Italy tours

Civil Works at Kigogo

Once we got back from Kigali with all the materials (and Alison!) we made some final touches on the system at Kigogo and reopened it for business. I’ll explain some of the problems of the system and how we went about solving them.

The main civil works issues that Kigogo had when we arrived in Banda were as follows:

1. Water overflowed at several points along the channel in the rainy season, which caused hillside erosion

2. The site operator had no robust way to control flow into the system; his method of stoping flow to the settling tank was a combination of mud and leaves inserted into the channel

 

After brainstorming, weighing specification importance and comparing design alternatives like we’ve been taught at Thayer :) we decided to construct a spillway just before the most severe point of rainy season overflow. The spillway was designed to let 12 L/s continue towards the settling tank while sending the remaining water back to the river. Downstream of the spillway, a sluice gate allows the site operator to fine tune the amount of water continuing to the settling tank and also stop the water completely when the system needs to be turned off.

 

Beginning to build the overflow at Kigogo

Beginning to build the overflow at Kigogo

Laying the base of the overflow

Laying the base of the overflow

Finishing the base of the overflow and checking the slope

Finishing the base of the overflow and checking the slope

Pete touches up the overflow

Pete touches up the overflow

The completed overflow structure! It is sized and sloped so that the necessary  amount of water continues down the channel and eventually to the turbine while all excess water flows over the small lip, into a pipe and back into the existing stream. By dealing with this excess water in a controlled manner upstream, we hope to prevent water from spilling on to the hillside and creating erosion downstream.

The completed overflow structure! It is sized and sloped so that the necessary amount of water continues down the channel and eventually to the turbine while all excess water flows over the small lip, into a pipe and back into the existing stream. By dealing with this excess water in a controlled manner upstream, we hope to prevent water from spilling on to the hillside and creating erosion downstream.

Another view of the completed overflow

Another view of the completed overflow

 

The overflow pipe transports extra water in the channel down to the existing stream.

The overflow pipe transports extra water in the channel down to the existing stream.

This is the bottom of the spillway, where the water is retuned to the stream. The water has a high velocity and must be slowed down so that it does not effect the stream. The area is in the photo is in the process of being filled with rocks that dissipates the water's high energy.

This is the bottom of the spillway, where the water is retuned to the stream. The water has a high velocity and must be slowed down so that it does not effect the stream. The area is in the photo is in the process of being filled with rocks that dissipates the water’s high energy.

 

The finished product seems to work pretty well. The real test will be during the rainy season though. We hope to get some pictures and reports of how it’s working in a few months. We did get great feedback from the community already though. When I was buying eggs, the shop owner told me, “God bless you, Kigogo is amazing.”  June also got several handshakes and blessings at the opening of the Kigogo, when the site successfully charged all types of batteries faster than it ever had before. It is exciting to see the community respond positively to our work!

 

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