On the 31st of October 2013, the failure of a working platform resulted in six fatalities as well as other people injured at the 1,332 MW Ingula pumped storage facility under construction near Ladysmith in KwaZulu-Natal. Eskom reports that the incident happened on the 31st of October at about 9:15am in the incline high pressure shaft, which connects the top dam to the power house. About 15 people were working in the tunnel.
The Ingula incident matches global trends in deaths associated with hydroelectric projects. Deaths associated with hydroelectric projects are higher than for other energy forms. For every 10 billion kWh of coal fired energy production there are 33 deaths. This number increases to 55 for the equivalent amount of hydroelectric energy. There are 1.6 deaths for the equivalent natural gas energy and 1.2 deaths for that amount of nuclear energy produced.
Ingula, like other pumped storage schemes, however, will be a valuable contributor to the power generation mix in South Africa. Ingula will have a rated head of 441 metres, a pump flow rate of 240 m3/s, and a generating flow rate of 350 m3/s. It will provide energy storage of 21,000 MWh (15.8 generating hours) and is to be the 21st largest pumped storage scheme in the world. It features 16 km of tunnels, of which eight are waterways. The power station itself will be 116 storeys underground and the project has seen three million cubic metres of rock excavated.
A nearby dolerite quarry produced 2.4 million tonnes of aggregate for the project and 3,600 tonnes of steel reinforcement was used. Ingula’s main machine hall housing the generators is the biggest cavern in this type of rock in the world. It measures 185 m long by 26 m high.
It comprises two dams, one at the top and the other at the bottom of the escarpment, underground waterways, an underground powerhouse complex, access tunnels and access roads. It is planned to be fully operational in 2014/15. The station is 350 metres underground.
At the end of October 2013, concrete lining of the tailrace tunnel was 93% complete, cavity grouting was 19% complete as was consolidation grouting. On construction of the base of the surge chambers 3 and 4 installation of formwork was in progress for construction of the base top slab. The base construction here is 90% complete.
On construction of the base of surge chambers 1 and 2 the apex lift was complete, the east wall lift 3 has been completed and the west wall lift 3 pour was completed. The base construction here is 78% completed.