The following is a guest article by Matthew Wood.

Before We Arrived.....Peace and Tranquillity
Before We Arrived.....Peace and Tranquillity

4th June 2012, Marriott Kensington hotel, after polishing off several bottles of mediocre wine at the CivSoc ball there is a sudden realisation that in less than two days we depart for Africa. More specifically Rwanda, the location of the atrocious 1994 genocides, in order to construct a hydro electric power system that will provide lighting, mobile phone charging and low wattage appliance use to more than 150 villagers. These basic facilities we take for granted, but in an area where children don’t understand the concept of electricity let alone have access to it; the improvements this hydro project brings to the standard of life of the villages served is enormous.

The project is the brainchild of e.quinox; a student led social enterprise project at Imperial. What does e.quinox have to do with hydroelectric power though? The short story is that after developing 5 solar energy systems to power rural Rwandan villages using a sustainable battery box distribution model; it was considered that Rwanda had equal potential for solar as well as hydropower. After all Rwanda is called the land of 1000 hills, and the temperate climate provides high flow rates all year round.

Almost two years to the day a group of e.quinox members met an American university organisation at a bar in the Rwandan capital, Kigali (yes they have bars and cheap beer!). The Americans run a similar student outfit called DHE (Dartmouth Humanitarian Engineering) and our two organisations, after realising their mutual interests, teamed up to design and build a small scale or pico hydro power station to serve 150 homes. Two years later, numerous skype sessions, $40,000 in grants & industrial sponsorship, many design iterations, calculations, about 50 drawings and we were nearly ready to build our first hydro project!

THE BEAST. Shuttering for 2.5m high retaining wall.
THE BEAST. Shuttering for 2.5m high retaining wall.

So what was involved? The project faced massive logistical challenges. We had to organise a workforce, purchase and transportation of materials to site, manage local and national government level bureaucracy all whilst adjusting to East African culture. Neither one of these tasks turned out to be an easy feat! One of the biggest things that we learnt from this project was that no matter how much programme planning you do in advance you can guarantee that as soon as your project hits the ground, that programme and Gannt chart you’ve spent weeks mulling over can go straight in the dustbin. Particularly in Africa where things seem to take ten times as long as anywhere else in the world.....a problem we have begun to term ‘The Africa Factor’.

We had to think smart when it came to transporting tools, people and materials to site. The waterfall, named the Rugaragara falls is some 3 hour drive away from the capital and principle location of all the cement, timber and bulky civils materials we required.

As the site is so remote what the locals may call roads we saw as dirt tracks not fit for mountain goats! On top of this there is a 1km steep decent from the village to the waterfall. Instead of trying to transport all materials to site at once, we stored them at the convent where we were staying. Then we operated a JIT (just in time) delivery system using smaller 4x4’s which could handle the dirt tracks. Essentially the nuns became a construction consolidation centre just as is being used on Crossrail!

At the projects peak we had some 30 local people working to shift nearly 150 m3 of earth by hand. There was 20 m3 of concrete to be mixed and poured by hand. The system starts at the top of the waterfall where there is a 3m long weir in the river for which we had to divert the stream to build the formwork and pour concrete. The weir is bolted into the riverbed-using specialist drilling equipment from Hilti. From the weir water is diverted through a pipe to a large concrete settling tank. The whole area has a low depth of unstable soil overlying a sandstone formation, for this reason All concrete elements have been rockbolted into the sandstone. From the settling tank water travels down a 63 m long160 mm OD penstock PVC pipe which has been buried and anchored into the hillside using mass concrete blocks. The most technical engineering appears at the bottom of the waterfall where a powerhouse has been built into the side of the hill slope. This involved large amounts of earthworks to regrade the hillside, in addition to a 7m long 3m high set of gabion walls and a 2.5m high 7m long concrete retaining wall to support the slope.

The Final Product. Working Hydropower!
The Final Product. Working Hydropower!

Throughout this project we strived to maintain high safety standards. Kier very generously provided us with full sets of PPE for 25 people so we were able to supply all personnel on site with appropriate equipment. Despite working in extremely challenging terrain with large numbers of people unused to construction we got through the project with no serious injuries, an achievement we are hugely proud of.

Finally a massive thank you to two civ engineers who gave it there all to make this project happen. Finlay McPhail (4th Year) and Adam Khamis (Graduated) were both extensively involved in the design and construction of the hydro project, without their help and insight none of this would have happened. Lastly also a massive thank you to General Electric, IEEE, Kier and Hilti for providing funding, advice, PPE and specialist tools.