7.1.1.1 This
section presents the potential implications of land contamination associated
with the Project.
·
Annex 19
of Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM)
·
Guidance
Note for Contaminated Land Assessment and Remediation (Guidance Note) – The
Guidance Note 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 remediation of
contaminated sites.
·
Practice
Guide for Investigation and Remediation of Contaminated Land (Practice Guide) –
The Practice Guide outlines typical investigation methods and remediation
strategies for the range of potential contaminants typically encountered in
Hong Kong.
·
Guidance
Manual for Use of Risk-based Remediation Goals for Contaminated Land Management
(Guidance Manual) – 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 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.
7.3.1.1 The
Project site covers the existing Tai Wai Nullah, which is approximately 2 km
long and 40 m wide, located at the northern region of the Tai Wai District and
is mainly surrounded by residential developments. The general layout of the Project is shown in
Figure 2.1.
7.4.1.1 Land
contamination assessment was carried out according to the abovementioned
EIAO-TM, Guidance Note, Practice Guide, Guidance Manual as well as the
requirements given in Section 3.4.8 and Appendix F of the EIA Study Brief.
7.4.1.2
A site appraisal, including site walkover and
desktop review, was conducted to identify the potentially contaminating
activities that may pose adverse impact to the Project. Site walkover was conducted within the
Project site to review the general site conditions and to identify any sources
of land contamination (or ‘hotspots’).
For the desktop review, the following information was reviewed:
·
Aerial
photographs and topographic maps held by the Lands Department;
·
Hong Kong
Geological Survey Map (Series HGM20) – Sheet No. 7 (1:20,000);
·
Records on
dangerous goods, Chemical Waste Producer, chemical spillage/leakage and fire
incidents from the identified potentially contaminated sites from Environmental
Protection Department (EPD) and Fire Services Department (FSD); and
·
Relevant
ground investigation (GI) reports from the Civil Engineering and Development
Department (CEDD) civil engineering library.
7.4.1.3
If potentially contaminated land use(s) were
identified within the Project site, the potential land contamination impacts arising
from the Project would be evaluated and appropriate mitigation measures would
be recommended. If necessary,
Contamination Assessment Plan (CAP), Contamination Assessment Report (CAR) and
Remediation Action Plan (RAP) would be submitted to EPD for endorsement. Any contaminated soil and/or groundwater
should be treated according to EPD’s approved RAP. A Remediation Report (RR), demonstrating
adequate remediation, should be submitted to EPD for endorsement prior to the
commencement of any development or redevelopment works within the Project site.
7.5.1.1
A review of historical aerial photographs was
undertaken to evaluate the likelihood of potential contamination associated
with past land uses within the Project site.
Findings of the review are summarised in Table 7.1
below and the aerial photographs reviewed are provided in Appendix 7.1.
Table 7.1 Aerial Photographs
Reviewed
|
Year
|
Reference of Aerial Photos in Appendix 7.1
(Photo Reference Number#)
|
Description of Land-Uses and Site Operation/Activities
|
|
1963
|
AP1
(#1963-6155)
|
The Project site was mainly occupied by agricultural
land, village houses and the Shing Mun River.
|
|
1973
|
AP2
(#03252)
|
The existing Tai Wai Nullah was observed within the
Project site. The village houses and
agricultural land were no longer observed in the Project site.
|
|
1983
|
AP3
(#48565)
|
The existing Shing Mun River Channel and Pok Ngar
Villa were observed in the south eastern and northern section of the Project
site respectively.
Existing Tsuen Nam Road and the riverbank of Shing
Mun River Channel were observed within the encroached portion of "Industrial (I)" zone.
|
|
1993
|
AP4
(#A36821)
|
The existing power cable bridge and Pak Tin Village
Section 5 Refuse Collection Point were observed at the centre and west of the
Project site respectively.
|
|
2003
|
AP5
(#CW53245)
|
No significant land use changes were observed within
the Project site.
|
|
2013
|
AP6
(#CS45201, #CS45203)
|
No significant land use changes were observed within
the Project site.
|
|
2021
|
AP7
(#E129333C, #E129336C,
#E129339C, #E129342C)
|
Existing Tai Wai Soccer Pitch was observed in the
southeast of the Project site. No
significant land use changes were observed in the remaining portions of the
Project site.
|
#Source of aerial photographs:
Survey and Mapping Office, Lands Department
7.5.1.2
Based on the review, no potentially
contaminating land uses were identified within the Project site. Non-contaminating land use including the
existing Tsuen Nam Road and the riverbank
of Shing Mun River Channel were observed within the encroached portion
of "Industrial (I)" zone since 1983.
No potential land contamination issues within the encroached portion of
the "Industrial (I)" zone were
noted.
7.5.2
Site
Geology
7.5.2.1 Based
on the HKGS 1:20,000 Geological Map Sheet No.7, 2nd Edition
(GEO, 2008), the Project site and the adjacent hillsides generally comprises
coarse-grained biotite granite of Needle Hill Granite of Kwai Chung Suite
(Jkt_gc). A layer of colluvium (Qd) and
alluvium (Qcd and Qfa) is identified as superficial soil.
7.5.2.2 Based
on available Ground Investigation (GI) records, a layer of fill with
thickness varying from 0.1 m to 8.5 m and grain size ranging from silt to
gravel was located on the top of the Project site. Approximately 0.1 m to 9.6 m thick of
alluvium (typically silt to gravel) was identified underneath the fill. A layer of colluvium with thickness up to
10.2 m and grain size varying between silt and sand was also encountered below
the fill / alluvium.
7.5.2.3
Approximately 1.18 m to 23 m thick of saprolite
comprising highly to completely decomposed granite was encountered. The inferred rockhead level varies from
-26.88 mPD to +14.97 mPD. In general,
the weathering profile appeared to become deeper towards the southeast. The bedrock was typically described as
moderately strong to strong, moderately to slightly decomposed granite.
7.5.3.1 The
EPD and FSD were contacted for (i) records of any spillage / leakage of
chemicals, (ii) records of Dangerous Goods (DG) and (iii) records of Chemical
Waste Producer(s) (CWPs) within the Project site.
7.5.3.2 EPD
and FSD’s replies on the request have been received and attached in Appendix 7.2. The information is summarised below.
Environmental
Protection Department
7.5.3.3 Based
on the replies given by EPD on 18 September 2020 and 14 September 2022, there
is no record of spillage / leakage of chemical wastes or chemicals within the
Project site.
7.5.3.4 Further
to the EPD’s reply, visits to EPD’s Southorn Centre Office were undertaken on
14 October 2020 and 4 November 2022 to review the available CWP records. No CWP records were found within the Project
site.
Fire Services
Department
7.5.3.6 As
shown in Table
7.2, of the 8 incident records, 7 (Record No. 1
to 7) are related to fire incidents whereas 1 (Record No. 8) is related to
animal rescue. Given the nature of the incident, no land
contamination issues are anticipated for Record No. 8.
7.5.3.7 For
the remaining 7 incident records (Record No. 1 to 7), based on the observation
from the site walkover (refer to Section 7.5.4),
no stains, burn marks or stressed vegetation were observed at the
locations. As such, these 7 incidents
were not expected to pose any potential land contamination issues to the
Project.
Table 7.2 Summary of Incident Records
|
Record No.
|
Address
/ Lamp Post No.
(Photo
Reference Number in Figure 7.1 to Figure 7.3
|
Date
|
Types
of Incidents
|
|
1.
|
Near Lamppost EA5356, Near Shing Mun Tunnel
Road, Roadside (#3472)
|
7 September 2019
|
Vegetation Fire
|
|
2.
|
Near Lamppost AE3708, Near Shing Wan Road,
Roadside (#3462)
|
20 February 2020
|
Rubbish Fire
|
|
3.
|
Near Lamppost BE4330, Chung Ling Road (#3465)
|
24 February 2020
|
Rubbish Fire
|
|
4.
|
7SW-D/C331, Near Shing Mun River (#3552)
|
26 February 2020
|
Rubbish Fire
|
|
5.
|
Lamppost BE4333, Near Shing Mun Tunnel Road,
Tung Lo Wan Hill Road (#3469)
|
24 May 2020
|
Vegetation Fire
|
|
6.
|
Near Lamppost BE4332, Near Shing Mun Tunnel
Road, Roadside (#3467)
|
20 June 2020
|
Vegetation Fire
|
|
7.
|
Lamppost CE0608, Near Heung Fan Liu Street (#3495)
|
20 January 2021
|
Rubbish Fire
|
|
8.
|
Near Lamppost CE0957, Near Mei Tin Road
(outside Project site)
|
18 February 2022
|
Animal Rescue
|
7.5.4.1 Site
walkovers were conducted on 14 August 2020 and 31 October 2022 to investigate
any contaminative issues associated with current land uses and activities
within the Project site. Findings of the
site walkover, including the photographic records and site layout plan, are
shown in Figure 7.1 to 7.3. Site walkover checklist is provided in Appendix 7.3.
7.5.4.2 The
Project site was occupied by non-contaminating land uses including vegetation,
Tai Wai Nullah, sections of Shing Mun River Channel and Mei Tin Road,
footbridges, bridges, a cable bridge, footpaths, pedestrian underpass, cycling
tracks, a football field (Tai Wai Soccer Pitch), a garden (Pok Ngar Villa) and
a refuse collection point. The areas
at/near the 7 FSD fire incident records (Record No. 1 to 7) as discussed in Section 7.5.3
above were occupied by footpaths, cycling tracks and slope. Based on the site walkover, no chemical / oil storage, burn marks or stressed
vegetation were observed within the Project site. The concrete paved ground was noted to be in
good condition with no oil stains observed.
No potentially contaminating land uses / activities were observed within
the Project site during the site walkover.
7.5.4.3 According
to the Approved Sha Tin Outline Zoning Plan (OZP) No. S/ST/36, part of the
Project site was identified as "Industrial (I)" zone. However, the encroached
portion only consists of Tsuen Nam Road, footpath, cycling tracks and vegetated
land. Based on the site walkover, no
chemical / oil storage or stressed vegetation were observed within the
encroached portion. The concrete paved
ground was noted to be in good condition with no oil stains observed. No potentially contaminating land uses /
activities were observed during the site walkover. Given the above, no potential land
contamination issues within the encroached portion of the "Industrial
(I)" zone were observed.
7.6
Prediction
and Evaluation of Environmental Impacts
7.6.1.1 Based
on the findings of site appraisal, the Project site has been occupied by non-contaminating
land uses (e.g. the existing nullah, football field, refuse collection point
and roads) and no potentially contaminating activities were observed. Therefore, no adverse land contamination impact arising from the Project is
anticipated and mitigation measures are considered not necessary. No further site investigation (SI) works at
the Project site is required.
7.7
Evaluation
of Residual Impacts
7.7.1.1 As
land contamination impacts are not anticipated for the Project, no residual
impacts are expected.
7.8
Environmental
Monitoring and Audit
7.8.1.1 Based
on the site appraisal, no land contamination impacts are anticipated for the
Project. No environmental monitoring and
audit programme would be required.
7.9.1.1 A site appraisal, in the form of desktop
review and site walkover, was conducted from August 2020 to November 2022 to
identify any current/historical potentially contaminating and uses within the
Project site.
7.9.1.2 Based on the findings of the site appraisal,
no adverse land contamination impact arising from Project is anticipated. No further SI works at the Project site is
required.