5.
WASTE MANAGEMENT AND MUD
CONTAMINATION
5.1.1
The main issues that relate to
waste management implications are waste management for dredged marine sediment
and other construction waste arisings, and the
potential biogas risk due to the release of methane gas from the sediment
underneath the reclaimed area during construction or after development.
5.1.2
In terms of other waste arisings which may be generated, these include general site
wastes such as residues, packaging and containers; workforce wastes from site
offices; and maintenance wastes from vehicles and equipment maintenance
activities; and construction and demolition material due to demolition of
existing buildings.
5.1.3
This section identifies the
types of wastes that are likely to be generated during the construction phase
and evaluates the potential environmental impacts which may result from these
waste arisings.
Mitigation measures and good site practice, including waste handling,
storage and disposal, will be recommended with reference to the applicable
waste legislation and guidelines. The
assessment of the potential biogas risk is presented in Section 6.
5.2
Environmental Legislation
and Standards
Waste Management
5.2.1
The following legislation
covers or has some bearing upon the handling, treatment and disposal of wastes
in Hong Kong:
·
Waste Disposal Ordinance (Cap 354);
·
Waste Disposal (Chemical Waste) (General) Regulation
(Cap 354);
·
Crown Land Ordinance (Cap
28); and
·
Public Health and Municipal Services Ordinance (Cap
132) Public Cleansing and Prevention of Nuisances (Urban Council) and (Regional
Council) By-laws.
5.2.2
The principal legislative
framework for waste collection and disposal is the Waste Disposal Ordinance
(Cap 354) which provides a licensing system for the collection and disposal of
wastes. Enacted in 1980, this ordinance
generally encompasses all stages of the waste management chain, from place of
arising to final disposal point. The
Waste Disposal Ordinance (WDO) prohibits the unauthorised
disposal of wastes, with waste defined as any substance or article which is
abandoned. Under the terms of the Waste
Disposal Ordinance (WDO) construction and demolition (C&D) waste is not
directly defined but is considered to fall within the category of “trade
waste”. Trade waste is defined as waste
from any trade, manufacturer or business, or any waste building, or civil
engineering materials, but does not include animal waste. Regulations for chemical waste control are
provided under a regulation of this Ordinance [Chemical Waste (General)
Regulation 1992] and administer the possession, storage, collection, transport
and disposal of chemical wastes. A
‘guideline’ document which details how the Contractor should comply with the
regulations on chemical wastes is the Code
of Practice on the Packaging, Labelling and Storage
of Chemical Wastes (1992), issued by the Environmental Protection
Department (EPD).
5.2.3
The Public Cleaning and
Prevention of Nuisances Bylaws provide control on the illegal tipping of wastes
on unauthorised (unlicensed) sites. Construction and
demolition material which are wholly inert may be taken to public filling
areas. Public filling areas usually form part of land reclamation schemes and
are operated by the Civil Engineering Department (CED). The Crown Land
Ordinance requires that dumping licences are obtained
by individuals or companies who deliver inert C&D material (or public fill)
to public filling areas. The licences are issued by
the CED under delegated powers from the Director of Lands.
5.2.4
The Hong Kong Planning
Standards and Guidelines (HKPSG), Chapter 9 (Environment), provides additional
information on regulatory compliance, and on the required methods of treatment
and disposal of different types of waste.
Marine Sediment
5.2.5
A new management and
classification system for dredged/excavated sediment has recently been
introduced in the form of WBTC No.
3/2000, Management of Dredged/Excavated Sediment. The new system applies to all projects which
involve the disposal of dredged and excavated sediment, except those projects
or portions of projects for which construction works has already commenced or
will commence before 31 December 2001. As the new system was not in place at the
time of the site investigation for the EIA Study, the waste management
assessment will follow the sediment classification system set out in EPD Technical Circular (TC) No. 1‑1‑92,
Classification of Dredged Sediments for Marine Disposal. With the proposed commencement of dredging
works for the YTB reclamation in 2004, a sediment sampling and testing programme will be required at the design stage in
accordance with the requirements of WBTC No. 3/2000. Procedures relating to the management and
disposal of dredged sediment are also laid down in WBTC No. 12/2000 Fill Management.
5.2.6
Under the EPD TC No. 1-1-92, sediments are classified according to their level of contamination
by toxic metals. The contamination
levels presented in the Technical Circular serve as criteria for determining
the disposal requirements of the dredged sediments.
5.2.7
Three classes of contamination
are categorized in accordance with the table given in EPD TC No. 1‑1‑92 (Table 7.1) and the classes are
defined as follows :
Class A Uncontaminated or
mildly contaminated material for which no special dredging, transport or
disposal methods are required except those which would normally be applied for
the purpose of ensuring compliance with EPD's Water
Quality Objectives, or for protection of sensitive receptors near the dredging
or disposal areas.
Class
B Moderately contaminated
material which requires special care during dredging and transport, and which
must be disposed of in a manner which minimizes the loss of pollutants either
into solution or by resuspension.
Class C Seriously
contaminated material which must be dredged and transported with great cares,
which should not be dumped in the Gazetted marine
disposal grounds and which must be permanently isolated from the environment
upon final disposal.
5.2.8
For sediments to be identified
within a particular class, it should be noted that only the concentration of
one metallic species needs to exceed the specified contamination criteria. The EPD contamination criteria delineating
these three classes are shown below in Table 5.1
Table 5.1 Classification of Sediments by Metal
Content (mg/kg dry weight)
|
|
Cd
|
Cr
|
Cu
|
Hg
|
Ni
|
Pb
|
Zn
|
|
Class A
|
< 0.9
|
< 49
|
< 54
|
< 0.7
|
< 34
|
< 64
|
< 140
|
|
Class B
|
1-1.4
|
50-79
|
55-64
|
0.8-0.9
|
35-39
|
65-74
|
150-190
|
|
Class C
|
³ 1.5
|
³ 80
|
³ 65
|
³ 1
|
³ 40
|
³ 75
|
³ 200
|
|
Source : EPD Technical
Circular 1-1-92
|
5.2.9
It should be noted that there
are no local standards on organic micro-pollutants in marine sediments under the
old sediment classification system. The
sediment quality criteria of the new management and classification system of
WBTC No. 3/2000 are presented in Table 5.2 below.
Table 5.2 Sediment Quality Criteria under the New Classification
System
|
Contaminants
|
LCEL
|
UCEL
|
|
Metals (mg/kg dry weight)
|
|
Cadmium (Cd)
|
1.5
|
4
|
|
Chromium (Cr)
|
80
|
160
|
|
Copper (Cu)
|
65
|
110
|
|
Mercury (Hg)
|
0.5
|
1
|
|
Nickel (Ni)
|
40
|
40
|
|
Lead (Pb)
|
75
|
110
|
|
Silver (Ag)
|
1
|
2
|
|
Zinc (Zn)
|
200
|
270
|
|
Metalloid (mg/kg dry wt.)
|
|
Arsenic (As)
|
12
|
42
|
|
Organic-PAHs (µg/kg dry
weight)
|
|
PAHs (Low Molecular
Weight)
|
550
|
3160
|
|
PAHs (High
Molecular Weight)
|
1700
|
9600
|
|
Organic-non-PAHs (µg/kg dry weight)
|
|
Total PCBs
|
23
|
180
|
|
Organometallics (µg TBT/L in
interstitial water)
|
|
Tributyltin
|
0.15
|
0.15
|
Source: WBTC No. 3/2000 Management of
Dredged/Excavated Sediment
Note: LCEL – Lower Chemical Exceedance Level
UCEL – Upper Chemical Exceedance Level
5.2.10
It can be seen that the
respective LCEL of the heavy metals in Table 5.2 are
equivalent to the Class C levels under the old system as shown in Table 5.1,
apart from the metal mercury for which the LCEL is lower than the Class C
level. A new guideline level, UCEL, has
been developed under the new management system.
The sediment will be categorized with reference to the LCEL and UCEL, as
follows:
Category L Sediment with all contaminant levels not
exceeding the LCEL. The material must be
dredged, transported and disposed of in a manner which minimizes the loss of
contaminants either into solution or by suspension.
Category M Sediment with
any one or more contaminant levels exceeding the LCEL and none exceeding the
UCEL. The material must be dredged and
transported with care, and must be effectively isolated from the environment
upon final disposal unless appropriate biological tests demonstrate that the
material will not adversely affect the marine environment.
Category H Sediment with any one or more contaminant
levels exceeding the UCEL. The material
must be dredged and transported with great care, and must be effectively
isolated from the environment upon final disposal.
Construction and Demolition (C&D) Material
5.2.11
The current policy relating to
the dumping of construction and demolition (C&D) material is documented in
the Works Branch Technical Circular No.
2/93, ‘Public Dumps’. In order to
dispose of the inert portion of C&D material (named as public fill) in a
public filling area, a license is required which is issued by the CED. The Works Branch Technical Circular states
that C&D material suitable for use as fill material should not be disposed
of to landfill, but placed in public filling area or reclamation and land
formation projects. The Public Fill
Committee (PFC) together with Project Departments are responsible for
considering the suitability of a site as a public filling area.
5.2.12
In addition to the Works Branch
Technical Circular, EPD and CED have produced a leaflet titled ‘New Disposal
Arrangements for Construction Waste’ (1992) which states that C&D material
with less than 20% by volume of inert material (i.e. public fill) will be accepted
at landfill. If the material contains
more than 20% inert material, the waste must be sorted with suitable material
and sent to public filling area and the non-inert material (i.e. C&D waste)
sent to landfill for final disposal.
Chemical Waste
5.2.13
The Waste Disposal (Chemical
Waste) (General) Regulation provides for the control of the storage,
collection, transportation and disposal of chemical wastes in Hong Kong. Under the Regulation, a chemical waste
includes any substance which is a scrap material or by-product arising from
industrial/trade activities, as specified under Schedule 1 of the Waste
Disposal Ordinance (WDO), in such form, quantity and concentration that it will
cause pollution or constitute a danger to health or risk to the environment. A
complete list of such substances is provided under the Ordinance. A chemical
waste producer will be required under the Ordinance to register with the
Director of Environmental Protection and must treat their wastes, utilising on-site plant licensed by the EPD, or have a
licensed collector take the wastes to a licensed facility (such as the Chemical
Waste Treatment Centre (CWTC) located at Tsing Yi,
which was commissioned in June 1993, and is designed to treat most of the
chemical waste from the territory). In
addition, any contractor employed for the collection of chemical waste must be
a registered chemical waste collector under the Ordinance. For each consignment of wastes, the waste
producer, collector and disposer of the wastes must sign all relevant parts of
a computerised trip ticket. This system is designed
to allow the transfer of wastes to be traced from cradle to grave.
5.2.14
Asbestos waste is classified as
chemical waste under the Waste Disposal (Chemical Waste) (General) Regulation
and its handling, collection, transportation and disposal is controlled by the
legislation. A Code of Practice on the Handling, Transportation and Disposal of
Asbestos Waste is published by EPD under the WDO. The purpose of this Code is to provide
guidance and advice on the collection, storage, treatment, transportation and
disposal of asbestos waste. A separate
code of practice, entitled Code of
Practice on Asbestos Control, is issued by EPD under the Air Pollution
Control Ordinance. This Code of Practice
comprises 4 sets of documents and provides advice on matters relating to
preparation of asbestos investigation report, asbestos management plan and
asbestos abatement plan; asbestos work using full containment or mini
containment method; asbestos work using glove bag method; and safe handling of
low risk asbestos containing material.
5.3
Mud Contamination
Assessment Methodology
5.3.1
The assessment included
sampling and testing of mud from the seabed at 9 locations in order to quantify
the extent of contamination within the proposed reclamation area. The locations of vibrocores
are shown in Figure 5.1.
5.3.2
The field sampling work was
carried out during January 1999. Vibrocores were recovered by pushing 6 m long vibrocore tubes into the seabed until refusal (subject to
the proposed dredging depth for the reclamation). Sediment samples were recovered from the vibrocore at depths stipulated in the WBTC No. 22/92 for
the purpose of contamination analysis.
5.3.3
Each sub-sample recovered from vibrocoring was laboratory tested for the following
parameters:
·
Heavy metals concentrations
including chromium (Cr), copper (Cu), mercury (Hg), lead (Pb),
cadmium (Cd), nickel (Ni) and zinc (Zn); and
·
Concentrations of organic
compounds including total polychlorinated biphenyls (PCBs), total polyaromatic hydrocarbons (PAHs)
and tributyltin (TBT).
5.3.4
Elutriation tests were also
conducted to assess the likelihood of release of contaminants from sediment to
the water, when the seabed is disturbed during dredging. If the contaminant levels are higher in the
elutriates in comparison with the sample of marine water from the same site, it
can be concluded that the contaminants are likely to be released into the open
waters during dredging activities. Two
composite samples of elutriate from each vibrocoring
location were tested for the same parameters as for the sediment analysis.
5.4
Baseline Conditions
Existing Sediment Characteristics
5.4.1
The results of the marine
sediment quality analysis as compared with the EPD TC No. 1-1-92 are presented in Table 5.3. The sediment is also classified with
reference to the sediment quality criteria under WBTC No. 3/2000. The full report of the laboratory tests is
presented in the "Test Report on Analysis of Sediment"
(no. 982874EN90065 & no. 982874EN90066) prepared by MateriaLab in February 1999.
Table 5.3 Classification of Contaminated Sediments
Analysis Results
|
Marine Sediment
|
|
Vibrocore
|
Sampling Depth
|
Cu
|
Cd
|
Cr
|
Pb
|
Ni
|
Zn
|
Hg
|
Total PCB
(mg/kg)
|
TBT3
(mg/kg)
|
PAH
(low)1
(mg/kg)
|
PAH
(high)2
(mg/kg)
|
Overall Classification 3
|
|
V1
|
0.0 – 0.5
|
180
|
<0.5
|
62
|
65
|
15
|
180
|
<0.4
|
<10
|
<10
|
47
|
492
|
C (H)
|
|
|
0.9 – 1.0
|
22
|
<0.5
|
7
|
44
|
<6
|
40
|
<0.4
|
<10
|
<10
|
20
|
34
|
A (L)
|
|
|
1.9 – 2.0
|
27
|
<0.5
|
26
|
60
|
13
|
64
|
0.7
|
<10
|
<10
|
28
|
99
|
A (M)
|
|
|
2.9 – 3.0
|
27
|
<0.5
|
28
|
22
|
10
|
57
|
<0.4
|
<10
|
<10
|
26
|
107
|
A (L)
|
|
|
5.8 – 5.9
|
<10
|
<0.5
|
14
|
29
|
7
|
27
|
<0.4
|
<10
|
<10
|
24
|
17
|
A (L)
|
|
|
8.8 – 8.9
|
20
|
<0.5
|
44
|
35
|
41
|
93
|
<0.4
|
<10
|
<10
|
20
|
5
|
C (H)
|
|
V2
|
0.0 – 0.5
|
170
|
<0.5
|
59
|
210
|
15
|
150
|
<0.4
|
<10
|
<10
|
61
|
409
|
C (H)
|
|
|
1.0 – 1.1
|
110
|
<0.5
|
50
|
51
|
16
|
100
|
<0.4
|
<10
|
<10
|
47
|
312
|
C (M)
|
|
|
1.9 – 2.0
|
87
|
<0.5
|
35
|
130
|
12
|
78
|
<0.4
|
<10
|
<10
|
236
|
1488
|
C (H)
|
|
|
2.9 – 3.0
|
22
|
<0.5
|
24
|
67
|
13
|
90
|
<0.4
|
<10
|
<10
|
144
|
643
|
B (L)
|
|
|
5.8 – 5.9
|
<10
|
<0.5
|
6
|
34
|
<6
|
20
|
<0.4
|
<10
|
<10
|
15
|
3
|
A (L)
|
|
V3
|
0.0 – 0.5
|
170
|
<0.5
|
57
|
53
|
15
|
140
|
<0.4
|
<10
|
<10
|
56
|
516
|
C (H)
|
|
|
1.05 – 1.25
|
240
|
<0.5
|
67
|
110
|
15
|
130
|
<0.4
|
<10
|
<10
|
108
|
392
|
C (H)
|
|
|
1.8 – 2.0
|
130
|
<0.5
|
61
|
120
|
16
|
170
|
1.0
|
<10
|
<10
|
247
|
2051
|
C (H)
|
|
|
2.8 – 3.0
|
<10
|
<0.5
|
15
|
11
|
9
|
34
|
<0.4
|
<10
|
<10
|
53
|
22
|
A (L)
|
|
|
5.7 – 5.8
|
<10
|
<0.5
|
5
|
39
|
<6
|
25
|
<0.4
|
<10
|
<10
|
29
|
4
|
A (L)
|
|
V4
|
0.0 – 0.5
|
150
|
<0.5
|
49
|
62
|
13
|
200
|
<0.4
|
<10
|
<10
|
167
|
629
|
C (H)
|
|
|
1.0 – 1.1
|
250
|
<0.5
|
100
|
87
|
22
|
240
|
0.9
|
<10
|
<10
|
177
|
1350
|
C (H)
|
|
|
1.9 – 2.0
|
64
|
<0.5
|
36
|
910
|
18
|
290
|
4.5
|
<10
|
<10
|
269
|
2286
|
C (H)
|
|
|
2.9 – 3.0
|
<10
|
<0.5
|
21
|
<15
|
12
|
45
|
<0.4
|
<10
|
<10
|
16
|
18
|
A (L)
|
|
|
5.7 – 5.8
|
<10
|
<0.5
|
13
|
24
|
10
|
39
|
<0.4
|
<10
|
<10
|
18
|
5
|
A (L)
|
|
V5
|
0.0 – 0.5
|
190
|
<0.5
|
49
|
98
|
14
|
140
|
<0.4
|
<10
|
<10
|
73
|
322
|
C (H)
|
|
|
0.3 – 0.5
|
91
|
<0.5
|
75
|
190
|
25
|
270
|
0.9
|
<10
|
<10
|
253
|
2015
|
C (H)
|
|
|
1.3 – 1.5
|
21
|
0.7
|
230
|
190
|
64
|
540
|
1.1
|
<10
|
<10
|
147
|
1178
|
C (H)
|
|
|
2.3 – 2.5
|
140
|
<0.5
|
48
|
27
|
11
|
80
|
<0.4
|
<10
|
<10
|
35
|
282
|
C (H)
|
|
|
3.3 – 3.5
|
180
|
<0.5
|
110
|
100
|
27
|
270
|
1.5
|
<10
|
<10
|
224
|
1430
|
C (H)
|
|
|
5.3 – 5.5
|
<10
|
<0.5
|
12
|
20
|
<6
|
28
|
<0.4
|
<10
|
<10
|
11
|
3
|
A (L)
|
|
|
8.2 – 8.4
|
<10
|
<0.5
|
13
|
86
|
<6
|
28
|
<0.4
|
<10
|
<10
|
18
|
5
|
C (M)
|
|
V6
|
0.0 – 0.5
|
420
|
0.7
|
330
|
150
|
45
|
400
|
0.6
|
<10
|
2970
|
603
|
3880
|
C (H)
|
|
|
0.4 – 0.6
|
470
|
0.8
|
160
|
170
|
42
|
240
|
0.7
|
<10
|
<10
|
201
|
896
|
C (H)
|
|
|
1.4 – 1.6
|
690
|
1.0
|
220
|
160
|
54
|
330
|
0.7
|
<10
|
<10
|
174
|
804
|
C (H)
|
|
|
2.4 – 2.6
|
640
|
0.9
|
190
|
120
|
50
|
280
|
0.7
|
<10
|
<10
|
122
|
794
|
C (H)
|
|
|
3.45 – 3.65
|
98
|
<0.5
|
61
|
200
|
19
|
180
|
1.9
|
<10
|
610
|
146
|
662
|
C (H)
|
|
|
5.7 – 5.9
|
<10
|
<0.5
|
15
|
20
|
<6
|
25
|
<0.4
|
<10
|
<10
|
21
|
24
|
A (L)
|
|
V7
|
0.0 – 0.5
|
490
|
0.5
|
140
|
220
|
28
|
470
|
0.5
|
<10
|
210
|
904
|
1732
|
C (H)
|
|
|
1.15 – 1.35
|
540
|
1.1
|
230
|
100
|
53
|
350
|
0.7
|
<10
|
290
|
154
|
953
|
C (H)
|
|
|
2.15 – 2.35
|
<10
|
0.6
|
30
|
<15
|
16
|
54
|
<0.4
|
<10
|
<10
|
24
|
15
|
A (L)
|
|
|
3.15 – 3.35
|
<10
|
0.6
|
24
|
<15
|
12
|
43
|
<0.4
|
<10
|
<10
|
12
|
13
|
A (L)
|
|
|
6.25 – 6.45
|
110
|
1.1
|
92
|
150
|
20
|
330
|
2.6
|
<10
|
<10
|
218
|
1707
|
C (H)
|
|
|
9.25 – 9.45
|
<10
|
<0.5
|
<5
|
30
|
<6
|
27
|
<0.4
|
<10
|
<10
|
14
|
87
|
A (L)
|
|
|
11.7 – 11.9
|
<10
|
<0.5
|
14
|
20
|
<6
|
24
|
<0.4
|
<10
|
<10
|
13
|
4
|
A (L)
|
|
V8A
|
0.0 – 0.5
|
350
|
1.5
|
220
|
220
|
36
|
440
|
0.8
|
<10
|
1900
|
275
|
1871
|
C (H)
|
|
|
1.8 – 2.0
|
540
|
2.0
|
320
|
620
|
87
|
640
|
3.6
|
<10
|
630
|
26326
|
55539
|
C (H)
|
|
|
2.7 – 2.9
|
770
|
2.5
|
610
|
900
|
200
|
600
|
1.2
|
<10
|
290
|
975
|
2327
|
C (H)
|
|
|
3.7 – 3.9
|
56
|
1.2
|
34
|
250
|
11
|
250
|
1.9
|
<10
|
<10
|
146
|
1525
|
C (H)
|
|
|
4.7 – 4.9
|
<10
|
1.2
|
18
|
21
|
10
|
43
|
<0.4
|
<10
|
<10
|
16
|
60
|
B (L)
|
|
|
7.7 – 7.9
|
<10
|
<0.5
|
<5
|
<15
|
<6
|
<15
|
<0.4
|
<10
|
<10
|
13
|
4
|
A (L)
|
|
V9B
|
0.0 – 0.5
|
420
|
1.7
|
310
|
210
|
43
|
430
|
0.7
|
<10
|
2850
|
275
|
2043
|
C (H)
|
|
|
1.7 – 1.9
|
700
|
3.1
|
920
|
100
|
560
|
880
|
1.2
|
<10
|
<10
|
456
|
937
|
C (H)
|
|
|
2.7 – 2.9
|
30
|
0.6
|
23
|
120
|
13
|
130
|
2.7
|
<10
|
<10
|
154
|
1075
|
C (H)
|
|
|
3.7 – 3.9
|
<10
|
0.6
|
27
|
<15
|
15
|
52
|
<0.4
|
<10
|
<10
|
14
|
27
|
A (L)
|
|
|
6.8 – 7.0
|
<10
|
<0.5
|
5
|
24
|
<6
|
20
|
<0.4
|
<10
|
<10
|
13
|
10
|
A (L)
|
|
|
7.8 – 8.0
|
<10
|
<0.5
|
<5
|
<15
|
<6
|
22
|
<0.4
|
<10
|
<10
|
19
|
20
|
A (L)
|
Notes:
1.
Low
molecular weight PAHs.
2.
High
molecular weight PAHs.
3.
Classification in accordance with WBTC No. 3/2000 is provisional and
based on available testing results for analysis of metals and organics.
4.
Values in underline indicate Category M sediment under WBTC No.
3/2000.
5.
Values in bold indicate
Category H sediment under WBTC No. 3/2000.
6.
Values in bold and underline
indicate Category H sediment under WBTC No. 3/2000 and that the contaminant
level exceeds the LCEL by 10 times.
7.
Units
of heavy metals = mg/kg
Heavy Metals
5.4.2
The results indicate that
seriously contaminated, Class C material, was found at all nine vibrocore locations.
There was a decrease in the level of metal contamination from surface to
deeper sediments. The degree of sediment
contamination, in terms of the number of metals exceeding the specified Class C
limits, was found to be less at vibrocores V1, V2 and
V3 located in the outermost part of the bay and along the proposed seawall for
the Full Reclamation option. At these 3 vibrocore locations, the metals Cu, Pb,
Ni and Hg were recorded at Class C level.
5.4.3
The extent of Class C sediments
was found to reach around 3 m at vibrocore V9B, and
around 4 m at vibrocores V6 (located near the
proposed seawall for the Minimized Reclamation option) and V8A. At vibrocore V5,
Class C sediment was found in the upper layers to a depth of around 3.5m and at
the bottom depth layer (8.2 – 8.4 m) (due to exceedance
of the Class C contamination criteria for the metal Pb
only). At vibrocore
V7, Class C sediment was found in the upper layers and also at a depth of
around 6 m. Marine sediments from vibrocores V2 and V3 located along the proposed seawall for
the Full Reclamation option showed Class C contamination to a depth of around 2
m. At vibrocore
V1, Class C contamination was found in the surface layer (0.0 – 0.5 m), with
the sediment below being uncontaminated Class A material. However, the marine sediment in the bottom
depth interval (8.8 – 8.9 m) of vibrocore V1 was
found to be Class C material, due to the concentration of the metal Ni just
exceeding the specified Class C contamination criteria.
5.4.4
Based on the testing results
for heavy metals content, the profile of Class C contamination in the sediment
is summarized in Figure 2.3a
and 2.3b. The contour values indicate the ratio of the
measured heavy metal concentration in the Class C sediment over the
classification criteria for Class C contamination as defined in the EPD TC No. 1-1-92. Physically, a ratio of 1
indicates that the heavy metal concentration in the sediment just reaches the
Class C contamination criteria, while higher ratios suggest that the
marine mud is highly contaminated with heavy metal concentrations exceeding the
Class C contamination criteria. The
contamination profile indicates that the sediment is highly contaminated by
heavy metals, particularly within the inner part of the bay.
5.4.5
The results of the measurement
of metal concentrations in the sediment samples with reference to the new
management and classification system for dredged/excavated sediment under WBTC
No. 3/2000 (Table 5.2) are also indicated for reference
on Table 5.3.
The results indicate that Category H material was found at all vibrocore locations due to high contaminant levels of Cu,
Cr, Pb, Ni, Zn and Hg. The concentration of the metal Pb at vibrocore V4 (1.9-2.0 m)
and the concentration of the metal Cu at vibrocore V6
(1.4-1.6 m) exceeds the respective LCEL by 10 times. Exceedance of the
LCEL by 10 times is also noted at vibrocores V8A (Cu
and Pb at sampling depth 2.7-2.9m) and V9B (Cu, Cr
& Ni at sampling depth 1.7-1.9m).
Category M material is identified at vibrocore
V1 (Hg at sampling depth 1.9-2.0m).
PCBs and PAHs
5.4.6
The Total PCB concentration in
the sediment samples at the nine vibrocore locations
were all less than 10 mg/kg.
With reference to the new sediment criteria under WBTC No. 3/2000 (Table 5.2), the measured concentrations are below the LCEL
for Total PCBs of 23 mg/kg.
5.4.7
The results of measurement of PAHs concentrations in the sediment samples are also shown
in Table 5.3.
The concentrations at each sampling depth are below the LCEL for low
molecular weight PAHs of 550 mg/kg
apart from vibrocore locations V6 (0.0-0.5 m), V7 (0.0-0.5
m) and V8A (1.8-2.0 m & 2.7-2.9 m).
The low molecular weight PAHs concentration of
26,326 mg/kg at vibrocore
location V8A exceeds the UCEL of 3,160 mg/kg and exceeds 10 times the LCEL. In terms of high molecular weight PAHs, exceedance of the LCEL of
1700 mg/kg is reported at vibrocore locations V3 (1.8-2.0 m), V4 (1.9-2.0 m), V5
(0.3-0.5 m), V6 (0.0-0.5 m), V7 (0.0-0.5 m & 6.25-6.45 m), V8A (0.0-0.5 m,
1.8-2.0 m & 2.7-2.9 m) and V9B (0.0-0.5m).
At vibrocore V8A (1.8-2.0 m), the measured
high molecular weight PAHs concentration of 55,539 mg/kg is in exceedance
of the UCEL of 9,600 mg/kg and exceeds 10 times the LCEL.
Tributyltin
5.4.8
The results of measurement of
the TBT content in the sediment samples are shown in Table
5.3. The TBT concentrations in the
sediment samples at vibrocore locations V1 to V5 were
all less than 10 mg/kg.
It can be seen that higher concentrations of TBT were found in the top
surface layer of sediment at vibrocores V6, V8A and
V9B. The highest measurements of TBT
concentrations were found at vibrocores V6 (2,970 mg/kg) and V9B (2,850 mg/kg). In a survey commissioned by EPD in 1994,
maximum concentrations of 53,000 and 18,300 ng Sn/g respectively were recorded in sediment beneath vessel
hoists in the Causeway Bay and Aberdeen Marinas. The average median value for
all sites in the study was approximately 500 ng Sn/g. The highest
TBT concentrations recorded in YTB at vibrocore
locations V6 and V9B correspond to 944.5 and 906.3 ng
Sn/g respectively.
Elutriate Tests
5.4.9
The measured heavy metal
concentrations in the elutriate samples tested from each vibrocore
location are presented in Table 5.4 below. The comparison of the elutriate test results
with the seawater sample from the site indicates that the concentrations of the
metals copper, nickel, zinc and lead in the elutriate samples are higher than
the background values recorded in the seawater sample. Therefore it can be concluded that these four
heavy metal species are likely to be released from the sediment into the marine
waters when the seabed is disturbed during dredging activities. As described in para. 4.7.62, however, the
heavy metal concentrations in the elutriate samples for the metals copper,
nickel, zinc and lead fall within the UK
Water Quality Standards.
Table 5.4 Results of Elutriate Tests on Marine
Sediments – Heavy Metal Content
|
Contaminant
|
Metal
content (mg l-1)
|
|
Seawater
sample
|
V1
|
V2
|
V3
|
V4
|
V5
|
V6
|
V7
|
V8A
|
V9B
|
|
Cu
|
<0.5
|
0.8
|
0.9
|
1.8
|
<0.5
|
<0.5
|
0.7
|
1
|
3.2
|
<0.5
|
|
Ni
|
<3
|
<3
|
<3
|
<3
|
<3
|
7
|
5
|
<3
|
8
|
12
|
|
Zn
|
<0.5
|
5
|
8
|
5
|
7
|
8
|
5
|
5
|
5
|
6
|
|
Pb
|
<0.5
|
<0.5
|
0.7
|
0.6
|
<0.5
|
0.6
|
<0.5
|
<0.5
|
<0.5
|
<0.5
|
|
Cd
|
<0.1
|
<0.1
|
<0.1
|
<0.1
|
<0.1
|
<0.1
|
<0.1
|
<0.1
|
<0.1
|
<0.1
|
|
Cr
|
<0.5
|
<0.5
|
<0.5
|
<0.5
|
<0.5
|
<0.5
|
<0.5
|
<0.5
|
<0.5
|
<0.5
|
|
Hg
|
<2
|
<2
|
<2
|
<2
|
<2
|
<2
|
<2
|
<2
|
<2
|
<2
|
Note: Shading
denotes that the metal concentration in the elutriate sample is in exceedance of the metal content measured in the seawater
sample from the site.
5.4.10
The measured PCB and PAH
concentrations in the elutriate samples tested from each vibrocore
location were all less than 1 mg l-1 and 5 mg l-1 respectively. The comparison of the elutriate test results
with the seawater sample from the site indicates that the PCB and PAH concentrations
in the elutriate samples are not higher than the background values recorded in
the seawater sample. Similarly, the
measured TBT concentrations in the elutriate samples (<1 mg l-1) are not higher than
the background values recorded in the seawater sample. Therefore it can be concluded that the PCB,
PAH and TBT contaminants in the sediment are unlikely to be released into the
marine waters when the seabed is disturbed during dredging activities.
Proposed Reclamation Method
5.4.11
It is recommended that a
drained reclamation should be carried out to minimize the volume of dredged
materials from Yau Tong Bay. As such, the very soft to soft marine clays
and other soft clays would be left in place with vertical band drains installed
within the reclamation area, and dredging would only be required for the
seawall foundation. This recommendation
is supported by the results of the sediment quality assessment as seriously
contaminated, Class C sediments were found to extend to greater depths within
the inner part of the bay and very high metal (Cu, Cr, Pb
& Ni) and PAH concentrations were also found within the inner part of the
bay. With reference to the sediment
criteria under the new management and classification system for
dredged/excavated sediment (Table 5.2), exceedance of the LCEL by 10 times is noted at vibrocores V8A (Cu and Pb at
sampling depth 2.7-2.9m) and V9B (Cu, Cr & Ni at sampling depth
1.7-1.9m). The reported concentration of
PAH (low & high molecular weight) at vibrocore
V8A (sampling depth 1.8-2.0m) exceeds the respective LCEL by 10 times. It should be noted that vibrocores
V8A and V9B are located within the inner part of the bay where sediment would
remain in-situ under the proposed drained reclamation method.
5.4.12
For the proposed Full
Reclamation option, dredging would be confined to areas beneath the seawall
foundation and located near vibrocores V1 to V3, for
which contamination was generally confined to a depth of 2m in the marine
sediments. The proposed Minimized
Reclamation option would involve dredging for the seawall foundation at the
mouth of the bay, with a shorter length of seawall on comparison with the Full
Reclamation. Minimization of the volume
of dredging would reduce the extent of potential heavy metal and organic
pollutants release from the contaminated sediment into the marine waters during
disturbance of the sediment.
Future Conditions
5.4.13
The development of Yau Tong Bay will involve the provision of a new sewerage system. The existing shipbuilding and repairing
facilities at all marine lots in the site will be decommissioned, thus removing
direct sources of pollution loads into the bay.
The demolition of industrial premises and workshops along the waterfront
will also remove potential sources of effluent discharges into the bay.
5.4.14
With the implementation of the
Water Pollution Control Ordinance (WPCO) and the Waste Disposal (Chemical
Waste) (General) Regulation, the indiscriminate discharge of effluent will be
brought under control. This will reduce
the pollutant loading to Victoria Harbour.
5.5
Construction Phase
Assessment
Marine Sediments
5.5.1
Dredged marine sediments will
arise from the dredging required for the seawall foundation and box culvert
extension. It is estimated that a volume
of approximately 82,800 m3 of Category H sediment will be dredged
for the Full Reclamation option. The
volume of Category M and Category L sediment is estimated to be
approximately 12,050 m3 and
80,300 m3, respectively.
The total volume of dredged sediment for the Full Reclamation
option is estimated to be approximately 175,150 m3. The total
volume of dredged sediment arising from the Minimized Reclamation option is
estimated to be approximately 112,170 m3, with the volume
of Category H mud estimated to be approximately 53,270 m3. The volume of Category M and Category L mud
is estimated to be approximately 4,200 m3 and 54,700 m3,
respectively. The potential
environmental effects of the removal of these sediments on water quality are
discussed in detail in Section
4.7.
5.5.2
Marine sediments will also
arise from the construction of the bored pile wall for the concrete decking
section at the northern part of Yau Tong Bay where
sediments will be dredged within the steel casing of the bore piled
seawall. The estimated volumes of
Category H and Category L material anticipated to arise from the bored pile
wall for the Full Reclamation option are 1,650 m3 and 3,300 m3
respectively. The uncontaminated
material will comprise marine sediments, in-situ weathered rock and
bedrock. The volume of Category H and
Category L material arising from the construction of the bored pile wall for
the Minimized Reclamation option is estimated to be 790 and 1,580 m3,
respectively.
5.5.3
In order to minimize any
potential adverse impacts arising from the dredged marine sediments, the
sediments should be disposed of in a manner which minimizes the loss of
pollutants into solution or by resuspension, as
detailed in the mitigation measures stated in Section 5.6. It is anticipated that, provided all these
recommended mitigation measures are enforced, including the measures
recommended in Section 4.8
for dredging and dumping activities, no unacceptable impacts will result from
the dredging, transport and disposal of the marine sediments.
General Site Wastes
5.5.4
Materials and equipment used on
site will produce packaging and container wastes. Introduction of these waste arisings from the construction activities into the sea
should not be permitted as they have a potential to cause water pollution and
indirect impacts on marine biota.
Mitigation measures should include provision of a collection area where
waste can be stored and loaded prior to removal from the site. The volume of general site wastes generated
will be dependent on the Contractor’s operating procedure and practices and
cannot be quantified. With the
implementation of the recommended mitigation measures in Section
5.6 (including good site practices), the potential environmental
impacts resulting from the storage, handling and transportation of general site
wastes are expected to be minimal.
Workforce Wastes
5.5.5
Throughout construction, the
workforce will generate general refuse, comprising food scraps, paper, empty
containers etc. Release of general
refuse into marine waters should not be permitted as introduction of these
wastes is likely to have detrimental effects on water quality in the area. Rapid and effective collection of site wastes
will be required to prevent waste materials being blown around by wind, flushed
or leached into the marine environment, and odour
nuisance. Putrescible
waste will not be suitable for incorporation into any reclamation works.
5.5.6
The amount of general refuse
which is likely to arise cannot be quantified at this time as it will be
largely dependent on the size of the workforce employed by the contractor. Though with the implementation of waste
management practices at the site (as recommended in Section 5.6), adverse
environmental impacts are not expected to arise from the storage, handling and
transportation of workforce wastes.
Maintenance and Chemical Wastes
5.5.7
Construction plant and
equipment will require regular maintenance and servicing which will generate
waste. Substances generated are likely
to include some chemical wastes such as cleaning fluids, solvents, lubrication
oil and fuel. Vehicle and equipment
maintenance activities will also involve the use of a variety of chemicals, oil
and lubricants, including heavy duty cleaners, organic solvents, degreasers,
brake fluids, battery acid and soldering fluids. The cumulative effect of a potentially large
number of small spillages during maintenance operations by faulty equipment,
accidents, carelessness and deliberate discharge to drain may be significant.
5.5.8
In the past, asbestos has often
been used in buildings for various purposes, including fire protection and
heat, sound and electrical insulation.
As the majority of the Yau Tong marine lots
have been operating since the late 1950s, a survey of the buildings scheduled
for demolition will be required to identify any asbestos containing materials
(ACM).
5.5.9
Chemical wastes arising during
the construction phase may pose serious environmental, health and safety
hazards if not stored and disposed of in an appropriate manner as outlined in
the Chemical Waste Regulations. These hazards
include:
·
toxic effects to workers;
·
adverse impacts on water
quality from spills and associated adverse impacts on marine biota; and
·
fire hazards.
5.5.10
Materials classified as
chemical wastes will need special handling and storage arrangements before removal
for appropriate treatment at the chemical waste treatment facility (CWTF) at Tsing Yi. Wherever
possible opportunities should be taken to reuse and recycle materials. Mitigation and control requirements for
chemical wastes are detailed in Section
5.6. Provided that the handling,
storage and disposal of chemical wastes are in accordance with these
requirements, adverse environmental impacts should not result.
5.5.11
Asbestos abatement plans in accordance
with EPD’s Code
of Practice on Asbestos Control – Preparation of Asbestos Investigation Report,
Asbestos Management Plan and Asbestos Abatement Plan will need to be
prepared and subsequently approved by the Government.
Construction and Demolition (C&D) Material
5.5.12
The existing shipyard buildings
and structures lying to the north, east and south of Yau
Tong Bay will be demolished. Industrial
premises and workshops located along the seaward side of Ko
Fai Road and Cha Kwo Ling
Road will also be demolished. The
preliminary demolition programme is assumed to have
demolition works carried out towards the end of the reclamation period, for a
duration of 6 months. Substantial
construction and demolition (C&D) material will be generated during this
period. The shipyard buildings to be
demolished are predominantly of reinforced concrete construction, but also
consist of wood/timber, glass, structural steel, plumbing fittings, ventilation
equipment, lighting, framework and pipes.
It is recommended that the selective demolition method be employed to
minimize the effort of sorting mixed C&D materials. Demolition material should be sorted on-site
into public fill which could be re-used on-site or disposed of to public
filling areas, and C&D waste which may need to disposed of to
landfill. An initial estimate of the
total volume of concrete likely to be generated from the demolition works is
approximately 39,500 m3 and the total volume of steel is estimated
to be approximately 1,700 m3.
By reducing the quantity of C&D material requiring off-site disposal
through the reuse of public fill on-site, the potential for traffic impacts
during the transportation of material will also be reduced. The construction noise assessment concluded
that the additional traffic flow from vehicle movements in and out of the site
is insignificant (para. 3.6.5), and that the
predicted noise levels due to vehicular movements on haul roads are
insignificant (para. 3.6.8
and 3.6.9).
5.5.13
On completion of the
reclamation and construction works, site buildings and facilities will be
demolished and removed from site. Demobilisation of infrastructure and site clearance will
generate C&D material and scrap material residues which will require
disposal. Certain elements may need to
be disposed to landfill or public filling areas, however, recyclable materials
should be salvaged for reuse (such as wood and metal) and inert waste utilized
as public fill.
5.6
Mitigation of Adverse
Impacts
Marine Sediments
5.6.1
The requirements and procedures
for dredged mud disposal are specified under the Works Bureau Technical Circular (WBTC) Nos. 3/2000 and 12/2000. The management of the dredging, use and
disposal of marine mud is monitored by the MFC, while the licensing of marine
dumping is the responsibility of the Director of Environmental Protection
(DEP).
5.6.2
The dredged marine sediments
will be loaded onto barges and transported to designated disposal sites
depending on their level of contaminants.
As discussed in Section 5.4,
the majority of the marine sediments to be dredged along the seawall foundation
fall into Class C contaminated material (or Category H sediment (biological
test not required)). In accordance with
the WBTC No. 3/2000, the contaminated
material must be dredged and transported with great care. Therefore appropriate dredging methods have been
incorporated into the recommended water quality mitigation measures (Section 4.8) and include the
use of closed-grab dredgers.
Furthermore, the dredged contaminated sediment must be effectively isolated
from the environment upon final disposal and shall be disposed at the East Sha Chau Contaminated Mud Pits
which is designated for the disposal of contaminated mud in the territory. The dredged sediments identified as Class A
or B (or Category L and Category M sediment passing biological test) will be
suitable for open sea disposal.
5.6.3
During transportation and
disposal of the dredged marine sediments, the following measures shall be taken
to minimize potential impacts:
·
Bottom opening of barges shall
be fitted with tight fitting seals to prevent leakage of material. Excess
material shall be cleaned from the decks and exposed fittings of barges and
hopper dredgers before the vessel is moved.
·
Monitoring of the barge loading
shall be conducted to ensure that loss of material does not take place during
transportation. Transport barges or
vessels shall be equipped with automatic self monitoring devices as specified
by the DEP.
5.6.4
With the recent implementation
of the new sediment management framework as detailed in WBTC No. 3/2000, a
sediment sampling and testing programme will be
required at the design stage of the Project in accordance with the requirements
of WBTC No. 3/2000. To determine the disposal
requirements of the dredged sediment along the seawall foundation and at the
bored pile seawall identified as Category H with the contaminant levels 10
times higher than the LCEL, Tier III biological screening (dilution test) would
be required for the sediment sampling and testing to be carried out at the
design stage. Biological screening would
also be required for any identified Category M sediment.
5.6.5
The need for any special treatment/disposal procedures for dredged
sediments from the YTB reclamation would be examined in detail at the design
stage of the Project, as necessary, based on the results of biological
screening. At this stage, based on the
existing vibrocore sampling results, it is estimated
that around 1,400m3 of contaminated sediment may require special
treatment/disposal arrangements. As the
concentration of Cu at vibrocore V6 (located near the
proposed seawall for the Minimized Reclamation option) only marginally exceeds 10 times the LCEL, it is considered likely that the sediment would pass the
biological screening (dilution test) and therefore special treatment/disposal
procedures are unlikely to be required.
5.6.6
The
reported contaminant levels in the sediment at vibrocore
V4 near the bored pile seawall exceed the LCEL by 10 times. Dredged sediment from the extension of the
existing box culvert may also contain contaminants levels in exceedance of the LCEL by 10 times (based on the testing
results for vibrocores V8A and V9B). To cater for the possibility that the
Category H sediments at these locations may fail the Tier III biological test,
a review of possible special disposal arrangements for the contaminated
sediment has been carried out with the objective of keeping the loss of
sediment to the surrounding marine environment to a negligible extent. Several options may be suitable, but the
method pursued as having the least potential for loss of contaminants to the
marine environment is by containment of the sediments in geosynthetic
containers. A feasible containment
method is proposed whereby the dredged sediments are sealed in geosynthetic containers and, at the disposal site, the
containers would be dropped into the designated contaminated mud pit where they
would be covered by further mud disposal and later by the mud pit capping,
thereby meeting the requirements for fully confined mud disposal. The technology is readily available for the
manufacture of the geosynthetic containers to the
project-specific requirements. Similar
disposal methods have been used for projects in Europe and the USA (for
example, geosynthetic fabric containers have been
used to contain contaminated dredged sediment at Marina Del Rey
in California) and the issues of fill retention by the geosynthetic
fabrics, possible rupture of the containers and sediment loss due to impact of
the container on the seabed have been addressed.
Nevertheless, field trials are recommended to be undertaken during the
detailed design site investigation stage (using uncontaminated mud) to
establish the optimum handling method for this approach.
5.6.7
It
will be the responsibility of the Contractor to satisfy the appropriate
authorities that the contamination levels of the marine sediment to be dredged
have been analysed and recorded.
According to the WBTC No. 3/2000, this will involve the submission of a formal
Sediment Quality Report to the DEP, at least 3 months prior to the dredging
contract being tendered.
Good Site Practices and Waste Reduction Measures
5.6.8
It is not anticipated that
adverse waste management related impacts would arise, provided that good site
practices are adhered to. Recommendations
for good site practices during the construction phase include:
·
Nomination of an approved
personnel, such as a site manager, to be responsible for good site practices,
arrangements for collection and effective disposal to an appropriate facility, of
all wastes generated at the site;
·
Training of site personnel in
proper waste management and chemical handling procedures;
·
Provision of sufficient waste
disposal points and regular collection for disposal;
·
Appropriate measures should be
employed to minimise windblown litter and dust during
transportation of waste by either covering trucks or by transporting wastes in
enclosed containers;
·
Separation of chemical wastes
for special handling and appropriate treatment at the Chemical Waste Treatment
Facility; and
·
Regular cleaning and
maintenance programme for drainage systems, sumps and
oil interceptors.
5.6.9
To minimize the potential
impact on health and safety/contamination exposure during the special disposal
arrangements for the seriously contaminated sediments, the following protective
measures should be followed:
·
No unauthorized persons shall
be allowed into the works areas, and necessary precautions shall be taken to
prohibit unauthorized entry to the Site or works areas.
·
Eating, drinking, smoking or any
practice that increases the probability of hand to mouth transfer and ingestion
of material is prohibited .
·
Food, beverages, tobacco
products, etc, are prohibited in any area designated as being
contaminated. Adequate warning signs
shall be posted to this effect.
·
Hands must be thoroughly washed
upon leaving the works area, and before eating, drinking or any other
activities.
·
All field personnel shall wear
protective gear such as gloves to minimize exposure to any contaminated
material.
5.6.10
In order to monitor the
disposal of C&D material and solid wastes at public filling areas and
landfills, and to control fly-tipping, a trip-ticket system should be included
as one of the contractual requirements and implemented by the Environmental
Team. An Independent Checker
(Environment) should be responsible for auditing the result of the system.
5.6.11
Good management and control can
prevent the generation of significant amounts of waste. Waste reduction is best achieved at the
planning and design stage, as well as by ensuring the implementation of good
site practices. Recommendations to
achieve waste reduction are as follows:
Planning
and Design Stage
·
Drained reclamation technique
to minimize volume of dredged materials;
·
Public fill generated from
demolition works to be re-used on-site in the reclamation works as far as
practicable to reduce off-site disposal.
Construction
Stage
·
Segregation and storage of
different types of waste in different containers, skips or stockpiles to
enhance reuse or recycling of materials and their proper disposal;
·
To encourage collection of aluminium cans by individual collectors, separate labeled
bins should be provided to segregate this waste from other general refuse
generated by the workforce;
·
Any unused chemicals or those
with remaining functional capacity should be recycled;
·
Prior to disposal of C&D
waste, it is recommended that wood, steel and other metals be separated for
re-use and/or recycling to minimise the quantity of
waste to be disposed of to landfill;
·
Proper storage and site
practices to minimise the potential for damage or
contamination of construction materials; and
·
Plan and stock construction
materials carefully to minimize amount of waste generated and avoid unnecessary
generation of waste.
5.6.12
A recording system for the amount
of wastes generated, recycled and disposed (including the disposal sites)
should be proposed. Quantities could be
determined by weighing each load or other suitable methods.
5.6.13
In addition to the above good
site practices and waste reduction measures, specific mitigation measures are
recommended below for the identified waste arisings
to minimize environmental impacts during the handling, transportation and
disposal of these wastes. The
transportation of these wastes by sea to the disposal location is recommended,
as far as practicable, in order to reduce potential noise and air quality
impacts from road transportation.
General Site Wastes
5.6.14
A collection area should be
provided where waste can be stored and loaded prior to removal from site. An enclosed and covered area is preferred to
reduce the occurrence of 'wind blow' light material. If an open area is unavoidable for the
storage or loading/unloading of wastes, then the area should be bunded and all the polluted surface run-off collected
within this area should be diverted into sewers.
Workforce Wastes
5.6.15
Suitable collection sites
around site offices and canteen will be required. It is recommended that for environmental
hygiene reasons and to minimise odour,
putrescible wastes are not stored for a period
exceeding 48 hours, however, removal every 24 hours is preferable.
Maintenance and Chemical Wastes
5.6.16
After use, chemical wastes (eg. cleaning fluids, solvents, lubrication oil and fuel)
should be handled according to the Code
of Practice on the Packaging, Labelling and Storage
of Chemical Wastes. Spent chemicals should be stored and collected by an
approved operator for disposal at the Chemical Waste Treatment Facility or
other licenced facility in accordance with the
Chemical Waste (General) Regulation.
5.6.17
Any service shop and minor
maintenance facilities should be located on hard standings within a bunded area, and sumps and oil interceptors should be
provided. Maintenance of vehicles and
equipment involving activities with potential for leakages and spillage should
only be undertaken with the areas appropriately equipped to control these
discharges.
5.6.18
Should ACM be found in the
buildings scheduled for demolition at the site, the ACM should be removed by
registered contractors and disposed of at a designated landfill site. For the
removal of ACM, the practices defined in EPD’s Code of Practice on the Handling,
Transportation and Disposal of Asbestos Waste should be followed. Where temporary on-site storage of ACM is
necessary, the storage facilities should be designed in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes issued by EPD.
Construction and Demolition Material
5.6.19
C&D material will be
generated from demolition of the existing shipyard buildings and structures at
the marine lots, and from the existing industrial premises and workshops. It is recommended that the selective
demolition method be employed to minimize the effort of sorting mixed C&D
materials. This requires a proper
demolition sequence to remove material of the same category at a time. The C&D material should be separated
on-site into public fill and C&D waste.
The former, such as concrete and rubble, should be disposed of to a
public filling area. C&D waste such
as wood, glass, plastic, steel and other metals should be reused or recycled
and, as a last resort, disposed of to landfill.
It is recommended that a suitable area be designated to facilitate the
sorting process and a temporary stockpiling area will be required for the
separated materials. These areas should
be located away from the locations of soil remediation activities, as shown in
Figure 6-2 of Appendix 7C. A suitable area for locating temporary stockpiles
is the Stage 1b reclaimed land.
Considering that a large quantity of C&D material will be generated
from the demolition works and in order to minimise
the impact resulting from collection and transportation of material for
off-site disposal, it is recommended that public fill should be re-used on-site
in the reclamation works where possible.
5.6.20
When disposing public fill at a
public filling area, it should be noted that the material should only consist
of earth, inert building debris, broken rock and
concrete, brick, cement plaster/mortar, aggregates and asphalt. The material shall be free from marine mud,
household refuse, plastic, metals, industrial and chemical waste, animal and
vegetable matter, and other material considered to be unsuitable by the public
filling supervisor. Small quantities of
timber mixed with otherwise suitable material would be permitted.
5.6.21
Table 5.5
provides a summary of the various waste types likely to be generated during the
reclamation works, together with the recommended handling and disposal methods.
Table 5.5 Summary of Waste Handling Procedures and
Disposal Routes
|
Waste Type
|
Handling
|
Disposal
|
|
Construction
& Demolition Material
|
Where possible
inert portion (i.e. public fill) should be re-used on-site
|
On-site for
reclamation
|
|
|
If off-site disposal
required, separate into:
• C&D waste
• Public fill: concrete
and rubble
|
Landfill
Public filling area or
reclamation
|
|
Dredged Sediments
|
Contaminated : techniques
to minimise resuspension
(closed grabs, tight seal on barges, controlled loading and transfer)
|
MFC Contaminated Mud Pit
|
|
|
Uncontaminated : minimise resuspension (closed
grabs, tight seal on barges, controlled loading and transfer, minimise concurrent activity)
|
MFC gazetted
marine disposal ground
|
|
Maintenance and Chemical
Wastes
|
Recycle on-site or by
licensed companies
Stored on-site within
suitably designed containers
|
Chemical Waste Treatment
Facility
|
|
|
Asbestos
Provision of appropriate
on-site temporary storage facility where necessary
To be removed off-site by
registered contractors
|
Landfill
|
|
Workforce Wastes
|
Provide on-site refuse collection
facilities
|
Refuse station for
compaction and containerisation and then to
landfill
Private hygiene company
|
Notes:
* The
need for special disposal procedures for dredged contaminated sediments will be
examined in detail at the design stage of the Project, as necessary, based on
the sediment testing results.
5.7
Definition and Evaluation of
Residual Impacts
5.7.1
No unacceptable residual
impacts are anticipated provided that the recommended mitigation measures on waste
management practices for the Yau Tong Bay reclamation
are implemented. In addition, it is
considered that no adverse environmental effects will result from the
employment of the recommended mitigation measures for waste management and
dredged sediment disposal during the reclamation of Yau
Tong Bay as described in Section
5.6.
5.8
Conclusions
5.8.1
It is recommended that a
drained reclamation should be carried out to minimize the volume of dredged
sediments. Dredging would be confined to
areas beneath the seawall foundation and box culvert extension. The estimated total dredged volume for the
Full Reclamation option is 175,150 m3, among which 82,800 m3
are classified as Category H mud. The estimated
total dredged volume for the Minimized Reclamation option is 112,170 m3,
with 53,270 m3 classified as Category H mud. It is considered that the potential
impacts of the dredging works and associated dredged sediment disposal will be
minimized provided that the recommended mitigation measures, including the
procedures detailed in Works Bureau
Technical Circular No. 3/2000 ‘Management of Dredged/ Excavated Sediment’,
are implemented.
5.8.2
With the recent implementation
of the new sediment management framework as detailed in WBTC No. 3/2000, a
sediment sampling and testing programme for the
Sediment Quality Report will be required at the design stage of the Project in
accordance with the requirements of WBTC No. 3/2000.
5.8.3
To determine the disposal
requirements of Category H sediment with contaminant levels exceeding 10 times
the LCEL, Tier III biological screening (dilution test) would be required for
the sediment sampling and testing to be carried out at the design stage. Biological screening will also be required
for any identified Category M sediment.
The need for any special treatment / disposal procedures for dredged
sediments will be examined in detail at the design stage, as necessary, based
on the results of biological screening.
A review of possible special disposal arrangements has recommended
containment of the contaminated sediments during dumping to prevent any release
of material to the marine environment.
Field trials are recommended to be undertaken during the detailed design
stage (using uncontaminated mud) to establish the optimum handling method.
5.8.4
Wastes generated by the
reclamation works are likely to include general site wastes, workforce wastes,
maintenance and chemical wastes and C&D material. Provided that the identified waste arisings are handled, transported and disposed of using
approved methods and that the recommended good site practices are adhered to,
adverse environmental impacts are not anticipated.
