12.1
Site
investigation (S.I.) at CLS site for land contamination assessment has
been carried out which includes 34144336 ssoil borings (31608 original and 1278 additional borings), 34567
groundwater monitoring wells (334 original and 23 additional groundwater wells), and 3.12-km
trial trenches. However, additional SI is still ongoing to delineate
the exact extent of contamination. Based on the laboratory results, available at the time of reporting, soil
contamination is noted in Areas 1, 2 and 3 of CLS site.
The soil in
Area 1 is predominantly contaminated predominantly with ‘metals’ and
‘metals/TPH/SVOCs’ whereas the soil in Area 3 is predominantly contaminated
with ‘metals’
and ‘dioxins/metals/TPH/SVOCs’. The
soil in Area 2 is contaminated with contaminants in Areas 1 and 2 are predominan‘metals’,
‘metals/TPH/SVOCs’ and ‘dioxins/metals/TPH/SVOCs’.tly TPH, metals, and
SVOCs. Dioxins
are the driver of risk in Area 3, but heavy metals are also extensively found.
12.2
The volumes of contaminated
soil in different areas hasve been estimated based on the laboratory results availableof soil samples collected. Various remedial methods have been evaluated
and screened for dioxin- and non-dioxin-contaminated soils. The proposed remediation methods are
recapitulated below:
|
Soil Contaminants |
Proposed Remediation Methods |
Quantities (m3) |
|
Metals only |
Cement Solidification |
4 |
|
TPH/SVOCs |
Biopiling |
|
|
Metals and TPH/SVOCs |
Biopiling followed by Cement Solidification |
8,300 |
|
Dioxins and Metals/ TPH/SVOCs |
Thermal Desorption followed by Cement
Solidification |
3 |
|
|
Total = |
87,00 |
12.3
The above
remedial methods are proposed based on the evaluation of their effectiveness
and implementability. In
addition, fall back options for soil remediation have been considered.
12.4
During
remediation, the contaminated soils will be excavated and treated on site for
metal-only-contaminated soil or off
site at TKW for other types of contaminated soilfrom CLS and barged to TKW
for off-site treatment.
With the incorporation of environmental mitigation measures during
excavation and operation of the remediation system, as well as the provisions
of safety measures to site workers, residue impact arising from land
contamination is minimal.
12.5
The IEC, through their own assessment, conclude that the
remedial approaches recommended in this
report can effectively meet the remedial action objectives and goals for the
CLS site. The IEC concurs with this report’s selected remedy of excavation
and treatment of metals-impacted soils by cement stabilisation, TPH and
SVOC-impacted soils by biopiling, and thermal treatment of dioxin-impacted soils
by thermal desorption.The IEC, through their own assessment, conclude
that the remedial approaches recommended in this report can effectively meet
the remedial action objectives and goals for the CLS site. The IEC also concur with this report’s
selected remedy of excavation and treatment of metals-impacted soils by cement
stabilisation, TPH and SVOC-impacted soils by biopiling, and thermal treatment
of dioxin-impacted soils by thermal desorption.
12.6
Dust emission
from the site is an area of the concern for the building demolition and slope improvement works
decommissioning activities of
CLS. TSP would be generated from
materials handling,
excavation
and truck movement over haul roads.
With the incorporation of dust control measures stipulated in the Air Pollution Control (Construction Dust)
Regulation, the TSP level at the ASR will be low and comply with the
criteria.
12.7
During Eexcavation of
contaminated area would the soils, pollutants such as and dioxins
bind tightly onto the soils, may be dispersed in form of dust. Mitigation measures have been recommended to limit
emission of the contaminated soil. MModelling
results confirm indicated
that the air quality impacts at the ASRs are low and satisfysatisfied follow the criteriahourly criteria when
the recommended excavation rates are satisfied.
12.8
Solidification will be conducted at the CLS to
stabilise heavy metals in soil.
Biopiling, thermal desorption and solidification as parts of the
decontamination process will be conducted at the TKW. Off site treatment
facilities including biopiles, solidification and thermal desorption plant; are
recommended at To Kau Wan. Design of biopiles will control the TOC
emission to 20 mg/m3 in
maximum. Off-gas from biopiles shall be treated by back-up carbon absorber to remove 99% pollutant and ensure
that the TOC
emission limit is satisfied prior to discharge. The biopiles could reduce
organic constitutes by 99%
whereas Tthe
solidifiacation process could
immobilise the heavy
metaltoxic material. The thermal description process together with the air treatment unit conducted
at could limit reduce dioxins
and organic gas
emission level by 0.000199.9999% of the contaminant in the soil., and
other organic compounds by 99%.
Air emissions from these facilities have been modelled and assessed to
be within the respective criteria. Air quality impacts
associated with decommissioning of the treatment facility are low.
12.9
The health risk level
associated with the operation of the treatment facilities is insignificant.
Water
Quality Impact
Demolition
and Excavation at Cheoy Lee Shipyard
Potential adverse water
quality impacts from the shipyard demolition and excavation would primarily be
from the contaminated groundwater (including seepage and dewatering),
potentially contaminated surface run-off and from sewage effluent generated by
the construction workforce. However, no
unacceptable water quality impact on the nearby sensitive receivers was
identified.
A number of mitigation
measures during demolition and excavation were specified to reduce the
potential adverse impacts to acceptable levels and no residual impact was
anticipated. No water quality
monitoring was recommended for the present project but site audit is
recommended to ensure that the recommended mitigation/remediation measures and
‘best practical’ site procedures are being implemented.
Slope Work
Behind Cheoy Lee Shipyard
No potential adverse impact
was anticipated with the implementation of ‘best practical’ site
procedures. Therefore no water quality
monitoring was recommended for the present project but site audit is
recommended to ensure that the recommended mitigation/remediation measures and
‘best practical’ site procedures are being implemented.
Off-site
Remediation
Biopile, thermal desportion
process and solidification are the major decontamination processes conducted at
the To Kau Wan decontamination site.
Potential water quality impact would be arising from the leachate from
contaminating the underlying soil/groundwater, surface run-off and the leakage
of contaminated waters to surroundings.
As a number of
mitigation/remediation measures and ‘best practice’ site procedures are being
undertaken, water quality impacts associated with the decontamination works is
expected to be insignificant and no residual impact is anticipated.
Potential
Impact on the Planned Water Recreation Centre
As the artificial lake at
the Water Recreation Centre is located at an elevation higher than the CLS
site, and there is a impermeable liner at the bottom of the lake and most of
the contaminants in the CLS site have been clean up, migration of the
contaminated groundwater from the CLS site to the artificial lake is not
expected. Therefore, no adverse water
quality impact or residual impact is anticipated.
12.10
C&D material will be
generated during the demolition of the shipyard facilities and the estimated
quantity is about 10,000m3.
In addition, about 1,000 tonnes of steel and 5,000 m3 of
general refuse will also be generated.
12.11
During slope improvement phase,
around 40,000m3 uncontaminated soil and 2,100m3
uncontaminated rock will be generated during excavation and soil nailing.
12.12
During remediation, about
39,000m3 contaminated material will be excavated from Cheoy Lee
Shipyard and will be transported to To Kau Wan for off-site treatment whereas
48,000m3 metal-contaminated soil will be treated on-site at
CLS. Environmental and safety measures
have been recommended to minimise secondary environmental impacts and health
risks during collection and transportation of contaminated soils from CLS to
TKW. After both on-site and off-site
treatment, around 100,000m3 clean inert materials suitable for
public filling will be generated. The
condensate of around 600m3 as the end product of the treatment and
other chemical wastes will be collected and disposed of at the Chemical Waste
Treatment Centre. Thus, no residual
waste impact and health risk concerns are expected.
12.13
During decommissioning of TKW,
around 5,000m3 C&D material and 500 tonnes steel will be
generated. C&D material will be
transported to PFAs and metal will be recycled, therefore, no residue impact is
envisaged.
12.14
The overall total of C&D
material to be generated by this Project is estimated around 0.4Mm3. The C&D material will be reused and
recycled as far as practicable in the land formation works within CLS site so
as to minimise the amount of C&D material to be disposed of at PFAs.
12.1
After both on-site and off-site treatment, around 100,000m3
clean will be generatedof around 600m3
12.1
C&D wastes will be
generated during the demolition of the shipyard facilities. It is estimated that about 10,000 m3
uncontaminated and 1,000 m3 contaminated C&D wastes will be
produced. In addition, about 1,000
tonnes of steel and 5,000 m3 of general refuse will also be
generated. It is considered that
adverse waste impacts will not be generated provided that good site practices
and waste handling recommended in Sections 6.69 to 6.107 are strictly followed.
12.1
During slope
improvement behind CLS, around 40,000m3 soil and
2,100m3 rock will be generated during
excavation and soil nailing. It is
considered that no adverse impact will arise provided that the excavated
materials will be reused/ recycled as much as practical and the surplus will be
transported for public fill or restoring CLS.
12.15
During
remediation, about 50,000 m3 and 150,000 m3 of soil
contaminated with heavy metals, PAHs and dixoins will be excavated from Cheoy Lee
Shipyard. The
contaminated soil will be transported to To Kau Wan for off-site
treatment. Most of the
soils after treatment will turn to clean inert materials suitable for public
filling. To
ensure proper waste handling and management procedures are strictly followed,
the Contractor shall
prepare the following documents for the Engineer’s approval prior to work.
·
Waste Management Plan;
·
Building Decommissioning Plan;
·
Spill Handling Contingency Plan; and
·
Operational Plan for the
Operation of Treatment Facilities at TKW.
12.16
In addition, the following registration/ licence/ approval/ permit
are required for the production, storage, collection, and off-site treatment of
chemical waste:
·
Waste
Producer Registration: The Contractor is required to be registered under the Waste Disposal (Chemical Waste) (General)
Regulation;
·
Waste
Collection Licence: A Waste Collection Licence under the Waste Disposal
Ordinance is required for the transport/ delivery of chemical wastes to
off-site waste disposal facilities;
·
Waste
Disposal Licence: A Waste Disposal Licence is required for the operation of the
off-site treatment facility a TKW for the treatment for dioxin-contaminated
soil.
·
Approval
for Using Large Container: Approval is required under the Waste Disposal (Chemical Waste) (General) Regulation for using
chemical waste container with a capacity exceeding 450L.
·
Part
A Notification: Prior notification to the Environmental Protection Department
is required before any collection of Part A chemical waste.
·
Noise
Permit: A Noise Permit under Noise
Control Ordinance is required for night-time operation of the
decontamination system and transportation of contaminated soil by trucks to TKW
at night.
·
Building
Demolition and Slope Improvement
12.17 During the building demolition and slope
improvement, adverse water quality impacts arising from runoff and sewage
effluent generated by the construction workforce are not likely with the
implementation of ‘best practical’ site procedures. Regular site audits are
therefore recommended to ensure that ‘best site practices’ and relevant
mitigation measures be implemented throughout the Project.
Soil
Remediation
At Cheoy Lee Site
12.18 After demolished the building, contaminated soils
at CLS would be excavated for on-site and off-site treatment. Local groundwater
will be drawn out (i.e. dewatering) when excavation proceeds below the water
table. The groundwater with elevated metal and TPH levels, though not
contaminated in accordance with risk-based assessment, would impose water
quality impact if being directly discharged into the drainage channel. As a
mitigation measure, the groundwater pumped out shall be recharged within CLS
site in such a manner that it would not cause local rising of water table
leading to contaminant migration. Wheel
wash water and decontamination water generated during this phase will be
considered contaminated. A mitigation
measure to install a centralised water treatment unit is recommended to treat
the effluent before discharged. With the implementation of the mitigation
measures, no adverse water quality impact is envisaged.
12.19 Impact of groundwater seepage to nearby marine
water via the future drainage channel to the north of CLS site was also assessed.
The drainage channel would be built above the existing CLS ground level thus
this effectively isolates the groundwater from seeping into the channel. In any
case, the groundwater, if any seeped into the channel would be diluted a lot,
therefore water quality impact arising from the groundwater seepage to the
nearby marine water is not likely. No
impact on the artificial lake of the future water recreation centre is
predicted arising from groundwater seepage.
This is because:
·
the
planned water level of the artificial lake will be higher than the CLS water
table level;
·
there
is an impermeable liner at the bottom of the lake to subsurface contaminants
infiltration; and
·
the
soil contamination would be cleaned up during the CLS decommissioning, thus
removing the contaminant source.
12.20 Pending receipt by the solidification facility,
there would be temporary stockpiles of metal-contaminated soil. It is recommended that temporary stockpiles
be lined with impervious sheeting, bunded and covered by impermeable sheeting
during rain events whereby the quantity of contaminated runoff and leachate
would be reduced. The generation of contaminated runoff and leachate would be
further minimised respectively by sheltering the solidification facility and
controlling water addition during the solidification process. In the end, a
licensed centralised wastewater treatment unit is recommended for treating the
contaminated runoff and leachate prior to their discharging into local
drainage.
At To
Kau Wan Site
12.21 Biopile, thermal desporption process and solidification are the major
decontamination processes conducted at the To Kau Wan decontamination
site. Potential water quality impact
would be arising from the plant leachate from contaminating the underlying
soil/groundwater, contaminated run-off from the thermal desorption plant, wheel
wash water and the decontamination water . Installation of a centralised
wastewater treatment unit to treat the effluent before discharged is therefore
recommended. With the wastewater treatment unit in place and in operation, no
adverse water quality impact is envisaged.
12.22
With the mitigation measures implemented (e.g.
floor lining and impermeability cover for the biopile, perimeter leachate
collection system for the biopile, soil storage bin and thermal desorption
plant and concrete bunds for biopile and thermal desorption plant to contain
the contaminated runoff), water quality impacts associated with the remediation
plants operation is expected to be insignificant and no residual impact is anticipated.
Demolition and Excavation at Cheoy Lee Shipyard
12.1Potential adverse water quality impacts from the shipyard
demolition and excavation would primarily be from the contaminated contaminated groundwater (including seepage and dewatering), potentially
contaminated surface run-off and from sewage effluent generated by the
construction workforce. However, no
unacceptable water quality impact on the nearby sensitive receivers was
identified.
12.1A number of mitigation measures during demolition
and excavation were specified to reduce the potential adverse impacts to
acceptable levels and no residual impact was anticipated. Water quality Nomonitoring of surface runoff to be discharged during
demolition and excavation at CLS water quality monitoring wasis recommended for the present
project. The exact
treatment and/or disposal method shall be proposed by the
Contractor should there is exceedance. Furthermore, but site audit is
recommended to ensure that the recommended mitigation/remediation measures and
‘best practical’ site procedures are being implemented.
Slope Work Behind Cheoy Lee Shipyard
No potential adverse impact was anticipated with
the implementation of ‘best practical’ site procedures. Therefore no water quality monitoring was
recommended for the present project but site audit is recommended to ensure
that the recommended mitigation/remediation measures and ‘best practical’ site
procedures are being implemented.
Off-site Remediation
12.1Biopile,
thermal desportion process and solidification are the major decontamination
processes conducted at the To Kau Wan decontamination site. Potential water quality impact would be
arising from the leachate from contaminating the underlying soil/groundwater, surface
run-off and the leakage of contaminated waters to surroundings.
12.1As a number
of mitigation/remediation measures and ‘best practice’ site procedures are
being undertaken, water quality impacts associated with the decontamination
works is expected to be insignificant and no residual impact is anticipated.
Potential Impact on the Planned
Water Recreation Centre
12.1As the
artificial lake at the Water Recreation Centre is located at an elevation
higher than the CLS site, and there is an impermeable liner at the
bottom of the lake and most of the contaminants in the CLS site have been cleaned up, migration of the
contaminated groundwater from the CLS site to the artificial lake is not
expected. Therefore, no adverse water
quality impact or residual impact is anticipated.
12.23 Based on the assessment, works associated with this
project have the potential to cause high level impacts on ecological resources.
12.24 The greatest possible disturbance is to Rice-fish
habitats at Mong Tung Hang Stream, and rare/restricted
and protected plant species around CLS.
12.25 Detailed measures to mitigate high level ecological
impacts arising from this project were recommended. Good construction practice
is recommended to avoid / minimise disturbance to other habitats surrounding
the shipyards.
12.26 With the proposed mitigation measures in place,
residual impacts arising from the Project project will be ecologicallyare considered acceptable.
Biopile, thermal desportion
process and solidification are the major decontamination processes conducted at
the To Kau Wan decontamination site.
Potential water quality impact would be arising from the leachate from
contaminating the underlying soil/groundwater, surface run-off and the leakage
of contaminated waters to surroundings.
As a number of
mitigation/remediation measures and ‘best practice’ site procedures are being
undertaken, water quality impacts associated with the decontamination works is
expected to be insignificant and no residual impact is anticipated.
Potential Impact on the Planned
Water Recreation Centre
As the artificial lake at the
Water Recreation Centre is located at an elevation higher than the CLS site,
and there is a impermeable liner at the bottom of the lake and most of the
contaminants in the CLS site have been clean up, migration of the contaminated
groundwater from the CLS site to the artificial lake is not expected. Therefore, no adverse water quality impact
or residual impact is anticipated.
Based on the
assessment, works associated with this project have the potential to cause high
level impacts on ecological resources.
The greatest
possible disturbance is to Rice-fish habitats at Mong Tung Hang Stream, and
rare/restricted and protected plant species around CLS.
Detailed
measures to mitigate high level ecological impacts arising from this project
were recommended (Appendices
A and B). Good construction practice is recommended to
avoid / minimise disturbance to other habitats surrounding the shipyards.
With the
proposed mitigation measures in place, residual impacts arising from the
project will be minimal and ecologically
acceptable.
12.27
An
archaeological survey has been conducted for the CLS, and revealed artifacts of
high archaeological values in CLS. Many
artifacts of different periods, including the Late Neolithic period, Bronze
Age, Tang Dynasty, Song Dynasty, Ming Dynasty and Ching Dynasty have been
recovered in CLS, along the ancient coastal area.
12.28
Potential
impact to archaeological resources may arise from landtake, ground compaction,
topsoil or subsoil disturbance during construction, change in watertable and a
limitation on accessibility for future investigation, which may result in
damage to, or loss of the archaeological remains. Preservation measures
include covering the archaeological potential sites, where are not subject
to rescue excavation, by impermeable sheeting before filling. Detailed design of filling
work should include diversion of site runoff to prevent any waterlogged
conditions at the archaeological sites.
For
areas where preservation
in situ is not possible, the impact on the heritage resources should be
mitigated by rescue excavation. All
rescue works have to be completed prior to the decontaminated works of CLS. Filling at the
archaeological potential site shall be covered by plastic sheets. Detailed design of filling work or ground
level adjustment work should consider diversion of site runoff to prevent any
waterlogged conditions. Mitigation
measures to heritage resources including, a rescue programme have been
recommended prior to the decontaminated works of CLS.
Environmental Monitoring and Audit
12.29
Environmental
monitoring and audit are recommended for land contamination, air quality, water
quality, waste management and ecology.
Details of the recommended mitigation measures, monitoring procedures
and locations will be presented in a stand-alone Environmental Monitoring and
Audit Manual (EM&A). This will
enable the Contractor to have early warning and provide necessary action to
reduce impacts at specific areas if the assessment criteria are
approached. The effectiveness of
on-site control measures could also be evaluated through the monitoring
exercise. All the recommended
mitigation measures should be incorporated into the EM&A programme for
implementation.
12.30
The findings
of this EIA have provided information on the nature and extent of environmental
impacts arising from the decommission of the CLS. The EIA has, where appropriate, identified mitigation measures to
ensure compliance with environmental legislation and standards.
12.31
Overall, the
EIA Report for the decommission of the CLS has predicted that the Project will
generally comply with all environmental standards and legislation after the
proposed construction and operational stage mitigation measures are implemented. This EIA has also demonstrated the general
acceptability of the residual impacts from the Project and the protection of
the population and environmentally sensitive resources. Environmental monitoring and audit
mechanisms have been recommended during the decommissioning of CLS,
where necessary, to verify the accuracy of the EIA predictions and the
effectiveness of recommended mitigation measures.
12.32 The nature
of the project is primarily of environmental improvement. Contaminated
materials are permanently removed from the ground and cleaned up, removing a
source of long term liability. After
the shipyard is decommissioned, it provides room for the infrastructure in
support of the Theme Park Development.
The safety of the slopes is improved.
The habitat of a locally restricted/protected fish species will be
recreated, and restricted/protected plants will be conserved on-site, or
transplanted to a suitable receptor site.
The archaeological artefacts are rescued or preserved from the site.