6 WASTE MANAGEMENT.. 1
6.1 Introduction. 1
6.2 Environmental Legislation, Policies,
Plans, Standards and Criteria. 1
6.3 Assessment Methodology. 2
6.4 Baseline Conditions. 2
6.5 Identification of Potential Sources
of Impact 2
6.6 Prediction and Evaluation of Environmental
Impacts. 2
6.7 Mitigation Measures. 2
6.8 Evaluation of Residual Impacts. 2
6.9 Environmental Audit 2
6.10 Conclusion. 2
6.1.1
This
section identifies the types of solid wastes that are likely to be generated
during the reclamation including associated dredging works (DP3) and evaluates
the potential environmental impacts that may result from these wastes. The main solid waste issues would be
related to dredged marine sediment and construction and demolition (C&D)
material generated from demolition and excavation works. Mitigation measures and good site
practices, including measures for waste handling, storage and disposal, are
recommended with reference to the applicable waste legislation and
guidelines. Since the reclamation
would be fully dredged, the investigation of ‘potential biogas problem’ stated
in the EIA Study Brief is not necessary.
6.2.1
The
criteria and guidelines for assessing waste management implications are set out
in Annex 7 and Annex 15 of the Technical Memorandum on Environmental Impact Assessment
Ordinance (EIAO-TM), respectively.
6.2.2
The
following legislation relates to the handling, treatment and disposal of wastes
in the Hong Kong SAR and has been used in assessing potential impacts:
·
Waste Disposal Ordinance
(Cap. 354)
·
Waste Disposal (Chemical
Waste) (General) Regulation (Cap. 354)
·
Land (Miscellaneous
Provisions) Ordinance (Cap. 28)
·
Public Health and Municipal
Services Ordinance (Cap. 132) - Public Cleansing and Prevention of Nuisances
Regulation
Waste Management
6.2.3
The
Waste Disposal Ordinance (WDO) prohibits the unauthorised disposal of
wastes. Construction waste is
defined as any substance, matter or thing that is generated from construction
work and abandoned, whether or not it has been processed or stockpiled before
being abandoned, but does not include any sludge, screenings or matter removed
in or generated from any desludging, desilting or dredging works. Under the WDO, wastes can be disposed of
only at designated waste disposal facilities.
6.2.4
Under
the WDO, the Chemical Waste (General) Regulation 1992 provides regulations for
chemical waste control, and administers the possession, storage, collection,
transport and disposal of chemical wastes.
The Environmental Protection Department (EPD) has also issued a
guideline document, the Code of Practice
on the Packaging, Labelling and Storage of Chemical Wastes (1992), which
details how the Contractor should comply with the regulations on chemical
wastes.
6.2.5
The Public Cleansing and
Prevention of Nuisances Regulation provides control on illegal tipping of
wastes on unauthorised (unlicensed) sites
Dredged Marine Sediment
6.2.6
The
ETWB TCW No. 34/2002 sets out the procedure for seeking approval to dredge /
excavate sediment and the management framework for marine disposal of dredged /
excavated sediment. This Technical Circular outlines the requirements to be
followed in assessing and classifying the sediment and explains the marine
disposal arrangement for the classified material. The sediment quality criteria for the
classification of sediment are presented in Table 6.1.
6.2.7
Dumping
permits from EPD are required for marine disposal of dredged materials.
Chemical Waste
6.2.8
Under
the Waste Disposal (Chemical Waste) (General) Regulations, all producers of
chemical waste must register with EPD and treat their wastes, either utilising
on-site plant licensed by EPD, or arranging for a licensed collector to
transport the wastes to a licensed facility. The regulation also prescribes the
storage facilities to be provided on site, including labelling and warning signs,
and requires the preparation of written procedures and training to deal with
emergencies such as spillages, leakages or accidents arising from the storage
of chemical wastes.
Construction and Demolition (C&D) Materials
6.2.9
The
current policy related to the disposal of C&D material is documented in the
Works Branch Technical Circular No. 2/93, ‘Public Dumps’. Construction and demolition materials
that are wholly inert, namely public fill, should not be disposed of to
landfill, but taken to public filling areas, which usually form part of
reclamation schemes. The Land
(Miscellaneous Provisions) Ordinance requires that dumping licences be obtained
by individuals or companies who deliver public fill to public filling
areas. The Civil Engineering &
Development Department (CEDD) issues the licences under delegated powers from
the Director of Lands.
6.2.10
Under
the Waste Disposal (Charges for Disposal of Construction Waste) Regulation,
enacted in January 2006, construction waste delivered to a landfill for
disposal must not contain more than 50% by weight of inert material. Construction waste delivered to a
sorting facility for disposal must contain more than 50% by weight of inert
material, and construction waste delivered to a public fill reception facility
for disposal must consist entirely of inert material.
6.2.11
Measures have been introduced
under Environment, Transport and Works Bureau (ETWB) TCW No. 33/2002,
“Management of Construction and Demolition Material Including Rock” to enhance
the management of construction and demolition material, and to minimize its
generation at source. The
enhancement measures include: (i) drawing up a Construction and Demolition
Material Management Plan (C&DMMP) at the feasibility study or preliminary
design stage to minimize C&D material generation and encourage proper
management of such material; (ii) vetting of the C&DMMP prior to upgrading
of the project to Category A in the Public Works Programme; and (iii) providing
the contractor with information from the C&DMMP in order to facilitate him
in the preparation of the Waste Management Plan (WMP) and to minimize C&D
material generation during construction.
Projects generating C&D material less than 50,000m3 or
importing fill material less than 50,000m3 are exempt from the
C&DMMP. The new ETWB TCW No. 19/2005
“Environmental Management on Construction Sites” includes procedures on waste
management requiring contractors to reduce the C&D material to be disposed
of during the course of construction.
Under ETWB TCW No. 19/2005, the Contractor is required to prepare and
implement an Environmental Management Plan (EMP) and the WMP becomes part of
the EMP.
General
6.3.1
The
criteria for assessing waste management implications are outlined in Annex 7 of
the EIAO-TM. The methods for
assessing potential waste management impacts during the construction phase
follow those presented in Annex 15 of the EIAO-TM and include the following:
·
Estimation of the types and
quantities of the wastes generated.
·
Assessment of potential impacts
from the management of solid waste with respect to potential hazards, air and
odour emissions, noise, wastewater discharge and transport.
·
Assessment of impacts on the
capacity of waste collection, transfer and disposal facilities.
Dredged Marine Sediment
6.3.2
The
Phase I marine site investigation works of WDII commenced on 25 August 2006 and
were completed on 14 September 2006 and included laboratory testing of
contaminants to determine the level of contamination in the marine sediments at
the proposed reclamation. The works
included vibrocoring in the HKCEC sea channel, the Causeway Bay
typhoon shelter, North Point waterfront and the proposed temporary typhoon
shelter to obtain sediment samples for chemical testing (Figure 6.1). The Phase II marine site investigation
works commenced on 27 September 2006 and were completed on 10 October 2006 and
included sampling locations to the west and east of the HKCEC and in the
Wanchai Public Cargo Working Area (PCWA) basin (Figure 6.1). Permission to sample in the WSD
prohibition zone and MTR protection zone in the area to the west of HKCEC was
not obtained from WSD and MTRC for the Phase II marine site investigation. In addition, MTRC advised that anchoring
is not permitted within 20m of their protection zone and hence it was not
possible to carry out sampling at the proposed locations.
Chemical Testing
6.3.3
Each
sub-sample recovered from the Phase I and II vibrocoring was tested in the
laboratory for the following parameters:
(i)
Metal and metalloid
concentrations including chromium (Cr), copper (Cu), mercury (Hg), lead (Pb),
cadmium (Cd), nickel (Ni), zinc (Zn), silver (Ag) and arsenic (As)
(ii)
Concentrations of organic
compounds including total polychlorinated biphenyls (PCBs), polyaromatic
hydrocarbons (PAHs)
6.3.4
Grab
samples collected from the vibrocoring locations were tested for tributyltin
(TBT) in interstitial water. Grab
samples were used in view of the difficulty to extract sufficient interstitial
water for the TBT analysis in the vibrocore samples to achieve the required
detection limit, as was encountered in the EIA study for Wan Chai Development
Phase II Comprehensive Feasibility Study.
6.3.5
Elutriate
tests were 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. The potential water quality impacts
associated with the dredging of sediment are discussed in Section 5 of this
Report.
6.3.6
Under
the management and classification system, dredged sediments destined for marine
disposal are classified according to their level of contamination by 13
contaminants (Table 6.1).
Table 6.1 Sediment Quality
Criteria for the Classification of Sediment
|
Contaminants
|
LCEL
|
UCEL
|
|
Heavy Metal (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 weight)
|
|
Arsenic
|
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-1 in
interstitial water)
|
|
Tributyltin
|
0.15
|
0.15
|
Source: Appendix A of ETWB TCW No. 34/2002 Management of Dredged
/ Excavated Sediment
Note: LCEL – Lower Chemical Exceedance Level
UCEL
– Upper Chemical Exceedance Level
6.3.7
Sediments
are categorised 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 that
minimises 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.
6.3.8
In
the case of Category M and Category H contamination, the final determination of
appropriate disposal options, routing and the allocation of a permit to dispose
of material at a designated site will be made by EPD and the Marine Fill
Committee (MFC) in accordance with the ETWB TCW No. 34/2002.
Biological Testing
6.3.9
For
Category M sediment, Tier III biological screening was carried out to determine
the appropriate disposal methods in accordance with the requirements of ETWB
TCW No. 34/2002:
(i)
a 10‑day burrowing amphipod
toxicity test
(ii)
a 20‑day burrowing polychaete
toxicity test
(iii)
a 48‑96 hour larvae
(bivalve) toxicity test.
6.3.10
Sediment
classified as Category H with one or more contaminant levels exceeding 10 times
the LCEL were also subjected to the above three biological tests but in a
diluted manner (dilution test).
6.3.11
The
species used for each type of biological test and the test conditions are
listed in Table 6.2 below.
Table 6.2 Test Species for Biological Testing
|
Test
Types
|
Species
|
Reference
Test Conditions*
|
|
10‑day burrowing amphipod toxicity test
|
Leptocheirus
plumulosus
|
U.S.EPA (1994)
|
|
20‑day burrowing polychaete toxicity test
|
Neanthes
arenaceodentata
|
PSEP (1995)
|
|
48‑96 hour bivalve larvae toxicity test
|
Mytilus
spp.
or Crassostrea gigas
|
PSEP (1995)
|
Notes:*
(i)
U.S.EPA (U.S. Environmental
Protection Agency) 1994. Methods
for assessing the toxicity of sediment-associated contaminants with estuarine
and marine amphipods. Office of
Research and Development. U.S.
Environmental Protection Agency, Cincinnati,
OH. EPA/600/R94/025.
(ii)
PSEP (Puget
Sound Estuary Program) 1995. Recommended guidelines for conducting
laboratory bioassays on Puget Sound sediments.
6.3.12
Sediment
samples were characterized by the testing laboratory for ancillary testing
parameters such as porewater salinity, ammonia, TOC, grain size and moisture
content. This provided necessary
information on the general characteristics of the sediment. The test endpoints and decision criteria
are summarized in Table 6.3. The sediment was deemed to have failed
the biological testing if it failed in any one of the three toxicity tests.
Table 6.3 Test Endpoints and Decision Criteria for
Biological Testing
|
Toxicity test
|
Endpoints measured
|
Failure criteria
|
|
10-day
amphipod
|
Survival
|
Mean
survival in test sediment is significantly different (p £ 0.05)1 from mean survival in
reference sediment and mean
survival in test sediment < 80% of mean survival in reference
sediment.
|
|
20-day
polychaete
|
Dry
Weight2
|
Mean
dry weight in test sediment is significantly different (p £ 0.05)1 from mean dry weight
in reference sediment and mean
dry weight in test sediment < 90% of mean dry weight in reference
sediment.
|
|
48-96
hour bivalve larvae
|
Normality
Survival3
|
Mean
normality survival in test sediment is significantly different (p £ 0.05)1 from mean normality
survival in reference sediment and
mean normality survival in test sediment < 80% of mean normality survival
in reference sediment.
|
1 Statistically significant differences
should be determined using appropriate two-sample comparisons (e.g., t-tests) at a probability of p £
0.05.
2 Dry weight means total dry weight after
deducting dead and missing worms.
3 Normality
survival integrates the normality and survival end points, and measures
survival of only the normal larvae relative to the starting number.
Existing Sediment Characteristics
6.4.1
The
results of the marine sediment quality analysis from the Phase I and Phase II
marine site investigation works, as compared with the sediment quality criteria
for the classification of sediment, are presented in Appendix 6.1. All
testing results of TBT in interstitial water were below the reporting limit of
0.015 µg/L. The practical limitation of being unable
to carry out the TBT interstitial water test is therefore not considered to
have any significant effect.
6.4.2
The
sediment testing results indicate that Category H sediment was found at the
HKCEC sea channel and to the immediate west of the sea channel. At grab sample V06-7, the reported
contaminant level of Ag exceeded the LCEL by 10 times.
6.4.3
Along
the Wan Chai waterfront, the sediment testing results indicate that Category H
sediment was found at all eight vibrocoring locations. At vibrocores V06-14 and
V06-17, Category H sediment with contaminant levels exceeding the LCEL by 10
times was reported for Ag. Category
M sediment was found at V06-13B.
6.4.4
At
the PCWA basin, Category H sediment was found at the two vibrocores. At V06-19, Category H sediment with
contaminant levels exceeding the LCEL by 10 times was reported for Ag. At V06-18A, Category M sediment was
reported for Hg.
6.4.5
At
the Causeway Bay typhoon shelter, the sediment testing results indicate that
Category H sediment was found at all but two of the fourteen vibrocoring
locations due to high contaminant levels of Cu, Pb, Zn, Hg and Ag that exceeded
the UCEL of these five metals.
Category L sediment was found at V06-31 and Category L and M sediment
was found at V06-32. At vibrocores
V06-20, V06-21, V06-22, V06-26, V06-30B, V06-33 and V06-34A, Category H
sediment with contaminant levels exceeding the LCEL by 10 times was reported
for Ag, Total PCB and Hg.
6.4.6
Along
the North Point waterfront, Category H sediment was found at vibrocores V06-35
to V06-37, Category L sediment was found at V06-38 and V06-39, and Category L
and M sediment was found at V06-40.
6.4.7
At
the proposed temporary typhoon shelter, the sediment testing results indicate
that Category H sediment was found at all but three of the eight vibrocoring
locations due to high contaminant levels of Cu, Hg and Ag. At V06-44, Category H sediment with the
contaminant level of Hg exceeding the LCEL by 10 times was reported. Category L
and M sediment was found at V06-41, V06-42 and V06-46.
6.4.8
Tier
III biological screening was conducted for the Category M sediment samples
(found at V06-13B, V06-18A, V06-19B, V06-21, V06-23A, V06-24, V06-25A, V06-27,
V06-29, V06-30, V06-32, V06-34A, V06-35, V06-36, V06-37A, V06-40A, V06-41,
V06-42 and V06-44), and the Category H sediment samples with the reported
contaminant levels exceeding the LCEL by 10 times i.e. >10xLCEL, as
described above. The results of the
biological screening are summarized in Table
6.4 below.
Table 6.4 Results
of Biological Screening of Category M and Category H (>10xLCEL) Samples
|
Vibrocore No. / Depth
|
Location
|
Amphipod Test
|
Polychaete Test
|
Bivalve Test
|
Result of Biological
Screening
|
Classification
|
|
V06-7
grab
|
HKCEC sea channel
|
Ö
|
Ö
|
Ö
|
Pass
|
Category H
|
|
V06-20
0-0.9m
|
Typhoon shelter
|
X
|
Ö
|
X
|
Fail
|
Category H**
|
|
V06-21
0-0.9m
|
Typhoon shelter
|
X
|
Ö
|
X
|
Fail
|
Category H**
|
|
V06-21 1.9-2.9m
|
Typhoon shelter
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-22
0-9-1.9m
|
Typhoon shelter
|
X
|
Ö
|
X
|
Fail
|
Category H**
|
|
V06-22 1.9-2.9m
|
Typhoon shelter
|
X
|
Ö
|
X
|
Fail
|
Category H**
|
|
V06-23a 0.9-1.9m
|
Typhoon shelter
|
X
|
X
|
X
|
Fail
|
Category M
|
|
V06-24
9-10m
|
Typhoon shelter
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-25A 1.9-2.9m
|
Typhoon shelter
|
X
|
X
|
X
|
Fail
|
Category M
|
|
V06-26
0-0.9m
|
Typhoon shelter
|
X
|
Ö
|
X
|
Fail
|
Category H**
|
|
V06-27 1.9-2.9m
|
Typhoon shelter
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-29
3-4m
|
Typhoon shelter
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-30B 0.9-1.9m
|
Typhoon shelter
|
X
|
Ö
|
Ö
|
Fail
|
Category H**
|
|
V06-30
3-4m
|
Typhoon shelter
|
Ö
|
X
|
Ö
|
Fail
|
Category M
|
|
V06-32 0.9-1.9m
|
Typhoon shelter
|
Ö
|
X
|
X
|
Fail
|
Category M
|
|
V06-33 3.0-4.0m
|
Typhoon shelter
|
Ö
|
Ö
|
Ö
|
Pass
|
Category H
|
|
V06-34A 0-0.9m
|
Typhoon shelter
|
Ö
|
Ö
|
Ö
|
Pass
|
Category H
|
|
V06-34A 0.9-1.9m
|
Typhoon shelter
|
X
|
X
|
X
|
Fail
|
Category M
|
|
V06-35 1.9-2.9m
|
North Point
|
X
|
X
|
X
|
Fail
|
Category M
|
|
V06-35 5.9-6.9m
|
North Point
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-36 0.9-1.9m
|
North Point
|
X
|
X
|
X
|
Fail
|
Category M
|
|
V06-36 4.9-5.9m
|
North Point
|
X
|
Ö
|
X
|
Fail
|
Category M
|
|
V06-37A 2.9-3.9m
|
North Point
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-37A 4.7-5.7m
|
North Point
|
X
|
Ö
|
X
|
Fail
|
Category M
|
|
V06-40A 0-0.9m
|
North Point
|
X
|
Ö
|
X
|
Fail
|
Category M
|
|
V06-40A 1.9-2.9m
|
North Point
|
X
|
Ö
|
X
|
Fail
|
Category M
|
|
V06-41
0-0.9m
|
Temporary breakwater
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-42
0-0.9m
|
Temporary breakwater
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-44
0-0.9m
|
Temporary breakwater
|
Ö
|
Ö
|
X
|
Pass *
|
Category H
|
|
V06-44 0.9-2.9m
|
Temporary breakwater
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-13B 0-0.9m
|
Wanchai waterfront
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-14
0-0.9m
|
Wanchai
waterfront
|
Ö
|
Ö
|
Ö
|
Pass
|
Category H
|
|
V06-17A 0-0.9m
|
Wanchai waterfront
|
Ö
|
Ö
|
Ö
|
Pass
|
Category H
|
|
V06-18a 1.9-2.9m
|
PCWA basin
|
Ö
|
X
|
Ö
|
Fail
|
Category M
|
|
V06-19B 0.9-1.9m
|
PCWA basin
|
Ö
|
Ö
|
Ö
|
Pass
|
Category M
|
|
V06-19 2.9-3.9m
|
PCWA basin
|
Ö
|
Ö
|
Ö
|
Pass
|
Category H
|
Notes:
1.
X = fail biological test
2.
Ö = pass biological
test
3.
* = high levels of unionized ammonia in overlying
water of 0.21 mg/L reported at test termination of the bivalve test. The laboratory test report stated
“results could be qualified as possible false positive when ammonia (unionized)
is greater than 0.13 mg/L”. This
sample is therefore not classified as failing the biological screening.
4.
** = sample failed biological screening and therefore
would require Type 3 special disposal.
Dredged Marine Sediments
6.7.1
The
basic requirements and procedures for dredged mud disposal are specified under
the ETWB TCW No. 34/2002. The MFC
is responsible for the provision and management of disposal capacity for
dredged/excavated sediment, and DEP is responsible for the issue of permits for
marine disposal under the provisions of the Dumping at Sea Ordinance (Cap.
466).
6.7.2
The
dredged marine sediments would be loaded onto barges, transported to and
disposed of at the designated disposal sites at South of Cheung Chau, East of
Ninepin, East of Tung Lung Chau, South of Tsing Yi and East of Sha Chau to be allocated
by the MFC depending on their level of contamination or at other disposal sites
after consultation with the MFC and EPD. Based on the chemical screening
results, the majority of the marine sediment to be dredged was classified as
contaminated and would require Type 2 confined marine disposal. In accordance with the ETWB TCW No. 34/2002, the contaminated material must be dredged and transported with
great care, and the mitigation measures recommended in Section 5 of this Report
should be strictly followed.
Furthermore, the dredged contaminated sediment must be effectively
isolated from the environment upon final disposal and the project proponent
will consult the MFC about the disposal requirement.
6.7.3
Based
on the biological screening results, the Category H (>10xLCEL) sediment which failed
the biological testing would require Type 3 special disposal. The volume of Category H sediment from
the Causeway Bay typhoon shelter which would require
special disposal arrangements is estimated to be approximately 0.05 Mm3. It was agreed with EPD during the WDII Comprehensive Feasibility Study (CFS)
that special disposal arrangements, rather than pre-treatment, would be
appropriate provided there would be negligible loss of sediment to the marine
environment during the dumping operations.() A detailed review of possible special
disposal arrangements for the contaminated sediment was carried out in the WDII
CFS with the objective of keeping the loss of sediment to the surrounding
marine environment to a negligible extent.
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, the USA and Japan (for example,
geosynthetic fabric containers have been used to contain contaminated dredged
sediment at Marina Del Rey in California and Yokohama Port in Japan) 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. The recommended field trials were
undertaken during the WDII Design and Construction (D&C) consultancy
(Agreement No. CE54/2001 (CE)) using uncontaminated mud to demonstrate the
feasibility of the proposed method.
6.7.1
The
ACE Report [to be endorsed by ACE] (Appendix
6.2) on the field
trials of geosynthetic containers concluded that disposal by sealing the
dredged sediments in geosynthetic containers and dropping these containers into
the contaminated mud pits at East Sha Chau has been shown to be a successful
and viable disposal method. The use
of a geosynthetic container system for special disposal was considered to be an
effective system with negligible loss of contaminants to the marine environment
during disposal. The container
design and handling method were refined through the field trials for the
determination of the optimal design and handling method.
6.7.2
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 ETWB TCW No. 34/2002, 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.
6.7.3
During
transportation and disposal of the dredged marine sediments requiring Type 1
and Type 2 disposal, the following measures should be taken to minimise
potential impacts on water quality:
·
Bottom opening of barges
shall be fitted with tight fitting seals to prevent leakage of material.
·
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.
·
Barges or hopper barges
shall not be filled to a level that would cause the overflow of materials or
sediment laden water during loading or transportation.
Good Site Practices
6.7.4
Adverse
impacts related to waste management are not expected to arise, provided that
good site practices are strictly followed.
Recommendations for good site practices during the construction
activities include:
·
Nomination of an approved
person, 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 waste handling procedures.
·
Provision of sufficient
waste disposal points and regular collection for disposal.
·
Appropriate measures to
minimise windblown litter and dust during transportation of waste by either
covering trucks or by transporting wastes in enclosed containers.
·
Regular cleaning and
maintenance programme for drainage systems, sumps and oil interceptors.
·
A recording system for the
amount of wastes generated, recycled and disposed of (including the disposal
sites).
Waste Reduction Measures
6.7.5
Good
management and control can prevent the generation of a significant amount 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 include:
·
Sort C&D waste from
demolition of the existing waterfront structures to recover recyclable portions
such as metals.
·
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.
·
Encourage collection of
aluminium cans, PET bottles and paper by providing separate labelled bins to
enable these wastes to be segregated from other general refuse generated by the
work force.
·
Any unused chemicals or
those with remaining functional capacity shall be recycled.
·
Use of reusable non-timber
formwork to reduce the amount of C&D material.
·
Proper storage and site
practices to minimise the potential for damage or contamination of construction
materials.
·
Plan and stock construction
materials carefully to minimise amount of waste generated and avoid unnecessary
generation of waste.
6.7.6
In
addition to the above measures, specific mitigation measures are recommended
below for the identified waste arisings to minimise environmental impacts during
handling, transportation and disposal of these wastes.
General Refuse
6.7.7
General
refuse should be stored in enclosed bins or compaction units separate from
C&D material. A licensed waste
collector should be employed by the contractor to remove general refuse from
the site, separately from C&D material. Preferably an enclosed and covered area
should be provided to reduce the occurrence of 'wind blown' light material.
Chemical Wastes
6.7.8
After
use, chemical wastes (for example, 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 collected by a licensed collector for disposal at the CWTF or other licensed
facility, in accordance with the Waste Disposal (Chemical Waste) (General)
Regulation.
Construction and Demolition Material
6.7.9
The
C&D material should be sorted on-site into inert C&D material (that is,
public fill) and C&D waste.
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 the inert C&D material should be re-used on-site in the
reclamation works as far as practicable.
All the suitable (inert) material should be broken down to 250 mm in size for reuse as public fill
and surcharge in the WDII reclamation.
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.
6.7.10
In
order to monitor the disposal of public fill and C&D waste at public
filling facilities and landfills, respectively, and to control fly tipping, a
trip-ticket system should be included as one of the contractual requirements
and implemented by an Environmental Team undertaking the Environmental
Monitoring and Audit work. An
Independent Environmental Checker should be responsible for auditing the
results of the system.
6.7.11
Table 6.6 provides a summary of the various
waste types likely to be generated during the construction phase, together with
the recommended handling and disposal methods.
Table 6.6 Summary
of Waste Handling Procedures and Disposal Routes
|
Waste Type
|
Generated from Works Item
|
Total Quantity Generated
|
Quantity to be disposed off-site / re-used
|
Handling
|
Disposal
|
|
C&D Material
|
Demolition of waterfront structures
|
0.058 Mm3
|
0.055 Mm3 of inert C&D material (public fill) to be
re-used
0.003 Mm3
of C&D waste to landfill
|
Sort on-site into :
·
Inert C&D material (public fill)
·
C&D waste
|
Suitable material broken down to 200mm in size for reuse as public fill and reuse of
removed temporary reclamation in WDII reclamation (approx. 0.085 Mm3 of
inert C&D material, i.e. public fill)
To be disposed to public fill reception facilities for other
beneficial uses
(approx. 0.17 Mm3)
To be disposed to landfill
(approx. 0.003 Mm3)
|
|
Removal of temporary reclamation
|
0.2 Mm3
|
0.03 Mm3 of inert C&D material (public fill) to be
re-used and the remaining 0.17 Mm3 to off-site public fill reception
facilities
|
|
|
Dredged Sediments
|
Causeway Bay Typhoon Shelter
– Category H sediment (>10xLCEL)
|
0.05 Mm3
|
0.05 Mm3
|
Special disposal
arrangement – containment of sediment in geosynthetic containers
|
Type 3 special disposal
– dropping of sealed containers at the designated contaminated mud pit
(approx. 0.05 Mm3)
|
|
Category H and
Category M sediment
|
0.7 Mm3
|
0.7 Mm3
|
Techniques to
minimise resuspension (closed grabs, tight seal on barges, controlled loading
and transfer)
|
Type 2 confined
marine disposal - contaminated mud pit
(approx. 0.7 Mm3)
|
|
Category L
sediment
|
0.4 Mm3
|
0.4 Mm3
|
Type 1 open sea
disposal - gazetted marine disposal ground
(approx. 0.4 Mm3)
|
|
Chemical Wastes
|
Cleansing fluids,
solvent, lubrication oil and fuel from construction plant and equipment
|
Few cubic metres
per month (preliminary estimate)
|
Few cubic metres
per month (preliminary estimate)
|
Recycle on-site
or by licensed companies
Stored on-site
within suitably designed containers
|
Chemical Waste
Treatment Facility or other licensed facility
|
|
General Refuse
|
Waste paper, discarded containers, etc. generated from workforce
|
approx. 65 kg per day (preliminary estimate based on workforce of 100)
|
approx. 65 kg per day
|
Provide on-site refuse collection points
|
Refuse station
for compaction and containerisation and then to landfill
|
6.8.1
With
the implementation of the recommended mitigation measures for the handling,
transportation and disposal of the identified waste arisings, no adverse
residual impact is expected to arise during the construction of the proposed
Project.
6.9.1
Waste
management will be the contractor’s responsibility to ensure that all wastes
produced during the construction of the Project are handled, stored and
disposed of in accordance with good waste management practices and EPD’s
regulations and requirements. The
mitigation measures recommended in Section 6.7 should form the basis of the
site Waste Management Plan to be developed by the Contractor in the
construction stage.
6.10.1
A
review of the sediment quality data from the marine ground investigation
indicated that the majority of marine sediments to be dredged for the WDII and
CWB reclamation were classified as contaminated. The total dredged volume was estimated
as approximately 1.15 Mm3, of which 0.7 Mm3 was classified as contaminated (Category M and
H) requiring Type 2 confined marine disposal, and 0.4 Mm3 was classified as Category L and
would be suitable for Type 1 open sea disposal. With the implementation of the
recommended mitigation measures in accordance with the requirements of ETWB TCW
No. 34/2002, no adverse residual impact was predicted. Since the dredging
activities are marine based activities and negligible dust impacts on nearby
air sensitive receivers would be expected. The findings of the noise impact
assessment in Section 4 of this report indicated that adverse noise impact
would not be expected during the course of the dredging activities.
6.10.2
Based
on the results of the biological screening, approximately 0.05 Mm3 of highly contaminated sediment from the CBTS
would require Type 3 special disposal arrangements. A review of possible disposal
arrangements has recommended the use of a geosynthetic container system with
negligible loss of material to the marine environment during disposal. It is proposed that 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. Field trials
undertaken during the WDII D&C consultancy using uncontaminated mud
established the optimum handling methodology of the proposed special disposal
method.
6.10.3
Wastes
generated by the construction activities will include C&D material
(including excavated material and demolition material), general refuse from the
workforce and chemical waste from the maintenance of construction plant and
equipment. C&D material with
suitable characteristics would be reused on-site as far as practicable
(approximately 0.085 Mm3). Surplus material would require disposal
to designed public filling facilities (approximately 0.17 Mm3). By reducing the quantity of C&D
material requiring off-site disposal, the potential impacts from the
transportation of material by road will be reduced (such as noise impacts,
possible congestion due to increased traffic flows, and dust and exhaust
emissions from the haul vehicles). Provided that these identified waste arisings are handled, transported
and disposed of using approved methods and that recommended good site practice
are strictly followed, adverse environmental impacts of air and odour
emissions, noise, potential hazards, wastewater discharge and transport would
not be expected during the construction phase.
6.10.4 Floating refuse is an existing waste
and the Project itself is not designed to generate floating refuse. Owing to
the project area in close proximity to or within Victoria Harbour,
limited amount of refuse and debris may be unintentionally brought from the
site into the harbour during heavy rains or typhoons. Given that the Project
would not worsen the shoreline configuration and the implementation of
appropriate control measures during construction phase, it is considered that the
future quantity of refuse to be found along the shoreline would be similar if
not better than the existing situation.
6.10.5 With the implementation of the
refuse collection system properly within the project area, no insurmountable
environmental impact with regard to floating refuse would be anticipated during
the construction phase, or after completion of the Project.