Residents fear pollution and noise from the proposed plant.
The city county will not approve buildings exceeding 18 storeys.
The megacity is now expected to span just 2.4 kilometres by 2030.
The project seeks to promote the use of rail transport over vehicles.
More than 66% of humanity projected to live in urban areas by 2050.
Nairobi has discarded the Dar es Salaam model that has been found wanting.
The masterplan proposes the creation of more than a dozen commercial centres.
Asian investors are planning to build a Sh65bn city in Athi River.