13.1 Contaminated land refers to the land which has been polluted by hazardous substances as a result of industrial operations carried out on site over a number of years. These contaminants, if present, may pose hazardous risks or cause adverse effects to the land users and the nearby environment.
13.2 The implications of land contamination associated with the Project and its works areas have been assessed with reference to the EIA Study Brief. This section summarises the site appraisal results from the Contamination Assessment Plans (CAPs), site investigation results as reported in the Contamination Assessment Reports (CARs), and any recommended remediation works outlined Remediation Action Plans (RAPs), together with overall findings and recommendations relevant to the EIA.
Environmental Legislation, Standards and
Guidelines
13.3
The relevant environmental legislation
guidelines and standards on land contamination aspect include the followings:
(i)
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).
(ii)
Guidance Note for Contaminated Land
Assessment and Remediation”
(Guidance Note 1)
Guidance Note 1 sets out the
requirements for 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
cleanup of contaminated sites.
(iii)
Guidance Notes for Investigation and
Remediation of Contaminated Sites of Petrol Filling Stations, Boatyards and Car
Repair /Dismantling Workshop” (Guidance Note 2)
Guidance Note 2 specifically sets
out guidance for land contamination assessment and remediation for sites
previously used for petrol filling stations, boatyards
and vehicle repair/dismantling workshops.
(iv)
Guidance Manual for Use of
Risk-based Remediation Goals for
The Guidance Manual introduces
the risk based approach in land contamination assessment and present
instructions for comparison of soil and groundwater data to the Risk-Based Remediation Goals (RBRGs) for 54 chemicals of concern commonly found in
13.4
The first step was to assess and identify any potentially contaminated sites within the Project
area. The following tasks have been undertaken to identify and evaluate the potential land contamination
impacts associated with the Project
l Desktop
study to review the current and historical land uses;
l Acquisition
of information related to potential land contamination from Environmental
Compliance Division of Environmental Protection Department (EPD) and Fire
Services Department (FSD); and
l Site
reconnaissance to identify the existing land uses and potential contamination.
13.5
In addition, the following sources of information
have been collated and reviewed:
l Selected
aerial photographs from Lands Department;
l
l Information
on dangerous goods for potentially contaminated areas from Fire Services
Department (FSD);
l Records
and photographs obtained during the site visit; and
l Relevant
approved EIA report (i.e. Environmental Assessment Report of West Island Line
(EIA-153/2008)).
13.6
According
to the findings of the site appraisal, a CAP was prepared
and submitted to EPD. Based on the desktop review and
site inspection, sampling locations and depths for soil and groundwater at
potentially contaminated sites have been proposed for the site investigation (SI)
works. The CAP also specified the
sampling and testing requirements for the SI works. It has been
endorsed by EPD and is given in Appendix 13.1.
13.7
During SI, sampling will be conducted at areas identified as having a high potential contamination (potential
hotspots), with the objective to preliminarily assess the soil and groundwater quality through sampling and laboratory
testing at worst-case locations of potential contaminated
sites as far as possible. After the
completion of the SI works, the soil and groundwater analytical results were compared to the adopted RBRGs. The nature, level and extent of land
contamination were evaluated
and findings were documented in the CAR. Due to current land use and site
constraints, the SI is proposed to be undertaken in two stages. The Stage 1 SI has been completed
with the CAR provided in Appendix 13.2.
13.8
Sites inaccessible or with SI constraints in Stage 1
will be assessed in Stage 2. The Stage 2 SI will be conducted after the
completion of this EIA
study/upon decommissioning and prior
to the commencement of construction works at the potentially contaminated
sites. Supplementary CAR(s) and if contamination is found, RAP(s) will be prepared and submitted to EPD for endorsement. A Remediation Report (RR) will be prepared
and submitted to EPD to demonstrate that the decontamination work is adequate
and is carried out in accordance with the endorsed CAR and RAP. Information such as soil treatment/ disposal
records (including trip tickets), confirmatory sampling results, and
photographs will be included in the aforesaid RR. No construction work will be carried out
prior to the endorsement of the RR by EPD.
Description of the Environment
13.9
The assessment areas of the land contamination impact
assessment under the Project are shown in Figure nos. NEX2213/C/361/ENS/M57/001 through NEX2213/C/361/ENS/M57/016 of
the endorsed CAP (Appendix 13.1).
Since the endorsement of the CAP, the Project boundary and the supporting works areas have been slightly
modified. Based on desktop studies and site inspections, there is no newly identified potential
contamination site requiring assessment within the modified project
boundary/works area and the planned SI works is, therefore, still
considered sufficient. The latest Project boundary and the designed
alignment are
indicated in Figure no.
NEX2213/C/331/ENS/M57/400 of the CAR (Appendix 13.2).
13.10
The assessment areas have been classified into
three geographic categories for easy reference and details can be referred to in the
endorsed CAP. Brief descriptions are as
follows:
(i)
Area 1: Works Area from the New
Hung Hom Station to
13.11
Area 1 starts from north of the
(ii)
Area 2: Works Area on
13.12
This area encompasses
(iii)
Area 3: Supporting Works Area
13.13 An
offsite supporting works area at Shek O Quarry will be
used as a casting basin for immersed tunnel (IMT), concrete batching plant,
material conveyor, site offices, workshops, storage for materials, plants and
equipment, barge loading and unloading and material delivery. Rehabilitation works was being undertaken at
the site by CEDD at the time of the site appraisal and was completed in 2010.
13.14 The offsite works areas for at Tseung
Kwan O Industrial Estate (Site ID 3-01), Siu Lam (Site ID 3-02), Chung Hom Kok (Site ID 3-03), Mount
Davis (Site ID 3-04), and Western District Public Cargo Working Area (Site ID
3-05) as proposed in the CAP are no longer required for this Project. No further investigation was therefore conducted
for these areas.
Identification of
Potential Environmental Impacts
Identification of Impact Sources
13.15
The identification of potentially contaminated land within the Project areas has been completed through the site appraisal exercise. The list of
potentially contaminated sites identified within Stage 1 SI is summarised in Table 13.1 below.
Table 13.1 Potentially Contaminated
Sites Identified and SI Conducted in
Stage 1
|
Site ID (Description) |
|
Reference Figure in
CAR (Appendix 13.2) |
|
Area 1 |
||
|
1-01 ( |
·
Emergency generator and associated fuel
tank |
NEX2213/C/331/ENS/M57/401 |
|
Area 2 |
||
|
2-10 (Police Officer’s Club near Causeway Bay Typhoon Shelter) |
Police Officers’ Club ·
Underground grease trap ·
Emergency generator and associated fuel
tank |
NEX2213/C/331/ENS/M57/402 |
|
2-24 (Area north of |
Open car park, vacant area, streets (historically used as a boat basin
of the former War Department) |
NEX2213/C/331/ENS/M57/404 |
13.16
For sites with constraints (e.g.
accessibility, site operation) (refers to Appendix 13.3)
in which the SI was not able to be carried out/completed during Stage 1, the SI
will be undertaken in Stage 2. The
details of such sites were listed in Table
5.2 of the CAP in Appendix 13.1 and
are also summarised in Table
13.2 below.
Table 13.2 Potentially Contaminated Sites Identified and SI
Conducted in Stage 2
|
Site ID (Description) |
|
Reference Figure in
CAR (Appendix 13.2) |
|
Area 2 |
||
|
2-15 (Southeast corner of Wanchai Swimming Pool) |
Aboveground diesel tanks for Wan Chai
Swimming Pool (only observation from the nearest overpass); it was in operation
and inaccessible during Stage 1 SI |
NEX2213/C/331/ENS/M57/403 |
Identification of Sensitive Receptors
13.17
Onsite construction
workers have the potential to be exposed to potentially contaminated materials during
the decommissioning stage. The principle exposure pathways for onsite workers
include:
l Direct
ingestion of contaminated soil through eating, drinking or smoking onsite; and
l Dermal
contact with contaminated soil.
13.18
Through the correct implementation of occupational
health and safety guidelines and usage of correct personal protective equipment
these potential pathways can be successfully managed.
13.19
Other potential sensitive receptors include water
bodies and other humans, working or travelling near the sites and during the
intrusive investigation and remediation work stages. During these stages there is a potential to
generate dust emissions and water discharges that have the potential to affect
the surrounding sensitive receivers (e.g.
human receivers and water bodies). However, adoption of appropriate work
practices and mitigation measures during
investigation and remediation works will ensure that
these risks can be successfully managed.
Prediction and Evaluation of Environmental Impacts
Stage 1 Site Investigation Results
13.20
Potentially contaminated sites have been identified
in the CAP (Appendix 13.1) and a site investigation involving
sampling and testing of soil and groundwater at identified hotspots has been
conducted. A summary of the number of
borehole/trial pits sampled, the number of samples tested, their compliance to
the adopted RBRGs, and the planned post-restoration land use is provided in Table 13.3 below:
Table 13.3 Summary of SI Findings in Stage 1
|
Site ID |
No. of Borehole/ Trial Pits
Sampled |
No. of Samples Tested# |
Compliance to Industrial
RBRGs |
Planned |
|
Area 1 |
||||
|
1-01 |
1 |
3* |
All
samples tested in compliance |
Construction
of cofferdam, tunnel and the |
|
Area 2 |
||||
|
2-10 |
2 |
6* |
All
samples tested in compliance |
SOV
and railway tunnel |
|
2-24 |
1 |
11* |
All
samples tested in compliance |
Ventilation shaft and railway tunnel |
|
Total |
4 |
20 |
- |
- |
#: Number of tested soil and groundwater (if
encountered) samples.
*: Number of
duplicated sample is not included in this table.
13.21
A total of 19 soil and 1 groundwater samples were collected at four borehole/trial pits under Stage 1 as scheduled in the CAP. According to the analytical results, no exceedances of the RBRG (industrial) or Soil Saturation
Limit/ Solubility Limit were found among the soil and groundwater samples
collected during Stage 1 SI.
Stage 2 Site Investigation
13.22
The Stage 2 SI will be conducted after the completion of this EIA study/land resumption/site
decommissioning and
prior to the commencement of the construction work. A revised CAP with sampling and testing
schedule updated based on site conditions should then be submitted to EPD for
endorsement. After completion of
sampling and testing, a supplementary CAR and if contamination is found, RAP
will be submitted for EPD endorsement. The revised CAP and supplementary CAR
and RAP should be submitted in separate packages for different works area
depending on the schedule of land resumption and the commencement of
construction works for each works area.
Based on the site appraisal conducted previously in the endorsed CAP,
the potential contamination (if any found) at the representative sites is
expected to be surmountable, with implementation of the mitigation measures
proposed in Section 13.37 of this
report.
Remediation Actions and Precautionary
Measures to Be Undertaken during
Construction
Sites under Stage 1 SI
Review of Remediation Options, Methods and Targets
13.23
Based on the Stage 1 SI results of the soil
and groundwater samples, no exceedance of the adopted
RBRG guidelines has been found at the identified potentially contaminated sites, therefore no remediation actions are needed for these
sites.
Summary of Proposed Precautionary Measures
to Be Undertaken during Construction
13.24
Although no exceedance
was found in Stage 1 SI, to be
conservative, precautionary measures such as visual inspection are recommended
to be undertaken during construction activities that disturb soil. The inspection process shall involve a
visual observation of excavated soils for discolouration and the presence of
oils, together with identifying the presence of odours, which may also indicate
soil and/or groundwater contamination.
13.25
If soil materials suspected to be contaminated are encountered during
excavation, sampling and testing shall be undertaken to verify the presence of
contamination. The soil extracted during
demolition, excavation and cut & cover construction shall be temporary
stockpiled. Should the concentrations of
contaminants of concern (COCs) exceed relevant RBRGs as indicated by laboratory
analyses, remediation works shall be undertaken with reference to the CAR and
RAP.
13.26
The following is a summary of proposed precautionary
measures to be
carried out at the sites Stage 1 SI:
Site IDs 1-01: Emergency Generator and the Associated Fuel
Tank
13.27
Due to site constraints, only a trial pit was only conducted outside the emergency
generator and its associated fuel tank rooms during Stage 1 SI. Visual inspection for the presence of
contamination shall therefore be carried out during construction of the
cut & cover tunnel onsite. Attention should be paid to potential contamination
due to the historic and current operation.
Site ID 2-10: Underground Grease Trap, Emergency
Generator and the Associated Fuel Tank
13.28
A trial pit was
constructed with a depth of 3 m bgs at the grease trap which is 1-2 m in depth. No exceedances of
the adopted RBRGs were recorded during the Stage 1 SI. However, to be conservative, visual
inspection shall be carried out at the underground grease trap when constructing
the SOV at the present Police Officers’ Club, for any sign of potential
contamination due to the storage of grease.
13.29
Due to site constraints, a trial pit was only conducted outside the
emergency generator and its associated fuel tank rooms
during the Stage SI. Visual inspection for the presence of contamination
shall therefore be carried out during construction of the
proposed the ventilation building onsite; attention should
be paid to potential
contamination due to the historic and current operation.
Site ID 2-24: Past Marine Boat Basin of the former War Department
13.30
Since the exact
area, extent and facilities of the previous War Department could not be confirmed, the Stage 1 SI was
conducted as a preliminary screening to confirm the presence of land
contamination in this area. Though all parameters tested did not exceed the
adopted RBRGs, to be conservative, a visual inspection shall be carried out during
the construction of ventilation shaft at which the boat basin was
identified, for any sign of potential contamination due to its past operations.
Sites with No SI Proposed
13.31
For some sites with currently no SI
proposed (i.e.
sites ID 2-02, 2-18, 2-22, 2-23, 2-27, 2-28), to be conservative, visual inspection shall be conducted during
demolition and excavation to
detect any abnormal colour, smell or other characteristics of the soil due
to the nearby land use and/ or construction method. If abnormal colour, smell or other
characteristics of contamination are identified for any of these sites, sampling and testing shall be
undertaken to verify the presence of contamination. The soil extracted during demolition,
excavation and cut & cover construction shall be temporary stockpiled. Should the concentrations of contaminants of
concern (COCs) exceed relevant RBRGs as indicated by laboratory analyses,
remediation works shall be undertaken with reference to the CAR and RAP.
13.32
In view of there are no historical potential contamination sources,
and no or limited amounts of chemicals are currently used at these sites, with
the ground generally in good condition, the potential contamination, if any
found at these sites, is expected to be limited extent and surmountable with
the implementation of the mitigation measures as proposed in Section 13.30 of this Report.
Sites under Stage 2 SI
Review of
Remediation Options, Method and Targets
13.33
If potential soil and
groundwater contamination is identified during the Stage 2 SI, a review of
remediation options (such as biopiling, ex-situ chemical oxidation (ESCO), soil
venting, landfarming, natural attenuation and
excavation and landfill disposals) shall be conducted in the RAP (if required).
Based on the site appraisal conducted previously in the endorsed CAP, the
potential contamination (if any found) at the respective sites under Stage 2 SI
is expected to be surmountable, with implementation of the mitigation measures
proposed in Section 13.39 of this
Report.
13.34 Remediation works will include the excavation of identified contaminated area, followed by a closure assessment to verify clearance of contaminated soil. The excavated contaminated soil will then be formed into piles for either biopiling or chemical oxidation. During this, monitoring of treatment performance will be carried out in the form of regular sampling and testing. Once the monitoring data indicates the treatment target is achieved, a closure assessment consisting of sampling and testing will be carried out at a defined sampling frequency for the treated soil.
13.35 The acceptance criterion is defined as contaminant concentrations complying with the remediation targets making reference to “industrial” land use category of the RBRGs. In the event that the samples are still exceeding the remediation target, treatment will continue until the soil target values are achieved. Following validation of successful soil treatment, the decontaminated soil will be used as fill materials for re-use on site with reference to the land use scenario in the RBRGs. A remediation report demonstrating completion of remediation works will be prepared and submitted to EPD for endorsement.
Summary of
Proposed Precautionary Measures to Be Undertaken during Construction
13.36
The Stage 2 SI is proposed for the site
considered to have the potential for land contamination but was impeded from
site appraisal and/or SI due to a constraint.
Since limited information is currently available to determine whether
remediation actions are required, in order to be conservative, precautionary
measures are suggested to be undertaken both during the SI and construction.
13.37
Visual inspection shall be undertaken during demolition or excavation
works at the Stage
2 SI works areas as listed below. If
discolouration and
the presence of oils and odours are detected, sampling and testing shall also be
undertaken to verify the presence of contamination. Should concentrations of COCs exceed the
adopted RBRGs, remediation works shall be undertaken with reference to the CAR and
RAP. A Remediation Report (RR) will
then be prepared and submitted to EPD to demonstrate that the decontamination
work is adequate and is carried out in accordance with the endorsed CAR and
RAP. Information such as soil treatment/
disposal records (including trip tickets), confirmatory sampling results, and
photographs will be included in the aforesaid RR. No construction work shall be carried out
prior to the endorsement of the RR by EPD.
13.38
The following is the precautionary measures to be undertaken at
the works area under the
Stage 2 SI:
Site ID 2-15: Aboveground
Diesel Storage Tanks
13.39
A SI including soil
and groundwater samplings was proposed for Site ID 2-15 under Stage 2. Due to site constraints, proper site appraisal and SI could not be conducted onsite for the aboveground diesel tanks, located near the proposed
EXH. Visual inspection shall be carried out during
construction where intrusive works and soil
excavation is encountered, for attention on any potential contamination due
to its current operation.
Potential
Remediation Works
13.40
If land contamination is identified during
the Stage 2 SI, a RAP detailing the proposed remediation works will prepared in
order to remediate the land. In order to minimise
environmental impacts arising from the handling of potentially contaminated
materials, the following environmental precautionary measures are recommended
to be utilised during the course of the site remediation:
·
Excavation profiles
must be properly designed and executed with attention to the relevant
requirements for environment, health and safety;
·
Excavation shall be
carried out during dry season as far as possible to minimise contaminated
runoff from contaminated soils;
·
Supply of suitable
clean backfill material is needed after excavation;
·
If remediation is required with chemical oxidation proposed as a contaminant mass reduction technology, chemicals shall be securely and separately stored away from sources of ignition or oxidisable items.
Handling shall be undertaken by personnel with appropriate training and personnel protective equipments (PPE).
·
Vehicles containing
any excavated materials shall be suitably covered to limit potential dust
emissions or contaminated wastewater run-off, and truck bodies and tailgates
shall be sealed to prevent any discharge during transport or during wet
conditions;
·
Speed control for the
trucks carrying contaminated materials shall be enforced;
·
Vehicle wheel and
body washing facilities at the site’s exist points shall be established and
used; and
·
Pollution control
measures for air emissions e.g. from biopile blower,
noise emissions e.g. from blower, and water discharges e.g. runoff control
shall be implemented and complied with relevant regulations and guidelines.
Summary of
Proposed Occupational Health and Safety Controls
13.41
In the event that remediation is required the Occupation Safety and Health
Ordinance (OSHO) (Chapter 509) and its subsidiary Regulations shall be followed
by all site personnel working on the site at all times to minimise the
potential adverse effects on the health and safety of construction workers
during the course of site remediation. In addition, basic health and safety
measures shall be implemented, but not limited to the followings:
·
Set up a list of
safety measures for site workers;
·
Provide written
information and training on safety for site workers;
·
Keep a log-book and
plan showing the contaminated zones and clean zones;
·
Maintain a hygienic working
environment;
·
Avoid dust
generation;
·
Provide face and
respiratory protection gear to site workers if necessary;
·
Provide personal
protective clothing (e.g. chemical resistant jackboot, liquid tight gloves) to
site workers if necessary; and
·
Provide first aid
training and materials to site workers.
13.42
The corresponding responsible party for the above precautionary measures
and supplementary site investigation are provided in the implementation
schedule of this EIA.
Evaluation of
Residual Environmental Impacts
13.43
No contaminants were detected in the soil and groundwater samples
collected in the Stage 1 SI. In terms of the potential soil and groundwater
contamination detected in Stage 2 SI, options of remediation methods will be reviewed
and implemented so that contaminants will be removed to achieve the remediation
targets. After completion of soil remediation for identified contaminated
areas, no adverse residual impact in respect of land contamination on the
future users is anticipated. Apart from these, precautionary measures as
mentioned in Sections 13.23 through
13.30 and Sections 13.35 through
13.38 should still be implemented during the construction phase for
conservancy.
13.44
This assessment has examined the potential
contaminating land uses within the relevant Assessment Area. It also covers potential impacts of the contamination on future use. The assessment involved site appraisal, site
investigation, and assessment of contamination extent. Stage 1 SI has been carried
out for Site IDs 1-01 (
13.45
Due to current land
use and site constraints, SI was not conducted for Site ID 2-15 (aboveground
diesel storage tanks at Wan Chai Swimming Pool) under
Stage 1. The investigation will be
conducted under Stage 2
after decommissioning of existing buildings and access has been granted. Based on the site appraisal conducted
previously in the endorsed CAP, the potential
contamination (if any found) at Site ID 2-15 under Stage 2 SI is expected to be
surmountable, with the mitigation measures proposed in Section 13.40 of this Report.