This Section
summarises the environmental outcomes associated with the demolition of the
CCPP.
With respect to the small scale of the
demolition works, the number of demolition plant and equipment to be used for
the works will be limited. Air emissions
from the operation of these plant and equipment will be minimal and it is
therefore not anticipated that it
will cause adverse air quality impact to the identified ASRs.
GIC will implement good construction site practices
and dust control measures stipulated in the Air
Pollution Control (Construction Dust) Regulation (as listed in Section 3.6) throughout the demolition
works. Special care will be taken when
dismantling the Co-Combustion unit of
the CCPP and removal of any residual dust attached to the internal lining or
surface of the equipment so that the
potential dust releases to the atmosphere will be minimal.
The removal of
the residual dust within the Co-Combustion unit will be carried out in an
enclosed cleaning workshop within MRRF building. The cleaning workshop will be provided with
ventilation which will maintain a slight negative pressure at all times with
the cleaning process is being carried out and the exhaust air will be cleaned
by passing through the HEPA filters.
With the implementation of the recommended
control measures described in this EIA Report and those stipulated in the Air
Pollution Control (Construction Dust) Regulation, the potential air quality
and dust impacts to the identified ASRs will be controlled within the relevant
standards as stipulated in Section 1
of Annex 4 of the EIAO-TM. No adverse air quality impact is
anticipated. Therefore no dust
monitoring will be required during the decommissioning and demolition works.
The assessment of land contamination
sources and the potential impacts to potential receptors were investigated in
accordance with the RBRG Guidance. Site appraisal comprising a site visit, and a
review of background information and land history in relation to possible land
contamination was conducted. Potential
sources of contamination and associated impacts, risks or hazards are
identified in the Contaminated Assessment
Plan (CAP) (see Annex A1).
Site investigation was conducted at the Project
Site in accordance with the recommendations of the CAP to determine if the soil
within the Project Site at the depth of excavation (ie up to 1.5m below ground)
is contaminated. Soil samples were taken
and tested for heavy metals, total petroleum hydrocarbons (TPH); BTEX
(including benzene, toluene, ethyl benzene, and xylene), dioxins and furans,
and Polychlorinated
biphenyls (PCBs). Levels of TPH analysed for all three carbon
ranges were below the reported detection limits for all samples. Concentrations of BTEX were also below the
reported detection limits at all locations.
Levels of all metals analysed in all samples were well below the RBRG
values. Levels of PCBs, dioxins and
furans analysed in all samples were well below the RBRG values for soil in
industrial area. Therefore, there is no
concern of heavy metals, TPH, BTEX and dioxins/PCBs contamination in the soil
within the depth that the excavation works will be undertaken.
The asphaltic concrete surface of the Project
Site will be removed. Excavation works
to be carried out will be limited to the removal of the concrete sub-structures
and the underground storage tank (previously used for the storage of wastewater
from the MRRF building). No soil
excavation or groundwater extraction will be required for the demolition works
and hence no potentially contaminated materials requiring off-site disposal
will be generated from the Site.
The assessment of land contamination
sources and the potential impacts to future use of the Project Site have been
assessed in accordance with the RBRG
Guidance and the results are presented in the Contaminated Assessment Report (CAR) (see Annex A2). The Project
Site’s future use remains industrial (manufacture of cement and cement related
products) and is surrounded by remaining areas of the GICP. It is considered that the only potential
receptors at risk might be site workers involved in decommissioning and
demolition works. As the contaminants
analysed were either not detected or with concentrations well below the RBRG
guideline values, the potential risk to the workers due to demolition
activities will be minimal.
After the demolition works, the Project
Site will be levelled using clean imported soil. The Project Site will remain as an open area
for the operation and future development of the GICP. It is currently proposed that the Project
Site will be rehabilitated into and restored to a grass lawn. The potential for human contact with any
underlying contamination (if any) in the future is considered low. It is therefore concluded that the risk of
future exposure to any contamination is deemed negligible. There will be no residual impacts due to the
Project after the decommissioning and demolition works have been completed.
It is therefore considered that no
environmental and audit requirement with respect to land contamination is
required.
8.4
Waste Management
Implications
The demolition
works will generate a variety of wastes (including public fill (about 1,806 m3),
scrap metals (about 369 tonnes), Co-Combustion residues (about 200 tonnes),
refractory bricks and lining (about 345 tonnes), general refuse (about 9.1 kg d-1) and sewage (about 2.1 m3
d-1)). The public fill will
be disposed of at the Tuen Mun Area 38 Fill Bank. It is proposed that the Co-Combustion
residues will be reused on-site as a raw material for the cement
production. Alternatively, Co-Combustion
residues could be disposed of at a designated landfill. The refractory brick and lining will be
disposed of at the designated landfill.
The TCLP tests for the Co-Combustion residues and refractory bricks and
lining show that the concentrations of metals in the leachate were well below
with the respective landfill disposal criteria (the concentrations of most of the
parameters are below the detection limits).
The disposal of these wastes at landfill will not cause adverse
environmental impacts.
The scrap metals will be recycled. The chemical waste and general refuse to be
generated from the maintenance of the construction plant/equipment and
construction workforce will be disposed of with other chemical waste and
general refuse arising from the GICP, respectively.
With respect to the small quantities of
the wastes to be generated from the demolition works, the handling and disposal
of these wastes will not cause adverse environmental impacts with the
implementation of general good site practices.
Potential sources of water quality impact associated
with the proposed demolition activities at the works areas include wastewater from the cleaning processes, surface runoff from the Project
Site and sewage from demolition workforce.
Wet wiping and vacuum cleaning will be used to clean the internal lining
of the ducting/equipment and remove the loose dust particles deposited on the
surface of the ducts and equipment.
Water flushing will not be used to clean the plant and equipment of the
Co-Combustion unit and hence the wastewater generated from the cleaning works
will be minimal. The anticipated quantity of wastewater to be
generated from the demolition works will be small and it will be treated at the
existing wastewater treatment plant of the GICP. With respect to the small volume of wastewater
to be generated from the demolition activities, it will have negligible impact
to the flow and load of the wastewater to be generated from the cement
production and hence the treatment capacity of the existing wastewater
treatment plant. GICP has confirmed that
the existing wastewater treatment plant will be able to handle the additional
flow and load of the wastewater arising from the demolition activities.
The surface runoff from the demolition area
will handle via the existing stormwater retention pond of the GICP prior to
discharge off-site. Therefore no adverse
water impact will be anticipated.
With the implementation of general good site
practices, the demolition works will not cause adverse water quality impact to
the identified water sensitive receivers.
8.6
Environmental
Monitoring and Audit Requirements
Monthly site audits will be undertaken
jointly by the site representative of GIC and the contractor during the
demolition works to ensure that dust control, construction waste, wastewater
and site runoff are properly managed in accordance with the good site practices
described in this EIA Report.
The Co-Combustion residues (including both
bottom ash, fly ash and the residual dust collected during the cleaning process)
will be used as part of the raw materials for the cement production. As the properties of the residues are similar
to the raw materials used for the cement production and residues contain
negligible concentration of dioxins (in terms of part per trillion) and very
low concentrations of heavy metals, the reuse of the residues for the cement
production at the proposed rates will not affect the air emissions of the
cement plant. Therefore no air quality
monitoring will be required.
An environmental impact assessment
(covering air quality, land contamination, waste management and water quality)
has been undertaken for the proposed decommissioning and demolition works of
the CCPP. The potential environmental impacts
are considered transient and minimal. No
adverse environmental impacts are envisaged due to the works in accordance with
relevant assessment criteria stipulated in the EIAO-TM. Therefore no
adverse residual environmental impact is anticipated.
The operation of the CCPP has provided
very useful technical and economic information on the operation of a materials
recovery/ recycling facility (MRRF) together with a thermal treatment facility
as part of an integrated waste management system in
After completion of the tests and
achieving the research objectives, the operation of pilot plant was stopped on
17 December 2005. The pilot plant will
be demolished so that the Project Site could be released for the operation and
future development of the GICP. The
Co-Combustion residues will be reused as a raw material for the cement
production. This will not only avoid the
disposal of the residues at landfill but also reduce the import of raw
materials for the cement production. The
process equipments and Co-Combustion units will also be properly cleaned and
recycled as much as possible to minimise the amount of waste to be disposed of
at landfills.