An explosion of dangerous methane gas could have triggered the Kitezi
landfill disaster. Some of the survivors of the incident reportedly heard some
explosions from the direction of the buried houses before the collapse of the
landfills.
On Tuesday,
Kyadondo East MP, Haroon Muwada Nkunyingi in Parliament, advanced the possibility
that a blast from the garbage might have triggered the incident.
“The witnesses
are reporting that it was a blast that blew up the sand and garbage and the smoke.
That is the narrative from the residents. They even continue to allege that
they saw Chinese installing pipes in the heap of garbage because there were two
heaps,” said Muwada.
////Cue IN “The
witnesses are....
Cue Out….what
were the Chinese doing? ”////
“We don’t want
to imagine and assume that it was a mere slide by the landfill. There is more likelihood
that it was either an accident or an intentional mistake or negligence by the Chinese
or KCCA,” said Muwada.
State Minister
for Kampala, Minsa Kabanda in response said no Chinese nationals were operating
near the Kiteezi landfill. She did not comment about the blast. The State
Minister for Disaster, Lillian Aber did not mention whether on the possibility
of an explosion.
The Kitezi site has been developed mainly as a land
raise with only limited basal engineering reportedly carried out before
landfill development. A scientific
explanation and real landfill accidents from methane gas explosions exist.
History of landfill
explosions
One such explosion
occurred in1986 in Loscoe England when a landfill ground gas explosion, badly injured three
people in a bungalow.
At Loscoe,
the incident occurred because of a lack of understanding of the process
operations and necessary controls, and, as such, the explosion could be seen as
a direct consequence of the landfill operation.
Another
landfill explosion was in Turkey.
On 28 April 1993, an “explosion” took place, followed by
the displacement of a large mass of solid wastes at Ümraniye-Hekimbaşi
open dump accident that engulfed II houses causing the death of 39
people.
The Kiteezi case early warning in 2008
Uganda Radio Network has come
across documentary evidence warning of a possible methane gas explosion at Kiteezi
then under the management of the defunct Kampala City Council (KCC).
The warning was contained in an
Environment Impact Assessment (EIA) report prepared by KCC for a gas-flaring project
that KCC has prepared for funding under the UN Framework Convention on Climate
Change’s Clean Development Mechanism (CDM)
CDM project activity was
suggested as part of the investment package planned for the Solid Waste Management
component of the World Bank-funded Kampala Institutional and Infrastructure
Development Project (KIIDP).
Gas extraction and flaring (LFG) by
KCC was to control gas both in terms of risk from the explosion
and to reduce harmful emissions of greenhouse gases.
The EIA report warned of subsurface migration
of landfill gas from landfills to other areas within the landfill property or
outside the landfill property.
“Most subsurface migration occurs
at older, unlined landfills because there is a minimal barrier for lateral
migration,” reads part of the report.
The Kiteezi landfill had outlived
its lifetime in 2008 when the EIA report was prepared.
The report also revealed that the
landfill had experienced a collapse on the southeast side before 2008.
“Which may have been due to the
subsurface migration of the landfill gas. Incidentally, there was no habitation
on this side of the site and hence local citizens did not witness large-scale
exposure to NMOC," said the report.
Landfill gas
also includes small amounts of nitrogen, oxygen, ammonia, sulfides, hydrogen,
carbon monoxide, and non-methane organic compounds (NMOCs) such as trichloroethylene,
benzene, and vinyl chloride.
“Since landfill, gas contains
approximately 50 percent methane (a potentially explosive gas) it is possible
for landfill gas to travel underground, accumulate in enclosed structures, and
ignite,” said the EIA.
The report further warned that possibly the biggest health and environmental concerns were related
to the uncontrolled surface emissions of landfill gas into the air.
“Landfill gas contains carbon dioxide, methane, VOC, HAP, and
odorous compounds that can adversely affect public health and the environment," it said.
Landfill Gasses
(LFGS) mostly constitute methane (CH4) (50–60%), carbon
dioxide (CO2) (30–40%),
and the Hazardous air pollutants (HAPs), THC, and volatile organic compounds (VOCs),"
Science of gases at landfills
The
decomposition of waste also brings about the generation of gases, mainly a
mixture of methane and carbon dioxide (about 50–50% in anaerobic conditions),
known as ‘biogas’.
Methane is lighter than air and highly flammable. If it
enters a closed building and the concentration increases to about 5–15% in the
air, a spark or a flame is likely to cause a serious explosion.
Why is
methane a fire hazard?
Methane burns
very easily and often is used as natural gas for cooking and heating. It is
lighter than air and collects at the top of enclosed spaces. When it rises
through the soil and enters buildings, it gets trapped in the lower parts of a
building, such as the basement.
As more methane enters the building, the level
in the air increases. When the methane level reaches 5 percent of the air, it
can cause a fire or an explosion if a spark or flame is present.
