10.1.1
This section identifies the types of
wastes that are likely to be generated during the construction and operation
phases of the proposed Project and evaluates the potential environmental
impacts that may result from these waste arisings. The main solid waste management implications are related to
construction and demolition material from earthworks for the proposed extension
works at Siu Ho Wan WTW, Siu Ho Wan Raw Water Booster Pumping Station, the
mainlaying works and demolition works for Pui O Raw Water Pumping Station. Mitigation measures and good site practices,
including waste handling, storage and disposal have been recommended with
reference to the applicable waste legislation and guidelines.
10.2.1
The criteria and guidelines for
assessing waste management implications are outlined in Annex 7 and Annex 15
respectively of the Technical Memorandum on Environmental Impact Assessment
Process (EIAO-TM).
10.2.2
The following legislation relates to
the handling, treatment and disposal of wastes in the Governement of the Hong
Kong SAR and was used in assessing potential impacts:
·
Waste
Disposal Ordinance (Cap. 354);
·
Waste
Disposal (Chemical Waste) (General) Regulation (Cap. 354C);
·
Land
(Miscellaneous Provisions) Ordinance (Cap. 28);
·
Public
Health and Municipal Services Ordinance (Cap. 132) - Public Cleansing and
Prevention of Nuisances Regulation.
10.2.3
The Waste Disposal Ordinance (WDO)
prohibits the unauthorised disposal of wastes.
Construction waste is not directly defined in the WDO but is considered
to fall within the category of “trade waste”.
Trade waste is defined as waste from any trade, manufacturer or
business, or any waste building, or civil engineering materials, but does not
include animal waste. Under the WDO,
wastes can be disposed of at sites licensed by the EPD.
10.2.4
The Public Cleansing and Prevention of
Nuisance Regulation provides control on illegal tipping of wastes on
unauthorised (unlicensed) sites.
Construction and Demolition (C&D) Materials
10.2.5
The current policy relating to the
disposal of C&D material()
is documented in the Works Bureau Technical Circular No. 2/93B, ‘Public Filling
Facilities’. 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 are obtained
by individuals or companies who deliver public fill to public filling
areas. The licences are issued by the
Civil Engineering Department (CED) under delegated powers from the Director of
Lands.
10.2.6
In addition to the Works Bureau
Technical Circular (WBTC), EPD and CED have produced a leaflet titled ‘New
Disposal Arrangements for Construction Waste’ (1992) which states that C&D
material with less than 30% by weight of inert material (that is, public fill)
will be accepted at landfill. If the
material contains more than 30% inert material, the waste must be sorted with
suitable material and sent to public filling area and the non-inert material
(that is, C&D waste) sent to landfill for final disposal.
10.2.7
Measures have been introduced under
Environment, Transport and Works Bureau (ETWB) TCW No. 33/2002 to enhance the
management of C&D material including rock, and to minimize its generation
at source. The enhancement measures
include: (i) drawing up a Construction and Demolition Material Management Plan
(C&DMMP) at an early design stage to minimize C&D material generation;
(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 less than 50,000m3 C&D material or importing less
than 50,000m3 fill material are exempt from the C&DMMP. A new technical circular ETWB TCW 15/2003
was recently issued to introduce additional measures to enhance waste
management on construction sites. The circular
sets out the policy and procedures requiring contractors to prepare and
implement an enhanced WMP to encourage on-site sorting of C&D material and
to minimize their generation during the course of construction
Chemical Waste
10.2.8
Under the regulation of WDO, the Waste
Disposal (Chemical Waste) (General) Regulation 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.
10.3.1
The methodology for assessing
potential waste management impacts during the construction and operation phases
of the Project included the following tasks:
·
estimation
of the types and quantities of wastes generated;
·
examination
of opportunities for waste reduction and re-use (both on-site and off-site) and
the required disposal options for each type of waste;
·
assessment
of potential environmental impacts from the management of solid wastes with
respect to potential hazards, air and odour emissions, noise and wastewater
discharges; and
·
identification
of impacts on the capacity of waste collection, transfer and disposal
facilities.
10.3.2
Mitigation measures and good site
practices have been recommended with reference to the applicable waste
legislation and guidelines.
Construction
Phase
10.4.1
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:
· Construction and demolition
(C&D) materials;
· general refuse; and
· chemical waste.
10.4.2
The nature of each type of waste
arising is described in the following section, together with an evaluation of
the potential environmental impacts associated with these waste arisings.
Construction
and Demolition Materials
10.4.3
Construction and demolition (C&D)
material would be generated from excavation works for the extension of Siu Ho
Wan WTW, Siu Ho Wan Raw Water Booster Pumping Station, the laying of raw water
mains along South Lantau Road at Pui O and demolition works for Pui O Raw Water
Pumping Station. The C&D material
from the site at the Siu Ho Wan WTW would comprise general fill material and
rockfill, and the C&D material from the mainlaying works at Pui O would
comprise mostly soil and rock material.
10.4.4
Based on the preliminary design of the
proposed extension works at this investigation stage of the Project, the total
volume of C&D material to be generated from the construction of the Project
was estimated to be approximately 70,692 m3 (Table 10.1
refers). A summary of the estimated
volumes of C&D material is presented in Table 10.1 below.
Table 10.1 Summary of C&D Material Volumes from Excavation Works
|
Works
Location
|
Volume
of C&D Material (m3)
|
Volume
of C&D Material to be re-used (m3)
|
Surplus
C&D Material (m3)
|
|
Extension
works at Siu Ho Wan WTW
|
50,092
|
0
|
50,092
|
|
Construction
of Siu Ho Wan Raw Water Booster Pumping Station
|
7,000
|
0
|
7,000
|
|
Demolition
of Pui O Raw Water Pumping Station
|
4,000
|
0
|
4,000
|
|
Mainlaying
works at Pui O
|
9,600
|
9,600
|
0
|
|
Total
|
70,692
|
9,600
|
61,092
|
Note:
1.
Surplus
C&D material to be disposed to public filling area
10.4.5
It is anticipated that C&D
material generated from the mainlaying works at Pui O would be suitable for
backfilling of the trench. There would
be very limited opportunity for the re-use of excavated material at the Siu Ho
Wan WTW as the works area would be used to construct the various water
treatment units, and therefore the majority of excavated material would require
disposal off-site. Surplus excavated
material would be suitable for disposal to a public filling area. The
potential environmental impacts arising from the handling and disposal of this
inert C&D material, such as air and odour emissions, noise and
potential hazards, would be negligible. The surplus C&D
material would be transported by trucks to the designated barging point for
disposal at the designated public filling area, or transported directly to the
public filling area. Appropriate
measures should be
taken to minimise potential
adverse
impacts from dust during the transportation
of the C&D material.
10.4.6
No waste material would be produced
from the proposed uprating of the Pui O No. 2 Raw Water Pumping Station since
the works would involve installation of equipment only. C&D material generated from the demolition
of the Pui O Raw Water Pumping Station would comprise concrete and would be
suitable for disposal to a public filling area.
General Refuse
10.4.7
Throughout the construction stage, the
workforce would generate general refuse comprising food scraps, waste paper,
empty containers, etc. Release of
general refuse into the nearby streams at Pui O or the drainage channel at Siu
Ho Wan should not be permitted as introduction of these wastes is likely to
have detrimental effects on water quality in the area. Effective collection of site wastes would be
required to prevent waste materials being blown around by wind, flushed or
leached into the aquatic environment, and odour nuisance. The work sites may also attract pests and
vermin if the waste storage area is not well maintained and cleaned regularly. Disposal of refuse at sites other than
approved waste transfer or disposal facilities can also result in similar
impacts.
10.4.8
Appropriate waste management practices
should be implemented at the site so as to prevent any adverse environmental
impacts arising from the storage, handling and transportation of refuse.
Chemical Waste
10.4.9
The maintenance and servicing of
construction plant and equipment may possibly generate some chemical wastes,
for instance, cleaning fluids, solvents, lubrication oil and fuel. Maintenance
of vehicles may also involve the use of a variety of chemicals, oil and
lubricants.
10.4.10
Chemical wastes 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) Regulation. The potential hazards include:
· toxic effects to workers;
· adverse impacts on water quality from spills; and
· fire hazards.
10.4.11
It is difficult to quantify the amount
of chemical waste that will arise from the construction activities since it
would be highly dependent on the Contractor’s on-site maintenance requirements
and the number 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 hundred litres per month. The amount of chemical waste
expected to be generated would be quantified in the site Waste Management Plan
to be prepared by the Contractor.
10.4.12
Materials classified as chemical
wastes would require special handling arrangements before removal for
appropriate treatment at the Chemical Waste Treatment Facility at Tsing
Yi. Wherever possible opportunities should
be taken to reuse and recycle materials. Provided that the handling and
disposal of chemical wastes are in accordance with these requirements, adverse
environmental impacts are not expected to result.
Operation
Phase
10.4.13
Sludge arising from the water
treatment process would be the major waste during the operation of the Project.
The sludge would be dewatered on site and then delivered to landfill (e.g.
WENT) for disposal. The total volume of
dewatered sludge in the year 2003 was advised by WSD to be approximately 204 m3
and relates to an output of about 40MLD.
Taking into account the full capacity of the WTW after extension, WSD
have advised that the total output could be as high as 300MLD, which would
generate a total volume of dewatered sludge of approximately 1500 m3. The same disposal method will be adopted for
the dewatered sludge after the proposed extension.
10.5
Mitigation Measures
Good Site Practices
10.5.1
Appropriate waste handling,
transportation and disposal methods for all waste arisings generated during the
construction works for the Project should be implemented to ensure that
construction wastes do not enter the nearby streams or drainage channel.
10.5.2
It is expected that adverse impacts
from waste management would not arise, provided that good site practices are
strictly followed. Recommendations for
good site practices during construction activities include:
·
nomination
of approved personnel, such as a site manager, to be responsible for good site
practices and making arrangements for collection of all wastes generated at the
site and effective disposal to an appropriate facility;
·
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
Waste Management Plan should be prepared and submitted to the Engineer for
approval. One may make reference to
ETWB TCW No.15/2003 for details, and
·
a recording system for the amount of
wastes generated, recycled and disposed (including the disposal sites) should
be proposed.
10.5.3
In order to monitor the disposal of
C&D material at public filling areas and to control fly tipping, a
trip-ticket system should be included as one of the contractual requirements to
be implemented by an Environmental Team undertaking the Environmental
Monitoring and Audit work. One may make
reference to WBTC No. 21/2002 for details.
Waste Reduction Measures
10.5.4
Good management and control can
prevent the generation of significant amounts of waste. Waste reduction is best achieved at the
planning and design stages, 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;
·
separate
labelled bins shall be provided to segregate aluminium cans from other general
refuse generated by the work force, and to encourage collection of by
individual collectors;
·
any
unused chemicals or those with remaining functional capacity shall be recycled;
·
maximising
the use of reusable steel 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; and
·
plan
and stock construction materials carefully to minimise amount of waste
generated and avoid unnecessary generation of waste.
10.5.5
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.
Construction and Demolition Material
10.5.6
In order to minimise the impact
resulting from collection and transportation of C&D material for off-site
disposal, the excavated soft spoil from open trench excavation at Pui O should
be reused on-site as backfill material as far as practicable. Suitable areas should be designated within the
works site boundaries for temporary stockpiling of C&D material. Within stockpile areas, the following
measures should be taken to control potential environmental impacts or
nuisance:
·
covering
material during heavy rainfall;
·
locating
stockpiles to minimise potential visual impacts; and
·
minimizing
land intake of stockpile areas as far as possible.
Chemical Wastes
10.5.8
If chemical wastes are 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.
Appropriate labels should be securely attached on each chemical waste
container indicating the corresponding chemical characteristics of the chemical
waste, such as explosives, flammable, oxidizing, irritant, toxic, harmful,
corrosive, etc. The Contractor shall
use a licensed collector to transport and dispose of the chemical wastes
generated at the Chemical Waste Treatment Centre at Tsing Yi, or other licenced
facility, in accordance with the Waste Disposal (Chemical Waste) (General)
Regulation. No chemical waste should be
allowed to be stored within the site of the waterworks installations including
the Siu Ho Wan WTW, Pui O Raw Water Pumping Station and Pui O No. 2 Raw Water
Pumping Stations.
All chemical wastes should be removed from the waterworks installations
at the first instance.
General Refuse
10.5.9
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.
10.6.1
With the implementation of the
recommended mitigation measures for the handling, transportation and disposal
of the identified waste arisings, residual impacts would not be expected during
the construction of the proposed Project.
10.7.1
Waste management would 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 recommended
mitigation measures should form the basis of the site Waste Management Plan to
be developed by the Contractor at the construction stage.