5 WASTE MANAGEMENT.. 5-1
5.1 Introduction. 5-1
5.2
Waste
Control and Mitigation Measures. 5-1
5.1.1
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 the
recommended good waste management practices and EPD’s regulations and
requirements. The contractor will
be required to ensure that loss of dredged material does not take place during
transportation of the material in barges to the designated marine disposal
ground.
5.1.2
Other waste materials generated during the construction
activities, such as construction and demolition (C&D) materials, chemical
wastes and general refuse from the workforce, are recommended to be audited at
regular intervals (at least quarterly) to ensure that proper storage,
transportation and disposal practices are being implemented. This monitoring of waste management
practices will ensure that these solid and liquid wastes generated during
construction are not disposed of into the surrounding marine waters. The Contractor will be responsible for
the implementation of any mitigation measures to minimise waste or redress
problems arising from the waste materials.
5.2.1
Mitigation measures for waste management of the
Projects are summarised below. Specific mitigation measures for each Schedule 2
Designated Projects are presented in Appendices
D to I. The Implementation Schedule of the recommended
mitigation measures is presented in Appendix A. With the
appropriate handling, storage and removal of waste arisings during the
construction of the Project as defined below, the potential to cause adverse
environmental impacts will be minimised. In order to ensure
that the mitigation measures are properly implemented by the Contractor, regular site inspections by the ET shall be
carried out at least once per week. Details of the audit
requirements are set out in Section 9 of this EM&A Manual.
Dredged Marine
Sediments
5.2.2
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).
5.2.3
The dredged marine sediments would be loaded onto
barges and transported to and disposed of at the designated disposal sites at
South of Cheung Chau, Eat of Ninepin, East of Tung Lung Chau, South of Tsing Yi
and East of Sha Chau to be allocated by the Marine Fill Committee depending on
their level of contamination 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 6 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 Marine Fill Committee about the disposal requirement. The final disposal site will be determined
by the Marine Fill Committee and a dumping licence will be obtained from EPD
prior to the commencement of the dredging works.
5.2.4
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.
5.2.5
The ACE Report() [to be endorsed by
ACE] 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.
5.2.6
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.
5.2.7
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
5.2.8
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
5.2.9
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, such as in
casting the tunnel box sections, 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.
5.2.10 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
5.2.11 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
5.2.12 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
5.2.13 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 excavation for the tunnel construction 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. The quantities of C&D materials
generated is estimated to be approximately 2.915Mm3
and around 1.17Mm3
will be reused on-site and the remaining surplus of around 1.745Mm3 will be disposed
off-site.
5.2.14 In order to monitor
the disposal of public fill and C&D waste at public fill reception
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.
5.2.15 Bentonite slurries
used in diaphragm wall and bore-pile construction should be reconditioned and
reused wherever practicable. The
disposal of residual used bentonite slurry should follow the good practice
guidelines stated in ProPECC PN 1/94 “Construction Site Drainage” and listed as
follows:
·
If the disposal of a certain residual quantity cannot
be avoided, the used slurry may be disposed of at the marine spoil grounds
subject to obtaining a marine dumping licence from EPD on a case-by-case basis.
·
If the used bentonite slurry is intended to be
disposed of through the public drainage system, it should be treated to the
respective effluent standards applicable to foul sewers, storm drains or the
receiving waters as set out in the Technical
Memorandum of Standards for Effluents Discharged into Drainage and Sewerage Systems,
Inland and Coastal Waters.
·
If the used bentonite slurry is intended to be
disposed to public fill reception facilities, it will be mixed with dry soil on
site before disposal.