During my initial ten weeks of training I, along with the other volunteers in my Group WASH Sector, learned about various latrine types. One of which is a common pit latrine, with a spin! Initially we were taught how to design and create a regular cement latrine plancha (base). This involved a measured wooden outline, many black plastic bags, rebar and concrete. For more info you can read about it in detail on the cement latrine plancha post.
A ferrocement latrine plancha is a bit more complicated. As opposed to simply pouring the concrete mixture into the wooden frame and waiting for it to dry, there are several layers. I learned this technique more in depth during our IST Sanitation Tech Week with WASH Coordinators Larry and David. The first step is a thin base. This is made exactly like a normal latrine plancha but way thinner. Measure out a wooden frame, place plastic bags overtop to make the removal easier, and reinforce the bottom with chicken wire. The wire can be reinforced with alambre dulce around the edges and center. Be sure to place a circular bucket in the center and cut the chicken wire around the base. To make removing the bucket easier in the end, rub on a thin layer of oil. Next, mix cement and pour into the frame until it just covers the wire. With a trowel, smooth out the base and even work some mixture up along the walls. Let this dry overnight, covering with plastic bags and wetting periodically. Just like other cement projects, this step is vital to ensure the plancha does not crack.
The following morning, fill several plastic bags full of dried leaves or wood shavings. Shavings hold up a lot better than leaves for ferrocement, so I would recommend that. Place these filled trash bags inside the latrine plancha, flattening as necessary to not measure higher then the surrounding wooden frame. Secure the bags with fine wire, criss-crossing to connect with each side of the frame. For handles, either place sturdy cans on all four sides, which can be secured with wire, or hook looped wire to the mid-sections. Make another concrete mixture and spread smoothly over the bags. Cover the plancha with plastic, wet 2-3 times a day, and allow it to strengthen for approximately a week. Carefully pull out the plastic cubo and secure a ferrocement toilet seat (see blog post for more details). Let this dry for several more days. The wait will be worth it!
By simply looking at it, one would never know there were bags filled with shavings on the inside. The result is a lighter plancha that uses less concrete and is therefore more economical. With the help of community members, haul it over to your pre-dug hole, build a caseta around it, enjoy, and spread the word to your community about latrines! To learn more about ferrocement, read about the Rainwater Tank Initiative in the community.