The construction of Kenya’s longest underground tunnel – Northern Water Collector Tunnel – is underway and its operation is expected to commence by end of year 2020.
The 12.7km tunnel will harness flood water from three rivers in Murang’a County and is expected to increase water volume at Ndakaini dam, the main water source for Kenya’s Capital, Nairobi.
Upon completion, the Northern Water Collector Tunnel is expected to supply Nairobi City residents with an additional 140 million litres of water daily, through Ndakaini dam.
The US$ 200 million project funded by the World bank will have a water treatment plant installed at a cost of US$ 65 million, 56km pipeline to Nairobi at US$ 46 million, while doing the tunnel will cost US$ 68 million.
“The excavation works is 89 percent complete and the remaining part will be concluded by end of this year. 1.3 kilometer is remaining for excavation so as to connect to Ndakaini dam,” said Eng. Mwangi Thuita, The Chief Executive Officer, Athi Water Services Board.
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He explained that after doing the tunneling, the works on treatment plant and laying of pipeline from Ndakaini to Nairobi will take at most one year.
The project will harness 152,000 cubic meters of flood water daily and is expected to boost water volume at the Ndakaini dam. Nairobi gets 580,000 cubic meters of water daily against a demand of 750,000 cubic meters per day.
Eng. Thuita reassured residents of Murang’a county that the tunnel will only collect flood water and will not interfere with normal flow of the rivers. In 2016, the local authorities opposed the project after a study indicated that it could run the county dry by 2035 due of massive abstraction.
The tunnel is more than 100 metres underground and is designed in such a way that there is no seepage of water from outside or inside of the underpass.
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The tunneling technology being used, the CEO said cuts across all fields of engineering, thus the upcoming professionals will learn more how to embrace the expertise to improve water services and transport among other sectors.
“Plans are underway to partner with universities to train others in the field on how to embrace the technology and utilize the same in improving services in different sectors.”
