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Mr. Muscle Returns to the Rescue

At Sanergy, our focus is on cleanliness because a clean toilet is a useable toilet. A few weeks back, I had the privilege of accompanying a CCS team to clean some toilets in the Kwangware slum in Nairobi. That's where I first ran into Mr. Muscle. Back then, we promised a closer collaboration and partnership with the amazing folks at CCS.

As promised, they have returned. And they brought along Mr. Muscle as well! Given CCS's experience cleaning and rehabilitating some of the worst toilets in Nairobi, we approached them to partner with us in building and implementing a training program for our toilet operators to keep the new Sanergy pilot toilets spotlessly clean. In addition to the training, Sanergy will be sourcing all their cleaning chemicals and equipment from CCS, an SC Johnson Company.  

Below are some pictures from the training session in Kibera. 

Positive -> Negative -> Positive

Mold Making in Kenya

The bulk of our success in constructing the pilots relied on the team's ability to make the molds for precasting the concrete forms. The team first split up: Joel, being fluent in swahili, navigated the Gikomba marketplace daily to make quick mock-ups of the molds for testing; Ani scoured the industrial district for fabricators to establish contracts for the roll-out; and Ella went to the University to recruit local talent; in doing so she wandered into the FabLab.

FabLab

Though not widely advertised, the facility located within the University of Nairobi Mechanical Engineering Building functions as a state of art, stand-alone technology park. Setup in affiliation with the  FabLab at MIT, it is equipped with a large bed CNC routing machine, laser cutter, 3D scanner/printer, teleconferencing capabilities, and more. This level of modernity is a rare find in a city of people that take pride in their resourcefulness, but that is another discussion all together.

When Ella first met Kamau Gachigi, Director of the FabLab. He explained that by sponsoring local projects the FabLab hoped to enable innovation and prepare projects and/or businesses to be competitive in the world marketplace. After describing our project Kamau was extremely accommodating; recommending material sources, recruiting help, and contacting student operators. Which is how Ella met teammate Tom Odoyo. Tom was irreplaceable, putting his own windmill project on hold to become part of the Sanergy team throughout the summer.

The CNC Router provided us a means to fabricate a highly accurate form of the floor plate out of fiber board that we used as a plug from which we created our mold for casting. Being that the floor plate was the interface between the walls of the superstructure and access to the containers in the substructure it required a level of precision that was not likely to be found using make-shift methods.

Having already modeled the floor plate in 3D we split the form into stratus layers, the thickness of our MDF board, which we later laminated together to get our 3 foot wide by 5 foot long and 6 inch tall floor plate. Splitting time at the machine, working late into the night and through the inevitable hick-ups we were able to route out a floor and corner piece in just over a week.

Unclear as to the best method to use the (positive) plug to form our (negative) mold we looked into the commonly used rammed sand and aluminum cast and also casting it straight into concrete, but decided on having a fiberglass mold made for a heightened level of accuracy. For this step, we contracted the services of experienced folks at Specialised Fibreglass. With their help, the mold was further developed to incorporate tapered edges so it would easily release each cast.

The other molds consisting of 5 walls, 4 corners, 4 foundation posts, and a roof ring were made from steel.

Painting Kibera Blue

A few days ago, we finished construction of our second pilot site in Kibera. As one of the largest slums in the world, Kibera is home to nearly 1m people. The 3 sq. miles that Kibera stretches is divided into 8 villages. We are working in Soweto West with our community partner Carolina for Kibera. The pilot site will be operated by the Zulu Youth Group.

We've spent the past couple of posts explaining the model and the design. So we'll get straight to the pictures this time. This time around we documented the construction process in detail to show exactly what it takes to put together a prefabricated ferrocement ecosan toilet in the slums of Nairobi. 

From Concept to Reality

Sanergy Design

The design process for the Sanergy EcoSan Toilet began with an intense brainstorming session at the MIT Sloan Entrepreneurship Center  throughout the month of June with revisions continuing well into the team's time in Kenya.

Sanergy's design goals were generally to create a toilet that was both economical and socially sustainable; and specifically for the pilot to 1) create a low-cost building solution under US$500, 2) design an efficient system for the ease of construction, and 3) provide a low-maintenance system for ease of operations. It was essential that the units be highly cost effective in order to make personal ownership attainable to entrepreneurs, yet not at the expense of its ability to attract and retain paying customers over its life cycle.

Low-cost construction:

In order to reach the largest population of users possible the model needed to be sustainable, scalable, and financially viable. Cost-saving techniques drove the team to consider using a building technique not yet used in Kenya called ferrocement. The structural components of the toilet were constructed of precast cement panels reinforced with chicken wire; just 1.5 inches thick, the unit mass was greatly reduced from that of a typical mortar and brick construction. Adorned with readily available bush-pole and corregated sheet roofing and doors, then finished with off-the-shelf collection containers and squat pan the design was economical to produce and maintain.

The precast process helped to control quality and cost of the panels. (Look for a post coming soon about the mold-making process.) Casting at a central location helped to ensure proper curing and limits material waste by using trained labor. After scale-up there would be significant benefits to buying material in bulk; including, economies of scale and flexibility to ride-out price hikes. Not fully developed in the pilot, the unit was designed to be a flexible, modular design that could be grouped to share walls and foundation posts, further saving on material.

Easy assembly: Precast panels, interlocking joints, one day assembly, limit skilled labor

Fast and easy assembly reduced the construction cost and time. It was essential to getting the business up and running as quickly as possible. Precast panels made for a fast assembly and reduced the need for skilled labor on-site. Because the units were fabricated off-site, the pieces were brought in and assembled for use in one day.

The design aimed to preempt elements of construction and maintenance into the cast forms. The corner panels were designed to receive the wall panels, which was received by the monolithic floor plate and roof ring which locked the whole assembly together without using fittings. Tongue and groove connections relieved the need for on-site mortar and resolved concerns of using typical screw connections which would likely have exposed the chicken wire to water penetration and compromised the structure. 

Using a the panel system reduced the area required for construction; only a 3 foot by 5 foot clear area, with no need for formwork or material storage, spaces that had been written-off in the past for being too small were reconsidered. Also, rather than the deep pits commonly associated with latrines in the settlements, the Sanergy EcoSan Toilet used shallow foundation tubes which eliminated the need for deep digging and stable soil.

Low-maintenance:

Precast concrete combined the benefits of high durability with low maintenance. Because all of the sealants and hardeners were integrated into the floor surface it requires little to no maintenance. Many design considerations were taken into account to promote perceived cleanliness. Plasticizer, water-proofer, and fiber reinforcement added in the mix the panels were cast with interlocking joinery so they were ready-to-use straight from the mold, without any further plaster, paint, or mortar required. Filleted corners along the low-wall of the floor plate and in the L-shaped corner panels helped to eliminate crevices that would normally collect dirt. A slope was molded into the floor surface to promote wash water flowed toward the drainage hole in the floor.

Kenya proved to be full of unforeseen challenges which required the team to remain adaptive. During the construction of the pilot some additional reinforcement was added on-site due to time constraints on mold edits and cast curing. Also paint and plaster was added because of discoloration in the panels due to casting conditions. These conditional and aesthetic issues will be worked out in the future to further reduce the cost of construction from the pilot model. Until then the team will continue to monitor the maintenance procedures of the pilots and train local youth groups on operations.