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This summer a team of eight students and two mentors traveled to Puerto Pando, Bolivia to implement the second phase of the water distribution system. A surveying team began to survey from the current dam and worked towards the storage tank. A wooden stake was hammered into the ground as a temporary benchmark to survey the construction site day to day without having to start from the dam. After tank locations were chosen based off previously calculated elevations, clearing and digging began for the sedimentation tank and slow sand filter.
The collection dam was constructed using concrete and two small pieces of plywood as forms. The forms were laced together using tie wire and wooden “ribs”. Six pieces of rebar were keyed into the surrounding clay and into the concrete to help hold the dam in place.
The sedimentation tank was rectangular in geometry and utilized wood framing for all concrete pours. Plywood and locally available lumber and bamboo was used to create the forms. Once the concrete cured for long enough, the forms were taken off and work began to install the flow control device, baffle, and effluent launderer. The plywood was not thick enough to sufficiently support the concrete, leaving the walls bowed. The tank also experienced leaks, which the community plans to fix using the same type of mortar as for the slow sand filter.
The slow sand filter was a tall, cylindrical structure. Rather than using wooded forms, the rebar was wrapped in two layers of wire mesh and then mortar was plastered on. The plaster had to be applied one layer at a time, giving the previous layer at least one night to cure before adding the next layer. To accommodate the 3+ meters of height, scaffolding was erected around the perimeter of the structure. It is up to the discretion of the community members whether they want to leave the scaffolding up or take it down until maintenance is needed.
There is also a bypass system which the community still needs to install. This will allow the community to direct water around one or both of the structures for any reason they need to. Once the community finishes the last few construction steps, the water project will be considered complete and EWB-S&T will move into the monitoring phase.