Operation of Northern Water Collector Tunnel which is under construction is expected to commence by end of year 2020.
The excavation works of the 12.7 kilometre tunnel is 89 percent complete and the remaining part will be concluded by end of this year.
The Chief Executive Officer, Athi Water Services Board Engineer Mwangi Thuita has noted that 1.3 kilometre is remaining for excavation so as to connect Ichichi intake area of Kangema sub County to Ndakaini dam.
Speaking when he led a group of engineers to learn more about tunnel technology on Saturday, Thuita explained that after doing the tunneling, the works on treatment plant and lying of pipeline from Ndakaini will take at most one year.
The tunnel which will draw water from three rivers in Murang’a County namely, Maragua, Gikigie and Irati is expected to increase water volume at Ndakaini dam, the main water source for Nairobi and its environs.
The project which is funded by World Bank to the tune of about Sh20 billion is expected to increase water volume at Ndakaini dam by 140, 000 cubic meters on daily basis.
The CEO stressed that the tunnel will only collect flood water saying it will not interfere with normal flow of the rivers.
“Doing the tunnel will cost Sh6.8 billion, the water treatment plant will cost another Sh6.5 billion, while the pipeline from Ndakaini to Nairobi will cost another Sh4.6 billion. All the funds are provided by World Bank,” he said.
Thuita stated that progress of the project is going on smoothly and all residents who were affected by the tunnel were compensated, thus dismissing any court injunction stopping the works.
“Some residents were not satisfied with the amount of money they were compensated but the valuation was done by National Lands Commission thus exempting us from any blame,” he said.
On the tunneling technology being used, the CEO said it 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.
Resident project Engineer Mathu Kimenge termed the project as unique, being the longest underground tunnel to be done in the country.
Eng. Kimenge said they will 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.
He explained that the tunnel which is more than 100 metres underground is designed in such a way that there is no seepage of water from outside or inside of the underpass.
“The tunnel will not in any way interfere with aquifers and with no seepage of water from the walls into the tunnel, only water collected from intakes will flow to the dam,” assured Kimenge.
By Bernard Munyao