Indonesia's Renun river is being diverted from its historic flow northwest to the Indian Ocean, to flow instead into Lake Toba.
The Renun Hydroelectric power project will transport up to 22m3/sec through an immense tunnel that has been bored for a distance of approximately 22km.
Sub contractor to the project, Nippon Koei UK, has recently enlisted the expertise of CSMA to oversee the grouting of a 3.5km branch tunnel and pre-grout preparation of the downstream, headrace tunnel.
When completed, the project will tap the main stream and eleven tributaries of the Renun river to generate 82MW of hydroelectric power at the village of Silalhai, on the shore of Lake Toba.
After following nearly the entire length of the lake, the Renun water will be re-used for power generation at the two Inalum power stations on the Asahan river.