6
Waste
Management
This section identifies and assesses the
potential environmental impacts associated with waste management aspects of the
construction and operation of the Designated and Potentially Designated
Elements of the Project.
6.2
Relevant Legislation and Guidelines
The criteria and guidelines for evaluating
potential waste management implications are laid out in Annexes 7 and 15 of the EIAO TM under the EIAO (Cap 499).
The
following legislation covers, or has some bearing upon, the handling, treatment
and disposal of wastes in the Hong Kong Special Administrative Region (HK SAR),
and will also be considered in the assessment.
· Waste Disposal Ordinance (Cap 354);
· Waste Disposal (Chemical Waste) (General) Regulation (Cap 354);
· Land (Miscellaneous Provisions) Ordinance (Cap 28);
· Public Health and Municipal Services Ordinance (Cap 132) - Public
Cleansing and Prevention of Nuisances (Urban Council) and (Regional Council)
By-laws.
Waste Disposal
Ordinance (Cap 354)
The Waste
Disposal Ordinance (WDO)
prohibits the unauthorised disposal of wastes, with waste defined as any
substance or article which is abandoned.
Construction and demolition (C&D) 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 wasted building, or civil engineering materials, but does
not include animal waste.
Under the WDO,
wastes can only be disposed of at a licensed site. A breach of these regulations can lead to the imposition of
a fine and/or a prison sentence.
The WDO also provides for the
issuing of licences for the collection and transport of wastes. Licences are not, however, currently
issued for the collection and transport of C&D waste or trade waste.
Waste Disposal
(Chemical Waste) (General) Regulation
Chemical waste as defined under the Waste Disposal (Chemical Waste) (General)
Regulation includes any substance being scrap material, or unwanted
substances specified under Schedule 1
of the Regulation, if such a
substance or chemical occurs in such a form, quantity or concentration so as to
cause pollution or constitute a danger to health or risk of pollution to the
environment.
A person should not produce, or cause to be
produced, chemical wastes unless he is registered with the EPD. Any person who contravenes this
requirement commits an offence and is liable to fine and imprisonment.
Producers of chemical wastes must treat their
wastes, utilising on-site plant licensed by the EPD or have a licensed
collector take the wastes to a licensed facility. For each consignment of wastes, the waste producer,
collector and disposer of the wastes must sign all relevant parts of a
computerised trip ticket. The
system is designed to allow the transfer of wastes to be traced from
cradle-to-grave.
The Regulation
prescribes the storage facilities to be provided on site including labelling
and warning signs. To minimise the
risks of pollution and danger to human health or life, the waste producer is
required to prepare and make available written procedures to be observed in the
case of emergencies due to spillage, leakage or accidents arising from the
storage of chemical wastes. He/she
must also provide employees with training in such procedures.
Land (Miscellaneous
Provisions) Ordinance (Cap 28)
The inert portion of construction and
demolition materials (C&DM)([1]) (also called public fill) may be
taken to public filling facilities.
Public filling facilities usually form part of land reclamation schemes
and are operated by the Civil Engineering Department (CED) and Territory
Development Department (TDD). The Land (Miscellaneous Provisions) Ordinance requires
that Dumping Licences are obtained by individuals or companies who deliver
public fill to the public filling facilities. The licences are issued by the CED under delegated authority
from the Director of Lands.
Individual licences and windscreen stickers are
issued for each vehicle involved.
Under the licence conditions public filling facilities will accept only
inert building debris, soil, rock and broken concrete. There is no size limitation on the rock
and broken concrete, and a small amount of timber mixed with inert material is
permissible. The material should,
however, be free from marine mud, household refuse, plastic, metal, industrial
and chemical wastes, animal and vegetable matters and any other materials
considered unsuitable by the Filling Supervisor.
Public Cleansing and
Prevention of Nuisances by-Laws
These by-laws provide a further control on the
illegal tipping of wastes on unauthorised (unlicensed) sites. The illegal dumping of wastes can lead
to a fine and imprisonment.
Other Relevant
Guidelines
Other 'guideline' documents which detail how
the Contractor should comply with the regulations are as follows:
Waste Disposal Plan
for Hong Kong
(December 1989), Planning, Environment and Lands Branch Government Secretariat;
Environmental
Guidelines for Planning In Hong Kong (1990), Hong Kong Planning and Standards
Guidelines, Hong Kong Government;
New Disposal
Arrangements for Construction Waste (1992), Environmental Protection Department
& Civil Engineering Department;
Code of Practice on
the Packaging, Labelling and Storage of Chemical Wastes (1992), Environmental Protection
Department;
Works Branch Technical
Circular, 32/92, The Use of Tropical Hard Wood on Construction Site; Works Branch, Hong Kong
Government;
Works Branch Technical
Circular Nos. 2/93, 2/93B, Public Dumps, Works Branch, Hong Kong Government;
Works Branch Technical
Circular No. 16/96, Wet Soil in Public Dumps; Works Branch, Hong Kong Government;
Works Bureau Technical
Circular Nos. 4/98, 4/98A, Use of
Public Fill in Reclamation and Earth Filling Projects; Works Bureau, HK SAR Government;
Works Bureau Technical
Circular No 5/98, On-site Sorting of Construction Waste on Demolition Site; Works Bureau, HK SAR Government;
Waste Reduction
Framework Plan, 1998 to 2007, Planning, Environment and Lands Bureau, Government Secretariat, 5
November 1998;
Works Bureau Technical
Circular Nos. 5/99, 5/99A Trip-ticket System for Disposal of Construction and
Demolition Material;
Works Bureau, HK SAR Government;
Works Bureau Technical
Circular No 19/99,Metallic Site Hoardings and Signboards; Works Bureau, HK SAR Government;
Work Bureau Technical
Circular Nos. 25/99, 25/99A, 25/99C Incorporation of Information on
Construction and Demolition Material Management in Public Works Sub-committee
Papers; Works
Bureau, HK SAR Government;
Works Bureau Technical
Circular No. 12/2000, Fill Management; Works Bureau, HK SAR Government;
Works Bureau Technical Circular No 29/2000, Waste Management Plan. Works Bureau, Hong Kong SAR
Government; and
Works Bureau Technical Circular No 31/2000, Specification Allowing the
Use of Recycled Inert Construction and Demolition Material. Works Bureau, Hong Kong SAR
Government.
Landfill Disposal
Criteria for Contaminated Soil
Excavated contaminated soil has to meet certain
criteria before disposal to landfills is allowed. The criteria presented in the EPD’s Guidance Notes for Investigation and Remediation of Contaminated Sites
of: Petrol Filling Stations; Boatyards; and Car Repair/Dismantling Workshops
issued by the EPD are set primarily in terms of Toxic Characteristic Leaching
Procedure (TCLP) limits, as shown in Table
6.2a.
Table 6.2a Landfill
Disposal Criteria for Contaminated Soil
|
Parameter (a) |
TCLP Limits (ppm) |
|
Cadmium (Cd) |
10 |
|
Chromium (Cr) |
50 |
|
Copper (Cu) |
250 |
|
Nickel (Ni) |
250 |
|
Lead (Pb) |
50 |
|
Zinc (Zn) |
250 |
|
Mercury (Hg) |
1 |
|
Tin (Sn) |
250 |
|
Silver (Ag) |
50 |
|
Antimony (Sb) |
150 |
|
Arsenic (As) |
50 |
|
Beryllium (Be) |
10 |
|
Thallium (Tl) |
50 |
|
Vanadium (V) |
250 |
|
Selenium (Se) |
1 |
|
Barium (Ba) |
1,000 |
|
Note: (a) In accordance with USEPA Method 1311 |
|
The potential environmental impacts associated
with the handling and disposal of waste arising from the construction and
operation of sewers, rising mains and pumping stations was assessed in
accordance with the criteria presented in Annexes
7 and 15 of the EIAO-TM, which are summarised as
follows:
· estimation of the types, timing and
quantities of the wastes to be generated;
· assessment of the secondary
environmental impacts due to the management of waste with respect to potential
hazards, air and odour emissions, noise, wastewater discharges and traffic; and
· assessment of the potential impacts
on the capacity of waste collection, transfer and disposal facilities.
6.4
Identification of Environmental
Impacts
Construction Phase
During the construction phase, the main
activities which will potentially result in waste generation involve site
clearance, and construction of the sewers and pumping stations.
The typical waste types associated with these
activities include:
· site clearance waste;
· excavated materials;
· C&DM;
· chemical wastes;
· sewage; and
· general refuse.
6.4.1
Site
Clearance Waste
Most of
the sewers/rising mains will be laid under existing roads/pavement and hence
minimal site clearance waste is expected.
The construction of the pumping stations may involve clearance of
vegetation depending on the proposed location. If not properly managed, the handling and disposal of the
clearance waste may cause adverse environmental impacts.
6.4.2
Construction
and Demolition Materials (C&DM)
Excavated Materials
As most of the sewers/rising mains will be laid
under existing roads/pavement, excavated materials will be generated from
excavation of the pipe trenches and site formation activities for the proposed
pumping stations. These materials
are expected to be mostly soil plus concrete/tarmac which are inert. The anticipated quantities of excavated
materials and backfilling materials are presented in Table 6.4a. As the
Designated and Potentially Designated Elements and the Non-Designated Elements
are differentiated by virtue of their classification under the EIAO and not by the works packages, the
estimated quantities also include the excavated materials from the
Non-Designated Elements which will be constructed in the same period.
Table 6.4a Estimated
Quantities of Excavated Materials to be Generated from Laying of Sewers and
Construction of Pumping Stations
|
Package |
Excavation Volume (m3) |
Backfilling Volume (m3)
|
Balance (m3) |
|
1A-1T (sewers/rising mains) |
115,950 |
84,630 |
31,320 |
|
1B-1T (sewers/rising mains) |
51,430 |
41,780 |
9,650 |
|
Pumping Stations |
26,415 |
17,562 |
8,853 |
|
Total |
193,795 |
143,972 |
49,823 |
The proposed sewers across the Yuen Long and
Kam Tin MDC will be laid by the trenchless pipe jacking method. Jacking pits and receiving pits will
need to be constructed in the vicinity of the river embankments and the
existing river embankment will
need to be demolished, removed and subsequently reinstated. It should be noted that one of the
risks inherent to the trenchless
pipe jacking method is that the lead shield may breakdown before it reaches the
receiving pit. In such an event, a
rescue pit will be sunk to remove the studded shield and therefore some dredging
works over the MDC may be required.
The proposed sewer/rising mains will also cross the MDC at three
places. In order to avoid dredging
and excavation of river sediment, it is proposed to use the trenchless pipe
jacking method to lay the twin rising mains. The mains will be laid at 1 to 2 m below the bottom of the
MDC. It is estimated that
approximately 2,900 m3 of inert materials will need to be
excavated, of which about 2,000 m3 (about 69%) could be used for
backfilling the launch and reception shafts. Approximately 900 m3 of surplus excavated materials will
need to be disposed of off-site.
In the event that the lead shield of the
tunnelling machine is broken before it completes the whole length, a rescue pit
will be sunk to remove it and therefore some dredging works over the river will
be required. It is estimated that
about 50m3 of river sediment will be required to be
excavated for the construction of the rescue pit. Some of these sediments will be used for backfilling of the
rescue pit.
C&DM from
Construction of Pumping Stations
The construction of the proposed pumping
stations will generate C&DM which includes packaging wastes, excess or
damaged materials, hoarding etc.
The proposed pumping stations will typically consist of a superstructure
and a substructure. Most of
the E&M equipment will be housed within the superstructure. The best means to estimate the
generation rate of C&DM will be to base the estimate on the floor
area. The typical floor areas of
the proposed pumping stations are shown in Table
6.4b.
Table 6.4b Typical
Floor Areas of Proposed Pumping Stations
|
Pumping Stations |
Dimensions |
|
Ng Ka Tsuen PS (P5) Sha Po PS (P2) Kam Tin PS (P1) |
~ 50 m x 35 m ~ Floor Area = 1,750 m2
each |
|
Pang Ka Tsuen PS (P6) Shui Tsan Tin PS (P4) Leung Uk Tsuen PS (P7) |
~ 27m x 23m ~ Floor Area = 620 m2 each |
|
Nam Sang Wai PS (P3) |
~ 50 m x 40 m ~ Floor Area = 2,000 m2 |
6.4.3
Chemical
Waste
Chemical waste, as defined under the Waste Disposal (Chemical Waste) (General)
Regulation, includes any substance being scrap material, or unwanted
substances specified under Schedule 1
of the Regulation. A complete list of such substances is
provided under the Regulation, however
substances likely to be generated from the construction activities for the
sewers construction will, for the most part, arise from the maintenance of
equipment. These may include, but
need not be limited to the following:
· scrap batteries or spent acid /
alkali from their maintenance;
· used paint, engine oils, hydraulic
fluids and waste fuel;
· spent mineral oils / cleaning fluids
from mechanical machinery; and
· spent solvents / solutions, some of
which may be halogenated, from equipment cleaning activities.
Chemical wastes may pose serious environmental,
health and safety hazards if not stored and disposed of in an appropriate
manner as outlined in the Waste Disposal
(Chemical Waste) (General) Regulation and the Code of Practice on the Packaging, Labelling and Storage of Chemical
Wastes. These hazards may
include:
·
toxic effect to
workers;
·
adverse effect on
air, water and land from spills; and
·
fire hazards.
6.4.4
Sewage
Sewage
will arise from the construction workforce, site office’s sanitary facilities and
night soil from chemical toilets.
If not properly managed, these materials could cause odour and potential
health risks to the workforce by attracting pests and other disease vectors.
6.4.5
General
Refuse
The presence of a construction site with
workers and site office will result in the generation of a variety of general
refuse requiring disposal. General
refuse will mainly consist of food waste, aluminium cans and waste paper.
The storage of general refuse has the potential
to give rise to adverse environmental impacts. These include odour if the waste is not collected frequently
(for example, daily), windblown litter, water quality impacts if waste enters
water bodies, and visual impact.
The sites may also attract pests, vermin, and other disease vectors if
the waste storage areas are not well maintained and cleaned regularly. In addition, disposal of wastes at
sites other than approved landfills, can also lead to similar adverse impacts
at those sites.
Operation Phase
6.4.6
Waste
from Operation of Pumping Stations
During the operation phase, the main waste types will include
screenings and chemical waste generated from the operation of the pumping
stations and the silt and debris from the maintenance of the sewers. If not properly managed, these could
have the potential to cause adverse environmental impacts. These include odour if the waste is not
collected frequently and water quality impacts if waste enters water bodies. Based on records from existing pumping
stations[2], it is estimated that the screenings
which will arise at the seven proposed pumping stations will amount to
approximately 46m3 per month.
6.5
Evaluation of Impacts
Construction Phase
6.5.1
Site
Clearance Waste
As most
of the proposed pumping stations are located on developed land, the quantity of
vegetation that needs to be cleared will be minimal. Vegetation cleared from proposed pumping station sites can
be disposed of as general refuse.
No adverse environmental impacts from the disposal of site clearance
waste is expected.
6.5.2
C&DM
Excavated Materials
As indicated in Table 6.4a, some of the excavated materials could be used
for backfilling the trenches. The quantities of excavated materials
which would need to be disposed of are shown in Table 6.5a. It is expected
that the majority of excavated material will be inert soil.
Table 6.5a Disposal
of Excavated Materials
|
Package |
Excavation Volume (m3) |
Backfilling Volume (m3) |
Volume to be Disposed (m3) |
Construction Period |
Disposal Rate (Average/ Peak(a))
(m3day-1) |
|
1A-1T (b) |
115,950 |
84,630 |
31,320 |
08/03 - 02/06 (~912 days) |
34/52 |
|
|
|
|
|
|
|
|
1B-1T (b) |
51,430 |
41,780 |
9,650 |
06/04 - 11/06 (~912 days) |
11/16 |
|
|
|
|
|
|
|
|
1A-2T(c) |
12,970 |
8,700 |
4,200 |
08/04 - 02/08 (~1008 days) |
4.2/6.3 |
|
P/Ss (d) |
26,415 |
17,562 |
8,853 |
08/03 - 01/06 (~312 days) |
24 /36 |
|
Pipe jacking under MDC |
2,900 |
2,000 |
900 |
08/03 - 02/06 (~912 days) |
1/1.5 |
|
|
|
|
|
|
|
|
Total |
209,665 |
154,672 |
54,923 |
|
74.2/111.8 |
|
Notes: (a) Assume a peak generation rate of 1.5 (b) Include Non-Designated Elements (c) From
Non-Designated Elements (d) Assume the materials will be excavated in
the first 12 months of construction. |
|||||
It is estimated that approximately 210,000 m3 of
materials will be excavated. Due
consideration was taken to reuse as much excavated material as possible
(approximately 155,000 m3 (about 74%) of the excavated materials
will be reused within the Project). The volume of excavated materials which needs to be disposed
of is approximately 55,000 m3.
The average and peak disposal rates for excavated materials are
approximately 75 m3 day-1 and 112 m3 day-1,
respectively. Due to the
relatively small volume of excavated materials which require disposal, it is
not envisaged that this will have adverse impacts on the capacity of the
available public filling facilities.
The final destinations of the excavated materials will be determined,
subject to the availability of public filling facilities, by the Waste
Management Plan to be submitted by the Contractors and agreed with the
Engineer.
A TIA has been conducted for this Project and
the report indicated that the construction traffic generated by this project (including
the traffic associated with the off-site disposal of the surplus excavated
material) is insignificant and will not cause adverse traffic impacts, provided
that the recommended temporary traffic measures are implemented.
As the proposed sewers/rising mains alignments
pass close to potentially contaminated sites in some areas (eg car
repair/dismantling works), there is the possibility that the excavated
materials will be contaminated. Section 7 addresses the land
contamination issues. The disposal
of contaminated materials, if any, needs to comply with the Landfill Disposal Criteria for Contaminated
Soil (see Table 6.2a).
The actual quantities of contaminated soil can
only be estimated after conducting intrusive site investigation works after
land resumption and hence cannot be estimated at this stage. It is estimated that under the worse
case scenario (ie assuming all the excavated materials from the trenches
adjacent to potentially contaminated sites are found to be contaminated), the
amount of contaminated soil to be treated and disposed of will be in the order
of 14,000m3. However,
it should be noted that this is a very conservative estimate. As discussed in Section 7, the potential for off-site
migration of contaminants to the excavation area will be minimal. It is expected that the actual quantity
of contaminated soil, if any, to be excavated will be much less than that
estimated under the worst case scenario.
If contaminated soils are found, their management will be addressed in
the Remedial Action Plan, to be approved by the EPD. A simplified procedure is shown in Figure 6.5a for reference.
Excavated river sediment (less than 50 m3)
will be generated in the event that a rescue pit is required during pipe
jacking across the MDC. In view
of the small quantities of surplus excavated sediment, it is envisaged that it
will be more cost effective to dispose of these sediments to landfill. The sediment should be dewatered
and the disposal of the sediment should also comply with the Landfill Disposal Criteria for Contaminated
Soil (see Table 6.2a). The final
disposal arrangement should be agreed in advance with EPD (for landfill
disposal) via the Waste Management Plan to be submitted by the Contractor.
Figure 6.5a Simplified Procedure for Disposal of
Contaminated Materials at Landfills
If excavated soil contains other contaminants
in addition to the parameters in Table
6.2a, approval for disposal will be assessed on a case-by-case basis by the
EPD. Apart from landfill, another possible
disposal outlet is the Chemical Waste Treatment Centre (CWTC) if volume is
small and the concentration of contaminants is so high that the soil can be
classified as chemical waste.
C&DM from
Construction of Pumping Stations
As indicated in Section 6.4, the best means to estimate the generation of C&DM
is based on the floor area. Table 6.4b indicates that the total
floor area to be constructed is approximately 9,110m2. Based on a C&DM generation of 0.1 m3
per 1 m2 of gross floor area (GFA) constructed[3], it is estimated that approximately
911m3 of C&DM will be
generated from the construction of the pumping
stations over a period of 17 months between August 2003 to January 2006. This represents the average and peak
C&DM generation of 2.2 m3day-1 and 3.3 m3day-1,
respectively. With proper
segregation, the volume of C&DM that could be reused as public fill is
approximately 730 m3 and the
volume to be disposed of to landfills (C&D
waste) is approximately 181m3. The average
and peak generation of C&D waste which
requires disposal at landfill is approximately 0.44 m3day-1
and 0.66 m3day-1, respectively The public fills will be transported to public
filling areas at average and peak
rates of 1.8 m3day-1 and 2.7 m3day-1,
respectively.
The generation of C&DM is considered to be
small and is not envisaged to have an adverse impact on the capacity of
landfills and public filling areas.
6.5.3
Chemical
Waste
It is difficult to quantify the amount of
chemical waste which will arise from the construction activities as it will be
highly dependent on the Contractor's on-site maintenance intention and the
quantities of plant and vehicles utilised. However, it is anticipated that the quantity of chemical waste,
such as lubricating oil and solvent produced from plant maintenance will be
small and in the order of a few hundred litres per month. The chemical waste to
be generated from the construction activities will be readily accepted at the
Chemical Waste Treatment Centre (CWTC) at Tsing Yi.
Storage, handling, transport and disposal of
chemical waste should be arranged in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical
Waste published by the EPD.
Provided that this occurs, the potential environmental impacts arising
from the handling, storage and disposal of a small amount of chemical waste
generated from the construction activities will be negligible.
6.5.4
Sewage
The
number of construction workers to be employed on site is not available at this stage,
however, is expected to be small.
As the workers will be scattered along the proposed sewers/rising mains
alignment, the more cost-effective solution will be to provide adequate number
of portable toilets along the alignment to ensure that domestic sewage from
site staff is properly collected.
Depending on site conditions, land availability and site activities, the
locations and number of portable toilets will be determined in the Waste
Management Plan to be submitted by the Contractors and agreed by EPD. No adverse waste impacts is envisaged
provided that maintenance by licensed contractors is conducted regularly.
6.5.5
General
Refuse
The number of workers to be employed for the
project is not available at this stage, however, it is expected to be small. Provided that the mitigation measures
recommended in Section 6.6 are
adopted, the environmental impacts caused by the storage, handling, transport
and disposal of general refuse are expected to be minimal. It is recommended that the general
refuse should be collected on a daily basis and be delivered to the WENT or
NENT Landfill for disposal. With
respect to the anticipated small quantity of general refuse to be disposed of,
adverse impacts to the operation of the landfills are not expected.
Operation Phase
6.5.6
Waste
from the Operation of the Pumping Stations
The screenings and silt, from the operation and
maintenance of the proposed pumping stations and sewers/rising mains will be
disposed of at the WENT or NENT landfill.
The relatively small quantity of these wastes (at total of 46m3
per month of screenings from seven proposed pumping stations) will have minimal
impact on the operation of the landfills.
Small quantities of chemical wastes (mainly
lubricant oil and paint) to be generated from the maintenance of the pumping
stations could be readily accepted at the CWTC. Provided that this occurs, the
potential environmental impacts arising from the handling, storage and disposal
of a small amount of chemical waste generated from the construction activities
will be negligible.
6.5.7
Summary
Table 6.5b summarise impacts during the
construction and operation of the Project.
Table 6.5b Summary of Waste Management Impacts
|
Waste Type |
General Evaluation |
|
Construction Phase |
|
|
Site Clearance Waste |
Vegetation cleared from proposed pumping station sites can be
disposed of as general refuse.
As most of the proposed pumping stations are located on developed
land, the amount of site clearance waste will be minimal. |
|
C&DM |
Excavated Materials It is estimated that approximately 210,000 m3 of excavated materials will be generated from the construction of the Project of which approximately 155,000 m3 (about 74%) will be reused on site. The volume of excavated materials to be disposed off-site will be approximately 55,000 m3. The average and peak disposal rate of excavated materials are 75 m3 day-1 and 112 m3 day-1, respectively. Due to the relatively small volume of excavated materials which requires disposal, it is not envisaged that this will have adverse impacts on the capacity of the public filling facilities. The final destinations of the excavated materials will be determined, subject to availability of public filling facilities, by the Waste Management Plan to be submitted by the Contractors and agreed with the Engineer. A Traffic Impact Assessment has been conducted for this Project and
the concluded that the construction traffic generating from this project (including the traffic associated
with the off-site disposal of the surplus excavated material) will not cause
adverse traffic impact provide that the temporary traffic measures as
recommended are properly implemented. The actual quantities of contaminated soil can only be estimated
after conducting the intrusive site investigation after land resumption. A rough estimation of worst case
scenario will be in the order of
14,000m3. However, it
should be noted that this is a very conservative assumption. If contaminated soils are
found, their management will be addressed in the Remedial Action Plan. |
|
|
C&DM from Construction
of Pumping Stations Based on a C&DM generation of 0.1 m3 per 1 m2
of GFA constructed, it is estimated that approximately 911m3 of
C&DM will be generated from the construction of the pumping stations over
a 17 months period between
August 2003 to January 2006.
This represents the average and peak C&DM generation of 2.2 m3day-1
and 3.3 m3day-1, respectively. With proper segregation, average and
peak generation of C&D waste which requires disposal at landfill is
approximately 0.44 m3day-1 and 0.66 m3day-1,
respectively The public fills
will be transported to the public filling areas at average and peak rate of
1.8 m3day-1 and 2.7 m3day-1,
respectively. With respect to the small quantity of C&DM to be generated from
the Project, it is not envisaged that the disposal of which to landfill and
public filling areas will affect the operations of these facilities. |
|
Chemical Waste |
It is difficult to quantify the amount of chemical waste which will
arise from the construction activities as it will be highly dependent on the
Contractor's on-site maintenance intention and the number of plant and
vehicles utilised. However, it
is anticipated that the quantity of chemical waste produced will be small and
in the order to a few hundred litres per month. The chemical waste to be
generated from the construction activities will be readily accepted at the
Chemical Waste Treatment Centre (CWTC) at Tsing Yi. Storage, handling, transport and disposal of chemical waste should be
arranged in accordance with the Code of
Practice on the Packaging, Labelling and Storage of Chemical Waste published
by the EPD. Provided that this
occurs, the potential environmental impacts arising from the handling,
storage and disposal of a small amount of chemical waste generated from the
construction activities will be negligible. |
|
Sewage |
The number of construction workers to be employed on site is not available
at this stage, however, is expected to be small. As the workers will be scattered along the proposed
sewers/rising mains alignment, the most cost-effective solution will be to
provide adequate number of portable toilets along the alignment. No adverse waste impacts is envisaged
provided that maintenance by licensed contractors is conducted regularly. |
|
General Refuse |
The number of workers to be employed for the project is not available
at this stage, however, it is expected to be small. Provided that the mitigation measures recommended in Section 6.6 are adopted, the potential
environmental impacts caused by the storage, handling, transport and disposal
of general refuse are expected to be minimal. With respect to the anticipated
small quantity of general refuse to be disposed of, there will be no adverse
impact to the operation of the strategic landfills. |
|
Operational Phase |
|
|
Screenings and Silt from Maintenance |
The screenings and silt from the maintenance of the proposed facilities
will be disposed of at the WENT or NENT landfill. With respect to their relatively small quantity (a total
of 46m3 per month of screenings), it is not anticipated that the
disposal of these wastes will cause any adverse impacts to the operation of
the landfills. |
|
Chemical Waste |
It is anticipated that the quantity of chemical waste arising during
operation, such as lubricating oil and paints will be small and no adverse
environmental impacts are envisaged. |
|
|
|
6.6.1
Introduction
This
section recommends the mitigation measures to avoid or minimise potential
adverse environmental impacts associated with handling, collection and disposal
of waste arising from the Project.
The Contractors should incorporate these recommendations into a Waste
Management Plan for the construction works. The Contractors should submit the plan to the Engineer for
approval prior to the commencement of the construction works. Such a management plan should
incorporate site specific factors, such as the designation of areas for the
segregation and temporary storage of reusable and recyclable materials.
It is the Contractor’s (for the construction
phase) and the Project Proponent’s (for the operational phase) responsibility to
ensure that only reputable licensed waste collectors are used and that
appropriate measures to minimise adverse impacts, including windblown litter
and dust from the transportation of these wastes are employed. In addition, the Contractor must ensure
that all the necessary waste disposal permits are obtained throughout the
construction and operation phases.
6.6.2
Construction
Phase
Excavated
Material
Wherever practicable, excavated materials should be segregated from other wastes to avoid contamination thereby ensuring acceptability at public filling areas and avoiding the need for disposal at landfill.
Measures Taken in the Planning and Design Stages to
Reduce the Generation of C&DM
The
various waste management options can be categorised in terms of preference from
an environmental viewpoint. The
options considered to be more preferable have the least impacts and are more
sustainable in the long term.
Hence, the waste management hierarchy is as follows:
· avoidance and minimisation, that is,
not generating waste through changing or improving practices and design;
· reuse of materials, thus avoiding
disposal (generally with only limited reprocessing);
· recovery and recycling, thus
avoiding disposal (although reprocessing may be required); and
· treatment and disposal, according to
relevant law, guidelines and good practice.
This hierarchy should be used to evaluate the
waste management options, thus allowing maximum waste reduction and often
reducing costs. For example, by
reducing or eliminating over-ordering of construction materials, waste is
avoided and costs are reduced both in terms the purchasing of raw materials and
in disposing of wastes. Records of
quantities of wastes generated, recycled and disposed (locations) should be
properly kept.
Standard formwork should be used as far as
practicable in order to minimise the arisings of C&DM. The use of more durable formwork or
plastic facing for the construction works should be considered.
Any uncontaminated soil should be reused on
site as far as possible, eg for landscape works, in order to minimise the
amount of public fill to be disposed off-site. The Project Proponent should liaise with the Public Fill
Committee to identify as far as possible suitable reclamation or site formation
projects near the project site to reuse the material.
The design of the foundation works will
minimise the amount of excavated material to be generated. Should piling be required, H-piling
will be used as far as practical.
The purchasing of construction materials will
be carefully planned in order to avoid over ordering and wastage.
Measures to be Taken in the Construction Stage to Reduce the Generation
of C&DM
The Contractor should recycle as much of the
C&DM as possible on-site.
Public fill and C&D waste should be segregated and stored in
different containers or skips to enhance reuse or recycling of materials and
their proper disposal. Concrete
and masonry, for examples, can be crushed and used as fill. Steel reinforcing bar can be used by
scrap steel mills. Different areas
of the sites should be designated for such segregation and storage.
The use of wooden hoardings shall not be
allowed. An alternative material, which
can be reused or recycled, for example, metal (aluminium, alloy, etc) shall be
used.
Government has developed a charging policy for
the disposal of waste to landfill.
When it is implemented, this will provide additional incentive to reduce
the volume of waste generated and to ensure proper segregation to allow
disposal of inert material to public filling areas.
Chemical Waste
Chemical waste producers should be registered
with the EPD. For those processes
which generate chemical waste, it may be possible to find alternatives which
generate reduced quantities or even no chemical waste, or less dangerous types
of chemical waste.
Chemical waste that is produced, as defined by
Schedule 1 of the Waste Disposal
(Chemical Waste) (General) Regulation, should be handled in accordance with
the Code of Practice on the Packaging, Handling and Storage of Chemical Wastes
as follows. Containers used for
storage of chemical wastes should:
· be suitable for the substance they
are holding, resistant to corrosion, maintained in a good condition, and
securely closed;
· Have a capacity of less than 450 L
unless the specifications have been approved by the EPD; and
· display a label in English and
Chinese in accordance with instructions prescribed in Schedule 2 of the Regulations.
The storage area for chemical wastes should:
· be clearly labelled and used solely
for the storage of chemical waste;
· be enclosed on at least 3 sides;
· have an impermeable floor and bunding,
of capacity to accommodate 110% of the volume of the largest container or 20%
by volume of the chemical waste stored in that area, whichever is the greatest;
· have adequate ventilation;
· be covered to prevent rainfall
entering (water collected within the bund must be tested and disposed as
chemical waste, if necessary); and
· be arranged so that incompatible
materials are adequately separated.
Disposal of chemical waste should:
· be via a licensed waste collector;
and
· be to a facility licensed to receive
chemical waste, such as the Chemical Waste Treatment Facility which also offers
a chemical waste collection service and can supply the necessary storage
containers; or
· be to a re-user of the waste, under
approval from the EPD.
Sewage
Adequate numbers of portable toilets should be
provided for the number of workers along the proposed sewer alignment. The portable toilets should be
maintained in a state which will not deter the workers from utilizing these
portable toilets. Night soil
should be collected by licensed collectors regularly.
Management of General
Refuse
General refuse generated on-site should be
stored in enclosed bins or compaction units separately from construction and
chemical wastes. A reputable waste
collector should be employed by the Contractor to remove general refuse from
the site, separately from construction and chemical wastes, on a daily basis to
minimise odour, pest and litter impacts.
The burning of refuse on construction sites is prohibited by law.
Aluminium cans are often recovered from the
waste stream by individual collectors if they are segregated and made easily
accessible, so separate, labelled bins for their deposit should be provided if
feasible.
Office wastes can be reduced through the
recycling of paper if volumes are large enough to warrant collection. Participation in a local collection
scheme should be considered if one is available. In addition, waste separation facilities for paper,
aluminium cans, plastic bottles etc., should be provided.
Management of Waste
Disposal
A trip-ticket system should be established in
accordance with Works Bureau Technical
Circular No. 5/99 to monitor the disposal of public fill and solid wastes
at public filling facilities and landfills, and to control fly-tipping. A trip-ticket system will be included
as one of the contractual requirements and implemented by the Engineer. The Engineer should audit the result of
the system.
A recording system for the amount of waste
generated, recycled and disposed of (including the disposal sites) should be
established during the construction stage.
Staff Training
Training should be provided to workers on the
concepts of site cleanliness and on appropriate waste management procedures,
including waste reduction, reuse and recycling at the beginning of the
Contract.
6.6.3
Operational
Phase
The main type of wastes generated during
operation phase will be screenings from the proposed pumping stations and silt
and similar materials removed during the maintenance of the sewers/rising mains
which will be similar in nature to general refuse. The waste generated at the proposed pumping stations and
sewers/rising mains should be stored in enclosed bins or compaction units separately
from chemical wastes. A reputable
waste collector should be employed by the operators to remove the screenings
from the pumping stations, on a daily basis to minimise odour, pest and litter
impacts.
For chemical wastes generated during the
operation phases, the mitigation measures are same for those in Section 6.6.2 under Construction Phase.
6.7
Residual Environmental Impacts
With the implementation of recommended
mitigation measures, in particular the establishment and implementation of a
Waste Management Plan, minimal residual impacts are anticipated from either the
construction or operation of the proposed Project.
6.8
Environmental Monitoring and Audit
It is
recommended that audit of each waste stream should be periodically carried out during the construction phase
to determine if wastes are being managed in accordance with the Waste
Management Plan. The audits should
look at all aspects of waste management including waste generation, storage,
recycling, transport and disposal.
An appropriate audit programme would be to undertake a first audit at
the commencement of the construction works and then quarterly audits,
thereafter.
6.9
Conclusion
The following quantities of waste are expected
to arise during the construction of the proposed sewers/rising mains: excavated
material (average and peak disposal rates are 69 m3 day-1
and 104 m3 day-1, respectively); C&D waste (average
and peak generation rates during construction are 0.44 and 0.66 m3
day-1, respectively); and chemical waste (a few cubic metres per
month); and general refuse.
Screenings will arise from the operation of the
proposed pumping stations.
Approximately 46m3 per month of screenings will be generated
from the pumping stations. The
impact of its disposal at landfill will be minimal. The generation of chemical wastes is expected to be very
small and no adverse environmental impacts are envisaged.
Good
waste management practices have been recommended to ensure that adverse
environmental impacts from the handling and disposal of construction and operational
wastes are prevented or minimised.
This EIA concludes that no unacceptable environmental impacts will
result from the storage, handling, collection, transport, and disposal of
wastes arising from the construction and operation of the Designated and
Potentially Designated Elements of proposed Yuen Long and Kam Tin Sewerage and
Sewage Disposal Stage 1 Sewers, Rising Mains and Ancillary Pumping Stations.