BWS Project - Northern Collector Tunnel

Construction of the Northern Collector Tunnel under the Bulk Water Supply Project in Nairobi comprising of : (a) Construction of 11.7 km by 3.2 meter diameter water diversion tunnel from Maragua River to Thika Dam; (b) Construction of three intakes and diversion weirs on Rivers Maragua, Gikigie and Irati; (c) Construction of 40 m drop shaft, two adits 270 m and 740 m long, and tunnel outfall on River Githika; (d) Construction of concrete weirs 4 meter in height with associated energy dissipation structures and other erosion protection works in perennial rivers subjected to regular flood events; and (e) The estimated work output for bulk earthworks is 320 000m³ and for concrete works is 120 000m³. Estimated project value : KSh 6.8 billion.