The Northern Water Collector Tunnel is 89 per cent complete, Athi Water Services Board chief executive officer Mwangi Thuita has said.
He said it is expected to be completed by the end of next year.
Thuita said the remaining excavation work is expected to be complete by the end of this year. Only 1.3 kilometres of the 12.7 kilometres long tunnel have not been excavated.
The tunnel, which has been under construction since 2015, will boost water supply to Nairobi county.
The project is being funded by the World Bank at a cost of Sh20 billion.
The tunnel alone is being constructed for Sh6.8 billion, the treatment plant at Sh6.5 billion, while the pipeline will cost Sh4.6 billion.
The tunnel starts at Ichichi in Kangema subcounty, runs through Kigumo before joining the Ndaka-ini dam in Gatanga subcounty. It is projected to channel 140,000 cubic metres of water to the reservoir every day.
After tunnelling is complete, Thuita said, the laying of pipes from Ndaka-ini dam to Kigoro water treatment plant and the Gigiri reservoirs will take another year to complete.
The government had earlier announced that the tunnel would be completed by the end of this year and it was to be opened by the President on Jamhuri Day.
Thuita spoke when he led a team of engineers on a visit to the tunnel.
He reiterated that the tunnel will not harm local rivers as it will only harness floodwaters.
It will draw its water from rivers Gikigie, Maragua and Irati – only when it is raining – and channel it to Ndaka-ini dam to increase supply to Nairobi county.
The project constitutes the construction of the tunnel in phase 1 of the project, construction of Kigoro treatment plant and construction of raw and treated water pipelines to Kigoro and Gigiri reservoirs
“The project is progressing smoothly, and we have compensated all residents who have been affected by the tunnel,” Thuita said.
Residents have been protesting the compensation they received from the government, saying it is not equal the property they lost.
Others in Kiria-ini village in Gatanga said a group of police officers descended on their coffee and tea farms and cut down their cash crops before the compensation issue was resolved.
Thuita, however, said the National Land Commission conducted the valuation of properties affected and Athi Water Services Board was not to blame for the issues involving valuation.
The CEO also noted that the technology being used in the construction of the tunnel cuts across all engineering fields and local engineers will learn from it to improve infrastructural services in the country.
Project’s resident engineer Mathu Kimenge said the tunnel is the largest underground project ever done locally.
“We will partner with universities to train upcoming engineers on how they can use the technology,” he said.
The tunnel that is 100 metres underground, will not allow seepage of water.
