| Other
Disposal Practices |
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| 3.5.3.6 |
The
Chemical Waste Treatment Centre (CWTC) at
Tsing Yi provides for treatment of an average
of 200 tonnes per day (tpd) of chemical
waste which was previously either discharged
within wastewater effluent or disposed to
landfill. The residues of the treatment
processes are generally stabilised and landfilled.
Stabilised residues from the CWTC total
45 tpd (EPD 1999b).
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| 3.5.3.7 |
Dredged mud, as well as excavated materials
(under special circumstances), are disposed
at designated ocean disposal sites under a
permitting process regulated by EPD under
the Dumping at Sea Ordinance (Cap 466). Uncontaminated
materials are accepted for disposal at open
seafloor disposal sites at East of Ninepins
and South Cheung Chau, or at exhausted marine
borrow areas at South Tsing Yi and North Lantau.
Contaminated materials must be disposed at
the East Sha Chau Contaminated Mud Pits which
operates under strict site supervision and
monitoring. The number of EPD licences issued,
and the amount of material disposed, has declined
since 1994 when the majority of work for the
new airport core projects work programme was
completed. |
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| 3.5.3.8 |
Proposals
for future incineration of various waste types
are currently under consideration. In order
to alleviate the pressure on Hong Kong's landfills,
Government's Waste Reduction Framework Plan
commits to providing up to 2 million tonnes
per annum of capacity for treatment of municipal
solid waste through provision of a waste-to-energy
incinerator by 2007. In addition, the implementation
of a Sludge and Difficult Waste Incineration
Facility which would use fluidised bed technology
to incinerate sludges arising from sewage
treatment works and other sources is planned
for 2007. An animal cremation facility is
also planned to be brought on-line in 2004.
As an interim measure, it has been decided
to route clinical waste to the ChemWaste facility
at Tsing Yi, however, incineration or treatment
by other methods (eg microwave, autoclave)
is under study for future use. |
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| 3.5.3.9 |
Aside
from the waste disposition options described
above, an unknown volume of wastes of various
types are illegally disposed every year. Black
Spot areas, which include areas of public
health concern and illegal dumping, and littering
are discussed under land use natural resource
capital stock in Paragraphs 3.2.2.8 - 3.2.2.10
and refuse in the marine environment is discussed
under marine ecological value (Paragraph
4.3.3.7). |
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Consequences
of Improper Waste Disposal for Local Groundwater
and Soils
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| 3.5.3.10 |
Improper waste disposal on land can lead to
contamination of either groundwater and/or
soils. The susceptibility of local areas to
contamination is determined in large part
by the underlying geological properties. Hong
Kong consists of volcanic sequences of Upper
Jurassic and Lower Cretaceous age, with areas
of intruded igneous rock formations which
form the hilly topography characteristic of
the area. Sedimentary formations underlie
and pre-date the granitic intrusions and are
generally represented in the more peripheral
areas of Hong Kong such as Mai Po and Yuen
Long. The geology, which is strongly faulted
and in some areas extremely permeable, tends
to allow groundwater to flow through its faults
and does not result in well-defined aquifers
(GCO 1989). Therefore, there is reduced local
potential for contamination of key aquifers
although, perhaps due to the dispersed nature
of Hong Kong's groundwaters, there is little
information available on the condition and
quality of local groundwater resources. |
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| 3.5.3.11 |
Site
specific studies of soil quality and land
contamination have been undertaken (eg as
part of EIAs), but an overall picture of the
extent of land contamination in Hong Kong
and the effect of such contamination on soils
is lacking. Hong Kong's soils can be broadly
classified as "tropical soils" which
are typically shallow and vulnerable to erosion.
Their organic content generally increases
with rainfall and temperature and they usually
consist of weathered in situ rock or colluvial
materials. Lowland soils, which because of
their proximity to development and anthropogenic
activity are more likely to become contaminated,
have silt and clay textures and are formed
from either alluvial, colluvial and/or marine
deposits. Their exact composition is dependent
upon the origin of the deposits and the elevation
of the land, as well as the extent of drainage
in the area. For example soils in poorly drained
areas frequently bake hard in winter with
deep cracking and become waterlogged in summer.
These characteristics cause Hong Kong soils
to have a fairly low capacity to assimilate
contamination. |
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| 3.5.3.12 |
Investigation
and remediation of contaminated land in the
territory has only recently been initiated.
Nevertheless, it is clear from the investigations
carried out to date that the existence of
decades of contaminating land uses in many
parts of Hong Kong, particularly in the urban
and industrial areas, has resulted in a legacy
of contamination. The extent to which the
quality of the soils, superficial geological
deposits and groundwaters in these areas has
been affected is not well known. The ability
to remediate these areas will depend on the
investment of effort and funds in remediation
and the degree to which pollutants have already
migrated underground from previous or existing
polluting land uses. |
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| 3.5.3.13 |
Hong
Kong's three strategic landfills have been
developed during the 1990s using high standards
of environmental protection which should ensure
that current waste disposal practices do not
cause the long term contamination of surrounding
soils and groundwaters associated with some
earlier facilities.
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