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  • From: Stella <stella@finca-luna.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] Ferrocement water tank pix
  • Date: Mon, 17 Dec 2007 11:01:47 +0100

thanks lots Robyn and Keith,

been looking around for all sorts of big recycled barrels and not much luck there, but nice to hear of the Sydney barrel garden :) Also our walls are from 1m to 3m high in places, so would need multiple barrel heights + they´re more than 20m in length in most terraces, so that would be a hell of a lot of barrels ... which is possibly doable if the 'barrels' are of ferrocement ..

combined with Keiths' comments (and very wary of expensive mistakes)... am thinking whether the most viable option could be tall small diameter (1- 1.5m on the inside) 'barrels' of ferrocement, as 2m columns joined together with metal bars .. to allow drainage in between (and interesting possibilities for vertical gardens in the gaps, which could shade the tanks too)

not sure of the embodied energy of all this being viable, as we're talking a lot more metal and cement ... but on the plus side is the fact that we could start small and make one or two of these 'columns' where the walls are already in need of repair, and only proceed if they stand up to real life conditions.

i´ve no idea if this group takes attachments,.. here's an attempt at sending a pic (not to scale).

yes most of the terraces need concave walls, so joining them up would help with strength.

The other plus is that in terms of water pressure ... we're in dry subtropics with occasional heavy rainfalls in winter season. Massive erosion and most of the water goes straight to the ocean.

but on the farm I´ve observed that where the walls fall down the earth stays up pretty well by itself for quite a while, so am guessing the sideways pressure of the earth on the stone walls isn´t that great - unless it gets very wet ... which would be when the tanks are fullest too, so this is another good point: matching altibajos..

There are a lot of very old round tanks on the island landscape which must be ferrocement of a kind (they're a lot thicker though, about 30cm min.), most of which are now in dis-use because of irrigation now being plumbed in from large reservoirs. They used to be also carp-breeding tanks also... but now palates are too 'refined' to apreciate this fish, apparently.

Interestingly ... the island govt. is now investigating telapia production because there are so many of these tanks around not being used, and so much banana waste not being used ... making all sorts of silly mistakes in the process (like relying on another mono-crop and focusing on large-scales & sterile fish) but bundling in the right general direction (food self-sufficiency and using existing infrastructure for better harvesting of sunlight).

If someone comes up with an energy-efficient (elegant & multi-functional) way of collecting water on small-scale farms we'd leap light years ahead in terms of sustainability here. .. which is why am interested in trying out new things whilst we go about solving our own small scale challenges on the farm.


thanks so much for all the help and inspiration!







El 16/12/2007, a las 23:54, Robyn Francis escribió:

Hi Stella
Another idea altogether...
Something I've seen used successfully for water storage is recycled pickle,
olive and caper barrels, especially the 80-100litre plastic ones. A permie
friend south of Sydney has around 20 of these set up for water storage as a
raised 1.2m high long narrow curvaceous garden bed. The lids protrude above
the soil & mulch (adorned by ceramic plant pots and funky garden
sculptures). The barrels are all connected with 50mm pipes about 10cm from
the base so the water simply flows from one to the next. Thought if you've
plenty of rock available you could build up the rock wall either side of the
barrels (my friend used colourbond roofing iron for the garden bed walls).


The main issue with long thin ferrous cement structures is they really need
to be built exceptionally strong as the weight of the water isn't equally
distributed against the walls as in a round tank structure - you could end
up with an expensive leaky structure that doesn't work.

Ciao
Robyn


On 17/12/07 12:32 AM, "Stella" <stella@finca-luna.com> wrote:

has anyone seen or tried ferrocement walls/tanks, as a multifunctioning
idea?

i´ve never built a ferrocement tank, but fell in love with them in
Brasil after seeing so many for the first time this year. Of all
different sizes and shapes, and heard of very few problems with them
(although of course this could be local bias..)

have been wondering if it would be possible to somehow combine two big
jobs we have to do on our new finca: re-build & repair some big and
small terrace walls, and build as much water storage capacity as
possible. It would be very handy as the positions of the walls are
perfect for both water capture and usage, and we'd like to avoid using
much land for making tanks as all of it is good for growing, and we
don´t have a lot...

the embrionic idea (so far... if nobody tells us it´s just completely
crazy) is to build 'walls' as 1m thick tanks of ferrocement which could
be as high as 2 or 3 m, dug into the earth about 1 to 1.5m, and as long
as drainage allows (either many small 'tanks' with gaps in between for
drainage, joint for support to one another, or install drainage tubes
across the back and front walls).
it´s all totally at the initial idea stage, would love some advice from
experienced folk.
no idea if it's been done but seems a logical thing to try, unless
there are some contra-indications with the material of course.

here terrace walls are traditionally of stone (about 50-70cm thick, big
stones with small 'fillings') and drainage is provided by the natural
gaps in the material (cement is only used in some 'modern' versions).
And most of our walls are curves (we have crecent-shaped terraces), so
that would help, am guessing.

in Brasil we were told on various occasions how suprisingly strong
these tanks are, even outside 'reccomended' sizes and shapes (normally
given in books and literature).

what am wondering about, is ..

1) if anyone has tried this / has similar practical experiences that
might help (not having anyone here with a 'feel' for the material but
yes some fairly good basic notions of pressures, etc, this is a
semi-blind guess)

2) the life expectancy of cement .. I suspect these tanks arent' 'for
life' as we were told ... but just how old are the oldest one we know
about? anyone tried it with lime? (cal)

3) how the ferrocement would be affected by constant contact with earth
on one side, water on the inside and just air on the other side
(long-term)


thanks for all the sites you have sent! will go study them with time ..



El 15/12/2007, a las 7:02, Keith Johnson escribió:

The steel rebar and expanded metal lath give it strength and the mortar
gives it rigidity. The two combined make it VERY strong. Very large
(130
f) ocean-going boats <http://www.ferrocement.org/> are made with this
technique (the Brits built a 120 foot submarine) and their walls are
not
much thicker. Many homes are built with it.

This is my fifth tank and my second 10,000 gallon one. We intend to add
onto the tank a ferrocement room that wraps around a third of the tank
and will serve as a root cellar, storm shelter and spring house
(utilizing the overflow). The tank will be bermed about 3 feet high
around the rest of the circumference. Freezing has not damaged our
tanks, though the coldest climates would require more extensive berming
or partial burying.

The cylindrical shape itself is a principal source of strength as the
outward pressure is equalized over the entire surface. The overall
thickness is one to one and a half inches. The walls are not thicker at
the bottom of the wall than the top of the wall. The roof is the same
thickness. When empty, it rings like a bell when you whack it with a
rubber mallet. If you sing in it, it echoes nicely. A really lovely and
versatile material and well worth the embedded energy.

http://ferrocement.com/Page_1/english.html

http://www.ferrocement.net/

http://en.wikipedia.org/wiki/Ferrocement

http://www.thefarm.org/charities/i4at/surv/ferro.htm

http://www.green-trust.org/2003/ferrocement/default.htm

http://www.eugenesargent.com/bench1.htm

The stone gutter you refer to WAS essential to direct a large flow of
water into a sinuous garden path that provided many infiltration points
to prevent erosion in a very erodable landscape.

Lawrence F. London, Jr. wrote:
Keith Johnson wrote
Peter and I recently finished laying pipe to plumb our water tank and
have started to install the roof catchment parts of the system.
You can look at pix of the project at
http://picasaweb.google.com/KeithDJPcA/FerrocementTankPix02

Nice work. What design factors are required to give it enough
vertical and circumferential structural rigidity to keep
it from bursting from hydrostatic pressure and is the concrete
thicker at the base that near the top?

http://picasaweb.google.com/lh/viewPhoto?
uname=KeithDJPcA&aid=5141688084664055841&iid=5141688179153336402
The stone gutter in this pic is just like downtown. I used to build
some of these for landscape customers.
If you have a lot of flow this feature is essential.


--
Keith Johnson
"Be fruitful and mulch apply."
Permaculture Activist Magazine
PO Box 5516, Bloomington, IN 47407
(812) 335-0383
http://www.permacultureactivist.net
http://www.PermacultureTradingPost.com
Switch to Solar Power the Easy Way
http://www.jointhesolution.com/KeithJ-SunPower
http://www.PowUr.com/KeithJ-SunPower
Blog: http://kjpermaculture.blogspot.com/
also Patterns for Abundance Design & Consulting
http://www.permacultureactivist.net/design/Designconsult.html
also Association for Regenerative Culture
http://www.ARCulture.org
also APPLE-Bloomington (Alliance for a Post-Petroleum Local Economy)
It's a small world after oil.
http://www.relocalize.net/groups/applebloomington
also Bloomington Permaculture Guild

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