The Dandora dumpsite perimeter wall is 25 per cent complete, according to immediate former county Environment chief officer David Makori.
The wall, which is intended to keep away unauthorised persons, was started by the former county government.
Makori said the County Committee for Environment has raised concern on the size and capacity of the dumpsite.
It is not clear whether it has extended to residential areas or the residents have encroached on it since it was declared full in 2001.
The planning department is yet to give its exact dimensions, Makori said. But it is said to cover more than 30 acres.
"The perimeter wall will separate the dumpsite from the residential areas. We have our county staff, inspectorate officers and the police who ensure that the place is secure," he told the Star on Monday.
There are two official entrances, one at the Shell petrol station and the other at Stage 41. The entrances are controlled by county officials based at the weighbridge.
The dumpsite was started in 1970 as a quarry. It grew in size as did the human population surrounding it.
Despite being declared full in 2001, waste continues to be dumped there.
These days the waste is burnt. It has, however, grown into a mountain.
The burning produces acidic fumes of chemicals like sulphur. The noxious fumes are a cause of air pollution and acid rain.
These pollutants affect the respiratory system of the neighbouring communities of Kariobangi, Baba Dogo, Gitare Marigo and Korogocho.
Children are the most vulnerable. They suffer from skin diseases, abdominal pains, eye infections and dental problems.
"Sixty-two per cent of the waste generated in Nairobi is organic waste and when it decomposes it emits fumes. It generates leachate (water that has percolated through a solid and leached out some of the constituents), which is very toxic and ends up in Nairobi River," Makori said.
