8.1.1.1
Section 8 of the EIA Report presents potential land
contamination implications associated with the Project. Land contamination implications
were assessed in accordance with Section 3.4.8 and Appendix G of the EIA SB
(No. ESB-340/2021).
8.2.1.1
Relevant environmental
legislation guidelines and standards relating to land contamination include:
(a)
Section 3 (Potential
Contaminated Land Issues) of Annex 19 “Guidelines for Assessment of Impact on
Sites of Cultural Heritage and Other Impacts” of the Technical Memorandum on
Environmental Impact Assessment Process (EIAO-TM).
(b)
Guidance Note for Contaminated
Land Assessment and Remediation (Guidance Note)
This Guidance Note sets out
the requirements for the proper assessment and management of potentially
contaminated sites such as oil installations (e.g. oil depots, petrol filling
stations), gas works, power plants, shipyards / boatyards, chemical manufacturing
/ processing plants, steel mills / metal workshops, car repairing / dismantling
workshops and scrap yards. In addition, this Guidance Note provides guidelines
on how site assessments should be conducted and analysed and suggests practical
remedial measures that can be adopted for the remediation of contaminated
sites.
(c)
Practice Guide for
Investigation and Remediation of Contaminated Land (Practice Guide)
This guide outlines typical
investigation methods and remediation strategies for the range of potential contaminants typically encountered in Hong Kong.
(d)
Guidance Manual for Use of
Risk-based Remediation Goals for Contaminated Land Management (Guidance Manual)
This Guidance Manual
introduces the risk-based approach in land contamination assessment and provides
details for the comparison of soil and groundwater data under Risk-Based
Remediation Goals (RBRGs) for 54 chemicals of concern (COCs) 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 where remediation is necessary.
8.3.1.1
Land contamination assessment
was undertaken in accordance with the EIAO-TM, Guidance Note, Practice Guide
and Guidance Manual, and the requirements stated in Section 3.4.8 and Appendix G
of the EIA Study Brief.
8.3.1.2
The following tasks were
undertaken to identify any potentially contaminated areas for the purpose of
land contamination assessment:
(a)
Desktop review of site history;
and
(b)
Site reconnaissance to identify
the potentially contaminated sites.
8.3.1.3
For the desktop review, the
following information was reviewed:
(a)
Topographic maps and relevant
aerial photographs (Lands Department);
(b)
Revised Recommended Outline
Development Plan;
(c)
Hong Kong Geological Survey maps;
(d)
Geospatial Data accessed via
the Public Sector Information Portal (data.gov.hk),
(e)
Records of dangerous goods and
chemical spillage/leakage incidents (Fire Services Department)
(f)
Chemical waste producer register and chemical spillage/leakage incidents
(Environmental Protection Department),
(g)
Relevant EIA reports and
Project Profiles (https://www.epd.gov.hk/eia/)
8.3.1.4
Potentially contaminated sites
were identified from the desktop review and site reconnaissance. Potentially
contaminated sites are presented in the Contamination Assessment Plan (CAP) in Appendix 8.1.
8.3.1.5
With reference to the
Preliminary Feasibility Study on Developing the New Territories North and the
Geochemical Atlas of Hong Kong published by the Geotechnical Engineering Office
Civil Engineering Department in 1999; natural occurrences of medium to high
levels of arsenic, antimony and lead exist over broad areas of the northern New
Territories. The Preliminary Feasibility
Study indicates the highest levels of arsenic are recorded in the Lok Ma Chau
(117- 492 ppm) and Ngau Tam Mei (118-922 ppm) areas. The Geochemical Atlas indicates that strong
arsenic anomalies are influenced by anthropogenic contamination superimposed on
a high natural background level.
8.3.1.6
As mapped information in the
Geochemical Atlas of Hong Kong is based on concentrations interpolated from
stream sediment sampling rather than soil sampling, a separate assessment as to
whether high levels of arsenic exist in soils within the Project area and any
associated works area was undertaken. The Health Impact Assessment relating to arsenic
in soil is provided in Appendix 8.2.
8.4.1.1
The Project occupies
approximately 610ha. and is located to the west of Kwu Tung North and Fanling North New
Development Areas (NDAs), Fanling and Sheung Shui New
Towns and to the northeast of Yuen Long and Tin Shui Wai New Towns. It is based
on the Project boundary in the Revised Recommended Outline Development Plan
(RODP). The location plan of the Project is provided in Figure 2.1.
8.5
Identification of Potential Land Contamination Concern
8.5.1
Review of Historical Land Uses
8.5.1.1
The development history of the Project
area was reviewed using aerial photographs covering the period 1963 – 2022.
Potentially contaminated sites were identified on the current land use
topographic map with the data is superimposed on selected aerial photography as
presented as in Appendix A of Appendix
8.1. Historical land use within the
Project area is summarised in Table 8‑1.
Table 8‑1 Historical Land Use
within the Project Area
|
Year
|
Historical Land Uses
|
|
1963
|
·
The majority of the Project area
comprised natural terrain, rural residential areas, fishponds and
agricultural land.
·
Castle Peak Road is identified.
|
|
1973
|
·
No significant change in land use in comparison with
1963.
|
|
1982
|
·
No significant change in land use in comparison with
1963 and 1973 except some land formation in the western portion (near Hop
Shing Wai)
|
|
1993
|
·
San Sham Road, San Tin Highway, San Tin Interchange
and Lok Ma Chau Control Point are identified.
·
Industrial activities (mostly open storage and
container/trailer yards) were observed in the western and northern portions
along Castle Peak Road and San Sham Road, and in the southern portion along Kwu Tung Road.
·
A few more fishponds observed in the northern
portion.
|
|
2002
|
·
Lok Ma Chau Control Point under expansion.
·
The extent of industrial activities along Castle
Peak Road and Kwu Tung Road increased
|
|
2006
|
·
Lok Ma Chau Spur Line was observed.
·
Land use in the Project area similar
to land use observed in the 2002 although the footprint of industrial
activities increased.
|
|
2010
|
·
Some open storage and container/trailer yards were
replaced by warehousing/logistic centres.
|
|
2014
|
·
Industrial activities (recycling yards, warehouses)
increasingly observed in the southern portion near San Tin Barracks
|
|
2017
|
·
No significant change in land use in comparison to
2014.
|
|
2020
|
·
No significant change in land use in comparison to
2017.
|
|
2022
|
·
No significant change in land use in comparison to
2020.
|
8.5.2
Site Geology
8.5.2.1
Ground investigation (GI) works
have been completed within the Project area for a variety of projects. Based on
the existing GI records, fill deposits beneath developed areas vary in
thickness from 1 m and 5 m. Much of the Project area is covered by terraced
alluvium except for some areas in the northwest and southwest where outcrops of
in-situ materials are exposed. The alluvium underlying the fill, marine
deposits or pond deposits are variable in terms of their composition and
typically described as soft to stiff sandy/silty clay and clayey silt, and
loose to very dense sand and gravel with cobbles. The thickness of alluvium
encountered within the Project area typically varies from 0.3 m to over 24 m. A
layer of in-situ soil, predominately saprolite and in places Grade IV rock is
located between the alluvium and rockhead. The predominant unit of the
saprolite is Grade V materials derived from weathered rock. The thickness of
saprolite varies from less than 1 m to over 115 m.
8.5.2.2
Based on the existing GI
records the general geological sequence of the soil strata is described in the
following Table 8‑2.
Table 8‑2 Description of Soil Strata
|
Stratum
|
Typical Descriptions
|
Approximate Strata Thickness (m)*
|
|
Fill
|
· Consists of various materials
including SILT, SAND with gravel, cobbles and in places clayey portions and locally
with boulders
· Absent in undeveloped areas and
natural hillsides
|
0.4 to 14.5
|
|
Pond deposits
(PD)
|
· Anticipated in current and former
ponds. Drillholes recording PD are
mainly located at the Northern Project area DN and locally in the Southern Project
area
· Where encountered, PD are generally
soft to firm locally stiff silty CLAY/ clayey SILT, in places sandy or
gravelly and with organic matter
|
0.5 to 5.5
|
|
Estuarine
deposits (ED)
|
· Drillholes recording ED are
generally located in the Northern part of the Project area
· Where encountered, ED are typically
soft to firm locally stiff, slightly sandy to sandy silty CLAY in places with
organic matter, sandy pockets or shell fragments
locally
|
0.5 to 9.1
|
|
Marine Deposits
(MD)
|
· Drillholes recording MD are
generally located in the Northern part of the Project area
· Where encountered, it is
generally overlain by fill, PD and/or ED, typically as very soft to firm
locally stiff CLAY / silty CLAY in places with sandy portions, with shell fragments
· Lacustrine deposits, up to about
3.5m thick, is recorded locally at the ST Interchange area as soft CLAY /
SAND
|
0.5 to 15.5
|
|
Alluvial
Deposits
|
· Alluvium and terraced alluvium
are anticipated at the original alluvial plains at the Southern Project area
and the Northern Project area
· Where encountered, alluvium is generally
highly variable and typically as soft to very stiff slightly sandy to sandy
silty CLAY/ clayey SILT or loose to very dense silty/ clayey SAND,
occasionally with gravelly and cobbly portions
|
0.35 to over 56
|
|
Colluvium
(COLL)
|
· Anticipated at the foot of hillslopes
within or near the eastern, southern and locally the
western (near Hop Shing Wai) boundaries of the Project area.
· Where encountered, it is
generally as firm slightly sandy to sandy SILT or silty SAND in places
clayey, with gravels and occasionally cobbles and boulders
|
0.4 to 23.1
|
|
In-situ
Material above Rockhead
|
· in-situ grade V materials are
generally extremely weak to very weak in strength.
· Grade IV is generally very weak
to moderately weak. Residual Soil (grade VI) material generally as firm to
stiff slightly sandy to sandy clayey SILT is recorded locally at the Project area.
· Corestones and rocks not meeting the
criteria of bedrock are recorded above the bedrock in the in-situ materials
|
0.21 to 76.32
|
Note:
* where encountered;
San Tin / Lok Ma Chau Development Node
Setting
8.5.2.3
Based on a review of
topographic survey plans, the Project area consists of low flat flood plains
surrounded by natural terrain in the north, south and west. About 65% of the Project area is low-lying
with gentle slope gradient less than 5°. The highest point in the vicinity is
at about 250 mPD on the natural terrain at Yuen Tau
Shan.
8.5.2.4
The existing ground levels of
the Project area vary generally from approximately +2 mPD
to +119 mPD with majority of the areas vary between
+5 mPD and +15 mPD. The
areas with existing ground levels lower than +6 mPD
are generally located at the eastern part of the Project area and commonly
along water courses. The areas with ground levels higher than 15 mPD are mainly located at the northwest and southeast of
the Project area although local small hills with ground level over +15 mPD are also found at other parts of the Project area.
8.5.2.5
Groundwater level monitoring
records from standpipes and piezometers in Geotechnical Assessment and Site
Investigation Reports in the Project area were reviewed. Records show that the
groundwater levels are generally shallow at about 2 m below the ground surface
in flat land. No groundwater monitoring records were reviewed for natural
terrain within the Project area.
8.5.3
Information from Government
Departments
8.5.3.1
The EPD and Fire Services
Department (FSD) were contacted for
(a)
records of any spillage /
leakage of chemicals.
(b)
records of Dangerous Goods (DG).
(c)
records of Chemical Waste
Producer(s) (CWPs); and
(d)
records of reported incidents
within the Project area.
8.5.3.2
EPD and FSD’s replies on the
request are attached at Appendix C and Appendix D of Appendix 8.1. The information is summarised below.
Environmental Protection Department
8.5.3.3
Based on EPD replies dated 15 March, 28 June 2022, 11 April 2023 and 31 May 2023 regarding requests for chemical
spillage/ leakage information; EPD has no record of any chemical spillage /
leakage within the Project area. EPD Environmental Compliance Division,
Territorial Control Office, Chemical Waste and WEEE (Licensing and Control
Support) Section was visited in March and April 2022
and April 2023 to
review CWP records; 114 CWPs with a site address / land
lot / identified occupant name were identified within the Project area.
Fire Services Department
8.5.3.4
Based on FSD replies dated 8 December 2021 and 22 August 2022, no DG
licence records are identified within the Project area. Two events of petroleum spillage events have been
recorded by FSD. The remaining incidents are minor (vegetation and rubbish
fire, No.1 & No. 2 alarm fire, vehicle fire, car accident and late call)
individual events and potential land contamination is not anticipated as a result of these incidents.
8.5.3.5
Since the two petroleum leakage incidents occurred on the paved road
carriageway with run-off collected by the drainage system, these incidental
releases of petroleum did not encroach any of the surveyed sites and as the
spillages were appropriately cleaned up, land contamination at the incident
spots is not anticipated. Further site investigation at the two incident spots
is not proposed.
8.5.4
Site Reconnaissance
8.5.4.1
Site visit with a
reconnaissance of accessible areas was undertaken in April – June 2022 and
April 2023 to confirm as far as practicable current land uses within the
Project area. Drone reconnaissance of the Project area was undertaken with
video and photographs taken to identify current land use.
8.5.5
Site Appraisal
8.5.5.1
Based on the results of desktop
review, drone reconnaissance and site visits, 500 surveyed sites were
identified for further study, however, the majority of
sites are privately occupied and inaccessible for site walkover. Given these constraints, information is
limited to observations from peripheral locations during the reconnaissance. A
summary of these surveyed site is provided in Table 8‑3. The
location of surveyed site is provided in Figure 8.1 – 8.4.
8.5.5.2
The majority of sites were inaccessible
for detailed reconnaissance, detailed reconnaissance was only carried out for
the following sites.
|
·
E034
|
·
W101
|
|
·
E068
|
·
W102
|
|
·
S201
|
·
W103
|
|
·
S202
|
·
W104
|
|
·
S301
|
·
W105
|
|
·
S302
|
|
8.6.1.1
A total of 500 sites were
surveyed as summarised in Table 8‑3.
Table 8‑3 Summary of Surveyed Site
|
Description
|
Number of Sites
|
|
Potentially Contaminated Sites
|
195
|
|
Site required further appraisal
|
106
|
|
Site not to be Developed
|
2
|
|
Non-Contaminated Sites
|
197
|
|
TOTAL
|
500
|
8.6.1.2
Based on the site appraisal,
the following land uses with the potential to cause land contamination issues
were identified:
·
Open area storage, container
storage and warehouse.
·
Construction equipment storage
/ equipment depot and vehicle / repair maintenance workshops.
·
Factories.
·
Recycling facilities.
·
Fueling facilities.
8.6.1.3
Various classifications were
assigned to the surveyed sites. Detailed assessment of surveyed sites is
provided in Appendix 8.1.
Potentially
Contaminated Sites
8.6.1.4
195 potentially contaminated
sites were identified. Identified land uses include container storage,
equipment/machinery storage; recycling facilities, vehicle repair/maintenance
workshops, diesel refuelling, waste dumping ground, metal workshops etc. Figures 8.5 – 8.8 presents the
locations of the potentially contaminated sites.
8.6.1.5
Detail site reconnaissance was
carried out for 9 of the 195 potentially contaminated sites. The nine (9) sites
(S201, S202, S301, S302, W101, W102, W103, W104 and W105) were identified as
possible vehicle maintenance workshops and/or open storage where operations
have potential to result in land contamination. All nine sites were vacant and
fenced at the time of site visit. Figure
8.9 presents the locations of these sites.
8.6.1.6
The proposed sampling and
testing plan for the nine accessible sites is presented in Section 6 of Appendix 8.1.
Site Requiring
Further Appraisal
8.6.1.7
106 sites are assessed to have
been used for warehousing or are occupied by inaccessible buildings (pump
houses, substations etc). As the nature
of operations within these buildings is not certain, site inspection is
necessary to further appraise the potential for land contamination issues
within these sites.
8.6.1.8
For these sites, the presence
and degree of contamination would greatly depend on the types of goods stored
within these warehouses. For example, warehouses that stored general household
goods (e.g., furniture and toys) are unlikely to cause contamination to the
underlying soil and groundwater. Re-appraisal of these sites will be required
at a later stage of development to (i) assess the
nature of these warehouses, site conditions and the historical usage, (ii)
confirm the necessity for site investigation works and, if required, (iii)
formulate the sampling and testing strategies.
Site not to be Developed
8.6.1.9
Sites E021 and S203 are not
anticipated to be redeveloped therefore further land contamination potential is
not necessary. The existing Chau Tau Ventilation Building (Site E021) and Mai
Po Substation (Site S203) will be retained including the structures and
facilities.
Non-Contaminated
Sites
8.6.1.10
197 surveyed sites assessed to
have low land contamination potential include logistics warehousing and farms. Detailed
reconnaissance was conducted for two (2) of the 197 sites, namely E034 and
E068. Potential land contamination is not typically associated with activities
undertaken within these types of facilities.
Machinery/vehicle maintenance is not anticipated on these sites.
8.7.1.1
Detail site reconnaissance was
carried out for 9 of 195 potentially contaminated sites (Sites S201, S202,
S301, S302, W101, W102, W103, W104 and W105). Site investigation (SI) is
recommended to be carried out to determine the presence, nature
and quantities of soil/groundwater contamination within the sites. The sampling
and testing plan for each site has been determined based on the recommendations
given in Section 2.4.1 of EPD’s Practice Guide and detailed in Section 6 of Appendix 8.1.
8.7.1.2
Access has not yet granted by the
Lands Department due to objections from villagers relating to the Simplified
Temporary Land Allocation (STLA) application, therefore site investigation for
the nine (9) sites was unable to instigated during the course
of the EIA.
8.7.1.3
These nine (9) potentially
contaminated sites have been fenced off by the Lands Department and are
unlikely to be privately re-occupied. The Project Proponent shall carry out
site investigation and sampling works in accordance
with the sampling plan proposed in Appendix
8.1 at a later stage.
8.7.1.4
For the other potentially
contaminated sites that were inaccessible for detailed site walkover, the
actual sampling and testing plan can only be determined when access for
detailed site walkover is granted.
However, the recommended minimum number of sampling locations for each
of the concerned sites, taking into consideration the area of the potentially
contaminated sites and adopting the regular grid sampling strategy in Section
2.4.1 of EPD’s Practice Guide, has been provided in Appendix H of the CAP in Appendix 8.1. Extra sampling
locations may be required after site walkover(s) are conducted,
if additional potential sources of contamination (or ‘hotspots’) are
identified within the concerned sites.
The final sampling and testing plan, considering the aforementioned
regular grid sampling strategy and any hotspots identified following the
site walkover will be reported in supplementary CAP(s) at the later stage of
the Project.
8.7.1.5
8.8.1.1
With reference to the possible
contaminants, remediation methods previously implemented in Hong Kong are
presented in Table 8‑4. If land contamination is identified, the
actual remediation method shall be proposed in the Remediation Action Plan (RAP)
for EPD endorsement. Remedial options
are not limited to the remediation method listed in Table 8‑4.
Table 8‑4 Possible
Remediation Methods for Potentially Contaminating Land Uses
|
Identified Potentially
Contaminating Land Uses
|
Potentially
Contaminating Activities
|
COCs(1)
|
Possible
Remediation Methods(2)
|
|
Open
area storage, container storage and warehouse
|
Loading,
unloading and storage of goods, fuel storage and transfer, maintenance of
equipment and vehicles.
|
Metals
(full list), PCRs, VOCs and SVOCs.
|
Biopiling, Cement Solidification / Stabilisation, Permeable
Reactive Barriers
|
|
Construction
equipment storage / equipment depot and vehicle / repair maintenance
workshops
|
Release
of oils, fuels and lubricants from vehicles, vehicle and equipment
maintenance and refuelling. Use of chemicals and solvents in
maintenance activities. Motor vehicle painting and storage and disposal of
wastes.
|
Metals (e.g. chromium, copper, lead, manganese, nickel, zinc),
PCRs, VOCs (e.g. acetone, BTEX, MTBE, and trichloroethene) and PAHs.
|
Biopiling, Cement Solidification / Stabilisation, Permeable
Reactive Barriers
|
|
Factories
|
Release of oils, fuels and lubricants from mechanical machinery,
equipment maintenance and refuelling. Use of chemicals and
solvents in maintenance activities.
|
Metals
(full list), PCRs, VOCs and SVOCs.
|
Biopiling, Cement Solidification / Stabilisation, Permeable
Reactive Barriers
|
|
Recycling
facilities
|
Storage
and processing of waste materials, storage and transfer of chemicals and
fuels. Storage and disposal of wastes.
|
Metals
(full list), PCRs, VOCs, SVOCs and PCBs.
|
Biopiling, Cement Solidification / Stabilisation, Permeable
Reactive Barriers, Thermal Desorption / Incineration
|
|
Fuelling
facilities (diesel)
|
Leaks from pipework, tanks and offset fill pipes. Spills during
customer refuelling, filling underground storage tanks and over filling of
portable containers.
|
PCRs, VOCs (BTEX) and PAHs.
|
Biopiling, Cement Solidification / Stabilisation, Permeable
Reactive Barriers
|
|
Note: (1) Metals include antimony, arsenic, barium,
cadmium, chromium III, chromium VI, cobalt, copper, lead, manganese, mercury,
molybdenum, nickel, tin and zinc.
Petroleum carbon ranges
(PCRs) include C6 – C8, C9 – C16 and C17 – C35.
Volatile organic chemicals
(VOCs) include BTEX (benzene, toluene, ethylbenzene, and total xylenes), MTBE
(methyl tert-butyl ether), acetone, bromodichloromethane, 2-butanone,
chloroform, methylene – chloride, styrene, tetrachloroethene, and
trichloroethene.
Semi-volatile organic
chemicals (SVOCs) include polyaromatic hydrocarbons (PAHs) (acenaphthene,
acenaphthylene, anthracene, benzo(a)anthracene, benzo(a)pyrene,
benzo(b)fluoranthene, benzo(g,h,i)perylene,
benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene,
fluoranthene, fluorene, indeno(1,2,3-cd)pyrene,
naphthalene, phenanthrene and pyrene), bis-(2-ethylhexyl)phthalate,
hexachlorobenzene, and phenol.
PCBs – Polychlorinated
biphenyls.
|
8.8.2
Surmountability of Potential Land
Contamination Issues
8.8.2.1
Contamination issues are not
insurmountable in view of the following factors:
·
The sizes of the potential
contaminated sites are relatively small.
·
The extent of any contamination
is expected to be localised rather than widespread.
·
Remediation methods available
in the market are well established with local remediation experience sufficient
to deal with the nature of the possible contaminants.
8.8.2.2
Land contamination issues
within those sites/areas identified as potentially contaminated are considered
not insurmountable due to the following factors:
Anticipated localised contamination from current operation scale
8.8.2.4
In addition, the potentially
contaminated sites are not large-scale polluting installations / facilities
such as oil depots and power plants. Therefore, the contamination extent, if
any, caused by the operations of the identified potentially contaminated sites
is anticipated to be localised.
Chemicals of Concern (COC) identified are readily treatable using
established physical, chemical and biological techniques
8.8.2.5
Based on the site appraisal,
the potential COCs identified with the potential to be present include metals,
VOCs, SVOCs, PCRs and PCBs. Remediation methods that have been demonstrated to
effectively treat the aforementioned soil and
groundwater contaminants include biological treatment and physical / chemical
treatment.
Local remediation experience is sufficient to deal with the nature
of the possible contaminants
8.8.2.6
Soil contaminated with the
abovementioned COCs had successfully been remediated in Hong Kong using proven
remediation techniques. Notable local remediation projects include the
followings:
·
Decommissioning of Kai Tak
Airport North Apron;
·
Decontamination works at the Cheoy Lee Shipyard;
·
Reclamation works at North
Tsing Yi Shipyard site; and
·
Decommissioning of Kwai Chung
Incinerator.
8.8.3
Recommendation of
Further Works
8.8.3.1
The area within the Project boundary
will remain in operation and potential exists for a change in land use or
operations prior to development. It is recommended to re-appraise the whole
area within the Project boundary. If there are land use changes which pose a
potential for land contamination, this information should be reported in
Supplementary CAP(s).
Potentially Contaminated Sites
8.8.3.2
The sites identified as
potentially contaminated remain in operation therefore potential exists for a
change in land use or operations prior to development. As the majority of these
sites were inaccessible at the time of reporting, proper assessment of site
conditions / identification of hotspots and formulation of sampling and testing
plan(s) is not practical within the CAP (Appendix 8.1).
8.8.3.3
Prior to development of these
sites, the Project Proponent should appoint a consultant to re-appraise these
sites and update the findings (e.g. locations of hotspots) and sampling and
testing requirements presented in the CAP. Supplementary CAP(s), incorporating
the findings of the site re-appraisal and the updated sampling and testing
strategy, should be prepared and submitted to EPD for
approval prior to conducting any SI works.
8.8.3.4
SI works should be implemented
according to the supplementary CAP(s). CAR(s) detailing the findings and, if
contaminated soil and/or groundwater is identified, RAP(s), should be prepared
and submitted to EPD for approval. Any contaminated soil and groundwater should
be treated according to EPD’s approved RAP(s) and RR(s) should be submitted to
EPD for agreement after completion of the remediation works. No development
works shall commence prior to EPD’s agreement of the RR.
8.8.3.5
For the nine (9) sites (namely
S201, S202, S301, S302, W101, W102, W103, W104 and W105) where detailed site
reconnaissance was carried out, these sites have been fenced off by the Lands
Department and are unlikely to be privately re-occupied. The Project Proponent
shall carry out site investigation and sampling works
in accordance with the sampling plan proposed in Section 6 of Appendix 8.1 at a later stage.
8.8.3.6
CAR(s) shall be compiled
following receipt of site investigation results. The CAR(s) shall detail the
methodology used during soil boring / well installation and soil and
groundwater sampling, details of field observations and interpretation of
laboratory testing results. The CAR(s) should be compiled according to the
Practice Guide and submitted to EPD for approval.
8.8.3.7
Should results / field
observations indicate that contamination is above the site-specific adopted
thresholds; remediation will be required to render a particular site safe for
future use. RAP(s) will be developed in conjunction with the CAR. The expected
content of a RAP is defined in the Section 4.2 of the Practice Guide. RAP(s)
shall be submitted to and approved by the EPD prior to the implementation of
remedial actions.
8.8.3.8
Following implementation of
remediation, RR(s) will be compiled following the completion of remedial works.
The RR(s) shall consist of the background information, remediation methods, programme and the interpretation of remediation results.
RR(s) demonstrate the clean-up is adequate and, will be submitted to EPD for
approval prior to the commencement of any development works within the sites.
Sites Requiring Further Appraisal
8.8.3.9
A requirement of any site
investigation within some of the surveyed sites (primarily those sites occupied
by warehousing) remains unconfirmed in the CAP (Appendix 8.1). For these sites, the presence and degree of
contamination would greatly depend on the types of goods stored within these
warehouses. For example, warehouses that stored general household goods (e.g.,
furniture and toys) are unlikely to cause contamination to the underlying soil
and groundwater.
8.8.3.10
Re-appraisal within these sites
is required at the later stage (once the land is resumed or access granted) to
(i) assess the nature of these warehouses, site
conditions and the historical usage, (ii) assess the need for site
investigation and, where required, (iii) formulate sampling and testing
strategies.
8.8.3.11
If the findings of re-appraisal
suggest a reasonable potential for land contamination that warrants site
investigation, supplementary CAP(s), incorporating the re-appraisal findings
and the updated sampling and testing strategy, should be prepared
and submitted to EPD for approval prior to conducting any SI works.
8.8.3.12
SI works should be implemented
according to the supplementary CAP(s). CAR(s) and, if contaminated soil and/or
groundwater identified, RAP(s) should be prepared and submitted to EPD for
approval. Any contaminated soil and groundwater should be treated according to
EPD’s approved RAP(s) with RR(s) submitted to EPD for agreement of completion
of the remediation works. No development works shall be commenced prior to EPD’s
agreement of the RR.
Sites not to be Developed
8.8.3.13
In the event of a change to the
Project plan wherein these sites will be developed, re-appraisal will be
required to assess the potential land contamination status at such time that
the site become accessible.
8.8.3.14
If potential land contamination
is confirmed after site re-appraisal and site investigation is deemed
necessary, Supplementary CAP(s), incorporating the findings of the site
re-appraisal and the updated sampling and testing strategy, should be prepared and submitted to EPD for approval prior to
conducting any SI works.
8.8.3.15
SI works should then be carried
out according to the supplementary CAP(s). CAR(s) and, if contaminated soil
and/or groundwater identified, RAP(s) should be prepared and submitted to EPD
for approval. Any contaminated soil and groundwater should be treated according
to EPD’s approved RAP(s) and RR(s) should be submitted to EPD for agreement
after completion of the remediation works. No development works shall be
commenced prior to EPD’s agreement of the RR.
Non-Contaminated Sites
8.8.3.16
Similarly, as the development
will only commence in phases from 2024, it is possible that the land uses of
the non-contaminated sites could change to contaminated land types. Hence,
after the sites are handed over to the PP for development, the PP’s appointed
consultant should also revisit these sites to assess the latest land uses and
site conditions as well as to ascertain the initial evaluation and
recommendation reported in this CAP. If any of these sites are found to have
potential land contamination issues, the PP’s appointed consultant should also
prepare and submit supplementary CAP(s), which incorporate the findings of the
site re-appraisal (e.g. locations of hotspots) and the sampling and testing
strategy, to EPD for approval prior to conducting any SI works.
8.9.1.1
Referring to Section 8.8.2, all land contamination issues are surmountable if the recommended
further works in Section 8.8.3 are followed and contaminated soil and groundwater (if any) is properly
treated using appropriate remediation methods and according to EPD’s approved
RAP. However, any localised soil/groundwater contamination within these sites,
if left untreated, could potentially pose health risks to existing or future
occupants.
8.9.1.2
By implementing the recommended
further works under this Project, the actual contaminated site(s) within the Project
boundary would be located and any contaminated soil and groundwater would be
identified and treated. The recommended further works would not only minimise
the health risks to the future occupants arising from the exposure of the
contaminated soil and/or groundwater, it would also provide the opportunity to
treat the contaminated soil / groundwater using proven remediation techniques
for reuse as useful materials (such as backfilling materials); thereby
minimising the amount of waste disposing into the already depleting landfills
in Hong Kong and achieving a more sustainable development.
8.9.1.3
Furthermore, the Project would
allow the conversion of the contaminated site(s) into land that are safe for
more optimal development (e.g. residential development).
8.10.1.1
Remediation works, if
necessary, would be carried out based on the recommended further works outlined
in Section 8.8.3. Mitigation measures as recommended in the future EPD approved RAP
should be implemented during the remediation works. The EM&A requirements
should be carried out in the form of regular site inspection to ensure the
recommended mitigation measures are properly implemented.
8.11.1.1
This Project is a Schedule 3
Designed Project under the EIAO, whilst there will be 7 Schedule 2 DPs. The details of these Schedule 2 DPs are
presented in Section
1.5 (i.e. Table 1.1) and Section 2.4.4, and the locations of
these Schedule 2 DPs are shown in Figure
1.2.
8.11.1.2
The identified potentially
contaminated sites are grouped under each Schedule 2 DP and the findings are
summarised in Appendix 8.3. As the land contamination potential of the
sites listed in Appendix 8.3 have
been assessed under this EIA Study, the land contamination issue within these
sites are considered surmountable (refer to Section 8.8.2 for details). Prior to the commencement of construction of each
Schedule 2 DP, the recommended further works under this EIA Study (including
site re-appraisal, SI works and if required, remediation works (refer to Section 8.8.3 for details)) will be carried out for the concerned sites listed in
Appendix 8.3. Any soil / groundwater contamination would be
identified and properly treated prior to the development of the concerned
sites. No residual land contamination
impacts are anticipated, it is considered environmentally acceptable if the
recommended further works In Section 8.8.3 were followed.
8.12.1.1
The EIA Study Brief
(ESB-340/2021) Clause 3.4.8 requires assessment of whether high levels of
arsenic exist within the Project area. If high levels of naturally occurring
arsenic are identified within the Project area and any associated works area, a
Health Impact Assessment (HIA) shall be conducted based on established
international practices. As high levels of arsenic is
identified during ground investigation works, a HIA report is provided in Appendix
8.2 for the health impact assessment on arsenic.
8.12.2
Findings on Ground
Investigation
8.12.2.1
With refence to available
ground investigation results, samples from the soil profile within 21 boreholes
have been analysed for arsenic. The
average arsenic content is 130mg/kg and maximum detection at 1,140 mg/kg. The
arsenic content in soil in the Project area is assessed to be naturally
occurring and not as a result of anthropogenic
contamination. It is considered that the
arsenic soil concentrations in the Project Area and NENT EIA (Kwu Tung North) are similar.
8.12.3
Soil Screening Level
8.12.3.1
Based on the Health Impact
Assessment for the Ingestion Pathway detailed in Section 3.2 of Appendix 8.2 with reference to NENT
EIA Report, a risk based arsenic threshold is calculated as 571 mg/kg.
8.12.4
Proposed Mitigation
Measures
8.12.4.1
During construction of the Project,
the Contractor shall follow all requirements under the Factories and Industrial
Undertaking Ordinance (F&IUO) and its subsidiary regulations. Control measures shall be proposed in a
safety plan which shall be fully implemented by the Contractor.
8.12.4.2
During operation of the Project,
provided further arsenic assessment and treatment (if required) of high arsenic
containing soil (HAC soil) will be implemented, arsenic content in the top 4-8
m of the development will be determined. In case of exceedance on soil
screening level, the HAC soil will be treated accordingly by cement
solidification/stabilisation (S/S). Treated materials may be backfilled in-situ or
ex-situ. A 4m – 8m thick free/treated arsenic zone will
be provided underneath further development. This 4m – 8m thick free/treated
arsenic zone will provide effective barrier for future users/residents during
operation phase and therefore, no mitigation measures is
required during operation phase.
8.12.5
Treatment
Approach
8.12.5.1
HAC soil is proposed to be
treated by Cement S/S and followed by in-situ or ex-situ as backfilling.
8.12.5.2
Further arsenic assessment
should be carried out during site formation and during construction of foundation.
The Government will treat the HAC soil in the shallow region before land
allocation or land lease. The treatment depth will depend on the future land
use in Revised RODP.
Subsequent Developer/Works Departments will treat HAC soil in deep
regions for excavations required for basements, piles
and utilities. Detail treatment approach is provided in Section 5 of Appendix 8.2.
8.13
Conclusion
8.13.1.1
This land contamination
assessment examined the potential contaminative land use within the Project
boundary and their potential impacts to future land use.
8.13.1.2
Based on the findings from
desktop review (e.g. review of historical aerial photos and relevant
information from EPD and FSD), drone reconnaissance and site surveys, 500
potentially contaminated sites have been identified.
8.13.1.3
For potentially contaminated
sites, findings of the desktop review and site surveys as well as the proposed
soil and groundwater sampling and testing strategy are presented in the CAP in Appendix 8.1.
8.13.1.4
The majority of 195 potentially
contaminated sites were inaccessible for detailed reconnaissance at the time of
reporting. As the identified potentially contaminated sites are still in
operation and the development will only commence in phases from 2024, potential
exists for changes in land use or the nature of operations prior to development
within both the potentially contaminated site and other surveyed sites.
8.13.1.5
Detail site reconnaissance was
carried out for 9 of 195 potentially contaminated sites (Sites S201, S202,
S301, S302, W101, W102, W103, W104 and W105). Access has not been granted by
the Lands Department due to objections from villagers relating to the STLA
application. The Project Proponent shall carry out site investigation and
sampling works in accordance with the CAP (Appendix 8.1).
8.13.1.6
Further works, including site
re-appraisal, SI works as well as submission of supplementary CAP(s) and CAR(s)
for EPD’s endorsement are recommended to be carried out after the sites are
handed over to PP for development. If contaminated soil and/or groundwater were
identified, remediation should be carried out according to EPD approved RAP(s)
and RR(s) should be submitted to EPD for agreement after completion of the
remediation works. No development works shall commence prior to EPD agreement
of the RR. The further works would need
to follow EPD’s Guidance Manual, Guidance Note and Practice Guide and according
to Section 8.8.3.
8.13.1.8
At all sites, contamination (if
any) is anticipated to be localised as the types of operations are not large-scale
polluting installations / facilities, such as oil depots and power plants, where
the nature of those operations has greater potential to result in widespread
contamination.
8.13.1.9
COCs with potential to be
present at potentially contaminated sites include metals, VOCs, SVOCs, PCRs and
PCBs. These COCs are treatable using
established physical, chemical and biological
techniques and have been successfully remediated using proven remediation
techniques in Hong Kong. By implementing the recommended works, contaminated
soil and groundwater within the Project boundary would be identified and
treated.
8.13.1.10 Recommended further works would not only mitigate health risk to
future occupants, the works would also demonstrate
sustainable reuse of treated soils as useful materials (such as backfill);
thereby minimising the amount of waste disposed to landfill.
8.13.1.11 Furthermore, the Project would allow the conversion of the
contaminated site(s) into land that are safe for more optimal development (e.g.
residential development).
8.13.1.12 High levels of naturally occurring arsenic in soil is confirmed by
ground investigation works. Health Impact Assessment has calculated a risk
based arsenic threshold of 571 mg/kg which acts as a remedial threshold
concentration. Further arsenic assessment and a detailed treatment approach has
been proposed based on the Revised RODP.
8.13.1.13 Further arsenic assessment should be carried out during site
formation and during construction of foundation. The Project Proponent will
treat the high arsenic containing soil in the shallow region before land
allocation or land lease to ensure no adverse health impact to future
occupants. The treatment depth will depend on the future land use. Subsequent
Developer/Works Departments will treat HAC soil in deep regions for excavations
required for basements, piles and utilities.