Table of Contents
8A Land
Contamination Assessment
8A.2 Legislation
Requirements and Evaluation Criteria
8A.3 Project Design and Site Setting
8A.4 Identification of Sensitive
Receivers
8A.6 Land Contamination Impact
Evaluation and Mitigation Measures
This
Section identifies the potential land
contamination problem due to historical land use of the Site. The assessment was undertaken in accordance
with the criteria set out in Annexes 19
of the EIAO-TM.
The
following legislation covers the handling, treatment and disposal of wastes in
·
Annex 19 of the Technical Memorandum on Environmental Impact
Assessment (Annex 19 of EIAO-TM);
·
Guidance
Manual for Use of Risk-based Remediation Goals for Contaminated Land Management (The RBRGs
Guidance Manual);
·
Guidance
Note for Contaminated Land Assessment and Remediation (The
Guidance Note); and
·
The Practice
Guide for Investigation and Remediation of Contaminated Land (The
Practice Guide).
Annex 19
of the EIAO-TM provides the legislative framework for the land contamination
assessment for designated projects in Hong Kong. This legislation framework remains valid.
Apart from the
abovementioned, the following legislation, documents and guidelines may cover
or have some bearing upon the assessment of contamination and the handling,
treatment and disposal of contaminated materials for the Project:.
·
Water Pollution Control Ordinance (WPCO) (Cap 358);
·
Waste Disposal Ordinance (WDO) (Cap 354);
·
Waste Disposal (Chemical Waste) (General) Regulation (Cap
354C); and
·
Code of Practice on the Packaging, Labelling and Storage
of Chemical Wastes.
The Project can be divided into three main
components, comprising the construction of a seawater desalination plant at Tseung Kwan O Area 137 (TKO137) with a fresh water supply
capacity of 135 million liter per day (MLD) (hereinafter referred as ‘the Plant
Area’), a dedicated trunk feed system which connects the future desalination
plant to the Tseung Kwan O Primary Fresh Water
Service Reservoir (TKOPFWSR) (hereinafter referred as ‘the Feed Area’) and
slope mitigation work on the natural slope within the Clear Water Bay Country
Park (hereinafter referred as ‘the Slope Area’). The trunk feed system consists
of pumping station (within desalination plant site), treated water storage tank
(within desalination plant site) and about 9km of fresh water mains along Wan
Po Road, Po Hong Road and Tsui Lam Road. There are also other minor works such as
pipeline fittings and flow monitoring. Figure
1.1 shows the three main components and minor works of the Project.
The current and historical land use covered
by the abovementioned three main project components are presented by using
Standard Form 3.1 and 3.2 of the RBRGs Guidance Manual (Tables 8A.1 and 8A.2)
below:
Table 8A.1 Standard Form 3.1 Summary of On-Site
Land Use – Current Use
|
Proposed Works Area |
Type of Existing Facility/Business |
On-site Property Land Use |
Date Began/ Period |
Description of Site Walkover Findings |
Owner or Occupier |
Approximate Size of On-site Property (m2) |
Off-site Property Affected? |
|
The Plant Area |
Public Fill/ Temporary Magazine
Storage Site (TMS Site) |
Industrial |
1995 - 2015 2012 – 2015 for TMS Site |
Part of the Plant Area was used as
the public fill bank for inert construction materials under the Civil
Engineering and Development Department (CEDD). The remaining part of the
Plant Area was used as TMS Site since 2012.
|
CEDD |
100,000 |
No |
|
The Feed Area |
Vehicle Access Road |
Public Roads |
1995– 2015 |
The proposed trunk feed system is
located along Wan Po Road and Po Hong Road, which are vehicle access roads. |
Highways Department |
11,400 |
No |
|
The Slope Works Area |
Country Park |
Green Belt |
NA – 2015 |
The Slope Area is part of the
Clear Water Bay Country Park |
Agriculture, Fisheries and
Conservation Department |
4,900 |
No |
Table 8A.2 Standard Form 3.2 Summary of On-Site
Land Use – Past Use
|
Proposed Works Area |
Type of Existing Facility/Business |
On-site Property Land Use |
Date Began/ Period |
Description of Site History |
Owner or Occupier |
Approximate Size of On-site Property (m2) |
Off-site Property Affected? |
|
The Plant Area |
Public Fill/ Temporary Magazine
Storage Site (TMS Site) |
Industrial |
Prior to 1995 |
The Plant Area was part of the
sea. |
CEDD |
100,000 |
No |
|
1995 - 2012 |
Part of the Plant Area was developed
into the public fill bank, while the TMS Site was still green area. |
||||||
|
2012 - 2014 |
No change of land use was observed
within the area occupied by public fill bank. The TMS Site was developed in
2012 and no change of operation was identified since then. |
||||||
|
The Feed Area |
Vehicle Access Road |
Public Roads |
Prior to 1995 |
The Feed Area was part of the sea.
|
Highways Department |
11,400 |
No |
|
1995 – 2014 |
Reclamation for the development of
Tseung Kwan O Industrial Park commenced and vehicle
access roads were developed alongside with it. |
||||||
|
The Slope Works Area |
Country Park |
Green Belt |
NA |
The Slope Area is part of the Clear
Water Bay Country Park and was not developed for other land use. |
Agriculture, Fisheries and
Conservation Department |
4,900 |
No |
A review of
land use history reveals that a majority of the areas are reclaimed land,
except for the Slope Area which has always been a green belt area of the Clear
Water Bay Country Park. After
reclamation, the future Feed Area was developed as road networks such as Wan Po
Road, Po Hong Road and Tsui Lam Road and the Plant
Area was used as a public fill bank for the dumping of inert construction
materials. Both the Slope Area and Feed
Area are not of industrial land use. In
2012, part of the southern Plant Area was developed into a temporary magazine
storage to provide service for the South Island Line Project of Mass Transit
Railway Corporation (MTRC). In
accordance with Annex 19 of EIAO-TM,
the Slope Area, the Feed Area and the public fill bank within the Plant Area
are not regarded as land uses with potential contaminated activities and are therefore
not covered in this assessment. However,
operations performed within the temporary magazine storage (hereinafter
referred as ‘the TMS Site’) may involve potential land contamination activities
(e.g. transfer and storage of explosive chemicals). This section assesses the potential land
contamination due to operation of the TMS Site.
The TMS Site comprised the following
facilities:
·
Nine individual temporary magazine storages aligned in L
shape, with six storages in a line to the north and three storages to the
south, fenced off from access;
·
A container office and a mobile toilet for the contractor
operating the temporary magazine storage;
·
A generator room housing four diesel-fired generators;
·
A fire hydrant tank;
·
A fire hydrant pump room;
·
A jetty; and
·
A vehicle access road connecting the above facilities.
The layout
of the TMS Site is illustrated in Figure 8A.1.
Future users of the Project and construction
workers are likely to be exposed to any potential contaminated soil/
groundwater within the Site.
Future users of the Project can be exposed to
potential contamination during the operation stage of the Project. As there will be green area around access
roads, part of these areas will not be paved and therefore allow direct contact
between potential contaminated soil and site users.
Owing to the nature of the construction work,
workers can be temporarily exposed to potential contamination during excavation
and preparation of foundation works. The principal exposure routes for future
site users and construction workers include:
·
Direct ingestion of contaminated soils through eating,
drinking or smoking on site;
·
Dermal contact with contaminated spoil; and
·
Inhalation of contaminations via fugitive emissions/
volatile chemicals.
The assessment of
potential land contamination impact within the Site was conducted by:
·
A desktop study to review the hydrogeology of the Site
from the Civil Engineering and Development Department (CEDD);
·
A desktop study to review the current and historical land
use information from Lands Department (LandsD); and
·
A site reconnaissance to identify the existing land uses.
The geological profile of the TMS Site was
reviewed by collating past site investigation records and survey maps from the
CEDD. Copies of relevant site
investigation records are attached as Annex
8A.1. Past conducted borehole/ trial
pits were located at the existing Public Fill Area of TKO137 under the project
‘Fill Bank at Tseung Kwan O Area 137, Ground
Investigation’. The general soil
profiles are summarised in Table 8A.3 below:
Table 8A.3 Summary
of Ground Elevation and Underground Geology
|
Depth (m below ground level) |
General Soil Profile |
|
|
0 – 9.0m |
Mainly
medium to coarse gravel with occasional concrete, metal, wood and brick
fragments |
|
|
9.0 –
11.5m |
Marine
deposit |
|
|
11.5m and
below |
Alluvium
and tuff |
|
As from the record of
past site investigations, the general site geology comprises a unified layer of
fill at the surface, immediately followed by marine sediment and alluvium. This suggested that the area is reclaimed and
not part of the naturally occurring land.
A review of
historical aerial photographs from the LandsD showing
the past land use of the Site was reviewed. The aerial photographs of the TMS
Site taken in 1990, 1995, 1998, 2000, 2005, 2009, 2012 and 2014 were reviewed
and illustrated in Figure 8A.2. Table
8A.4 below summarizes the type of land use within the Site.
Table 8A.4 Summary
of Historical Land Use Information from Aerial Photographs
|
Referenced Year |
Referenced Aerial Photographs |
Land Use Description |
|
1990 |
A23785 |
Prior to
1990, the TMS Site was part of the sea (Junk Bay). |
|
1995 |
CN11830 |
Between 1990
and 1995, reclamation of the Tseung Kwan O
Industrial Estate and part of the public fill can be observed to the north of
the TMS Site. The TMS Site was still part of the sea. |
|
1998 |
CN21155 |
Between
1995 and 1998, the reclamation work was extended towards south up to Fat Tong
Chau, an outlying island immediate to the west of the TMS Site. Most of the
public fill can be observed, but the TMS Site was still part of the sea. |
|
2000 |
CN27340 |
Between
1998 and 2000, the reclamation work already extended to cover the TMS
Site. In 2000, the TMS Site was vacant
and surrounded by construction work of road networks. A concrete jetty was
observed at the southern part of the Site. |
|
2005 |
CW66157 |
The TMS Site
was left vacant and vegetation was observed growing within the Site. |
|
2009 |
CS22996 |
The TMS
Site was observed with thick vegetation growth. No activity was observed
being conducted within the Site. |
|
2012 |
CS36650 |
The
temporary magazine storages were constructed in 2012. Concrete pavement was observed within the
TMS Site, except part of the access roads. |
|
2014 |
CS47482 |
No change
was observed compared to that of 2012. |
A site reconnaissance
was conducted at the Site on 7 August 2014 to obtain updated information of
land use within the TMS Site as well as to identify areas with possible soil
and groundwater contamination activities. The site reconnaissance was
accompanied by representative from the CEDD and an interview was conducted with
the site contractor representative who managed the magazine storage to
understand the operations conducted within the TMS Site. A site reconnaissance
checklist is attached as Annex 8A.2.
Findings
from the magazine storage
The nine
magazine storages were located on a concrete paved ground and fenced off from
rest of the TMS Site. Access into the
magazine storages was not permitted due to health and safety concern. As observed from the outside of the fence,
the magazine storages were one-storey concrete
structures surrounded by sand bags covered by tarpaulin sheets. The sand bags were reportedly used to
minimize the impact in case of accidental explosion.
According to
the interview with the site contractor (Nishimatsu Construction Company
Limited), both explosives and detonators were stored within the magazine
storages and the ground was concrete paved.
Explosives and detonators were reportedly in solid form and stored
within paper boxes. The package of an
individual explosive or detonator unit includes a paper wrap enclosed by
another layer of plastic wrap. No
information regarding the number of individual explosive or detonator unit
stored within the magazine storages was provided.
The logistics
practice of the explosives and detonators could not be observed at the time
when the site reconnaissance was conducted.
As reported by the site contractor, explosives and detonators were
transported to the TMS Site by ships and were loaded onto the Jetty and further
transferred to the magazine storages.
The explosives and detonators were supplied to the South Island Railway
Line project of the MTRC of Hong Kong.
When needed, the explosives and detonators were loaded onto concealed
trucks and transport away from the Site.
During the
site reconnaissance, no chemicals were observed being stored within the
magazine storages and no aboveground/ underground storage tanks was observed/
reportedly present. The concrete ground
surface was maintained in good condition and the structure of the magazine
storages can provide cover to explosives and detonators from adverse
weather. No sign of leakage or spillage
of explosive or detonator was observed.
Therefore, it is anticipated the risk of land contamination due to
activities performed within the magazine storages is minimal. The indicative
location of the magazine storages is shown in Figure 8A.1. Photos taken at the magazine storages are
included in Figure 8A.3.
Findings
from the generator room
The generator
room was located approximately 20m southeast of the magazine storages,
separated by an unpaved vehicle access road.
The generators inside the generator room provide electricity for the
site office of magazine storages and were managed by the site contractor. The generator room occupied an approximate
area of 10m X 20m, housing a total of 4 diesel-fired generator sets. The generator room was concrete paved and
enclosed from surrounding by corrugated metal sheets.
The
generator sets were provided with secondary containments. However, oil stains were observed on the
paved ground inside the generator room.
Approximately 10 diesel oil drums (with capacity of 2 Liters) were
stored within the generator room and no secondary containment was
provided.
Although the
generator room is paved, obvious signs of spillage of diesel oil were observed
within the generator room. Also, the
surrounding area of the generator house was not paved with concrete. The possibility of spilled diesel oil leak
out from the generator room and cause land contamination cannot be ruled
out. The indicative location of the
generator room is shown in Figure 8A.1. Photos taken at the generator room are
included in Figure 8A.3.
Findings
from the vehicle access road
The vehicle
access road connecting the magazine storages, the jetty, the fire hydrant tank
and the generator room was not concrete paved.
During the Site reconnaissance, approximately 30 waste chemical drums
with the label of ‘bituminous waterproofing emulsion’ were observed being
stored at the side of the vehicle access road southwest of the magazine
storages. No secondary containment was
provided for these chemical drums and potential leakage from these waste
chemical drums could impact the underlying soil. The location of the waste chemical drums
storage is shown in Figure 8A.1. Photos
taken at the vehicle access road are included in Figure 8A.3.
Based on the
review of historical aerial photographs, the TMS Site was once part of the sea
prior to reclamation finished in 2000.
After the completion of the reclamation work, the TMS Site was left
vacant until the magazine storages and other associated facilities were
constructed in 2012. Therefore the risk
of potential land contamination due to land use prior to the 2012 is
anticipated to be low.
Since 2012,
the TMS Site was used as a temporary magazine storage facility, which comprised
the main magazine storages and supporting facilities such as site office,
generator room and fire hydrant tank.
Based on the observation from the Site reconnaissance, potential risks
of land contamination due to operation activities of the magazine storages were
identified at the generator room and the waste chemical drums storage at the
side of the vehicle access road.
The TMS Site
operates under the Environmental Permit EP-438/2012/G of the Shatin to Central Link (SCL) Project and was currently
under the control of the Contractor of the SCL Project. It is anticipated that under its EP
conditions and current Environmental Monitoring & Audit (EM&A) programme of the SCL Project, if soil and groundwater
contamination occurred during the occupancy period, the owner of TMS Site
and/or its contractor(s) shall ensure the TMS site is properly cleaned up
before handover to CEDD.
After the
TMS Site is handed over to WSD and before the commencement of any construction
work at the TMS Site, the contractor of WSD shall prepare a Contamination
Assessment Plan (CAP) for EPD endorsement prior to the commencement of site
investigation. A Contamination Assessment Report (CAR) shall be prepared to
summarise the results of the site investigation. If land contamination is identified, a
Remediation Action Plan (RAP) shall be prepared to identify feasible
remediation methods and a Remediation Report (RR) shall be prepared to
demonstrate completion of remedial actions for EPD endorsement.
In order to
minimize the potential adverse effect to the environment due to the handling of
contaminated materials, the following environmental mitigation measures are
proposed during the course of site remediation.
·
Excavation profiles shall be properly designed and
executed;
·
An impermeable surfacing shall be placed under the
stockpile and a cover should be employed to prevent dust emission and possible
cross contamination. If not applicable, regular watering shall be applied; and
·
Trucks carrying contaminated materials shall be enforced
with speed control.
In order to confirm that the construction Contractor(s) has(have)
implemented the recommendations of the EIA Report, regular site inspections and
audits during construction phase will be conducted in accordance with the
approved procedures in CAP. The visual
inspections/audits will look at all aspects of construction activities that
disturb soil. The first inspection/audit
will be conducted at the commencement of the construction works.
A land contamination
assessment has been conducted for the Project.
The Project comprised the construction of a desalination plant (the
Plant Area); a trunk feed system (the Feed Area) connecting the plant to the TKOPFWSR and other associate
supporting facilities as well as the slope mitigation work (the Slope Area) at
part of the Clear Water Bay Country Park.
Based on a review of historical information, only the area covered by
the TMS Site was identified with low risk of potential land contamination.
The TMS Site was part
of the sea prior to 2000 and was left vacant after the completion of
reclamation until 2012. It was then used
as a magazine storage facility. A site
reconnaissance was conducted on 7 August 2014 and potential land contaminating
risks were identified at the generator room and the waste chemical drum storage
at the side of the vehicle access road.
Before the hand-over
of the TMS Site to WSD for further development, the
owner of TMS Site and its contractor shall ensure the TMS site is properly
cleaned up before handover to CEDD. After the TMS Site is handed over to WSD and
before the commencement of any construction work, the contractor of WSD shall
prepare a Contamination Assessment Plan (CAP) for EPD
endorsement prior to the commencement of site investigation. A Contamination
Assessment Report (CAR) shall be prepared to summarise the results of the site
investigation. If land contamination is identified, a
Remediation Action Plan (RAP) shall be prepared to identify feasible
remediation methods and a Remediation Report (RR) shall be prepared to
demonstrate completion of remedial actions for EPD endorsement
With the above
mitigation measures in place, the overall impact due to land contamination, if
identified, of the Site is considered to be insignificant after the site
investigation and remediation (if necessary).
No contamination causing insurmountable impacts to the environment is
expected.