6.1.1
This section identifies the types of wastes that are likely to be
generated during the construction and operation phases of both the upgrading of
the Cheung Chau STW and Pak She SPS and the sewers works of the Project, and
evaluates the potential environmental impacts that may result from these
wastes.
6.1.2
The primary waste arising will be generated during the construction
phase would mainly be construction and demolition (C&D) materials from the
works. During the operational phase,
general refuse and sewage sludge are expected to be generated from the Cheung
Chau STW and Pak She SPS. Mitigation
measures and good site practices, including waste handling, storage and
disposal, are recommended with reference to the applicable waste legislation
and guidelines.
6.1.3
This assessment has based on the criteria and guidelines stated in
Annexes 7 and 15 of the EIAO-TM for evaluation and assessment of waste
management implications and has covered the scope outlined in Section 3.4.5 of
the EIA Study Brief.
6.2.1
In carrying out this assessment, reference has been made to the
following relevant Hong Kong legislations governing waste management and
disposal:
Ÿ
The Waste Disposal Ordinance (Cap. 354) and
subsidiary legislation such as the Waste Disposal (Chemical Waste) (General)
Regulation and Waste Disposal (Charges for Disposal of Construction Waste)
Regulation that set out requirements for the storage, handling and
transportation of all types of wastes.
Ÿ
Environmental Impact Assessment Ordinance (Cap.
499), Technical Memorandum on Environmental Impact Assessment Process
(EIAO-TM), Annexes 7 and 15;
Ÿ
Public Health and Municipal Services Ordinance
(Cap. 132) – Public Cleansing and Prevention of Nuisance Regulation – control
of disposal of general refuse; and
Ÿ
Land (Miscellaneous Provisions) Ordinance (Cap.
28).
6.2.2
Other relevant documents and guidelines that are applicable to waste
management and disposal in Hong Kong include:
Ÿ
Development Bureau Technical Circular (Works)
(TC(W)) No. 6/2010, Trip Ticket System for Disposal of Construction &
Demolition Materials;
Ÿ
Development Bureau TC(W) No. 8/2010 Enhanced
Specification for Site Cleanliness and Tidiness;
Ÿ
ETWB TC(W) No. 19/2005, Environmental Management
on Construction Sites;
Ÿ
ETWB TC(W) Nos. 22/2003 and 22/2003A, Additional
Measures to Improve Site Cleanliness and Control Mosquito Breeding on
Construction Sites;
Ÿ
ETWB TC(W) No. 33/2002, Management of
Construction and Demolition Material Including Rock;
Ÿ
Works Bureau TC No. 12/2002, Specification
Facilitating the Use of Recycled Aggregates;
Ÿ
Works Bureau TC Nos. 25/99, 25/99A and 25/99C,
Incorporation of Information on Construction and Demolition Material Management
in Public Works Sub-committee Papers; and
Ÿ
Works Bureau TC No. 2/93, Public Dumps.
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. 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
Public Cleansing and Prevention of Nuisance Regulation provides control
on illegal tipping of wastes on unauthorised (unlicensed) sites.
6.2.6
The Land (Miscellaneous Provisions) Ordinance provides control on
dumping of public fill. The inert
portion of construction waste (also called public fill) may be taken to public
fill reception facilities which are operated by the Civil Engineering and
Development Department (CEDD). The Land
(Miscellaneous Provisions) Ordinance requires that dumping licences be obtained
by individuals or companies who deliver public fill to public filling
areas. The CEDD issues the licences
under delegated powers from the Director of Lands.
6.2.7
Under the licence conditions, public fill reception facilities will
only accept inert earth, soil, sand, rock, boulder, rubble, brick, tile,
concrete, asphalt, masonry or used bentonite.
In addition, in accordance with Development Bureau Technical Circular
(Works) (TC(W)) No. 6/2010, the Public Fill Committee will advise on the
acceptance criteria (e.g. no mixing of construction waste, nominal size of the
materials less than 250mm, etc) for disposal of construction and demolition
(C&D) materials at public fill facilities.
Construction and Demolition (C&D)
Material
6.2.8
The current policy related to the disposal of C&D materials is
documented in the Works Branch TC No. 2/93, ‘Public Dumps’. C&D 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.
6.2.9
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 materials.
6.2.10
The ETWB TC(W) No. 19/2005 “Environmental Management on Construction
Sites” includes procedures on waste management requiring contractors to reduce
the C&D materials to be disposed of during the course of construction. The ETWB TC(W) No. 33/2002, “Management of
Construction and Demolition Material Including Rock” to enhance the management
of C&D materials, and to minimize its generation at source, submission of
C&D Material Management Plan (C&DMMP) is not required for less than
50,000 m3 C&D materials from Designated Projects and less than
300,000 m3 from non-Designated Projects. Under ETWB TC(W) No. 19/2005, the contractor
is required to prepare and implement an Environmental Management Plan (EMP) and the Waste Management Plan becomes part of
the EMP.
Chemical Waste
6.2.11
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.
6.3.1
The assessment of potential waste management implications includes the
following tasks:
Ÿ
Estimation of the types and quantities of waste
arising;
Ÿ
Evaluation of potential impacts from the
handling, collection, transportation and disposal of waste; and
Ÿ
Proposal of mitigation measures for the waste
management.
Waste Arisings
6.4.1
The construction activities to be carried out under the Project
include:
Ÿ
trench excavation of pipe laying;
Ÿ
modification works of Pak She SPS (mechanical
and electrical installations);
Ÿ
removal of surface and sub-surface materials
unsuitable as fill;
Ÿ
cutting and installation of new pipelines; and
Ÿ
upgrading of Cheung Chau STW.
6.4.2
These construction activities will generate a variety of wastes which
includes:
Ÿ
C&D materials;
Ÿ
site clearance wastes;
Ÿ
chemical wastes; and
Ÿ
general refuse.
6.4.3
During the construction phase of the upgrading of Cheung Chau STW, the
sludge handling arrangements would remain the same, which is to be disposed of
to Cheung Chau Refuse Transfer Station daily by v-v vehicles. Based on the current design, installation of
temporary sludge handling arrangements is considered unnecessary thus no
temporary waste management implications regarding the sludge handling are
expected.
6.4.4
No special nor hazardous wastes are expected to be generated during the
construction phase of the project.
6.4.5
The nature of each type of waste to be arisen and an evaluation of the
potential environmental impacts associated with generation, handling, storage
and transport of the waste are provided as below.
C&D Materials
6.4.6
C&D materials would be generated from the excavation works for the
sewer construction, modification works of Pak She SPS and upgrading works of
Cheung Chau STW. The total quantity of
C&D materials generated from the works is estimated to be approximately
52,333m3. The quantity of inert C&D materials to be generated
from excavation (soil, rock, sand and concrete) is estimated to be approximately
52,221m3 while the quantity of non-inert C&D materials (C&D
waste) generated is estimated to be approximately 112m3.
6.4.7
To minimize the net amount of inert C&D materials generated from
the Project, the inert C&D materials will be re-used on-site as far as possible. It is estimated that approximately 35,054m3
of inert C&D materials will be reused on-site as backfill materials.
6.4.8
The estimated quantity of inert C&D materials to be disposed of
will be 17,167m3. Final
destinations of the inert C&D materials will be determined to the
availability of public filling facilities and are subject to the agreement with
CEDD.
6.4.9
The volume of C&D materials generated from the modification works
of the Pak She SPS is 278m3.
Thus, it is will not have adverse impacts to landfills and public
filling facilities
6.4.10
The breakdown of the amount of C&D materials are summarized in Table 6.1.
Table 6.1 :
Summary of Estimated C&D Materials Generation
|
Type of Construction
|
Total C&D Materials (m3)
|
Inert C&D Materials (e.g. soil, rock, concrete) (m3)
|
Non-inert C&D Materials (m3)
|
Backfilling Volume (m3)
|
Volume of inert C&D Materials to be Disposed of (m3)
|
|
Sewers
|
13,561
|
13,561
|
0
|
13,431
|
130
|
|
Modification Works of SPS
|
282
|
278
|
4
|
134
|
144
|
|
Upgrading of Cheung Chau STW
|
38,490
|
38,382
|
108
|
21,489
|
16,893
|
|
Total
|
52,333
|
52,221
|
112
|
35,054
|
17,167
|
6.4.11
Provided proper management for C&D materials and adoption of good
site practices are implemented, it is anticipated that the impacts due to
C&D materials arising from the Project would be insignificant.
6.4.12
Inert and non-inert C&D waste materials will be sorted on-site and
disposed of properly. Based on the
current design information, it is planned to use barges to transport the
C&D waste materials from the barging point of Cheung Chau STW to the
designated disposal facilities once per day.
Proper management of C&D materials and good site practice will be
implemented to minimise the potential environmental impacts.
General Refuse
6.4.13
The construction workforce will generate a small amount of general
refuse such as waste papers, plastic packaging and possibly food wastes. Such refuse will be collected on-site on a
regular basis, separately from C&D materials by an appropriate waste
collector to be employed by the contractor.
6.4.14
Prior to disposal off-site, such wastes will have to be temporarily put
in suitably covered storage areas/bins where they will have to be regularly
cleaned and maintained to avoid attracting vermin and pests. With proper on-site handling and storage as
well as regular disposal of the wastes, no adverse impacts are envisaged.
Chemical Waste
6.4.15
The maintenance and servicing of construction plant and vehicles may
generate a small amount of chemical wastes such as waste oil/grease, spent
solvents/detergents, empty fuel/lubricant drums, used oil filters and scrap
batteries. The volume of chemical waste
to be generated is difficult to estimate at this stage. It will depend on the total number of plant
or vehicles to be used on-site and the frequency of maintenance. However, with consideration of the nature of
the project, it is expected that the volume of chemical waste to be generated
would be small. Should proper handling,
storage and disposal of chemicals are implemented, no unacceptable
environmental impacts are anticipated.
6.5
Operational Phase Waste Generation and Potential Impacts
Waste Arisings
6.5.1
During the operational phase of the project, wastes to be generated
include screenings and chemical wastes from the Pak She SPS and Cheung Chau
STW, silts and debris from the maintenance of sewers, general refuse from the
office of the Cheung Chau STW and dewatered sludge.
6.5.2
The screenings from Pak She SPS and Cheung Chau STW, silt and debris
from the maintenance of sewers and general refuse from the STW will be properly
stored in a covered container and disposed of daily to Cheung Chau Refuse
Transfer Station by a reputable waste collector employed by the operators to
reduce the potential pest, odour and litter impacts. The estimated volume of waste to be generated
from screening is about 80m3 per month.
6.5.3
The grits collected from grit chamber of Cheung Chau STW will be stored
in covered containers and disposed to Cheung Chau Refuse Transfer Station. The estimated volume of grits to be generated
is approximately 4.5m3 per month.
6.5.4
The dewatered sludge generated from the sewage treatment process will
be the main stream of waste during the operation of the Cheung Chau STW. According to the design capacity of the
upgraded STW, the average quantity of dewatered sludge is about 100m3
per month.
6.5.5
The maintenance works of Pak She SPS and Cheung Chau STW will generate
a small amount of chemical wastes which will be collected by a license
collector and disposed of properly following standard practices.
6.5.6
Deodourizers will be provided in the upgraded Cheung Chau STW and Pak
She SPS. The chemicals used in the
deodourizers (e.g. granulated activated carbon (GAC)) have to be replaced
regularly to ensure the odour removal efficiency. The handling, storage and disposal of the
used chemicals will follow the Waste Disposal (Chemical Waste) (General)
Regulation.
6.5.7
No special nor hazardous wastes are expected to be generated during the
operation of the project.
6.5.8
Mitigation and control measures to minimise the potential environmental
impacts generated from the waste management is provided in the following
section.
Construction Phase
6.6.1
Adverse impacts from waste management are not expected, provided that
good site practices are strictly followed.
Recommendations for good site practices during the construction
activities include:
Ÿ
The Contractor shall prepare a Waste Management
Plan (WMP) in accordance with the requirements set out in the ETWB TCW No.
19/2005, Waste Management on Construction Site, for the Engineer's
Representative approval. The WMP shall
include monthly and yearly Waste Flow Tables that indicate the amounts of waste
generated, recycled and disposed of (including final disposal site);
Ÿ
The Contractor’s waste management practices and effectiveness
shall be audited by the Engineer's Representative on regular basis;
Ÿ
The Contractor shall provide training for site
staff for the concept of site cleanliness and appropriate waste management
procedures, including waste reduction, reuse and recycling;
Ÿ
Sufficient waste disposal points and regular
collection of waste shall be provided;
Ÿ
Trucks with covering for the open-box bed and
enclosed container shall be used to minimise windblown litter and dust during
transportation of waste;
Ÿ
Regular cleaning and maintenance programme for
drainage systems, pumps and oil interceptors;
Ÿ
Separation of chemical wastes for special
handling and appropriate treatment at a Chemical Waste Treatment Facility
(CWTF);
Ÿ
Encourage collection of aluminium cans, paper
and plastic bottles by providing separate labelled bins to enable these wastes
to be segregated from other general refuse generated by the workforce;
Ÿ
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;
Ÿ
A recording system for the amount of wastes
generated, recycled and disposed (including disposal sites) should be proposed;
and
Ÿ
Plan and stock construction materials carefully
to minimise amount of waste generated and avoid unnecessary generation of
waste.
C&D Materials
6.6.2
With good site management it can reduce the over-ordering of C&D
materials such as concrete and mortars.
Alternatives such as steel frameworks and plastic fencing can be
considered to increase the chances for reuse.
6.6.3
In order to minimise the potential environmental impacts resulting from
collection and transportation of C&D materials for off-site disposal, the
excavated materials comprising fill materials should be reused on-site as backfilling
materials as far as practicable.
6.6.4
C&D waste, such as wood, plastic, steel and other metals should be
reused or recycled and, as a last resort, disposed of to Cheung Chau Refuse
Transfer Station. A suitable area should
be designated within the site for temporary stockpiling of C&D materials
and to facilitate the sorting process.
In order to monitor the disposal of C&D materials at the designated
public fill reception facility and landfill and to control fly-tipping, a trip
ticket system should be included. Reference can be made to Development Bureau
Technical Circular (Works) (TC(W)) No. 6/2010 for details.
6.6.5
The C&D materials to be disposed of at public filling reception
facilities shall be materials only consist of brick, concrete, cement plaster,
soil and inert building debris. The
materials shall be free from plastics, chemical waste, industrial metals and
other materials that are considered unsuitable at the facility.
General Reuse
6.6.6
General refuse should be stored in enclosed bins or compaction units
separate from C&D materials. A
reputable waste collector should be employed by the Contractor to remove
general refuse from the site regularly, separately from C&D materials. An enclosed and covered area is preferred to
reduce the occurrence of ‘wind blown’ light materials. In addition, a
sufficient number of enclosed bins shall be provided on site for containment of
general refuse to prevent visual impacts and nuisance to the sensitive
surrounding.
Chemical Wastes
Sewage
6.6.8
Chemical toilets to be provided on-site shall be regularly cleaned and
the night-soil collected and transported by a licensed contractor to a
Government Sewage Treatment Works facility for disposal.
Operational Phase
6.6.9
The major waste generated during the operational phase will be
screenings, silt and debris, grits and dewatered sludge. The screenings, silt and debris and grits are
considered similar in nature to general refuse and will be disposed of Cheung
Chau Refuse Transfer Station regularly by a reputable waste collector to reduce
pest, odour and litter impacts. As the
project will be commissioned in 2019, it is expected that dewatered sludge will
be disposed of at Sludge Treatment Facilities regularly,
6.6.10
For chemical waste generated during the operational phase, the handling
procedures and disposal method are the same as those presented in Section 6.6.7.
6.6.11
Table
6.2 provides a summary of the various types of waste to be generated
during the construction and operational phases of the Project and the
corresponding handling and disposal methods.
Table 6.2 :
Summary of Waste Handling Procedures and Disposal Routes
|
Waste Type
|
Handling
|
Disposal
|
|
Construction
|
|
C&D Materials
|
Where possible should be reused on-site. If off-site disposal is required,
separate into:
Ÿ Non-inert
C&D waste.
Ÿ Inert
C&D materials.
|
Ÿ Non-inert
C&D waste to strategic landfill.
Ÿ Inert
C&D materials (Public fill) to Public Filling Reception Facilities.
|
|
Chemical Wastes
|
Recycle on-site or by licensed companies. Store on-site
within suitably designed containers.
|
CWTF
|
|
General Refuse
|
Provide on-site refuse collection facilities.
|
Employ a reputable hygiene company for collection and
disposal of general refuse to landfill sites.
|
|
Operation
|
|
Screenings, Silt and Debris from Operation and Maintenance
|
Off-site disposal required
|
Cheung Chau Refuse Transfer Station
|
|
Grits
|
Off-site disposal required
|
Cheung Chau Refuse Transfer Station
|
|
Dewatered Sludge
|
Off-site disposal required
|
Sludge Treatment Facilities
|
|
Chemical Waste
|
Off-site disposal required
|
CWTF
|
6.7
Residual Impacts
6.7.1
Waste management implication has been discussed in this section. By following relevant regulations and statutory
requirements, and with proper implementation of good practice and recommended
mitigation measures as in Section 6.6, no unacceptable residual impacts are
expected to occur during the construction and operation of the Project.
6.8.1
The assessment has concluded that proper handling, storage, collection,
transportation and disposal of waste materials generated during construction
and operation of the Project will not give rise to any significant impacts to nearby
sensitive receivers.
6.8.2
It is recommended that during the construction phase, site inspections
and supervisions of waste management procedures and auditing of the
effectiveness of implemented mitigation measures should be undertaken on a
regular basis (e.g. weekly as a minimum).
These tasks shall be scheduled in the WMP to be prepared by the
Contractor, and a summary of the site audit findings shall be presented in the
EM&A reports.
6.8.3
No EM&A requirement is considered necessary during the operational
phase.
6.9.1
The construction activities associated with the proposed works will
generate a variety of wastes including site clearance waste, C&D materials,
chemical waste and general refuse. With
the implementation of good site practice and recommended mitigation measures,
there would be no adverse environmental impacts.
6.9.2
Major wastes to be generated from the operation of the STW include
screenings, silt and debris, grits and dewatered sludge. Provided proper handling procedures and
disposal method are adopted, no unacceptable environmental impacts are
anticipated.