. It's the same granite but the stuff in the shot with my hand can be removed without damaging my fingernails, the stuff the house is made of is much harder, guess it must be the amount of compaction when it was formed!

After trying various pumps I've been using the one in the pictures for about 3 months now and it seems fine. The other pumps had a pressure vessel to smooth the flow but the pressure controllers can be prone to failure causing premature failure of the 'baloon' in the vessel. The current unit is a simple centrifugal pump with a pressure controller built-on. This starts the pump when it detects a pressure drop (open tap etc) then shuts off the pump 5 seconds after the pressure drop stops. Seems to work fine, it holds at about 4 bar and maintains 3 bar with the hosepipe running. I've fitted a 3 bar Pressure regulating valve at the stop tap to the house to prevent over pressure problems in the case of the pump controller failing. The water for the house is filtered as you can see (the filter and flexible pipe are usually covered to prevent UV contamination). The filters are only €1.80 and I change them about once every 3 months. We don't drink the water (the locals say it's good though)as there's a 'font' nearby and we collect drinking water there in 5 ltr containers. I have a similar back-up unit and can now change them if needed in 5 minutes without dropping my tools and glasses into the water mine!

As promised I added a roof to the water mine 'pond' this also gives me better/safer access to the veg plot. I will continue the existing wall over the mine roof and render it to match the rest of it. I also added the walkway so that I could access the dam and pump more easily, this has made a big difference.

I've cleaned out the 'pond' and the water is clear, the salamanders are thriving and I'm thinking of adding some fish. I've also taken a photo of the inside of the mine, the entrance is about 3m long then two legs go off at 45 degrees one about 70 metres long, the other 30 metres. I've also added a picture of this years 'water mine nest', I removed the old one after the occupants fledged last year, must be much more comfortable now with a roof and no wind. Also believe it or not, the mine emits warm air, god knows why, but it's noticeably warmer in there and in the mouth than outside.

I'll put the final couple of photo's on the next post as I can't post more than 6 images.

The water flows out of the water mine 'pond', through an open culvert for about 10 metres then into a tank that was used for clothes washing. A previous owner tripped on the granite steps above the tank, knocked himself out on the edge of the tank then drowned with his head in the tank!

Guess that's the end of the water mine saga now, if anyone wants more information drop me a line. Many thanks for your interest, I'm embarking on chicken keeping now (see separate post)