3.1 SAN NICOLAS ELEMENTARY SCHOOL
The school of San Nicolas is situated in the zone of Pukara in the ninth district of Cochabamba prefecture, approximately 15 kilometres south of the Cochabamba city centre. In this area there is no collective system for potable water or sewage. The wetland system at San Nicolas was first put in use two months before this study was conducted. 116 pupils are attending the school using the toilets and showers that are connected to the constructed wetland system.
The school has an agreement with the government to have their two water tanks, in total 10,000 litres, filled up once every week. So far this has not worked so well, sometimes they do not come at all or most of the water is bought by people further down in the valley. The water in the tanks is led down to the toilets and showers. From here the used water then goes into two septic tanks holding 3,000 litres each. From the septic tanks the water is lead through plastic tubes to the wetland where it is equally spread over the short side of the wetland. The constructed wetland has a 20-25 centimetre bottom layer of compacted clay to protect the water from contaminating the groundwater. The clay layer is covered with a plastic foil to further prevent leakages. Over the plastic linen a layer of stones and gravel is put. This layer is 1.20 metres thick and the water is supposed to reach maximum one metre above the bottom to prevent it from exceed the gravel layer. From the constructed wetland the treated water is then collected into a tank holding 1,200 litres. The treated water is then distributed through a plastic tube system to 150 planted trees. The whole system is driven by gravity force only.