Building 2 dams part 1


G’day folks. Today I’m talking about dams
and whilst our neighbours all have dams, we don’t. So I’ve been in the process of
building some dams and they’re just in the early stages and I’m gonna walk you
through what I’ve been doing. As you can see all around here I’ve been gathering
rather large boulders, these boulders are about uh, the largest one is probably
about 50 centimetres long and then you’ve got this one on the end here,
that’s about 35 centimetres from that to that, in that direction. The one on the
end over here, there, this big fellow here is probably 60 centimetres in length,
probably a little longer he’s quite large. So ranging in weight from all
the way up to probably about a 30 kilo chunk of stone there. The area that I’m
in is a creek bed, it’s a dry creek bed, so it only gets water when the
rain happens. So that flows on through there. I’ll get a better shot for you. That flows down here cuts across there
and winds its way through here. And we go upstream, it comes through here
and goes around that thing there and goes all the way up here the neighbour
has a dam up there, it’s quite large, so it never goes dry and that’s what I’m
trying to achieve here, but we’ll see. So I’ve started digging out this little
space in around here to get a bit of extra depth because the water retention
ability of a dam is to do with its depth as a ratio of its surface area. So if you
put a bowl of water outside and it’s a deep bowl and you put a plate of water
outside with the same amount of water in it that plate will evaporate a lot
faster than the bowl, okay, so you want to create your dam to be more like a bowl
than a shallow plate. Now in order to retain water you need to have clay. Sand
is essential too because sand is 2 parts to 1 part clay for making sort
of like a cob-clay cement and you can add ash from a fire. Preferably if you
get a whole bunch of eggshells or oyster shells and you put those into a Dutch-oven, like a camp up in one of those cast-iron steel pots and you heat those
over a fire, until they turn to ash, you will have created calcium carbonate or
what’s known in the cement world as ly ‘L’ ‘Y’ ‘E’ sometimes called limestone or lime, as well. So you add a little bit of that in there and you get a very hard cement.
Now the purpose of this, it comes down to the size of the granule. So sand,
when you’re doing a soil test, sand, if you shake up the soil in a jar of water
the sediments that fall first to the bottom that’s sand, in the
first 30 seconds that’s all sand. The next 30 minutes
that’s silt and the next 30 days is clay. It takes a long time for clay to
settle down because it’s very small molecules. So the sand is up to a
millimeter in size or down to a millimeter in size. Silt is between 1
millimeter and I think it’s 1 micron which is like a point 1 (0.1) of a
millimeter and then clay is from about 0.1 of a millimeter down to 0.001 of a
millimeter so very, very tiny. The purpose of that is to stop the water from
getting through the clay and that’s how you retain the water. Now I’m going to
show you a 2nd dam that I’ve been building a 2nd type of dam and I’m
going to be gathering the clay from that 2nd dam to then line this 1st dam.
Eventually, I want this wall to be quite large, I want it to be at least at least
probably up to the height of this rock here so that’s probably another meter (1m) of height that I need to give it, because, I do want this to retain probably at least
10,000 litres, enough for me to have a swim in the hottest of days. And now to
damn number 2. Here is the 2nd dam, obviously in the
very early stages and this area is predominantly clay. So with the
tanks uphill we get a lot of overflow water. We don’t have any dams on the
property (as I mentioned) but we do have these two big tanks. And this one
particularly has a bit of a leak in it a crack, which I hopefully fixed recently.
As you can see, there’s a lot of Cumbungi, the cattail, bulrush grass there
and you might be able to hear some froggies. Okay so when the waters
come through they trickle down through here and they come in down this little
path here and then they end up right about here and I want to catch water
here and I would like to grow some rice down here. And I reckon it would be nice
to have an open dam as well then I can turn this entire area into a real lush
ecosystem so I want to do a bit of a terraced, stepped sort of system going on
here, where I have an upper rice paddy and a lower one and a third tier, if
possible or dig this section out here to a depth of about 5 meters or maybe
2 meters, see how low I want to go before I get exhausted. As I do that I’m
going to be getting the clay from here into a wheelbarrow and taking it down to
my other little dam down in that section over there. As ‘they’ say “killing 2wo birds with 1
stone.” So that’s the early stages of the 2
dams.

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