7. WASTE MANAGEMENT IMPLICATIONS
7.1 Introduction
7.2 Environmental
Legislations, Policies, Plans, Standards and Criteria
7.3 Assessment Methodology
7.4 Identification
and Evaluation of Environmental Impacts
7.5 Mitigation of Adverse Environmental
Impacts
7.6 Evaluation of Residual Impacts
7.7 Environmental
Monitoring and Audit
7.8 Conclusion
Table 7.1 Summary of Waste Handling Procedures and Disposal Routes
for Construction Phase
Appendix 7-1 ETWB
TCW No. 31/2004 “Trip Ticket System for Disposal of Construction and Demolition
Materials”
7.
WASTE MANAGEMENT IMPLICATIONS
7.1
Introduction
7.1.1.1
This
section identifies the types of wastes that are likely to be generated during the
construction and operation phases of the Project and evaluates the potential
environmental impacts that may result from these waste arisings. The main solid
waste management implications during the construction phase would be
construction and demolition (C&D) material from site formation works for
provision of new facilities and units e.g. sedimentation tanks and UV contact
tanks at the STW. Mitigation measures and good site practices, including waste
handling, storage and disposal are recommended with reference to applicable
waste legislation and guidelines.
7.2
Environmental Legislations, Policies, Plans, Standards and Criteria
7.2.1.1
The criteria and guidelines for
assessing waste management implications are outlined in Annex 7 and Annex 15 of
the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM)
respectively.
7.2.1.2
The following legislations on
handling, treatment and disposal of wastes in the Hong Kong Special
Administrative Region were used to assess the potential impacts:
l
Waste Disposal Ordinance (Cap. 354)
l
Waste Disposal (Chemical Waste)(General) Regulation
(Cap. 354C)
l
Waste Disposal (Charges for Disposal of
Construction Waste) Regulation (Cap. 354N)
l
Land (Miscellaneous Provisions) Ordinance (Cap. 28)
l
Public Health and Municipal Services Ordinance
(Cap. 132) – Public Cleansing and Prevention of Nuisances Regulation
7.2.1.3
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.
7.2.1.4
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 issued a
guideline namely, “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.
7.2.1.5
The Public Cleansing and
Prevention of Nuisances Regulation provide control on illegal tipping of wastes
on unauthorised (unlicensed) sites.
7.2.1.6
The current policy related to
the dumping of C&D material is documented in the Works Branch Technical Circular
No.2/93, Public Dumps’. Construction and demolition materials that are entirely
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 licenses be obtained
by individuals or companies who deliver public fill to public filling areas.
The Civil Engineering and Development Department (CEDD) issues the licenses
under delegated powers from the Director of Lands Department.
7.2.1.7
Under the Waste Disposal
(Charges for Disposal of Construction Waste) Regulation, enacted in January
2005, 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. The Environment, Transport and Works Bureau
(ETWB) TCW No. 31/2004, “Trip Ticket System for Disposal of Construction &
Demolition Materials” provides measures to track the disposal of C&D
materials. Details of the ETWB TCW No.
31/2004 are given in Appendix 7-1.
7.2.1.8
Measures have been introduced
under Environmental, Transport and Works Bureau (ETWB) TCW No.33/2002,
“Management of Construction and Demolition Material Including Rock” to enhance
the management of C&D 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 to reuse inert
material generated including rock, as far as possible; and (ii) 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 including rock less than
50,000m3 or
importing fill material less than 50,000 m3 are exempted from the C&DMMP. The 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. A WMP which forms part of the
Environmental Management Plan (EMP) should be submitted by the contractor prior
to the commencement of construction works. Reference
should also be made to the ETWB TCW No. 31/2004 “Trip Ticket System for
Disposal of Construction and Demolition Materials” as attached in Appendix 7-1.
7.3
Assessment Methodology
7.3.1.1
The methodology for assessing
potential waste management impacts during the construction phase of the Project
included the following tasks:
l
Estimation of the types and quantities of waste
generated;
l
Assessment of potential impacts from the management
of solid waste with respect to potential hazards, air and odour emissions and
wastewater discharges;
l
Identification of disposal options for each type of
waste;
l
Assessment of impacts on the capacity of waste
collection, transfer and disposal facilities.
7.4
Identification and Evaluation
of Environmental Impacts
Construction
Phase
7.4.1.1
The construction activities to
be carried out for the proposed Project would generate a variety of wastes that
can be divided into distinct categories based on their composition and ultimate
method of disposal. The identified waste types include:
l
Construction and Demolition (C&D) materials;
l
General refuse;
l
Chemical waste;
7.4.1.2
During the construction phase,
the sludge handling arrangements would remain the same as far as possible. The
installation of temporary sludge handling arrangements during the construction
period is considered unnecessary at this stage.
7.4.1.3
Each
type of waste arising is described below, together with an evaluation of the
potential environmental impacts associated with generation, handling, storage, transport
and disposal of the waste.
Construction and Demolition Material
7.4.1.4
Construction and demolition
(C&D) material would be generated from excavation works for the provision
of new treatment units and facilities. However, the C&D material should be
re-used on-site as far as possible to minimize the net amount of C&D
material generated from the Project.
7.4.1.5
In accordance with the
preliminary design, the estimated volume of C&D materials is 61,489m3
and most of them are general fill materials (approximately 90 percent of the
total quantity). It is therefore
designed to reuse 14,926m3 of the C&D material on-site for the
site formation works, which makes the excavated material requiring off-site
disposal to the designated public fill reception facility to approximately
46,563m3. A small portion of the
C&D material (approximately 10 percent of the total quantity) would
comprise artificial hard material and rock. The amount of C&D material to
be generated would be quantified in the site Waste Management Plan to be
prepared by the Contractor.
7.4.1.6
The
C&D material should be transported and handled in a manner
that would minimise the disturbance to the environment. Mitigation measures to minimise potential
environmental impacts are recommended in Section 7.5. With the implementation of the recommended
mitigation measures, no unacceptable impacts would be expected from the
transportation and disposal of the C&D material.
General Refuse
7.4.1.7
The construction workforce
would generate refuse comprising food scraps, waste paper, empty containers,
etc. Such refuse should be properly managed so intentional or accidental
release to the surrounding environment does not occur. Disposal of refuse at
sites other than approved waste transfer or disposal facilities shall be
prohibited. Effective collection of site wastes would be required to prevent
waste materials being blown around by wind, flushed or leached into the marine
environment, or creating an odour nuisance or pest and vermin problem. Waste
storage areas should be well maintained and cleaned regularly. With the
implementation of good waste management practices at the site, adverse
environmental impacts are not expected to arise from the storage, handling and
transportation of workforce wastes.
Chemical Waste
7.4.1.8
The maintenance and servicing
of construction plant and equipment may generate chemical wastes such as
cleaning fluids, solvents, lubrication oil and fuel. Maintenance of vehicles
may also involve the use of a variety of chemicals, oil and lubricants. It is
difficult to quantify the amount of chemical waste that will arise from the
construction activities since it will be dependent on the Contractor’s on-site
maintenance requirements and the amount of plant utilised. However, it is
anticipated that the quantity of chemical waste, such as lubricating oil and
solvent produced from plant maintenance, would be small and in the order of a
few cubic meters per month. The amount of chemical waste to be generated will
be quantified in the site Waste Management Plan to be prepared by the
Contractor. For the disposal of chemical wastes, the Contractor would be
required to register with the EPD as a Chemical Waste Producer and to follow
the requirements stated in the Code of Practice on the Packaging, Labelling and
Storage of Chemical Wastes.
7.4.1.9
Chemical
waste arising during the construction phase may pose environmental, health and
safety hazards if not stored and disposed of in an appropriate manner as
stipulated in the Waste Disposal (Chemical Waste) (General) Regulations. The
potential hazards include:
l
Toxic effects to workers;
l
Adverse impacts on water quality from spills;
l
Fire hazards;
7.4.1.10
Materials
classified as chemical wastes will require special handling and storage arrangements
before removal for appropriate treatment at the approved Chemical Waste
Treatment Facility. Wherever possible opportunities should be taken to reuse
and recycle materials. Mitigation and control requirements for chemical wastes
are detailed in Section 7.5. Provided that the handling, storage and disposal
of chemical wastes are in accordance with these requirements, adverse
environmental impacts are not expected.
Operation Phase
Sludge
7.4.1.11
During
the operation phase of the Pillar Point STW, the main waste arising would be
dewatered sludge. The primary sludge arising from the sewage treatment process
is thickened and dewatered in the sludge handling facilities within the Pillar
Point STW. Screenings and grit would also be generated at the inlet works
during the operation phase of the Pillar Point STW. Screenings would be
compacted first. Screenings after compaction and grits would be discharged to
storage containers and trucked to an off site solid disposal facility.
Screenings and grit are currently disposed to the WENT landfill site.
7.4.1.12
Based
on the design capacity of the upgraded STW, the average quantity of dewatered
primary sludge is about 182m3 per day. The estimated total quantity
of screenings and grit from the upgraded STW is 4.6 m3 per day. The dewatered sludge,
screenings and grits would be disposed to
government waste disposal facilities to be agreed by EPD before commissioning
of the upgraded Pillar Point STW.
7.4.1.13
Mitigation
and control requirements to minimize potential odour and water quality impacts
from sludge handling are detailed in Section 7.5. Provided that these
mitigation measures are properly implemented, adverse environmental impacts are
not expected.
Spent UV Disinfection Lamps
7.4.1.14
The type of the UV system to be
used at the UV disinfection facility would be the low pressure high intensity
(LPHI) system. Spent UV lamps, which are classified as chemical
waste, would require disposal during the operation phase of the STW. It is estimated that
the amount of the spent UV lamps to be generated from the UV system would be
about 2,800 no. per year. Currently, spent UV lamps can be disposed to the
Chemical Waste Treatment Centre, which is capable to collect around 9,000 no.
of spent UV lamps at a time or even on a daily basis. The total numbers
of UV lamps that have been disposed are relatively small and generally in small
batches.
7.4.1.15
As the
spent UV lamps are classified as chemical wastes, they would require special
handling and storage arrangements before removal for disposal to the Chemical
Waste Treatment Centre. Mitigation and control requirements for chemical
wastes are detailed in Section 7.5.1.12. Provided that the handling,
storage and disposal of the spent UV lamps are in accordance with these
requirements, adverse environmental impacts would not be expected.
7.5
Mitigation of Adverse Environmental Impacts
Construction Phase
Good Site
Practices
7.5.1.1
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:
l
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
l
Training of site personnel in proper waste
management and chemical handling procedures
l
Provision of sufficient waste disposal points and
regular collection of waste
l
Appropriate measures to minimise windblown litter
and dust during transportation of waste by either covering trucks or by
transporting wastes in enclosed containers
l
Regular cleaning and maintenance programme for
drainage systems, sumps and oil interceptors
l
Separation of chemical wastes for special handling
and appropriate treatment at the Chemical Waste Treatment Facility
Waste
Reduction Measures
7.5.1.2
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:
l
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
l
Encourage collection of aluminium cans by providing
separate labelled bins to enable this waste to be segregated from other general
refuse generated by the workforce
l
Proper storage and site practices to minimise the
potential for damage or contamination of construction materials
l
Plan and stock construction materials carefully to
minimise amount of waste generated and avoid unnecessary generation of waste
7.5.1.3
In
addition to the above measures, specific mitigation measures are recommended
below for the identified waste arising to minimise environmental impacts during
handling, transportation and disposal of these wastes.
General Refuse
7.5.1.4
General refuse should be stored
in enclosed bins or compaction units separate from C&D material. A reputable 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.
Construction and Demolition Material
7.5.1.5
In order to minimise impacts
resulting from collection and transportation of C&D material for off-site
disposal, the excavated material generated from site formation works for the
proposed new facilities and units at the STW should be reused on-site as
backfilling material as far as practicable.
The surplus excavated material should be disposed of at the designated
public fill reception facility, as agreed with the Secretary of the Public Fill
Committee, for other beneficial uses.
7.5.1.6
Mitigation
measures and good site practices should be followed to control potential
environmental impact from handling and transportation of C&D material. The mitigation measures include:
l
Where it is unavoidable to have transient
stockpiles of C&D material pending collection for disposal, the transient
stockpiles shall be located away from waterfront or storm drains as far as
possible.
l
Open stockpiles of construction materials or
construction wastes on-site should be covered with tarpaulin or similar fabric.
l
Skip hoist for material transport should be totally
enclosed by impervious sheeting.
l
Every vehicle should be washed to remove any dusty
materials from its body and wheels before leaving a construction site.
l
The area where vehicle washing takes place and the
section of the road between the washing facilities and the exit point should be
paved with concrete, bituminous materials or hardcores.
l
The load of dusty materials carried by vehicle
leaving a construction site should be covered entirely by clean impervious
sheeting to ensure dust materials do not leak from the vehicle.
l
All dusty materials should be sprayed with water
prior to any loading, unloading or transfer operation so as to maintain the
dusty materials wet.
l
The height from which excavated materials are
dropped should be controlled to a minimum practical height to limit fugitive
dust generation from unloading.
7.5.1.7
When
disposing C&D material at a public filling facility, it shall be
noted that the material shall only consist of earth, building debris and broken
rock and concrete. 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 Filling Supervisor.
In order to monitor the disposal of the surplus C&D material at the
designed public fill reception facility 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 with reference to the ETWB TCW No. 31/2004 “Trip Ticket System
for Disposal of Construction and Demolition Materials” as attached in Appendix 7-1. An Independent Environmental Checker should
be responsible for auditing the results of the system.
Chemical Waste
7.5.1.8
If chemical waste is produced
at the construction site, the Contractor would be required to register with the
EPD as a chemical waste producer and to follow the guidelines stated in the Code
of Practice on the Packaging, Labelling and Storage of Chemical Wastes.
Good quality containers compatible with the chemical wastes should be used, and
incompatible chemicals should be stored separately. Appropriate labels should be securely
attached on each chemical waste container indicating the corresponding chemical
characteristics of the chemical waste, such as explosive, flammable, oxidizing,
irritant, toxic, harmful, corrosive, etc.
The Contractor shall use a licensed collector to transport and dispose
of the chemical wastes, to either the approved Chemical Waste Treatment Centre,
or another licensed facility, in accordance with the Waste Disposal (Chemical
Waste) (General) Regulation.
7.5.1.9
Table 7.1 provides a summary of the various waste types likely to be
generated during the construction activities for the Project, together with the
recommended handling and disposal methods.
Table 7.1 Summary of Waste
Handling Procedures and Disposal Routes for Construction Phase
|
Waste Material Type
|
Generated from works item
|
Total Quantity Generated
|
Quantity to be reused on site
|
Quantity to be disposed off-site
|
Disposal Site
|
Handling
|
|
C&D Material
|
Site
formation works
|
61,489
m3
|
14,926
m3
|
46,563
m3
|
Quantity
of C&D material to be disposed to public fill reception facility for
other beneficial uses: 46,563 m3
|
Segregate
C&D material to avoid contamination from other wastes
|
|
General Refuse
|
Waste
paper, discarded containers, etc. generated from workforce
|
Few
cubic metres per month
(preliminary
estimate)
|
|
Few
cubic metres per month
(preliminary
estimate)
|
Refuse
station for compaction and containerisation and then to landfill
|
Provide
on-site refuse collection points
|
|
Chemical Waste
|
Cleansing
fluids, solvent, lubrication oil and fuel from construction plant and
equipment
|
Few
cubic metres per month
(preliminary
estimate)
|
Not
applicable
|
Few
cubic metres per month
(preliminary
estimate)
|
Chemical
Waste Treatment Centre
|
Recycle
on-site or by licensed companies.
Stored
on-site within suitably designed containers
|
Operational Phase
Sludge
7.5.1.10
The practices of good
housekeeping for PPSTW listed below should
be followed to ameliorate any odour impact from handling, collection,
transportation and disposal of sludge:
·
Screens
should be cleaned regularly to remove any accumulated organic debris
·
Grit
and screening transfer systems should be flushed regularly with water to remove
organic debris and grit
·
Grit
and screened materials should be transferred to closed containers
·
Scum
and grease collection wells and troughs should be emptied and flushed regularly
to prevent putrefaction of accumulated organics
·
Skim
and remove floating solids and grease from primary clarifiers regularly
·
Frequent
sludge withdrawal from tanks is necessary to prevent the production of gases
·
Screened
material should be transferred to closed containers to minimise odour escape
·
Sludge
cake should be transferred to closed containers
·
Sludge
containers should be flushed with water regularly
7.5.1.11
In addition, all wastewater
generated from the sludge dewatering process and all contaminated water from
the cleaning operations recommended for odour control will be diverted to the
PPSTW for proper treatment.
Spent UV
Disinfection Lamps
7.5.1.12
For
the disposal of spent UV lamps, the PPSTW operator would be required to
register with the EPD as a Chemical Waste Producer and to follow the
requirements stated in the Code of Practice on the Packaging, Labelling and
Storage of Chemical Wastes. Good quality containers compatible with the chemical
wastes should be used. Appropriate labels should be securely attached on
each chemical waste container indicating the chemical characteristics of the
chemical waste, such as explosives, flammable, oxidizing, irritant, toxic,
harmful, corrosive, etc. Any specific requirements regarding the disposal
of spent UV lamps would be specified by EPD following the provision of design
information of the UV disinfection system. In handling UV lamps,
caution should be exercised to avoid breakage and contaminant release. A licensed waste collector should be engaged to
transport and dispose of the chemical wastes in accordance with the Waste
Disposal (Chemical Waste) (General) Regulation.
7.6
Evaluation of Residual Impacts
7.6.1.1
With the implementation of the recommended
mitigation measures for the handling, transportation and disposal of the
identified waste arisings, no residual impact is expected to arise during the
construction and operation of the proposed upgrading works.
7.7
Environmental Monitoring and Audit
7.7.1.1
Waste management would be the
contractor’s responsibility to ensure that all wastes produced during the
construction of the upgrading works are handled, stored and disposed of in
accordance with good waste management practices and EPD’s regulations and
requirements. The recommended mitigation
measures should form the basis of the site Waste Management Plan to be
developed by the Contractor in the construction phase.
7.8
Conclusion
7.8.1.1
Waste types generated by the
construction activities are likely to include C&D material (from excavation
works), general refuse from the workforce, and chemical waste from the
maintenance of construction plant and equipment. Wastes generated by the
operational activities would include sludge and spent UV lamps. Provided that
these wastes are handled, transported and disposed of using approved methods
and that the recommended good site practices are strictly followed, adverse
environmental impacts are not expected during the construction and operation
phases.