Sunday, February 22, 2015

A Micro-catchment Workshop in Léogâne--September 2014

Mark (left) and Luccène, working Sunday AM on digging the 2 meter by 2 meter hole for the first micro-catchment, a preclude to the workshop starting on Monday, September 22nd.

Saturday, September 20th, Buzz Durham, Herve Delisma, Lucien Joseph and I headed down the highway from Papaye, through Port au Prince, to Léogâne, to lead a workshop there on in-ground cisterns, a technique for capturing rainwater (micro-catchments) that I had learned from members of COSECHA, a non-profit rural development organization located in southern Honduras. COSECHA does not appear to have a web-site, but here are a couple of links to articles about their work:

COSECHA-micro catchments 

COSECHA-what we have learned in five years
COSECHA-What we have learned in five years 

The workshop was hosted by the Organization for Development in Léogâne (ODEPOL for its name in Haitian Creole), one of our partners in the FONDAMA Yard Garden Program since April 2012.

Here are pictures and a rough idea of the process:

Sunday afternoon, as we  were frantically getting the first hole ready, we got help from neighbors, both tools and labor.

Monday AM, the workshop begins. Buzz Durham (green shirt) from Grace Covenant Presbyterian Church in Asheville, NC, told me later that he could follow the general ideas, without speaking a word of Creole, because of my hand gestures and the drawings. There are many kinds of intelligence; Buzz has the kind that makes it easy to integrate him into pretty much anything we are doing.

The finished first hole, with a healthy slope on each side. The top measurements were slightly more than 2 m and the bottom was about 1.6, 1.7 width and length. The total depth was just at a meter.

Lucien Joseph helping me peg in the 3/8" rebar at the top of the hole. We had to go down from the top because one side of the hole was up against cultivated land and the first 6 inches were loose. The soil for this kind of cistern needs to firm and undisturbed as much as possible. If we had thought about this clearly when we marked out the hole on Sunday, we could have moved it over a foot or so away from the cultivated soil. But then as it turns out, we would have hit a mine of rocks and more rocks.

Lucien (right) guiding workshop participants in weaving the mesh that will give the internal strength to the thin layer of cement we will lay over it. Lucien became my assistant because he built his own cistern in his family's yard several years ago, in the community of Saintville, as part of a Hunger Program Project.

Weaving the mesh. Luccène, the coordinator for ODEPOL is on the left, red hat. Ullia Augustave, red shirt, is watching and waiting to get her hand in on the work. Ullia started with the Yard Garden Program in 2012, one of the very first participants. She is smart, hard working and faithful. She is rarely absent from any of the workshops or meetings.

Because we had 12 or 13 participants, we committed to digging a second hole and doing a second cistern, to give everyone a chance to participate in every step of the work.

After finishing the mesh from top to to bottom of the hole, we put in a second 3/8" re-bar at the bottom and tied off the mesh, nice and tight. We used pieces of 1/4" re-bar, about 40 cm long, doubled over, to create what Buzz called "earth anchors." Then we plastered the sides. We typically use 3 parts sand to 1 part cement. If I remember correctly, Buzz would have used more cement and less water. The difficulty is getting the mix so that you can plaster quickly and efficiently so that you finish all four sides well before the first section gets dry.

You can see that we have cut out all around on top and laid some gravel down. You cut out the extra soil on top to lay a border and you do it carefully so that you do not disturb the 3/8" re-bar on top. The gravel was because we had it as what was left after sieving the sand.

The ideal is to use river sand, well washed, without sediment. What we were able to get by Tuesday AM was white sand, from a nearby quarry. I have been led to understand that the white sand corrodes the metal embedded in the mortar more quickly and reduces the life of the structure.

In any case, my original instructors came from the countryside where river sand was very accessible.

After the first plastering, comes the "finishing" a rich mix with more cement than sand, and the sand sieved very fine. At the bottom left you can see the border, made from rocks we scavenged from all around ODEPOl's meeting site. Families doing the cisterns tend to want the border to be big, so that the cistern will hold more water. But with this type of cistern, the border needs to be as simple as possible so that we are not putting any extra strain on the side walls. The border is simply to protect the walls, not to augment them.

The depth came to just over half a meter (0.6 m) in part because we lost some depth from the top, but also because we poured a good thick base--at least 5 cm (2 inches) thick of cement, sand and gravel. After pouring this, we capped the base off with the same rich cement mix we used to finish the sides. This mix seals the cement so that water is not lost through the base or the walls.

Merandieu Ceus (left) from Verettes, works with Mireille Domingue to weave the mesh for the second cistern. Buzz works in the far corner.  With this cistern we had so many rocks we had to do crazy things to create the inner structure. That turned into a good exercise for the group on problem-solving.

The reality is that I have never been part of building one of these cisterns where we had an easy time of it. There is always something off with the sand or the hole, or something else.

Plastering the second cistern. The participants who did not get a chance to do much the first time get a feel for it in the second. It was a bit insane, but we did it.

The criteria for one of these cisterns to work, including the type of terrain, the tools and the material.s

Step by step, how to do the cisterns.

The "Rules and the Principles" of micro-catchment systems.

The actual costs for the materials for the first cistern. We ended up using 2 pieces of 20' lengths of 3/8" re-bar; 5 pieces of  20' lengths of 1/4" re-bar; about 14 pounds of binding wire (fil aligati) #18; half a sheet of "siloteks", a pretty cheap material usually used for paneling ceilings (to mix up the mortar in the hole, to keep dirt out); 6 wheelbarrows of sand; and 4 sacks of cement. Total cost HTG 3,625--around $US 80.

The actual capacity of the cistern, when we did the final measurements, was 1.9 m3 or 1,900 liters (about 500 gallons).

We compared the cost to buying plastic barrels, which hold 60 gallons. Our cistern holds the equivalent of around 8 plastic barrels, each of which sells for HTG 1,500 in Port au Prince. Eight barrels would cost HTG 12,000. So our cistern is considerably cheaper than buying the equivalent in plastic barrels.

If we were to pay for a skilled mason to build the same cistern, and pay for the hole to be dug, we would probably lose most, if not all of the difference. The serious advantage of this type of water catchment system is the fact that pretty much anyone can learn to do it, and then pass it on.

That said, with Buzz's experience in pretty much everything, we were able to offer quite a few points on how to improve the success of this type of cistern. One simple but tedious point we discovered from Buzz is that to acquire maximum strength, the cement should be maintained humid for at least a week, preferably two. That means splashing water on the sides four or five times a day or more.

If you would like more information, please contact us. You can (try to) leave a comment on this page, or you can contact me through my Mission Connections e-mail address. Click on Mark and Jenny-Mission Connections: Mark and Jenny-Mission Connections

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