The winner will be awarded a cash prize of Sh100,000.
Developers to pay Sh10,000 to Sh40m for environmental audits.
George Mbugua takes over from David Gatende who has retired.
The owners have failed to meet loan restructuring measures.
The facility will hold 15 million cubic metres of water.
The project is funded by EDCF via the Export-Import Bank of Korea.
Atkins was commissioned by Kenya to design the new facility.
Angama Airstrip is being converted into an international airport.
The move follows a spate of deadly building collapse in Kiambu and Nairobi.
Olkaria 1 Unit 6 will inject 83MW into the national grid.