5
SOLID WASTE MANAGEMENT
5.1
Introduction
5.1.1
Waste
management will be the contractor’s responsibility to ensure that all wastes
produced during the construction of the WDII are handled, stored and disposed
of in accordance with 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 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
monthly) 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 are summarised below. With the appropriate
handling, storage and removal of waste arisings during the construction of the
WDII as defined below, the potential to cause adverse environmental impacts
will be minimised.
Marine Sediments
5.2.2
The
basic requirements and procedures for dredged mud disposal are specified under
the WBTC No. 3/2000. 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).
5.2.3
The
dredged marine
sediments will be loaded onto barges and transported to designated disposal
sites depending on their level of contaminants.
As discussed in EIA Report, the majority of the marine sediment to be
dredged is Category H (biological test not required). In accordance with the WBTC No. 3/2000, the contaminated material must be dredged and transported with
great care, and the mitigation measures recommended in Sections 4.9.7 and 5.2.5
of this Manual should be strictly followed.
Furthermore, the dredged contaminated sediment must be effectively
isolated from the environment upon final disposal and shall be disposed of at
the East Sha Chau Contaminated Mud Pits that is designated for the disposal of
contaminated mud in Hong Kong.
5.2.4
At
this stage, based on the existing vibrocore sampling results, it is estimated
that some 2,100 m3 of PCB-contaminated sediments may require
pre-treatment or special disposal arrangements.
Pre-treatment by techniques such as bioremediation, dechlorination, soil
washing, solvent extraction and thermal desorption have been examined. Treatability studies would be needed to
confirm the suitability of the pre-treatment process and material sizing and
dewatering may also be required. An
off-site treatment facility would need to be established. For these reasons, especially in view of the
relatively small amount of contaminated sediments involved, and given the
possible consequential implementation implications for the project,
pre-treatment is not considered suitable for the WDII project. It has therefore been agreed with EPD 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.
5.2.5
During
transportation and disposal of the dredged marine sediments, 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. 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 Director of Environmental Protection.
Good Site Practices and Waste Reduction Measures
5.2.6
It
is not anticipated that adverse waste management related impacts would 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 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;
·
separation of chemical
wastes for special handling and appropriate treatment at the Chemical Waste
Treatment Facility (CWTF);
·
regular cleaning and
maintenance programme for drainage systems, sumps and oil interceptors; and
·
a recording system for the
amount of wastes generated, recycled and disposed of (including the disposal
sites).
5.2.7
In
order to monitor the disposal of C&D waste at landfills 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 IC(E) should be responsible for auditing the results of the system.
5.2.8
Good
management and control can prevent the generation of 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:
·
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 labelled bins shall be
provided to segregate this waste 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;
·
prior to disposal of C&D
waste, it is recommended that wood, steel and other metals shall 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 minimise amount of waste generated and avoid unnecessary
generation of waste.
5.2.9
In
addition to the above good site practices and waste reduction measures,
specific mitigation measures are recommended below for the identified waste
arisings to minimise environmental impacts during handling, transportation and
disposal of these wastes. The
transportation of these wastes by barge to the disposal location is
recommended, as far as practicable, in order to reduce potential noise and air
quality impacts from road transportation.
Construction Waste and General Refuse
5.2.10
A
collection area should be provided where wastes 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.
Chemical Wastes
5.2.11
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 stored and collected by an approved operator
for disposal at the CWTF or other licensed facility in accordance with the
Chemical Waste (General) Regulation.
5.2.12
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 shall
only be undertaken within areas appropriately equipped to control these
discharges.
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 excavation and 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. Inert C&D
material should be broken down to 250 mm in size for reuse as public fill 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 shall
be designated to facilitate the sorting process and a temporary stockpiling
area will be required for the separated materials. 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 on Standards for Effluents Discharged into Drainage
and Sewerage Systems, Inland and Coastal Waters (TM-DSS).
5.2.14
Table
5.1 provides a summary of the various waste types likely to be generated during
the reclamation works, together with the recommended handling and disposal
methods. The implementation schedule of
the recommended mitigation measures is presented in Appendix A.
Table 5.1 Summary of Waste Handling
Procedures and Disposal Routes
Waste Type
|
Handling
|
Disposal
|
Construction
and Demolition Material (include excavated material)
|
Sort
on-site into :
·
Inert C&D material (public fill)
·
C&D waste
·
Segregate inert fill material to avoid contamination from other waste
arisings
|
Reuse
on-site for reclamation provided material broken up to 250 mm in size
(approx. 44,000m3)
Off-site
disposal to landfill (approx. 5,800 m3)
Reuse
on-site as far as practicable (approx. 400,000 m3)
Surplus
fill material to be disposed off-site (approx. 170,000 m3)
Surplus
rock fill arising from the temporary breakwater to be disposed off-site
(approx. 100,000 m3)
|
Dredged
Sediments*
|
Contaminated: techniques to minimise resuspension (closed
grabs, tight seal on barges controlled loading and transfer)
|
MFC
contaminated mud pit
(approx.
600,000 m3)
|
|
Uncontaminated: minimise resuspension (closed grabs, tight
seal on barges, controlled loading and transfer)
|
MFC
gazetted marine disposal ground
(approx.
420,000 m3)
|
Chemical
Wastes
|
Recycle
on-site or by licensed companies
Stored
on-site within suitably designed containers
|
Chemical
Waste Treatment Facility
|
General
Refuse
|
Provide on-site
refuse collection facilities
|
Refuse
station for compaction and containerisation and then to landfill
|
Notes:
* Details of handling procedures and
disposal methods for dredged sediment should refer to Sections 4.9.7 and 5.2.5. The need for special disposal procedures for
dredged contaminated sediments from the Causeway Bay Typhoon Shelter will be
examined in detail at the design stage of the Project, as necessary, based on
the sediment testing results of the further ground investigation works.