9
Land Contamination
9.1.1
This section presents the potential land contamination
implications associated with the Project.
8
9
9.1
9.2
9.2.1
The
relevant legislation, standards and guidelines applicable to the present study
for the assessment of land contamination include:
·
Annex 19 of the Technical Memorandum on
Environmental Impact Assessment Process (EIAO-TM), Guidelines for Assessment of
Impact On Sites of Cultural Heritage and Other Impacts
(Section 3 – Potential Contaminated Land Issues), Environmental Protection
Department (EPD);
·
Guidance Note for Contaminated Land Assessment
and Remediation, EPD, 2007 (Revised in April 2023);
·
Guidance Manual for Use of Risk-Based
Remediation Goals (RBRGs) for Contaminated Land Management, EPD, 2007 (Revised
in April 2023); and
·
Practice Guide for Investigation and
Remediation of Contaminated Land, EPD, 2011 (Revised in April 2023).
9.2.2
Under
Annex 19 of the EIAO-TM, a number of potentially contaminating historical and
present land uses should be considered, including oil installations, gas works,
metal workshops, car repair and dismantling workshops, which have the potential
to cause or have caused land contamination.
Nevertheless, any other potential contaminating activities/
installations/ facilities within the boundary of the Project and the works of
the Project should be identified and considered based on professional
judgement.
9.2.3
In accordance with EPD’s Guidance Note for
Contamination Land Assessment and Remediation, a contamination assessment
evaluation should:
·
Provide a clear and detailed account of the
present land use and the relevant past land history, in relation to possible
land contamination;
·
Identify areas of potential contamination and
associated impacts, risks or hazards; and
·
Submit a plan to evaluate the actual
contamination conditions for soil and/or groundwater, if required.
9.2.4
The Guidance Manual introduces the risk-based approach
in land contamination assessment and presents instructions for comparison of
soil and groundwater data to the RBRGs for 54 chemicals of concern commonly
found in Hong Kong. The RBRGs were
derived to suit Hong Kong conditions by following the international practice of
adopting a risk-based methodology for contaminated land assessment and
remediation and were designed to protect the health of people who could
potentially be exposed to land impacted by chemicals under four broad post
restoration land use categories. The
RBRGs also serve as the remediation targets if remediation is necessary.
9.2.5
The EPD’s Practice Guide for Investigation and
Remediation of Contaminated Land includes a summary of the general steps of a
contamination assessment study, which include site appraisal, site
investigation and remediation.
9.3.1
Figure
Nos. C1603/C/NOL/ACM/M50/301 to 304 show the location of the Project. The Project would
involve the following key construction activities:
·
approximately
10.7km of underground railway line between KSR(NOL) Station and KTU(NOL)
Station;
·
five
new stations, namely KSR(NOL) Station, AUT Station, NTM Station, SAT Station
and KTU(NOL) Station;
·
seven ancillary buildings which serves as EAPs/EEPs/VBs;
·
a
depot at Ngau Tam Mei (i.e. NTD); and
·
enabling
works for potential extension to the south of KSR(NOL) Station, to the east of
KTU(NOL) Station for potential extension to Ping Che areas and potential
bifurcation to LMC Loop and Huanggang Port to the
north of SAT Station.
9.3.2
The assessment area for
this land contamination assessment includes the Project and the associated
works sites and areas of the Project as shown in Figure Nos. C1603/C/NOL/ACM/M50/306 to 318.
9.4.1
The
land contamination assessment was conducted according to the following
procedures. Each of these procedures
listed below is further discussed in the following sections.
·
Desktop review of the site history; and
·
Site surveys for identification of any
potentially contaminated areas.
9.4.2
For
the purpose of conducting the desktop review, the best available relevant
information in the public domain was collected.
This information which illustrate the features
of the assessment area as well as any changes in land use over the previous
decades includes:
·
Selected historical aerial photographs between
Year 1963 and Year 2018; and
·
Records on dangerous goods (DGs), chemical wastes
and chemical spillage/leakage incidents from Fire Services Department
(FSD) and Environmental Protection Department (EPD).
9.4.3
Site
surveys were conducted from December 2021 to December 2022 and June 2023 to verify the findings of the
desktop review and to identify any other land uses within the assessment area
which may have potential to cause land contamination. Possible contaminants, if any, were
identified in accordance with EPD’s Practice
Guide for Investigation and Remediation of Contaminated Land.
9.5.1
Selected historical aerial photographs between Year
1963 and Year 2018 of the assessment area were reviewed to ascertain any
historical land use with potential for land contamination. The historical aerial
photographs are shown in the CAP (Appendix
9.1). The findings of the historical aerial
photographs are summarised in Table 9.1.
Table 9.1 Summary
of Historical Landuse of the Project Site
|
Year
|
Observation
|
|
Year 1963
|
·
The majority is agriculture land
and scattered village type house.
·
Fish ponds were observed at the sites of
Shui Mei Road Ancillary Building (EAP/EEP/VB), SAT Station and KTU(NOL)
Station.
·
Natural terrain was observed at
temporary explosive magazine site at Tai Shu Ha (Yuen Long).
|
|
Year 1973
|
·
Fish ponds were observed at the sites of
San Tin Ancillary Building (EEP/VB).
·
Fish pond at the sites of SAT Station had
been replaced by Agricultural land.
·
Agricultural land at the sites
of Ka Lung Road Ancillary Building (EAP/EEP) and Pak Shek Au Ancillary
Building (EAP/EEP) had been replaced by village houses.
·
Fish ponds at the sites of KTU(NOL)
Station had been replaced by village houses.
·
No significant change in land
use was observed for the other parts of the site in comparison with land use
from the 1963 aerial photograph.
|
|
Year 1982
|
·
Village houses were observed at
the sites of NTM Station.
·
Part of the agricultural land at
the sites of San Tin Ancillary Building (EEP/VB) had been replaced by
grassland.
·
Fish pond at the sites of San Tin
Ancillary Building (EEP/VB) had been replaced by agricultural land.
·
Vacant land was observed at the
sites of KTU(NOL) Station.
·
No significant change in land
use was observed for the other parts of the site in comparison with land use
from the 1973 aerial photograph.
|
|
Year 1993
|
·
Suspected storages were observed
at the sites of NTD.
·
More grassland was observed at
the sites of KTU(NOL) Station.
·
Access road was constructed at temporary
explosive magazine site at Tai Shu Ha (Yuen Long).
·
No significant change in land
use was observed for the other parts of the site in comparison with land use
from the 1982 aerial photograph.
|
|
Year 2006
|
·
Suspected workshops, storages
and village houses were observed at the sites of AUT Station.
·
Agricultural land in Long Ha
Tsuen Ancillary Building (EAP/EEP) were replaced by grove.
·
Some Agricultural land had been
replaced by grassland at the sites of NTM station.
·
Some village house had been
replaced by suspected storage at the sites of NTM station.
·
Suspected workshops, warehouses,
and more suspected storages were observed in NTD.
·
Some village house and more
suspected workshop were observed at the sites of SAT Station.
·
Village houses at the sites of
Kwu Tung Road Ancillary Building (EAP/EEP/VB) were replaced by suspected
workshops.
·
Some village houses were
demolished at the sites of KTU(NOL) Station and Pak Shek Au Ancillary
Building (EAP/EEP).
·
No significant change in land
use was observed for the other parts of the site in comparison with land use
from the 1993 aerial photograph.
|
|
Year 2018
|
·
Stream at the sites of Shui Mei
Road Ancillary Building (EAP/EEP/VB) had been replaced by grassland.
·
Some village houses and
suspected storage were observed at the sites of Long Ha Tsuen Ancillary
Building (EAP/EEP).
·
Suspected workshops were
observed at the sites of NTM station.
·
More suspected warehouses and
workshop were observed at the sites of NTD and AUT Station.
·
More suspected workshops were
observed at the sites of SAT Station.
·
Suspected workshop was observed
at the sites of KTU(NOL) Station
·
At temporary explosive magazine
site at Tai Shu Ha (Yuen Long), the vegetation at the area of the access road
ending were removed.
·
No significant change in land
use was observed for the other parts of the site in comparison with land use
from the 2006 aerial photograph.
|
9.6
Information from
Relevant Government Departments
9.6.1
Information
requests were sent to EPD to enquire:
·
Past and present chemical spillage/ leakage
records within the assessment area; and
·
Records of Chemical Waste Producers
Registration (CWPR) within the assessment area.
9.6.2
Based on the information provided by EPD, 11 active (valid) and 4 inactive (invalid) Chemical
Waste Producers Registrations were found. There were also no records of reported
accidents of spillage/leakage of chemicals in the past 3 years (2020 to 2023),
hence the land contamination impact in the assessment area is considered unlikely. Details are presented in the CAP (Appendix 9.1 refers).
9.6.3
Information
requests were sent to Fire Services Department (FSD) to enquire:
·
Records of Dangerous Goods (DGs) License issued
within the assessment area;
·
Any past and present information related to the
use and/ or storage of DGs in the assessment area; and
·
Past and present incident records within the
assessment area.
9.6.4
Based on the information provided by FSD, there are 25 nos. of licensed dangerous goods stored identified. After identifying these locations of
dangerous good storage, none of them are located within the assessment area. The relevant details are presented in the CAP (Appendix 9.1 refers).
9.6.5
In
addition, a total of 455 incidents were recorded from Oct 2020 to Sep 2023 and there was no
reported case of dangerous goods spillage/leakage in the assessment area. One chemical incident was recorded at Chau
Tau Tsuen, near 98 Kwu Tung Road which is within the Project Site on 11 June
2023. After identifying the rest incident locations, most of them are located
outside the Project Site except a few fire alarm incidents which will not cause land contamination. The land contamination impact in the Project Site (except the above location
with chemical incident) is considered unlikely. The relevant details are presented in the
CAP (Appendix 9.1 refers).
9.7.1
Site surveys were conducted from December 2021 to December 2022 and June 2023 to identify the
existing land uses within the assessment area which may have potential for
causing soil contamination. The photographs taken during site surveys are presented in Appendix 4.1 in the CAP (Appendix
9.1 refers). The
site walkover checklists were annexed in Appendix 4.2 the CAP (Appendix
9.1 refers).
9.7.2
Detailed findings of the potentially
contaminated sites identified during site survey is summarised in Section 9.9.
9.8.1
The
RBRGs have developed four different post-restoration land uses, namely “Urban
Residential”, “Rural Residential”, “Industrial” and “Public Parks”, to reflect
the actual settings which people
could be exposed to contaminated soil or groundwater. Definition of
post-restoration land uses are given in EPD’s Guidance Note for Contaminated Land Assessment and Remediation and
Guidance Manual for RBRGs. “Industrial” land use will be adopted for result comparison in this land
contamination assessment study as railway facilities will be built within the
Project Site.
9.9.1
Identification
of potentially contaminated sites within the Project was conducted with
reference to EPD’s Practice Guide for Investigation and Remediation of
Contaminated Land and with the aid of the information collected from
desktop review of selected historical aerial photos and site surveys.
9.9.2
Site
surveys were conducted from December 2021 to December 2022 and June 2023 to
identify the current status of the assessment area. However, some of the potentially contaminated
sites were inaccessible and site surveys were only conducted along the site
boundary of these sites, and thus site re-appraisal should be conducted in the
later stage (i.e. after land resumption). Hence, no drillholes were proposed for those
sites. The photos records, site walkover
checklists for those accessible sites, and site observations are shown in the
CAP (Appendix
9.1 refers). Several land uses/
activities with the potential to cause land contamination issues were observed
at AUT Station, NTM
Station and NTD, SAT Station, and KTU(NOL) Station and 4 locations of EAPs/EEPs/VBs including LHA, KLA, KTA and PAA. These land uses/ activities mainly comprise:
·
Open storage;
·
Workshop;
·
Open carpark;
·
Vehicle maintenance;
·
Recycling facilities, and
·
Warehouse.
9.9.3
A
total of 121 potentially contaminated sites were identified, including 69
inaccessible sites and 52 accessible sites.
Among the 52 accessible sites, 16 sites were wholly accessible
and 36 sites were partially accessible.
Among the 16 wholly accessible sites, 9 sites were identified with no
potentially contaminated source, and thus no drillholes were proposed for these
sites.
9.9.4
Locations of the potentially contaminated sites within the assessment area and the location of proposed drillholes are given in Figure Nos. C1603/C/NOL/ACM/M64/000
to 008 and Appendix 4.1 in the CAP (Appendix
9.1 refers), with a summary of the potentially
contaminated sites provided in Table 9.2.
Table
9.2 Summary of Potentially Contaminated Sites
|
Works Location
|
No. of Accessible & Partially Accessible Site (1)
|
No. of Inaccessible Site
|
No. of Potentially Contaminated Sites
|
|
AUT
Station
|
9
|
5
|
14
|
|
NTM
Station and NTD
|
14
|
11
|
25
|
|
SAT
Station
|
14
|
34
|
48
|
|
KTU(NOL)
Station
|
0
|
1
|
1
|
|
Ancillary
Buildings
|
15
|
18
|
33
|
|
Total (1)
|
52
|
69
|
121
|
Note:
(1)
Details refer to the CAP in Appendix 9.1.
9.10
Site Investigation Plan
9.10.1
Based on the site observation and
review of historical landuse of the 52 accessible
sites (including 16 wholly accessible sites and 36 partially accessible sites),
drillholes are proposed under below conditions.
Ø The accessible sites with no potential contamination land use, i.e.,
carpark and office, no drillhole is proposed.
Ø The accessible sites with localised potential
contamination land use, i.e. workshop and warehouse,
drillholes are localisely proposed in potential
contamination area.
Ø The accessible sites with potential contamination within the whole site,
drillhole are proposed within the whole site.
Ø The partially accessible sites, some suspected contamination activities
(e.g. workshop/ materials storage etc.) were observed
in the part of the inaccessible area from the outside of the accessible area
and/or advised by the tenant during site survey, hence drillholes were
proposed.
9.10.2
As mentioned in Section 9.9.3,
among the 16 wholly
accessible sites, 9 sites were identified with no potentially contaminated
source, and thus no drillholes were proposed for these sites. Therefore, drillholes are then proposed for the 43 accessible sites (including 7 sites are wholly
accessible and 36 sites are partially accessible).
9.10.3
Total of 537 drillholes were
proposed for the 43 accessible sites. The proposed numbers of drillhole are provisional and are
subject to the results of further site re-appraisal after land resumption
(Section 4.3 of the CAP in
Appendix
9.1 refers). The COCs
proposed for laboratory analysis included metals, VOCs, SVOCs, PCRs and
PCBs. The potential COCs for the
identified potentially contaminating land uses is presented in Table 9.3.
9.10.4
For the inaccessible sites (i.e. total 69 inaccessible sites), only peripheral site
inspections were undertaken. The actual site condition cannot be identified,
the contamination extent would be varied and localised
based on the accessible sites observations. Hence,
drillholes are not proposed for those inaccessible sites at this stage and they
should be proposed after site re-appraisal based on site observation after land
resumption.
Table 9.3
Potential COCs for the Identified Potentially Contaminating Land Uses
|
Land Use(2)
|
Potentially
Contaminating Activities
|
COCs(1)(3) for Soil
|
COCs(1)(4) for Groundwater
|
Possible
Remediation Methods (5)
|
|
Open
storage
|
Loading,
unloading and storage of goods, transfer, maintenance of equipment and
vehicles, and leakage of stored goods.
|
Metals
(Full List), VOCs, SVOCs, and PCRs
|
Metals
(Mercury), VOCs, SVOCs, and PCRs
|
Stabilisation/
Solidification, Biopile for soil;
Air
Sparging/ Recovery trenches or wells for groundwater.
|
|
Warehouse
|
Loading,
unloading and storage of goods, storage and processing of waste materials,
storage and transfer of chemicals and fuels, storage and disposal of wastes
and maintenance of equipment and vehicles.
|
|
Vehicle
maintenance
|
Lubricants
from vehicles, use of chemicals and solvents, possible spillage/ leakage of
fuels and oils during maintenance activities.
|
|
Vehicle
maintenance and workshop
|
Lubricants
from vehicles, use of chemicals and solvents, possible spillage/ leakage of fuels
and oils during maintenance activities.
|
|
Open
Storage and Vehicle maintenance
|
Loading,
unloading and storage of goods, transfer, maintenance of equipment and vehicles,
and leakage of stored goods; possible spillage/ leakage of fuels and oils
during maintenance activities.
|
|
Workshop
and open storage
|
Loading,
unloading and storage of goods, transfer, maintenance of equipment and
vehicles, and leakage of stored goods; possible spillage/ leakage of fuels
and oils during maintenance activities.
|
|
Workshops
|
Lubricants from vehicles, use of chemicals and
solvents, possible spillage/ leakage of fuels and oils during maintenance
activities.
|
|
Recycling
Facilities
|
Loading,
unloading and storage of goods, storage and processing of waste materials,
storage and transfer of chemicals and fuels, storage and disposal of wastes
and maintenance of equipment and vehicles.
|
Metals
(Full List), VOCs, SVOCs, PCRs and PCBs
|
Metals
(Mercury), VOCs, SVOCs, PCRs and PCBs
|
Notes:
(1)
The proposed testing
schedule in this table is provisional and is subject to the results of further
site re-appraisal after land resumption.
(2)
The land use refers
to Table 4.1 of the CAP (Appendix
9.1 refers). Residential and
office are not considered as potential contaminated land use. The sites with
land use of open carpark were identified with no contamination source.
Therefore, they are not presented in this table.
(3)
The proposed testing
parameters refers to Table 2.3 of EPD’s Practice
Guide for Investigation and Remediation of Contaminated Land, with potentially contaminating activities (Table 4.1
of the CAP in Appendix
9.1 refers).
Metals: Antimony, Arsenic, Barium, Cadmium, Chromium III, Chromium VI,
Cobalt, Copper, Lead, Manganese, Mercury, Molybdenum, Nickel, Tin, Zinc;
Volatile Organic Compounds (VOCs): Acetone, Benzene,
Bromodichloromethane, 2-Butanone, Chloroform, Ethylbenzene, Methyl tert-Butyl
Ether, Methylene Chloride, Styrene, Tetrachloroethene, Toluene,
Trichloroethene, Xylenes (total);
Semi Volatile Organic Compounds (SVOCs): Acenaphthene, Acenaphthylene,
Anthracene, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(g.h.i)perylene,
Benzo(k)fluoranthene, Bis-(2-Ethylhexyl)phthalate, Chrysene, Dibenzo(a,h)anthracene, Fluoranthene, Fluorene, Hexachlorobenzene, Indeno(1,2,3-cd)pyrene, Naphthalene, Phenanthrene, Phenol,
Pyrene;
Petroleum Carbon Ranges (PCRs): Carbon Ranges C6-C8, C9-C16 and C17-C35
PCBs: Polychlorinated Biphenyls
(4)
The proposed testing
parameters refers to Table 2.3 of EPD’s Practice
Guide for Investigation and Remediation of Contaminated Land, with potentially contaminating activities (Table 4.1
of the CAP in Appendix
9.1 refers).
Metals: Mercury;
Volatile Organic Compounds (VOCs): Acetone, Benzene,
Bromodichloromethane, 2-Butanone, Chloroform, Ethylbenzene, Methyl tert-Butyl
Ether, Methylene Chloride, Styrene, Tetrachloroethene, Toluene,
Trichloroethene, Xylenes (total);
Semi Volatile Organic Compounds (SVOCs): Acenaphthene, Acenaphthylene,
Anthracene, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(g.h.i)perylene,
Benzo(k)fluoranthene, Bis-(2-Ethylhexyl)phthalate, Chrysene, Dibenzo(a,h)anthracene, Fluoranthene, Fluorene, Hexachlorobenzene, Indeno(1,2,3-cd)pyrene, Naphthalene, Phenanthrene, Phenol,
Pyrene;
Petroleum Carbon Ranges (PCRs): Carbon Ranges C6-C8, C9-C16 and C17-C35
PCBs: Polychlorinated Biphenyls
(5)
Details of possible remediation methods for the COCs are listed in
Section 7 of the CAP (Appendix
9.1 refers).
9.11
Proposed
Re-appraisal for Potentially Contaminated Land Uses
9.11.1
Further
site appraisal should be carried out once site access is available for the
whole Project Site (including identified accessible sites, partially accessible
sites and inaccessible sites) (e.g. after land
resumption), in order to identify the presence of “hot spots” for intrusive
site investigation and confirm the evaluation of the contaminated site in
initial land contamination assessment.
9.11.2
A
supplementary CAP should be prepared to summarise the relevant findings of the
further site appraisal. After approval
of the supplementary CAP and upon completion of the SI works, if any, a
Contamination Assessment Report (CAR) should be prepared to present findings of
the SI works. If contamination was
identified, a Remediation Action Plan (RAP) should be prepared to formulate
appropriate remedial measures to deal with the contamination identified.
9.11.3
Considering
the current landuse/ activities with the potential to
cause land contamination are mainly open storage, workshop, vehicle
maintenance, recycling facilities and warehouse which are operated within the
respective site area. It is expected that the land contamination (if any) due
to these landuse/ activities would be localized and
within the identified contamination area. The contamination extent would also
be identified by the closure assessment of remediation works. Therefore, except for land remediation works, no
construction works by mean of excavation shall be carried out at the respective
identified contamination area (if any) prior to the endorsement of the closure
assessment.
9.11.4
Following
the completion of any necessary remediation works, a Remediation Report (RR)
should be prepared to demonstrate adequate clean-up and submit to EPD for
approval.
9.12.1
The
most relevant RBRGs corresponding to the future land use should be adopted in
assessing its land contamination level.
Laboratory testing results from SI should be compared with correspondent RBRGs, the soil
saturation and solubility limits for the testing parameters in accordance with
the EPD’s Guidance Manual for Use of RBRGs for Contaminated Land Management.
9.12.2
Following
the completion of environmental SI and lab testing works, a CAR should be
prepared to present the findings of the SI and evaluate the level and extent of
potential contamination. The potential
environmental and human health impact based on the extent of potential
contamination identified would also be evaluated.
9.12.3
If
land contamination is identified in the proposed environmental SI and
remediation is required, a RAP should then be prepared. The objectives of RAP are:
·
To undertake further site investigation where
required;
·
To evaluate and recommend appropriate remedial
measures for the contaminated materials identified in the assessment;
·
To recommend good handling practices for the
contaminated materials during the remediation works;
·
To recommend approximate handling and disposal
measures; and
·
To formulate optimal and cost-effective
mitigation and remedial measures for EPD’s agreement.
9.12.4
A
RR should also be prepared to demonstrate that the clean-up works are adequate
and submitted to EPD for agreement.
9.13.1
Based
on the findings of site appraisals, a total of 121 potentially contaminated sites were identified with potential land contamination concerns within the Project and
intrusive SI works were proposed for the 43 accessible potentially contaminated sites. However, as the concerned sites are still in operation, it would not
be feasible to carry out the proposed SI works under the EIA Study.
9.13.2
The
potential land contamination concerns for the concerned sites were associated
with open storage, workshop, vehicle maintenance, recycling facilities, and
warehouse. As the identified potential land contamination landuse/activities
were operated within the respective site area, therefore, the potential land
contamination were considered localized. Also,
according to the information provided by EPD and FSD, there were no records of
spillages / leakages accidents of chemicals / dangerous goods within the
Project. It is therefore considered that
the contamination (if indeed present) would unlikely be extensive within the
assessment area.
9.13.3
Land
contamination assessment including intrusive SI works and, if required,
remediation works would need to be carried out at a later stage of the Project
(refer to Section 9.13 below for details) and should follow EPD’s Guidance
Manual, Guidance Note and Practice Guide.
Any soil/groundwater contamination would be identified and properly
treated. The potential COCs identified
include metals, VOCs, SVOCs, PCRs and PCBs and there are commercially available
technologies that could tackle these COCs.
9.13.4
The
contamination issue at the potentially contaminated sites is considered
surmountable with the following supportive views:
9.13.5
Based
on the site survey and desktop review, the majority of the sites were
identified as open storage, warehouses and workshop. As discussed previously, some of the sites
were inaccessible, only peripheral site inspections were undertaken. As such, the site inspections were unable to
determine what type of goods are stored within these sites. For open storage areas and warehouses, the majority
of these sites are usually kept for the storage of goods, whilst only a small
portion of the site is reserved for chemical storage. As such, it was considered that if there is
indeed any land contamination present at these sites, it is expected that it
would be localised.
9.13.6
Furthermore,
around 90% of these sites are less than 4,000m2 in area which is
considered relatively small in scale.
Therefore, the contamination extent, if any, caused by the operations of
the identified potentially contaminated sites would be anticipated to be
localised.
9.13.7
Based
on the COC’s identified in this site appraisal (including VOCs, SVOCs, metals,
PCRs and PCBs), it was considered that the remediation measures outlined in Table
9.3 (Details in Table 7.2 and Table 7.3 of the CAP (Appendix 9.1 refers)) were
demonstrated to effectively treat such contamination, both in soil and
groundwater.
9.13.8
In
addition, remediation methods available in the market as outlined in Table
9.3 (Details in Table 7.2 and Table 7.3 of the CAP in Appendix 9.1 refers)) are
well established and nature of the possible contaminants could be dealt with by
sufficient local remediation experience.
9.13.9
Given
the above, land contamination impacts in the identified potentially
contaminated sites would not be considered as insurmountable if the recommended
actions as outlined in Section 9.14 were followed and contaminated soil
and groundwater (if any) were properly treated using appropriate remediation
methods and according to EPD’s agreed RAP.
9.14.1
Although
many of the sites were not identified as potentially contaminated or could not
be accessed for visual inspection during the site survey,
these sites would still in operation until land resumption. Any potential change of land uses may result
in potential land contamination. Re-appraisal
of the whole Project Site (including identified accessible sites, partially
accessible sites and inaccessible sites) is therefore required. Details of re-appraisal are summarised in Section 4.3 of
the CAP (Appendix 9.1 refers).
9.14.2
Findings
of the re-appraisal and strategy of the recommended SI will be presented in a
supplementary CAP. Upon approval of the
supplementary CAP and completion of the SI works, a Contamination Assessment
Report (CAR) would be prepared to present findings of the SI works.
If contamination was identified, a RAP will be prepared to recommend specific
remediation measures. Except for land remediation works, no
construction works by mean of excavation shall be carried out at the respective
identified contamination area (if any) prior to the endorsement of the closure
assessment. Upon completion of the remediation works, if
any, a Remediation Report (RR) will also be prepared to demonstrate that the
clean-up works are adequate. The CAR,
RAP and RR should be submitted to EPD for approval.
Possible
Remediation Measures
9.14.3
According
to the Practice Guide, the need to remediate the concerned areas would be
determined based on the findings of the SI presented in the CAR and the actual
nature, level and extent of contamination can only be evaluated
through SI. The appropriate remediation
methods should be selected in the RAP based on the SI findings. The possible remediation methods and the
selection criteria are detailed in Section 7 of the CAP (Appendix
9.1 refers).
Mitigation
Measures for Remediation Works
9.14.4
Mitigation
measures for the remediation works would depend on the nature / extent of
contamination and the method of treatment.
The mitigation measures will be recommended in the
RAP and would typically include the following:
·
Excavation profiles must be properly designed
and executed with attention to the relevant requirements for environment,
health and safety;
·
Excavation should be carried out during dry
season as far as possible to minimise contaminated runoff from contaminated
soils;
·
Supply of suitable clean backfill material (or
treated soil) after excavation;
·
Stockpiling site(s) should be lined with
impermeable sheeting and bunded. Stockpiles should be fully covered by
impermeable sheeting to reduce dust emission;
·
Pollution control measures for air emissions (e.g. from biopile blower and
handling of cement), noise emissions (e.g. from blower or earthmoving
equipment), and water discharges (e.g. runoff control from treatment facility)
shall be implemented and complied with relevant regulations and guidelines;
·
Vehicles containing any excavated materials
should be suitably covered to limit potential dust emissions or contaminated
wastewater run-off, and truck bodies and tailgates should be sealed to prevent
any discharge during transport or during wet conditions
; and
·
Speed control for the trucks carrying
contaminated materials should be enforced;
·
Vehicle wheel and body washing facilities at
the site’s exit points should be established and used.
Evaluation
of Residual Environmental Impacts
9.14.5
Recommended
further works for the proposed works extent within the Scheme Boundary would
need to follow EPD’s Guidance Manual, Guidance Note and Practice Guide,
and any soil / groundwater contamination would be identified and properly
treated. Land contamination impacts are therefore considered surmountable to
future occupants if the recommended actions as outlined in Section 9.13 were
followed and contaminated soil and groundwater (if any) were properly treated
using appropriate remediation methods according to EPD’s approved RAP.
9.15
Conclusion
9.15.1
Site
appraisals, in the form of desktop review and site walkovers, were conducted
between December
2021 to December 2022 and June 2023 to
identify any current/historical potentially contaminating and uses within the
Project. Based on the findings of site
appraisals, a total of 121 potentially contaminated sites including 69 inaccessible sites and
52 accessible sites were
identified with
potential land contamination concerns within the Project. Among the 52
accessible sites, 16 sites are wholly accessible and
36 sites are partially accessible.
9.15.2
A
sampling and testing programme, including the
potential hotspots identified within the assessment area, was proposed and
documented in the CAP (Appendix
9.1 refers). As
the concerned facilities are still in operation, there could be change in site
activities and land uses within the assessment area prior to the commencement
of construction works which may cause further contamination issues. Further site re-appraisal,
associated SI works and any necessary remediation action are recommended to be
carried out after land resumption but prior to the
commencement of construction works by mean of excavation at the respective
identified contamination area (if any).
9.15.3
The
recommended further works, including the submission of Supplementary CAP(s),
CAR(s) / RAP(s) and RR(s), would need to follow EPD’s Guidance Manual, Guidance
Note and Practice Guide.
9.15.4
With
the implementation of the recommended further works for the concerned areas,
any soil / groundwater contamination would be identified and properly
treated. Land contamination impacts are
therefore considered surmountable to future occupants.