After one year of latrines use, one main problem has emerged. During the rainy season, the pit in use is full of liquid, which prevents the use of the latrine anymore. The clay soil in the area makes infiltration very tricky which requires a new system that is reliable even when rainfalls are very intense. As with the use of a soak pit we would face the same problems it has been decided to implement a horizontal sand filter. So this year with guidance by Maryel Dutrey, MAP, France it was renovated for proper utilization of the lavatory.

Finding a location to collect the effluent was very difficult as the outlet of the filter was more than 60 cm deep. The pond was inappropriate because when full, its level is above the outlet level. The solution we found was to dig a long trench (60 metres) outside the campus to reach an existing trench beside the pond. This was quite complex because a slope is needed (around 0.5%, not more and not less) to prevent being above the trench level and to allow water to flow sufficiently. Breaking the concrete wall between the pond and the road had to be done to make a sufficiently large hole for the passage of a 110 mm diameter pipe.

The horizontal sand filter is made of layer of sand and gravel (around 30 to 35 cm) where filtration occurs and micro-organisms purify the effluent from the twin pits. This kind of construction implies infiltrations pipes made from normal pipes which have been partially cut with 5 mm slits, concrete boxes (inlet and outlet), a plastic sheet and geo-textile brought from France to prevent entrance of soil in the filter.

Effluent from latrine is therefore partially treated now, which should avoid any complaints from downhill households. This water is suitable for gardening; for this reason a water tank was built with 1-meter-diameter concrete rings. This sand filter also receives liquid from the new urinal which is located near the twin pits.

A few things must be known about management of this sand filter. First, the effluent that enters in it should not be raw effluent from the latrine. For that reason, the pit in use must not be full in order to enable storage of solid material. Therefore, good management of the twin pits is necessary: emptying the pit after composting period of two years and switching the role each pit plays every two years also. After a period of several years it could be necessary to remove the gravel layer at the entrance of the filter to clean or change it. This aims to allow infiltration rate in the filter to become sufficient again. Finally, it is unadvised to put heavy things on top of the filter like vehicles and to cover it with concrete. If these rules are followed, the system should be efficient for many years.

URINALS: Many schoolgirls urinate in the open in the school, which is a source of odors and is not hygienically acceptable. To remedy for this issue, two urinals were constructed. One is located behind the classrooms and the second one near the latrine and dormitory. To get rid of urine mixed with water, a trench was dug and then filled with gravel and a 6 meters infiltration pipe. It was then laid with geo-textile and covered with soil. With the idea to collect urine for hydroponic agriculture, a system was specially built to collect urine in a jerry-can allowing the non-used urine to be treated in the sand filter.

EXISTING LATRINES WITH NEW IMPROVEMENTS: Two major projects were completed to make latrine use more attractive to the school children. A submersible pump of around 500 Watts is now feeding the two water tanks previously built last year on the roof of the latrines building. To get a reliable water supply, even when electricity is cut, the hand pump has been kept in place. It was very gratifying to see the pleasure of the girls and their cry of surprise when they discovered the water flowing through taps in latrines and bathroom. In addition, to make latrine use safer at night, we installed lights in the facility. A solar panel was fixed onto the roofs of the latrines and three low energy bulbs light both the latrine building and the urinal. The produced light is powerful enough to light the access also from the dormitory. These projects are expected to halt open defecation and motivate girls to systematically use latrines and urinals.