Tuesday, August 21, 2012

A Fun Ferrocement Water Tank



  Apologies to my regular blog followers, but this post is primarily geared to an audience of fellow volunteers, to provide step-by-step instructions for making the water tank I've mentioned here before.

   Ferrocement  refers to a technique of making concrete structures with very thin but strong walls, by plastering a rich sand-cement mortar over a reinforcing framework of rebar or wire mesh, or chicken wire, etc. One great thing about ferrocement is that you can fabricate objects in just about any shape that you can form the mesh into, such as this basin that fits into a composting latrine seat for the improvised bidet described in an earlier post.
  We are promoting ferrocement water tanks for rainwater collection in rural communities as a user-built alternative to store-bought plastic tanks which cost about a dollar per gallon of water storage plus the cost of transport, which can be substantial for sites with difficult access. The 85 gallon tank pictured above on the other hand can be built by local people using free, locally available sand, 3/4 of a bag of cement and eleven feet of chicken wire, costing a total of about fourteen dollars. We´ve been making tanks ranging from twenty to eighty-five gallons, but the same basic technique can be used to build a tank up to 800 gallons. (Look for Art Ludwig's book, "Water Storage" for details on larger tanks.)

  The tank is made by applying a sand-cement mortar over a cloth bag that has been stuffed with sawdust or chopped grass and wrapped with chicken wire. Once the cement hardens, the stuffing is removed and the bag is pulled out, leaving the finished tank. A lot like paper maché. The bag will be reusable for many tanks.

 You make the bag by cutting out five coffin-shaped side panels from sturdy cloth- There is an inch of extra material all around the panel for the seams to overlap (two inches at the top). Sew the panels together side to side and then sew it all onto the circular bottom panel. Fold over the extra cloth at the top of each side panel and sew a little pocket for a drawstring to pull the bag tight at the top where the mouth of the tank will be.

. This sketch is for the eighty-five gallon tank, which is about as large a tank as you can easily move around (with help) once it's finished. If you need to provide more storage, two or more of these tanks can be plumbed in series by connecting their outlets. Only one tank will need an inlet for the rainwater. As long as the overflow level of the two tanks are at the same height.they will fill and drain together, maintaining equal water surface levels in each tank.

  Once you have your bag, the first step in building the tank is to make the bottom plate which is cast in the shape of a shallow dome giving it extra strength to resist the weight of the water. You could dig out an area on the ground to cast the plate, but in my case it´s easier to bring the ground up to the porch where we can work in the shade and not expose the work in progress to the elements (including curious animals and children).

 My porch slants pretty severely, so it takes a good bed of clay to level things up. A circle with a radius equal to that of the bottom panel of your bag is scratched into the clay by stretching a string from a center nail like a compass.

Roll up clay "snakes" and place them along the outside of the circle.

  The bottom plate is  5/8 inch thick, so we used a 5/8 inch thick scrap of wood as a gauge to flatten and smooth the ring of clay. This forms a little wall that serves as the the form for the perimeter edge of the plate.

  Smooth up a central mound of clay to make the nice dome shape that gives extra strength to the floor. The plate is flat and level for the outer two inches or so around the perimeter, and gently slopes up in the dome shape with a height of about three quarters of an inch in the center.
  Here's how the form for casting the base plate looks when built one on a floor that doesn´t need a mud buildup to compensate for an uneven floor.

  Once the form is ready, use plastic to line the form and shape some chicken wire to fit within it, leaving a few inches of extra wire sticking out all around. Shaping the chicken wire to lay reasonably flat over the dome takes some doing, but if you can get it pretty close, the wet mortar will help hold it down when you fill the form. 
  The idea is that the chicken wire will end up centered the cement plate, with the extra chicken wire sticking out from the top, right along the outer edge. Once the chicken wire is ready, repair any damage to the form, making sure the wall is still smooth and even all the way around, with a sharp inside corner at the bottom.

  Mix the mortar using two parts sand to one part cement and just enough water to make the mortar workable. Start filling the form along the perimeter, compacting the mortar as you go. The outer ring of clay will let you to get the thickness of the plate correct around the perimeter. Poke a nail into the wet cement to check the depth in the center as it slopes up into a dome to make sure that the plate has the same 5/8" thickness all the way across..

  Cover the base plate with plastic and let it harden at least overnight before disturbing it. Once the plate is well set up leave it sitting on the clay form, but remove the outer ring of clay and pull the plastic down to expose the the edge of the plate. Clean up the edge, chipping away any excess cement where you might have overflowed the form, leaving a good flat edge.

  The next step is to place the cloth bag on top of the base and fill it with stuffing. Sawdust is often used, but chopped grass also works very well if you carefully pack it in as you fill the bag to achieve the desired urn shape. You should pat and push the bag into shape as you fill it, stepping back and looking at it from all angles to avoid lopsidedness and unsightly bulges. Like most unsightly bulges, it's a lot easier to avoid getting them than it is to get rid of them later.

  Fold the chicken wire that is sticking out of the base plate up onto the bag and then wrap a roll of chicken wire around the bag, overlapping the wire from the base, and tie it off with light gauge tie wire or with the cut ends of the chicken wire itself.. Because the shape of the bag is not a straight cylinder, it takes some reshaping to get the chicken wire laying smoothly over the bag, but the flexibility of chicken wire makes it possible. You can twist the wire together in spots to shrink the little hexagons until the chicken wire conforms to the curves of the bag. The wire doesn´t need to be squeezing real tightly onto the bag, but neither should there be any noticable gaps between the wire and the bag.
  Trim off the extra chicken wire at the top of the bag and make several vertical cuts down from the top to form little flaps that can fold down flat onto the top of the bag. Make a ring of with several loops of thicker gauge tie wire. The ring should be the diameter that you want the neck of the tank's  opening to be. Lay this ring of wire on top of the bag, pull the ends of the flaps of chicken wire up and out through the ring and fold them back down onto bag. Trim the excess from the flaps and use the thin wire to tie them off, centering the ring of wire where the mouth of the tank will be.
  This photo also shows a ring of garden hose that will serve as a form to plaster up against to make a neck at the opening of the jar. It should be around 3/8 inch wider than the ring of wire all around. The hose can be put aside until both coats of plaster have been applied. 

  Cut a little X-shaped slit in the sack an inch or so above the bottom and insert a half inch PVC fitting for the outlet. A single coupling isn't long enough to give you much room to bulk up the wall thickness where the coupling penetrates the wall, so I suggest using a pair of threaded adapters. Screw the male and female adapters together and stick that into the slit in the sack.That will give you an extra long coupling that you can connect half inch tube to. The little shoulders built into the adapters also add "tooth", giving the mortar something to grab on to and should minimize the chance of leakage around the coupling.


The mix is again one part portland cement to two parts clean and screened sand, with just enough water to make a good spreadable mortar. Before you start plastering, wet the sack down by spraying or sprinkling water on it.

The mortar is troweled on in two coats of 1/2  centimeter each, waiting a couple of hours in between coats. Two people or even three can be working at once, each working up their side of the tank.
With a fourth and fifth person keeping the mortar coming the work will go quickly which is all the better.

Start plastering from the bottom, using short, upward strokes with your trowel and firmly pressing the mortar enough to compact it well and squeeze it in behind the chicken wire. Be sure to get good thick coverage on the outer edge of the base plate all around and also get plenty of plaster around the plastic coupling. Systematically work your way up the tank, smearing on plaster in a small sections, packing it and smoothing it a little, then smearing on some more right next to it, keeping it all of an even thickness as you work your way around and up the tank. Don't overwork the plaster once it´s on the tank. You don't need a really smooth surface on this first coat. Just get an even coat all around. You will see the outline of the chicken wire in most places and that is fine for the first coat. Continue to the top, completely covering the ring of wire where the mouth of the jar will be. 

Let the first coat start setting up for a couple of hours.

 Before applying the second coat, carefully shave off any excess plaster that you find sticking out below the bottom of the base plate (Do this again after the second coat). Plaster the second coat just as you did the first, again with special attention around the base and around the outlet fitting. Work systematically from bottom to top so you don't lose track of where you've applied your second coat. Try to keep a consistent half centimeter thickness for the second coat, but when in doubt, be a little generous.

  Once you've plastered up over the ring at the top you can set the loop of garden hose on top of the plaster and build up a little 3/4 inch neck of cement inside the hoop that will support the tank lid. You can make an  extra loop of wire and imbed it in the plaster as you build it up to provide reinforcement for the neck. If you are going to make a lid for your tank you should take special pains to get the neck flat and level so the lid will sit evenly.

  Once the plaster is firm to the touch, cover it completely with plastic and leave it alone. Keep the tank damp while you wait at least a three days before pulling out the stuffing and peeling the bag away from the inside of the tank. it is absolutely crucial that you not let the tank dry out during these few days.Clean out any loose plaster from the inside, moisten the inside walls, and then spread a thin coat of the mortar onto the inside of the tank making sure to cover up any exposed chicken wire. Give the joint where the tank wall meets the base plate a little extra thickness as well as around the pipe fitting. It's hard (impossible) to plaster the curved wall inside the tank with a trowel, and so you may end up using your hands a fair amount. Use rubber gloves. I'm told by another comarca PCV that a sponge or piece of upholstery foam works very well.  The tank should be solid enough to lay down gently on its side which will make the work easier. Wrap it back up in plastic while this inside coat of mortar sets up. The final step is to mix up a slurry of portland cement and water to the consistency of melted ice cream. This "neat cement" is then brushed on and pressed in to the still damp inside walls of the tank. Now cover the tank again with plastic and keep it damp for at least two weeks to allow the slow curing necessary for cement to develop its full strength.

  In the meantime you can cast a lid using the same clay technique used to make the base plate. (This step could also be done the same day you make the base plate) The hose you used to form up the neck of the jar can also serve to form the outer edge of the lid. Shape the contours of the clay so that your lid will have a flat ring that sits atop the jar's neck, and then has a deeper section that fits inside the neck and keeps the lid from being able to slide from side to side. You can mound up the center just as you did on the base plate to give the lid a domed shape that will shed water without being too thick. We used a scrap of two inch PVC that we thermaformed into a bell to serve as a socket for connecting a rainwater downspout. Cut some notches that can be heated and pulled up to form little ears that will be embedded in the cement of the lid. Cover the finished form with plastic, insert the pipe socket and add some wire or chicken wire to give it some reinforcement and plaster up the lid with the same mortar as the tank.
The result is a really beautiful tank. Made on site for a fraction of the cost of even a recycled plastic tank of similar size,  it should last as long or longer. Since it remains completely dark inside it won't grow algae like plastic tanks tend to do. As you can see these tanks can be built with transferrable skills and relatively available and affordable materials, making it a more sustainable solution to household water storage needs. And for any of my regular, non Peace Corps readers who have read all the way to the end, you can try this at home!


Tuesday, July 31, 2012

Child´s Play


  Dispatches from the developing world often use images of children living in poverty to tug at our heartstrings and evoke pity and maybe a little guilt at our own comfortable lifestyles. But relax, this blog post won’t be like that.
  It's not that the kids here don’t live in poverty—by World Bank measures our people are clearly among the 86 percent of indigenous Panamanians that live in “extreme” poverty. And it would be easy enough to frame up some cringe-worthy photos.  But I’d rather focus on the up side of a Ngäbe kid’s life.
  Although kids here have  no T.V.’s or video games, no books or tinker toys, no soccer teams or karate lessons, they do have the forest, the creeks and the sea, and lots of other kids who are determined to find ways to have fun. And most importantly they have the freedom to go for it.
  There is also plenty of work to be done, and most kids have their share of chores to do: washing clothes in the quebrada,
helping carry food down from the finca,
 or catching and cleaning the little minnows  known as sardinas that provide some much needed protein when there are no bigger fish to fry.
And to cook it all up takes a lot of firewood, which has to be hauled down from the forest in impressive chakras loaded to the breaking point,
over terrain that would certainly break all safety standards and child labor norms  in our world.
And for the girls, there is the minding of younger children -- there are always younger children to be minded.
  ...and boys can be seen wielding  machetes at a shockingly young age to fend off the ever encroaching monte.
But does it look like these guys are whining about it?
  It’s no great revelation that all the trappings of a wealthy lifestyle don´t necessarily equate with a happy childhood, or that a kid can have fun without a bunch of store-bought toys. And for kids, having fun is what it’s all about once the most basic needs are more or less met. Where these kids really excel and have it all over their counterparts in the developed world is their ability to invent ways to have fun.

There are toy boats whittled from the locally abundant balsa wood,

and even hand carved tops, cleverly tipped with a broken off  piece of a nail.
  When the breezy months arrive, kites fashioned from sticks and old plastic bags become all the rage. I'm not sure where the little stickers came from, but they work brilliantly to hold it all together...
... and with a little spare fishing line and some room to run, you´re in business.
  No X-Box?  Try this; flatten out a pop bottle cap with a rock, poke a pair of holes in it with a nail, unravel some plastic string from an old rice bag and make a loop  to thread through the holes.. Set the bottle cap spinning by rhytmicallly tightening and loosening the tension on the loop and you’ve got yourself a toy that can entertain for hours.
 The real fun though is matching up with your friends to see who can cut the other's string with your "battling bottle caps".
No one would ever accuse Ngäbes of being overprotective "helicopter" parents, hovering over their offspring and swooping in to save them from experiencing their lumps, and I have to admit  there are things to envy in the freedom these kids have to go out and play. I'm pretty sure that building a fire is something that universally appeals to kids. What could be better than building a fire right under your house? Mom won´t mind.
  A while back, all the kids were making bows and arrows, some of them with some pretty serious arrow points- They used then for shooting at fish and crabs and stuff down by the shore. It seemed pretty dangerous to me, but I´m glad to report the tally of eyes put out is still at zero.
  It's not that Ngäbe parents don´t love and take care of their kids. They do, especially when they're tiny babies,
   And they have lots of them. Six or seven children per family is still about average here.
  Teen pregnancy is the norm, but it doesn´t cause a lot of hand-wringing.  Having babies is what women do, and they embrace that role. After all, there´s no angst wasted on questions of balancing carreer and motherhood. Motherhood is the only carreer of women here.
Grandmothers continue in their childrearing role, since daughters almost never leave home to start their families.  Ngäbe society is basically matricarchal and the norm is for a man to move in with his woman´s family, at least to live there part time, and eventually build a house next to theirs.

  All in all it makes for a pretty full life for the kids. And if you're a kid who's lucky enough to have a Peace Corps volunteer living your town, well, you can go over and play on his porch and look at his books or maybe help out with little projects,
or even share a late supper of beans and rice, 
or maybe just hang out being a kid and remind him of just how lucky he is to be living out a dream. That's when it all really does seem like child's play.




Sunday, July 1, 2012

Still Afloat

After such a long hiatus from posting to this blog I've been feeling a little writer's block. So instead of trying to talk about all the things I've been up to I'm just going to  break the ice again with a little snapshot of my life in Peace Corps Panama ,

  I took a few days away from my home in Bahía Azul and paddled across the bay where a trail leads over to a community called Playa Balsa, where my fellow volunteer and very good friend Charles lives. It's also one of the most stunningly beautiful places you could ever hope to visit, let alone live and work.
    This wasn't a vacation though. I went to help out with construction of a small water storage tank for an aqueduct the town is building. The local men had already done some of the hardest physical work you can imagine, hauling tons of rock, sand, rebar and cement through treacherously muddy forest trails and up the steep hills|to where the the water tank was to be built. Making this hike empty handed left me winded, so loading a 95 pound bag of cement into a chakara and strapping it to my head like the muchachos were doing never even entered my mind.


We broke ground and started setting up forms, and some girls carried a bucket of water up from a nearby stream to make chicha to drink.



 Each day while we worked with a crew of men on the hilltop, women were preparing lunch down in town.

 Boiled green bananas with rice and little sardines might not be considered gourmet cuisine, but it certainly is filling


The work days were long and hard, but the tank construction went great. The rains came and went with fortuitous timing and we got the foundation , floor, and first level of walls all poured as planned.




The day I was heading for home, clouds moved in and I walked the forty five minutes back to the bay in a steady warm rain that was drenching, but at the same time welcome. Another forty minutes of paddling and I was back home, back in my hut, relaxing in my hammmock, weary but satisfied,  warmed by a nice glass of rum and the images of loved ones in the glow of the candles, very, very happy to still be afloat here in Panama.
 

 
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