9.1
This
section identifies the types of solid 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 wastes. The major solid waste would be construction
and demolition (C&D) materials
generated from the tunnels excavation and shaft sinking for the sewage
conveyance system (SCS). Waste arisings
in the future, as with current operations at the Stonecutters Island Sewage
Treatment Works (SCISTW) and Preliminary Treatment Works (PTW),
would comprise the collected screenings, grit and sludge. Mitigation measures and good site practices,
including waste handling, storage and disposal, are recommended with reference
to the applicable waste legislation and guidelines.
9.2
In
accordance with Clause 3.4.4.2 (iii) of the EIA Study Brief, a Waste Management
Plan (WMP) shall be included in the EIA Report should the construction
method(s) adopted lead to the generation of significant amount of wastes
material. The WMP is included in Appendix 9.1.
9.3
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.
9.4
The
following legislation relates to the handling, treatment and disposal of wastes
in the Hong Kong Special Administrative Region (HKSAR) and has been used in assessing potential impacts:
l
Environmental Impact Assessment Ordinance (Cap 499)
l
Waste Disposal Ordinance (Cap. 354)
l
Waste Disposal (Chemical Waste) (General) Regulation (Cap. 354)
l
Land (Miscellaneous Provisions) Ordinance (Cap. 28)
l
Public Health and Municipal Services Ordinance (Cap. 132) - Public
Cleansing and Prevention of Nuisances Regulation
l
Dumping at Sea Ordinance (Cap 466)
9.5
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.
9.6
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 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.
9.7
The Public
Cleansing and Prevention of Nuisances Regulation provide control on illegal
tipping of wastes on unauthorised (unlicensed) sites.
9.8
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
wholly inert, namely public fill, should not be disposed of to landfill, but
taken to public filling reception facilities, which usually form part of
reclamation schemes. The Land
(Miscellaneous Provisions) Ordinance requires that dumping licences be obtained
by individuals or companies who deliver public fill to public filling reception
facilities. The Civil Engineering &
Development Department (CEDD) issues the licences under delegated powers from
the Director of Lands.
9.9
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 material.
9.10
Measures
have been introduced under the former Environment, Transport and Works Bureau
in a Technical Circular (ETWB) TCW No. 33/2002, “Management of Construction and
Demolition Material Including Rock” to enhance the management of construction
and demolition 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 encourage proper management of such material; (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 the preparation of the Waste Management Plan
(WMP) and to minimize C&D material generation during construction. Projects generating C&D material less
than
9.11
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.
9.12
The
criteria for assessing waste management implications are outlined in Annex 7 of
the EIAO-TM. The methods for assessing
potential waste management impacts during the construction and operation phases
of the Project follow those presented in Annex 15 of the EIAO-TM and include
the following:-
l
Estimation of the types and quantities of the wastes to be generated;
l
Assessment of potential impacts from the management of solid waste with
respect to potential hazards, air and odour emissions, noise, wastewater
discharges and transport; and
l
Assessment of impacts on the capacity of waste collection, transfer and
disposal facilities.
9.13
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, including site
clearance waste
l
General refuse
l
Chemical waste, including asbestos waste
9.14
Each type
of waste arising is described below, together with an evaluation of the
potential environmental impacts associated with generation, handling, storage
and transport of the waste.
9.15
Site
clearance at currently unused areas is required for updating the PTW, expansion of the SCISTW and construction of shafts. The
majority of clearance waste is expected to consist of general refuse, low grade
vegetation and timber.
9.16
Site
clearance activities would be limited and the waste would be mainly composed of refuse, low grade vegetation and timber. It
is considered that handling and disposal of these clearance wastes would not be a key environmental issue provided that
the WMP is properly followed.
9.17
Construction
and demolition (C&D) material would be generated from the construction of
the SCS. Two construction options, i.e. drill & blast (D&B) or tunnel
boring machine
(TBM) may
be adopted for excavation of the SCS depending on the design of the Contractor at the construction stage. The minimum excavated
diameter for TBM option would be about 3m while that for D&B would also be
around 3m to allow for construction space. As such, the quantity of C&D
material generated would not be sensitive to the choice of tunnel construction
method.
9.18
The
quantity of C&D materials generated is estimated and shown in Table 9.1. For both options, the
C&D material would comprise mainly rock (approximately 84%) and soil (14%),
the remaining as C&D waste (1%) and broken concrete (1%).
Table 9.1 Summary
of C&D Material Quantities from Construction of Sewage Conveyance System
|
|
Quantity (m3) (1) |
Recycle of backfilling materials from fill
bank (m3) (1) |
Surplus C&D Materials (m3) (1)(2) |
|
Inert C&D Materials |
|
|
|
|
Soil |
108,300 |
78,000 (as a form of
aggregate) |
35,800 |
|
Broken
concrete |
5,500 |
||
|
Rock |
|
|
|
|
Tunnel |
667,000 (by D&B) |
- |
667,000 (by D&B) |
|
|
613,600 (by TBM) |
613,600 (by TBM) |
|
|
C&D Waste |
10,800 |
- |
10,800 |
|
Sub-total |
791,600 (by D&B) 738,200 (by TBM) |
Total: |
713,600 (by
D&B) 660,200 (by
TBM) |
Note:
(1) All the figures in this table
are in bulk volume.
(2) 366,600 m3 (bulk
volume) of surplus material (Grade I/II granite, by D&B) would be delivered
to Lam Tei Quarry.
9.19 The estimated timing of generation of the C&D materials throughout the period of construction of the SCS is shown in Appendix 9.2.
9.20
The C&D
material should be reused on-site as far as possible to minimize the net amount
of C&D material generated from the Project. Bulk filling for the excavated
SCS is not required. Reuse of the excavated materials as backfilling materials
is only considered feasible at temporary facilities for the tunnel construction
such as production shafts at North Point, Wan Chai East, Sai Ying Pun,
9.21
The surplus
rocks can be re-used on other construction projects where good quality fill
material is required either in the
9.22
The
excavated spoils would be transported away
from the tunnel to ground level via shafts. The estimated volume of excavated
materials transported away from each shaft and maximum frequency of trucks are
shown in
Table 9.2.
Table 9.2 Estimated Volume of Excavated
Materials Outlet from Each Shaft
|
Locations of
Production/Drop/Riser Shafts |
Volume of Excavated Materials Outlet (m3)(3) |
Max. freq. of trucks (2) |
|
|
Soil |
Rock(4) |
||
|
North Point |
16,638 |
67,597 |
41/day |
|
Wan Chai East |
13,946 |
161,914 |
40/day |
|
Central |
4,843 |
2,083 |
13/day |
|
Sai Ying Pun |
30,074 |
204,700 |
48/day |
|
|
22,011 |
68,080 |
80/day |
|
|
10,921 |
83,175 |
38/day |
|
Cyberport |
1,990 |
10,579 |
18/day |
|
Wah Fu |
1,071 |
1,608 |
12/day |
|
|
5,125 |
64,004 |
20/day |
|
Ap Lei Chow |
1,494 |
3,467 |
4/day |
Note:
(1) The
volume of
excavated materials output from each shaft is estimated based on the drill
& blast option which is considered as the worst case scenario in
terms of C&D material generation.
(2) The rate
of generation of excavated materials may vary with time and thus the frequency
of trucks.
(3) All
the figures in this table are in bulk volume.
(4) 366,600m3 (bulk volume) of rock
material (Grade I/II granite) would be delivered to Lam Tei Quarry
9.23
C&D
material would also be generated from the upgrading works of the PTWs and demolition of chemical enhanced primary
treatment (CEPT) complex next to the Cyberport PTW after commissioning of HATS
2A. An estimated quantity of
C&D material generated from the PTW upgrading works and frequency of trucks
are given in Table 9.3.
Table 9.3 Summary of Surplus C&D Material
Quantities from PTW Upgrading
|
PTW Location |
Proposed Major Upgrading Works |
Estimated Bulk Volume (m3)(4) |
Frequency of Trucks |
|||
|
Public Fill (waste concrete) |
Public Fill (other inert materials) |
C&D Waste |
Marine Deposit |
|||
|
North Point |
Screening
& degritting facilities, Seawater P/S for SCS |
8,330 |
560 |
2,800 |
- |
3/day |
|
Wan Chai East |
Transfer
pumping station |
130 |
9,760 |
130 |
3,230 |
3/day |
|
Central |
Screening
& degritting facilities |
2,000 |
4,510 |
670 |
50 |
2/day |
|
|
Transfer
pumping station & connection channel |
- |
10,130 |
- |
1,220 |
3/day |
|
Connection
channel only |
- |
40 |
- |
- |
- |
|
|
Cyberport (1) |
Transfer
pumping station & connection channel |
26,670 |
13,500 |
8,930 |
- |
11/day |
|
Connection
channel only |
26,670 |
40 |
8,930 |
- |
8/day |
|
|
|
Screening
& degritting facilities, Seawater P/S for SCS |
2,050 |
4,720 |
690 |
- |
2/day |
|
Ap Lei Chau |
Screening
& degritting facilities, Transfer P/S |
3,810 |
3,520 |
1,270 |
- |
2/day |
|
Wah Fu |
Screening
& degritting facilities |
2,330 |
1,330 |
- |
- |
1/day |
|
Total (m3) |
||||||
|
Scenario 1 (2) |
45,320 |
34,570 |
14,490 |
4,500 |
23/day |
|
|
Scenario 2 (3) |
45,320 |
37,940 |
14,490 |
3,280 |
23/day |
|
Note:
(1) The
transfer pumping station may either be built at Sand Bay PTW or Cyberport PTW
(2) Transfer
Pumping Stations built at Wan Chai East PTW & Sandy Bay PTW
(3) Transfer
Pumping Stations built at Wan Chai East PTW & Cyberport PTW
(4) All
the figures in this table are in bulk volume.
9.24
As
mentioned in previous paragraph, land available for the construction works is
very tight, space for temporary stockpile of C&D materials for re-use is
limited. To minimize production of surplus C&D materials, aggregates or
backfilling materials should be recycled from fill banks whenever possible. A
preliminary estimate is that approximately 5,330 m3 (bulk volume) of
soil could be recycled for backfilling. The breakdown of the C&D materials
generated is given in Appendix 9.3.
9.25
Expansion
works undertaken at SCISTW include construction of the following structures:-
l
Influent pumping station;
l
Chemically enhanced primary treatment facilities using double-deck
sedimentation tanks;
l
Sludge storage, dewatering and handling facilities;
l
Chlorination/dechlorination disinfection facilities;
l
Effluent deep tunnel and its associated chambers;
l
Odour control facilities;
l
Primary substation and switch gear building;
l
Interconnection of the existing and new influent pumping station and
flow diversion works; and
l
Minor upgrade and modification works.
9.26
The
estimated quantity of C&D material generated from the SCISTW expansion
works and frequency of trucks are given in Table 9.4. A preliminary estimate is that approximately
23,854m3 (bulk volume) of soil and 1,641m3 (bulk volume)
of rock could be reused on-site for backfilling. The C&D material would
arise from the on-site excavation works in a 27-month period. Breakdown of the
C&D materials generated is attached in Appendix
9.4.
Table 9.4 Summary of
Surplus C&D Material Quantities from SCISTW Expansion
|
Location |
Proposed Major Construction Works |
Estimated Bulk Volume (m3)(1) |
Frequency of Trucks |
|||
|
Rock Fill |
Public Fill |
C&D Waste |
Marine Disposal |
|||
|
SCISTW |
Pumping station, Treatment units, Effluent tunnels, Sludge treatment facilities |
14,771 |
214,687 |
7,337 |
13,018 |
60/day |
Note:
(1) All
the figures in this table are in bulk volume.
9.27
The
majority of the C&D materials are excavated spoils which are inert waste
and not expected to give rise to any potential hazard during handling,
collection and disposal. Air and noise emissions would also be limited as the
loading and unloading activities would be shielded by wind screen or temporary
noise barriers. Besides, the loaded waste on trucks would be properly covered before leaving the site.
9.28
The
excavation activities would be land based and therefore it is not expected to
generate any adverse water quality impact due to excavation.
9.29
The C&D
materials generated from PTW upgrading works are mainly reinforced concrete,
bituminous material and soil which are not anticipated to cause unacceptable
environmental nuisance such as odour, wastewater discharge and potential hazard
to the surroundings. The major concern would be on stockpiling of soils which
may give rise to dust and siltation problems if not properly maintained and
managed.
9.30
Similar to
the C&D materials generated from upgrading of the PTWs, the C&D
materials from SCISTW are mainly composed of
reinforced concrete, bituminous material, rock and soil which are odourless by
their nature. Apart form potential dust and siltation problems caused by
improper stockpiling of soils, no other unacceptable environmental nuisance and
potential hazard is expected from handling of the C&D materials.
9.31
Marine
deposit would be mainly generated from excavation works for upgrading of PTWs
and expansion works of SCISTW. The marine deposit should be transported to the
designated disposal site allocated by the Marine Fill Committee (MFC). The disposal arrangement and disposal site
would depend on whether the marine deposit is contaminated and contamination
level if it is the case. Apart from the
MFC, the allocation of disposal space would be delegated to Director of Environmental Protection (DEP) if
the silt and marine disposal is classified as Category L with a quantity less
than 50,000 m3.
9.32
The marine
deposit should be transported by covering trucks during transportation to
designated barging point. The barge transporting the marine deposit to the
designated disposal site should be fitted with tight fitting seals to prevent
leakage. Besides, the barge should not be filled to a level that would cause
overflow of materials or laden water during loading or transportation. As such,
no unacceptable impacts would be expected from the transportation and disposal
of the marine deposit.
9.33
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. The maximum number of construction workers to be employed for the SCS
construction, PTW upgrading and SCISTW expansion is estimated to be about 900
workers, 400 workers and 300 workers respectively. Based on a generation rate
of
9.34
Reliable
waste collectors shall be assigned by the Contractor to collect general refuse
generated from the construction site on a daily basis to minimize the potential
odour, pest and litter impacts.
9.35
Chemical
wastes likely to be generated from the construction activities for the proposed
SCS, its
associated structures as well as
the upgrading and extension works on existing PTWs and SCISTW will include:-
l
Scrap batteries, spent acid or alkali;
l
Used paint, engine oils, hydraulic fluids and waste fuel;
l
Spent mineral oils or cleansing fluids from mechanical plants; and
l
Spent solvent or solutions, some of which may be halogenated, from
equipment cleansing.
9.36
It is difficult
to quantify the amount of chemical waste that may arise from the construction
activities since it will be dependent on the Contractor’s on-site maintenance
practice and arrangement, 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, would be small and in the order of a few cubic metres 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.
9.37
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) Regulations. The
potential hazards include:
l
Toxic effects to workers
l
Adverse impacts on water quality from spills
l
Fire hazards
9.38
Materials
classified as chemical wastes require special handling and storage arrangements
before removal for appropriate treatment at the approved Chemical Waste
Treatment Centre. Mitigation and control requirements for chemical wastes are
detailed in the Section of Mitigation
Measures. Provided that the handling, storage and disposal of chemical wastes
are in accordance with the Waste Disposal (Chemical Waste)(General) Regulation
and the Code of Practice on the Packaging Labelling and Storage of Chemical
Wastes, it would not cause an
unacceptable environmental impact.
9.39
Asbestos
may be located at any of the older PTW buildings, the Project Proponent shall
employ a registered Asbestos Consultant to conduct asbestos surveys before the
demolition works according to the Air Pollution Control Ordinance, and submit
the Asbestos Investigation Report and Asbestos Abatement Plan before the
commencement of asbestos abatement works to EPD for approvals. Asbestos waste is classifiable as chemical
waste under the Waste Disposal (Chemical Waste) (General) Regulation and shall
be handled, collected, transported and disposed in accordance with the
Regulation and the Code of Practice on the Handling, Transportation and
Disposal of Asbestos Waste. Hence, the
environmental impact would not be anticipated.
9.40
Sewage will
arise from amenity facilities used by the construction workers and site
office’s sanitary facilities. Night soil from chemical toilets will also be
generated. The sludge should be properly managed
to minimize odour and potential health risks to the workforce by attracting
pests and other disease vectors.
9.41
No unacceptable
environment impact is envisaged if the chemical toilets are properly maintained
and licensed contractors are employed for collection and disposal of the sewage
regularly.
9.42
The
estimated annual disposal quantity of the surplus C&D materials to public
and rock fills for the entire HATS Stage 2A Project is shown as below.
Table 9.5 Summary of Annual Disposal Quantities
of C&D Materials for HATS 2A
|
Proposed Disposal Sites |
Volume by Years (million m3) |
Total |
|||||
|
2009 |
2010 |
2011 |
2012 |
2013 |
2014 |
||
|
Public
Fill |
0.087 |
0.103 |
0.146 |
0.048 |
(0.077) |
0.027 |
0.334 |
|
Rock
Fill |
0.018 |
0.210 |
0.297 |
0.157 |
0.000 |
0.000 |
0.682 |
Note: The
volume of excavated materials generated from D&B option, which is
considered as the worst case scenario for SCS, is adopted.
( ) denotes net backfilling of materials
9.43
A breakdown
of C&D materials generated from SCS, PTW upgrading and SCISTW expansion is
attached in Appendix 9.5.
9.44
A summary
of anticipated annual fill requirements for the concerned years is summarized
in Table 9.6:-
Table 9.6 Summary of Annual Fill Requirements
and Surplus Disposal
|
Disposal Sites |
Volume by Years (million m3) |
Total |
|||||
|
2009 |
2010 |
2011 |
2012 |
2013 |
2014 |
||
|
Public Fill Requirement |
0.629 |
0.330 |
0.270 |
0.270 |
0.270 |
0.000 |
1.769 |
|
Surplus disposal |
0.087 |
0.103 |
0.146 |
0.048 |
(0.077) |
0.027 |
0.334 |
|
|
|
|
|
|
|
|
|
|
Rock Fill Requirement |
0.434 |
1.434 |
0.416 |
0.40 |
0.400 |
0.000 |
3.084 |
|
Surplus disposal |
0.018 |
0.210 |
0.297 |
0.157 |
0.000 |
0.000 |
0.682 |
Source: CEDD Fill Management Database
9.45
From the
above figures, the surplus C&D materials constitute about 18.9% and 22.1%
of the capacity of the public fill and rock fill respectively.
9.46
The
capacity of the landfills is able to
cater for the C&D waste arising from this Project during the construction period. Despite this, waste
avoidance and reduction measures should be implemented to alleviate the loading
of the landfills.
9.47
At present,
two open sea disposal areas at South Cheung Chau and East Ninepin and various
empty marine borrow pits are used for disposal of
uncontaminated mud. Contaminated mud is disposed of at East Sha Chau in an
environmentally acceptable manner. Prior to excavation of the silt and marine
deposit, a proposal for sampling and chemical testing of the materials should
be submitted to the Director of Environmental Protection (DEP) in accordance
with ETWB(W) 34/2002 to determine the category of the silt and deposit with
reference to the Chemical Exceedance Levels (CEL). Upon completion of the sampling
and chemical testing, a Preliminary Sediment Quality Report (PSQR) should be
submitted to DEP with a copy to the Secretary of the Marine Fill Committee
(MFC). MFC will determine the most appropriate open sea or confined marine
disposal site on the basis of the chemical and biological test results and
formally allocate disposal space. If the silt and marine disposal is classified
as Category L with a quantity less than 50,000 m3, the allocation of
disposal space would be delegated to DEP.
9.48
Annual
generation of the marine deposit of this Project is estimated in Table 9.7. It is
anticipated that less than 50,000 m3 of marine deposit would be
generated from the construction stage of the project. This quantity of marine deposit should not cause a
serious loading on the marine disposal areas.
Table 9.7 Summary of Annual Marine Disposal
Quantities for HATS 2A
|
Disposal Sites |
Volume by Years (million m3) |
Total |
|||||
|
2009 |
2010 |
2011 |
2012 |
2013 |
2014 |
||
|
Marine Disposal |
- |
0.005 |
0.008 |
0.004 |
- |
- |
0.016 |
9.49
During the operation phase of HATS Stage 2A, the
identified waste types include:
l
Screenings and grit at the upgraded PTWs
l
Sewage sludge, screenings and grit at the expanded SCISTW
9.50
The current
SCS has been designed to ensure that self-cleansing of the tunnels is achievable. Hence, the waste would be
carried along the tunnel by the sewage to SCISTW for treatment.
9.51 The estimated quantities of screenings and grit to be collected at the upgraded PTWs are provided in Tables 9.8 and 9.9 for the ultimate development scenario.
Table 9.8 Estimated Quantities of Screenings
|
PTW |
Average Flow at Ultimate Scenario |
Average Screenings Collected |
Assumed volume reduction (4) |
Daily Screenings (compacted) Generation (3) |
|
|
Assum.(1) |
Assum.(2) |
||||
|
North Point |
122,759 |
0.1 |
0.0596 |
50% |
6.1 |
|
Wan Chai East |
182,690 |
0.1 |
0.0158 |
50% |
9.1 |
|
Central |
138,193 |
0.1 |
0.0175 |
50% |
6.9 |
|
|
11,431 |
0.1 |
0.0113 |
50% |
0.6 |
|
Cyberport |
9,816 |
0.1 |
0.0363 |
50% |
0.5 |
|
|
95,059 |
0.1 |
0.0169 |
50% |
4.8 |
|
Ap Lei Chau |
39,940 |
0.1 |
0.0361 |
50% |
2.0 |
|
Wah Fu |
10,518 |
0.1 |
0.0473 |
50% |
0.5 |
|
Total: |
30.5 |
||||
Table 9.9 Estimated Quantities of Grit
|
PTW |
Average Flow
at Ultimate Scenario |
Avg. Grit
Collected |
Daily Grit
Generation (3) |
|
|
Assum.(1) |
Assum.(2) |
|||
|
North Point |
122,759 |
0.05 |
0.0036 |
6.1 |
|
Wan Chai East |
182,690 |
0.05 |
0.0094 |
9.1 |
|
Central |
138,193 |
0.05 |
0.0182 |
6.9 |
|
|
11,431 |
0.05 |
0.0181 |
0.6 |
|
Cyberport |
9,816 |
0.05 |
0.0099 |
0.5 |
|
|
95,059 |
0.05 |
0.0071 |
4.8 |
|
Ap Lei Chau |
39,940 |
0.05 |
N/A |
2.0 |
|
Wah Fu |
10,518 |
0.05 |
N/A |
0.5 |
|
Total: |
30.5 |
|||
Note:
(1) Assumption
1: The generation rates are based on the assumptions adopted in the Final
Report on Upgrading of Existing Preliminary Treatment Works for Agreement no.
CE 45/89 Strategic Sewage Disposal Scheme – Site Investigation &
Engineering Studies.
(2) Assumption
2: The generation rates are based on operational records obtained from DSD.
(3) The
daily generation rates are based on Assumption 1.
(4) The
volume reduction of screenings normally ranged from 55 – 85% depended on the
equipment model and specification. For assessment purpose, a conservative
value, i.e. 50% is assumed.
9.52
The daily generation rates of screenings and grit are estimated based on
the assumptions adopted in the “Final Report on Upgrading of Existing Preliminary Treatment Works for
Agreement no. CE 45/89 Strategic Sewage Disposal Scheme – Site Investigation
& Engineering Studies” due to the following consideration:-
l
Large variations in screenings and grit production rate are observed
based on the existing operation records.
l
The production rate obtained from existing PTWs may not be able to
reflect the future production rate:
- Screenings production would
likely correlate to the bar spacing of the fine screens to be used (4 mm or 6
mm); and
- Variation of sewage
characteristics in different sewerage catchments
Owing to the above-mentioned
reasons, the more conservative
figures (i.e. the ones quoted in previous design report) are adopted for the
estimation.
9.53
Screenings
are the materials collected by screens from sewage and include small rags,
paper, plastic materials of various types, razor blades,
undecomposed food waste, faeces, etc. The screenings normally would be attached with faecal solids and light
organic materials which are considered as the main odour source from screenings
during storage, transportation and disposal operations. Currently, the
screenings at
9.54
Grit is the material collected by grit removal devices,
such as detritors or grit traps. They generally consist of sand, gravel, cinders, or other
heavy materials. Though grit removal
system is normally designed to remove inorganic materials that have specific
gravities substantially greater than those of the organic matters, untreated
grit may inevitably contain putrescible organic materials. The PTWs, except Ap
Lei Chau and Wah Fu PTWs, are equipped with rake/screw classifier by which
organic matters are removed from the grit and remained in the wash water which
will be returned to the inlet of the PTWs for further treatment. At Ap Lei Chau
and Wah Fu PTWs, removal of settled grit is performed manually and no further
treatment, i.e. washing of grit, is performed prior to disposal.
9.55
Both
untreated screenings and grit may contain substantial amount of organic
materials. Upon decomposition of these organic materials,
offensive odour might be generated. Based on the site observations, lower level of odour emission from grit was
experienced as compared with screenings and
dewatered sludge.
9.56
The screenings
and grit are currently bagged and collected either by roll-off truck or refuse
collection vehicles for landfill disposal. There does not have considerable
odour emission, noise nuisance and hazard during loading, transportation and
unloading process. The existing disposal process would be adopted for the future upgraded PTWs. Thus, it is not
anticipated to have significant environmental nuisance during handling and
transportation of the screenings/grit from the upgraded PTWs. Good practices
for handling screenings and grit mentioned in the “Mitigation Measures” Section
should be continued in the future.
9.57
Only a
small quantity of screenings and grit would be generated from each PTW.
Currently, some PTWs do not need to collect and dispose of the waste from each
PTW at a daily interval. The waste may be stored temporary in sealed containers inside the PTWs and
transported away by trucks until certain quantity of waste is reached. The
current and estimated future removal frequencies are given in Table 9.10.
Table 9.10 Current and
Estimated Future Removal Frequencies of Screenings/Grit
|
PTW |
Current
(1) |
Future |
||
|
Screenings |
Grit |
Screenings |
Grit |
|
|
North Point |
Daily |
Once every 2 days |
Daily |
Daily |
|
Wan Chai East |
Once every 3 days |
Daily |
Daily |
Daily |
|
Central |
Daily |
Once every 2 days |
Daily |
Daily |
|
|
Weekly |
Weekly |
Daily |
Daily |
|
|
Weekly |
Weekly |
Daily |
Daily |
|
Cyberport |
Daily |
Daily |
Daily |
Daily |
|
Ap Lei Chow |
Daily |
N/A |
Daily |
Daily |
|
Wah Fu |
Once every 3 days |
N/A |
Daily |
Daily |
Note:
(1) The
information is extracted from the Technical Note – Assessment of Odour Impacts
arising from Sludge, Grits and Screenings generated during operation.
9.58
Mainly sludge is generated from
operation of the SCISTW treatment. Nonetheless, the North West Kowloon Preliminary Treatment Work (NWKPTW) situating within the SCISTW boundary would generate screenings and grit. The estimated quantities of screenings
and grit for the ultimate development scenario to be collected at the NWKPTW and the SCISTW
are tabulated in Tables 9.11, 9.12 and 9.13.
Table 9.11 Estimated Quantities of Screenings from
NWKPTW
|
PTW |
Average Flow at Ultimate Scenario |
Avg. Screenings Collected |
Assumed volume reduction |
(3)Daily Screenings (compacted) Generation |
|
|
Assum.(1) |
Assum.(2) |
||||
|
NWK PTW |
497,381 |
0.1 |
0.0322 |
50% |
24.9 |
Table 9.12 Estimated Quantities
of Grit from NWKPTW
|
PTW |
Average Flow at Ultimate Scenario |
Avg. Grit Collected |
(3)Daily Grit Generation |
|
|
Assum.(1) |
Assum.(2) |
|||
|
NWK PTW |
497,381 |
0.05 |
0.0044 |
24.9 |
Note:
(1) Assumption
1: The generation rates are based on the assumptions adopted in the Final
Report on Upgrading of Existing Preliminary Treatment Works for Agreement no.
CE 45/89 Strategic Sewage Disposal Scheme – Site Investigation &
Engineering Studies.
(2) Assumption
2: The generation rates are based on operational records obtained from DSD.
(3) The
daily generation rates are based on assumption 1.
9.59
The daily generation rates
of screenings and grit are estimated based on the assumptions adopted in the
“Final Report on Upgrading of
Existing Preliminary Treatment Works for Agreement no. CE 45/89 Strategic
Sewage Disposal Scheme – Site Investigation & Engineering Studies” due to
the following consideration:-
l
Large variations in screenings and grit production rate are observed
based on the existing operation records.
l
The production rate obtained from existing PTWs may not be able to
reflect the future production rate:
- Screenings production would likely
correlate to the bar spacing of the fine screens to be used (4 mm or 6 mm); and
- Variation of sewage
characteristics in different sewerage catchments
Owing to the above-mentioned
reasons, the more conservative
figures (i.e. the ones quoted in previous design report) are adopted for the
estimation.
Table 9.13 Estimated Quantities of Sludge from
SCISTW
|
|
Average Flow at Ultimate Scenario |
Avg. Sludge Collected |
Daily Sludge Generation |
|
SCISTW |
2,450,000 |
0.440 |
1,078 |
9.60
During the ultimate
development scenario, increase in the waste quantity from the NWK PTW and the
SCISTW is estimated, as shown in Table 9.14.
Table 9.14 Increased in Waste Quantity under
Ultimate Development Scenario
|
|
Type of Waste |
Current Daily Waste Generated |
Future Daily Waste Generated |
Increased Quantity of Waste |
|
NWK PTW |
Screenings |
18.9 m3/day |
24.9 m3/day |
6 m3/day |
|
NWK PTW |
Grit |
18.9 m3/day |
24.9 m3/day |
6 m3/day |
|
SCISTW |
Sludge |
598.4 ton/day |
1,078 ton/day |
479.6 ton/day |
9.61
A
centralized sludge treatment facility (STF) would be built at Ash Lagoon
located at the east of existing WENT Landfill. The STF is planned to be
commenced in operation in 2012 and capable for treating 2,000 ton/day of sludge
from SCISTW and 10 regional STWs[1].
9.62
Based on
the recent data provided by DSD, dry solids content of 35% on average can be
maintained at SCISTW. There is approximately 600 tpd dewatered sludge generated
from SCISTW. Average 250 tpd dewatered sludge is currently transported to SENT
Landfill by road, while the remaining 350 tpd is transported to West Kowloon
Refuse Transfer Station (WKRTS), then WENT Landfill by barge. Sludge delivery
tankers should arrive SENT Landfill at not closer than 15 minutes interval
according to EPD’s requirement.
9.63
Arrangement
for handling of screenings/grit generated from the NWKPTW located within the
SCISTW is similar to that adopted in the 8 PTWs in the
9.64
Chemicals would be used and stored on site during the operation
phase. Chemicals that may be used for the operation
of the SCISTW include:-
l
Sodium hypochlorite for chlorination system for CEPT;
l
Sodium bisulphite for dechlorination system for CEPT;
l
Ferric chloride used in existing sewage treatment process;
l
Sodium hydroxide used in existing sewage treatment process;
l
Anionic polymer and cationic polymer used in existing sewage treatment
process; and
l
Granulated activated carbon (GAC) used in deodorization units
9.65
The
chemicals would react with the materials in sewage or sludge
and converted to other physical and chemical forms becoming part of the sludge.
The sludge would be dewatered, bagged
and transported by licensed waste collector by means of sealed sludge tankers.
Therefore, negligible amount of residual chemical waste is expected during
normal treatment process.
9.66
Apart from
the above-mentioned chemicals, some other chemicals including grease, paint,
gasoline, diesel, thinner and acetylene would be used for operation and
maintenance of plants in the PTWs. As these chemical substances are
consumables, only negligible amount of residual chemical waste is expected.
9.67
Storage,
handling, transport and disposal of chemical waste should be arranged in
accordance with the Code of Practice on the Packaging, Labeling and Storage of
Chemical Wastes and collected by a licensed chemical waste collector.
Therefore, it is not anticipated to cause environmental nuisance to
surroundings during handling, transportation and disposal of the chemical
waste.
9.68
The
majority of the C&D materials would be
generated from excavation of the tunnel and SCISTW. The spoil from the tunnel would be transported by conveyor belt system to the
nearest production shafts and loaded onto the ground level and then transported
by dump trucks to the final disposal sites.
9.69
A meeting
was held on 15 November 2007 among CEDD, DSD, the contractor of Lam Tei Quarry
and our team, Grade I/II granite (366,000 m3 (bulk volume))
generated from construction of shafts and tunnels for SCS would be delivered to
Lam Tei Quarry for crushing into aggregate.
The remaining surplus rock and other inert C&D material would be disposed of at the Government’s public fill
reception facilities (PFRFs), for beneficial use by other projects in the
HKSAR.
9.70
At present,
the PFRFs in
Table 9.15 are operated by CEDD to receive the public fill generated
from local construction activities.
Table 9.15 Existing Operating PFRFs
|
PFRFs |
Description |
|
Tuen Mun
Area 38 Fill Bank |
Planned
to be replaced in phase by the long-term C&D material handling facilities
in Tuen Mun Area 38. |
|
Tseung Kwan
O Area 137 Fill Bank |
Planned
to be replaced in phase by the long-term C&D material handling facilities
in Tseung Kwan O Area 137. |
|
|
Planned to
be replaced by the long-term barging point in Chai Wan. |
|
Mui Wo
Temporary Public Fill Reception Facility |
Operation
after 2008 is subject to confirmation. |
Source: Information provided by CEDD
9.71
CEDD has
advised that the surplus inert C&D material may be delivered to the PFRFs
at Chai Wan and Tuen Mun Area 38
by land transport.
9.72
Designation
of the PFRFs to where the C&D materials can be disposed of is considered by
CEDD subject to the prevailing operating conditions at PFRFs upon endorsement
of the proposed Construction and Demolition Materials Management Plan
(C&DMMP) by the Public Fill Committee (PFC). At the time of preparation of
this report, C&DMMP for PTWs and SCISTW is unavailable for CEDD to
designate appropriate PFRFs. It is likely that the C&D materials would be
delivered to the same PFRFs assigned for disposal of inert C&D materials generated by SCS subject to the arrangement of the PFC.
9.73
The proposed Project would generate about 0.042 million m3
of C&D waste which is to be disposed of at the designated landfill site,
mainly comprising vegetation and timber cleared from the proposed works areas
during site clearance. Metals and timber should be separated from the C&D
waste for recycling as far as possible, in particular steel which has re-sale
value.
9.74
The C&D
waste shall be collected and transported by waste collectors holding
appropriate permits to landfill sites designated by EPD The waste shall be
transported by either covering trucks or contained in enclosed containers
during transportation. It is not anticipated to cause environmental nuisance
such as air, odour impacts, wastewater discharge and potential hazard to
surroundings during transportation.
9.75
Handling
procedures for marine deposit will depend on whether it is contaminated or not.
If the marine deposit is contaminated, more stringent handling procedure should
be adopted and disposed of to dedicated sites depending on the contamination
levels in accordance with ETWB(W) 34/2002. The following types of disposal are
identified in the ETWB(W) 34/2002:-
l
Type 1 –
l
Type 2 – Confined Marine Disposal;
l
Type 3 – Special Treatment / Disposal
9.76
During
transportation and disposal of marine deposit requiring Type 1 and Type 2 disposal,
the following measures should be taken to minimize potential impacts on water
quality:-
l
Bottom opening of barges should be fitted with tight fitting seals to
prevent leakage of material.
l
Monitoring of the barge loading should all be conducted to ensure that
loss of material does not take place during transportation. Transport barges or vessels should be
equipped with automatic self-monitoring devices as specified by the DEP.
l
Barges or hopper barges should not be filled to a level that would cause
the overflow of materials or sediment laden water during loading or
transportation.
9.77
If the
sediment quality test results reveal that the marine deposit shall be disposed
as Type 3 special disposal, appropriate treatment and/or disposal arrangement
shall be agreed with Director of Environmental Protection (DEP).
9.78
As the
sediment quality test results were not available at the time of preparation of
this report, the treatment (if necessary)
and disposal arrangement could not be prescribed.
9.79
The general
refuse shall be collected and transported by waste hauliers holding appropriate
permits, in a timely manner, to landfill sites. The waste shall be transported
by either covering trucks or contained in enclosed containers during
transportation. It is thus not anticipated to cause environmental nuisance such
as air, odour impacts, wastewater discharge and potential hazard to
surroundings during the transportation.
9.80
Storage,
handling, transport and disposal of chemical waste should be arranged in
accordance with the Code of Practice on the Packaging, Labeling and Storage of
Chemical Wastes published by EPD, and should be collected by a licensed
chemical waste collector.
9.81
The
registered chemical waste producer (i.e. the contractor) has to arrange for the
chemical waste to be collected by licensed collectors. A trip ticket system
shall be in place to control the movement of chemical wastes. The licensed
collector should regularly take chemical waste to a licensed chemical waste
treatment facility. At present, chemical waste is normally disposed of at the Chemical Waste Treatment Centre in Tsing
Yi. It is anticipated that the future chemical waste arising from the
construction site will follow the same collection and transportation protocol
and be disposed of at the Chemical Waste Treatment Centre. It is thus not
anticipated to have significant hazard during loading, transportation and
disposal of the chemical waste.
9.82
Table
9.16 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 9.16 Summary
of Waste Handling Procedures and Disposal Sites
|
Waste Material Type |
Generated from works item |
Total Quantity Generated(1) |
Quantity to be disposed
off-site(1) |
Disposal(1) |
Handling |
|
C&D Material |
Construction
of shafts & tunnels for SCS |
791,600 m3 (for
D&B) or 738,200 m3 (for
TBM) |
791,600 m3 (by
D&B) Or 738,200 m3 (by
TBM) |
Surplus
inert C&D material to be disposed of to
public fill reception facilities (PFRF)
(336,200m3)(2) Surplus
Grade I/II granite to be delivered to the Lam Tei Quarry (366,600 m3)(2) 78,000
m3 backfill materials to be recycled from fill bank C&D
waste to be disposed of to landfill (10,800 m3) Marine
Dumping (0 m3) |
Segregate
rock to avoid contamination from other wastes Sort on-site into : ·
Inert C&D material
(public fill) · C&D waste |
|
C&D Material |
Excavation
works for PTWs upgrading (assume
transfer pumping stations at |
106,360 m3 |
101,030 m3 |
5,330
m3 backfilled materials to be recycled from fill bank Surplus
inert C&D material to be disposed of to
PFRF (83,260
m3) C&D
waste to be disposed of to landfill (14,490 m3) Marine
Dumping (3,280
m3) |
Sort on-site into : ·
Inert C&D material
(public fill) ·
C&D waste · Marine Deposit |
|
|
Excavation
works for SCISTW expansion |
275,308 m3 |
249,813 m3 |
To
be reused on-site as backfill (25,495
m3) Surplus
inert C&D material to be disposed of to
PFRF (229,458
m3) C&D
waste to be disposed of to landfill (7,337 m3) Marine
Dumping (13,018
m3) |
Segregate
rock to avoid contamination from other wastes Sort on-site into : ·
Inert C&D material
(public fill) ·
C&D waste · Marine Deposit |
|
General Refuse |
Waste
paper, discarded containers, etc. generated from workforce |
1,040 kg per day (preliminary
estimate based on max. workforce of 1,600) |
585 kg/day (SCS) 260
kg/day (PTW) 195
kg/day (SCISTW) |
Refuse
transfer 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) |
Few cubic metres per month (preliminary estimate) |
Chemical
Waste Treatment Centre |
Recycle
by licensed companies. Stored
on-site within suitably designed containers |
Note:
(1) The figures of quantities are measures
in bulk volume.
9.83
Transportation
routings for disposal of C&D materials would depend on the PFRFs designated by CEDD during the detail
design stage as well as planning of the Contractor during the construction
stage. The possible transportation routings are identified as follows:-
Table 9.17 Possible
Disposal Routes to PFRFs
|
Routing |
PFRFs |
Description |
|
1 |
Tuen Maun Area
38 |
Possible Route
1: Victoria Road,
Connaught Road, Western Harbour Crossing, (Stonecutters Island), West Kowloon
Expressway, Tsing Kwai Highway, Cheung Tsing Tunnel, Ting Kau Bridge, Tai Lam
Tunnel, Route 3, Yuen Long Highway, Tuen Mun Road, Lung Mun Road. Possible Route
2: Island Eastern
Corridor, Gloucester Road, Connaught Road, Western Harbour Crossing,
(Stonecutters Island), West Kowloon Expressway, Tsing Kwai Highway, Cheung
Tsing Tunnel, Ting Kau Bridge, Tai Lam Tunnel, Route 3, Yuen Long Highway,
Tuen Mun Road, Lung Mun Road. Possible Route
3: Connaught Road,
Gloucester Road/Island Eastern Corridor, Cross Harbour Tunnel, Hong Chong
Road, Gascoigne Road, Ferry Street, West Kowloon Corridor, Kwai Chung Road,
Tsuen Wan Road, Tuen Mun Road, Lung Mun Road |
|
2 |
Chai Wan Barging
Point |
Possible Route
1: Possible Route
2: Cyberport Road,
Shek Pai Wan Road, Aberdeen Praya Road, Wong Chuk Hang Road, Aberdeen Road,
Canal Road, Victoria Park Road, Island Eastern Corridor. |
9.84
C&D waste
may be delivered to the SENT, NENT and WENT Landfills. The transportation
routings would depend on planning of the Contractor or waste collector during
the construction stage. The possible transportation routings are identified as
follows:-
Table
9.18 Possible Disposal Routes to Landfills
|
Routing |
Landfills |
Description |
|
1 |
SENT |
|
|
2 |
NENT |
Victoria Road,
Connaught Road, Western Harbour Crossing, (Stonecutters Island), Ching Cheung
Road, Tai Po Road, Tolo Highway, Fanling Highway, Sha Tau Kok Road, Wo Keng
Shan Road |
|
3 |
WENT |
By marine
route: West By land
route: Possible Route 1: Island Eastern
Corridor, Victoria Park Road, Gloucester Road, Connaught Road, Western Harbour
Crossing, (Stonecutters Island), West Kowloon Expressway, Tsing Kwai Highway,
Cheung Tsing Tunnel, Ting Kau Bridge, Tai Lam Tunnel, Route 3, Yuen Long
Highway, Tuen Mun Road, Lung Mun Road, Lung Kwu Tan Road, Nim Wan Road. Possible Route 2: Connaught Road,
Gloucester Road/Island Eastern Corridor, Cross Harbour Tunnel, Hong Chong
Road, Gascoigne Road, Ferry Street, West Kowloon Corridor, Kwai Chung Road,
Tsuen Wan Road, Tuen Mun Road, Lung Mun Road, Lung Kwu Tan Road, Nim Wan
Road. |
9.85
Wheel washing
system shall be provided at all exit points where vehicles will be leaving the
Site. All the C&D materials shall be delivered to appropriate designated
disposal sites by dump trucks fitted with mechanical covers. After the cover is
closed, any gap left on the system of enclosure should be less than 25mm wide
in according to the Technical Circular No.19/2005. With these provisions, it is
not anticipated to have considerable air pollution impacts on surroundings
during transportation of the C&D materials.
9.86
The
transportation routes of the C&D materials are mainly principal roads and
highways, increase of trucks merely constitute a small percentage of the
traffic flow. As such, it is not anticipated to have considerable increase in traffic
noise impact during transportation.
9.87
Under the
existing sludge disposal arrangement, the dewatered sludge from the SCISTW is
disposed of at EPD’s designated landfill
sites, including WENT Landfill and SENT Landfill. The dewatered sludge is delivered to the SENT Landfill by
road transport along the designated transportation route. For WENT landfill, the dewatered sludge is delivered using sludge transfer tanks by road transport to the nearby West
Kowloon Refuse Transfer Station (WKRTS) and then loaded onto marine vessels for
transportation by sea to the WENT Landfill pier.
9.88
According
to the updated Sludge Treatment Facility (STF) programme, it is anticipated to
be commissioned in 2012 which is 2 years ahead of the Project. Hence, upon
completion of HATS 2A, the STF should be ready to receive the sludge generated
in SCISTW.
9.89
As the most
preferable option, dewatered sludge would be transported from the SCISTW by
marine transport to WENT Landfill pier following the existing sludge transportation
arrangement and delivered to the STF by trucks or other means (such as conveyor
belt). The advantages of marine transport are that it is a more direct
transport mode which reduces traffic impact, particularly through Tuen Mun area
and along
9.90
Capacity of
the existing WKRTS for handling the increased loading needs to be assessed at
the detail design stage. Capacity of the WKRTS may not be sufficient to cater
for the increased sludge loading. A SCISTW berth developed at Stage 1 for
transportation of lime may be utilized for transportation of sludge to STF.
Shared usage of the SCISTW marine frontage for sludge and chemical supply
deliveries and the associated interfaces to optimize the berthing arrangement
is an operational issue. As the sludge vessels will be more regularly berthing
and for a longer period, liaison and coordination among the operators of the
sludge vessel, chemical supply vessel as well as the adjacent WKRTS would be
required.
9.91
During
emergency situation where the sludge from SCISTW needs to be transported by
road or any alternative barging point to WENT, the dewatered sludge should be
contained in water tight containers, skips or in truck-mounted containers to
ensure a water-tight seal in order to minimize the potential odour nuisance
during transportation.
Table
9.19 Possible Disposal Routes to STF
|
Description |
|
By marine route: West Kowloon Refuse Transfer
Station (adjacent to SCISTW) or SCISTW berth, WENT prier By land route (during emergency or abnormal condition): West Kowloon Expressway, Tsing
Kwai Highway, Cheung Tsing Tunnel, Ting Kau Bridge, Tai Lam Tunnel, Route 3,
Yuen Long Highway, Tuen Mun Road, Lung Mun Road, Lung Kwu Tan Road, Nim Wan
Road |
9.92
Odour
nuisance would be a concern if appropriate mitigation measures are not
implemented during loading and transportation of the sludge. Proposed
mitigation measures are given in later paragraphs. With implementation of the
proposed measures, the potential odour nuisance could be alleviated.
9.93
Currently,
skip is employed at PTWs of relatively higher capacities (such as Central, Wan
Chai East and North Point) while wheelie bin is used at the PTWs of smaller
size. The containers are fitted with plastic bags for bagging of the
screenings/grit. Significant odour emission from the loading operation is thus
not experienced. After the containers are fully loaded, the opening of the
plastic bag will be seal manually and stored for subsequent disposal. The
collected screenings/grit will be disposed of at the designated landfill sites,
i.e. SENT or NENT Landfill. The waste collectors will identify the most
suitable transportation route to the landfill.
9.94
Existing
transportation routes and disposal sties i.e. SENT or NENT Landfills are
expected to be continued during the operational phase of the upgraded PTWs. As
predicted in Table 9.10, there should not be a large increase in daily averaged
traffic flow. As such, it is not expected to have significant evaluated noise
impacts during transportation of the waste. As the screenings and grit would be
bagged and air sealed, it is not anticipated to have noticeable odour emitted
from loading and transportation of the wastes.
9.95
The
recommended general waste management hierarchy for the Project is as follows:-
l
Avoidance and minimization of waste generation;
l
Reuse of materials as far as practicable;
l
Recovery and recycling of residual materials where possible; and
l
Treatment and disposal according to relevant laws, guidelines and good
practices
9.96
Factors
such as geological and hydrogeological conditions, land and programming
constraints, construction method, public concerns, urban setting as well as locations of existing PTWs and
SCISTW, etc have limited the availability of alternative schemes for tunnel
alignment and design options. Measures have been adopted to minimize the
generation of C&D materials at the preliminary design stage, including:-
l
Considering tunnel construction options, i.e. construction by Drill and
Blast Method (D&B) or Tunnel Boring Machine (TBM), in the aspect of
generation of C&D materials ;
l
Adopting advance technology, e.g. use of horizontal directional drilling
(HDD) technique in the section between
l
Minimizing the number of production shafts during construction.
9.97
The main
difference between the D&B and TBM methods is that D&B utilizes
explosives to break the rock for excavation. D&B requires less mobilization
time compared with TBM but it is only suitable for rock stratum. TBM is
advanced by mechanical grinding action between the cutterhead and ground
surface.
9.98
Excavated
rock generated by TBM method will be disintegrated by the grinding and crushing
action of the cutterhead. Therefore, excavated rock can only be used as filling
materials. On the other hand, rock generated by D&B method may be processed
for use as aggregates, which is of a higher commercial value, depending on the
rock type. Granite rock can be used as aggregates while volcanic rock can only
be used as filling materials as this rock type would cause alkaline-aggregate
reaction. The predominant rock type for Tunnels J, K and L is granite and that
for Tunnels M, N and P is mainly volcanic rock.
9.99
The choice
of tunnel excavation method would depend on the predominant geology of the project
site. In the aspect of minimization of surplus C&D material, possibility to
re-use and quality of the excavated materials would be concerned. Having a
preliminary review of the pre-dominant geology of the project site and
considering the quality of excavated rock as above-mentioned, D&B method
would be a more preferable construction method (except for Tunnel Q) as the
excavated granite rock could be re-used as aggregate while that generated by
TBM method may not.
9.100
For Tunnel
Q, due to engineering constraint, HDD would be preferred. The rock generated by
HDD would be fractured, of low quality (Grades IV and V) and could not be
re-used.
9.101
The
capacities of some existing facilities at PTWs are inadequate to handle the
projected flow under the ultimate development scenario. Instead of upgrading
the building structure, replacement of existing E&M equipment with high
capacity facilities in addition to some minor civil modification works is
considered to minimize the scale of demolition and re-construction works so as
to minimize the C&D materials generated.
9.102
Careful
design, planning and good site management should be adopted to minimize
over-ordering and generation of waste materials such as concrete, mortars and
cement grouts.
9.103
The
Contractor should avoid, reduce or minimize the use of timber in temporary
works as far as possible. Steel formwork or plastic facing should be used to
increase the potential for reuse.
9.104
Ordering
procedures should be carefully controlled to minimize the amount of surplus
materials. Avoidance of over-ordering and segregation of materials would minimize the quantity of waste requiring
disposal.
9.105
As
mentioned in Section 9.20, stockpiling area for long term storage of C&D
materials generated at earlier construction stage for reuse or recycle at later
stage (such as backfilling of production shafts) may not be available. To
minimize the quantity of surplus C&D materials, aggregates and backfilling
materials should be recycled from fill banks operated by CEDD if the CEDD’s
fill bank is still under operation when the Contractor is carrying out
backfilling. However,
if the fill bank is decommissioned, the Contractor would be required to carry
out backfilling using fill materials from his own source.
9.106
Grade I/II
granite generated from SCS construction would be delivered to Lam Tei Quarry
for crushing into aggregate, as an alternative to deliver it to CEDD’s fill
bank for processing.
9.107
Reusable
steel or concrete panel shutters, fencing and hoarding and signboard should be
used as a preferred alternative to items made of wood, to minimise wastage of
wood. Attention should be paid to WBTC No. 19/2001 - Metallic Site Hoardings
and Signboards to reduce the amount of timber used on construction sites.
Metallic alternatives to timber are readily available and should be used rather
than new timber. Precast concrete units should be adopted wherever feasible to
minimize the use of timber formwork.
9.108
Prior to
export of material from the site, the potential for it to be reused should be
assessed. Waste separation methods should be followed to ensure that C&D
waste is separated at source. Whenever possible, suitable soft materials should
be used for landscaping and fine material should be separated out and used as
topsoil.
9.109
All waste
materials should be segregated into categories covering:
l
excavated materials suitable for reuse on-site;
l
excavated materials suitable for public filling reception facilities;
l
remaining C&D waste for landfill;
l
chemical waste; and
l
general refuse for landfill.
9.110
Proper
segregation and disposal of construction waste should be implemented. Separate
containers should be provided for inert and non-inert wastes.
9.111
Sorting is
important to recover materials for reuse and recycling. Specific area should be
allocated for on-site sorting of C&D materials and to provide a temporary
storage area for those sorted materials such as metals, concrete, timber,
plastics, glass, excavated spoils, bricks / tiles and waste papers. If area is
limited, all C&D materials should at least be sorted on-site into inert and
non-inert components. Non-inert materials (C&D waste) such as bamboo,
timber, vegetation, packaging waste and other organic materials should be reused
and recycled wherever possible and disposed of to designated landfill only as
the last resort. Inert materials (public fill) such as concrete, stone, clay,
brick, soil, asphalt and the like should be separated and reused in this or
other projects (subject to approval by the relevant parties in accordance with
the ETWB TCW No. 31/2004) before disposed of at a public filling reception
facility operated by CEDD. Steel and other metals should be recovered from
demolition waste stream and recycled.
9.112
The feasibility
of using recycled aggregates in lieu of virgin materials should be rigorously
considered during the detailed design and construction stages as stipulated in
WBTC No. 12/2002 and ETWB TCW No. 24/2004. In general, recycled aggregates are
suitable for use as fill materials in earthworks, road sub-base formation, and
drainage works.
9.113
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
Sort C&D waste from demolition of existing facilities to recover
recyclable portions such as metals;
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, PET bottles and paper by
providing separate labelled bins to enable these wastes to be segregated from
other general refuse generated by the work force;
l
Any unused chemicals or those with remaining functional capacity shall
be recycled; and
l
Proper storage and site practices to minimise the potential for damage
or contamination of construction materials.
9.114
Plan and
stock construction materials carefully to minimise amount of waste generated
and avoid unnecessary generation of waste.
9.115
Adverse
impacts related to waste management are not expected to arise, 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 waste
handling procedures
l
Develop and provide toolbox talk for on-site sorting of C&D
materials to enhance worker’s awareness in handling, sorting, reuse and
recycling of C&D materials.
l
Provision of sufficient waste disposal points and regular collection of
waste
l
Regular cleaning and maintenance programme for drainage systems, sumps
and oil interceptors
9.116
The
Contractor shall prepare and implement an Environmental Management Plan (EMP)
in accordance with ETWB TCW No. 19/2005 which describes the arrangements for
avoidance, reuse, recovery, recycling, storage, collection, treatment and
disposal of different categories of waste to be generated from the construction
activities. Such a management plan should incorporate site specific factors,
such as the designation of areas for segregation and temporary storage of
reusable and recyclable materials. The EMP should be submitted to the Engineer
for approval. The Contractor should implement the waste management practices in
the EMP throughout the construction stage of the Project. The EMP should be
reviewed regularly and updated by the Contractor, preferably in a monthly
basis. The EMP should take into account the recommended mitigation measures in
this EIA Report.
9.117
Unless
otherwise stated, all surplus C&D materials arising from or in connection
with the Works shall become the property of the Contractor when it is removed
from the Site. The Contractor will be responsible for devising a system to work
for on-site sorting of C&D materials and promptly removing all sorted and
process materials arising from the construction activities to minimize
temporary stockpiling on-site. The system should be included in the EMP
identifying the source of generation, estimated quantity, arrangement for
on-site sorting, collection, temporary storage areas and frequency of
collection by recycling Contractors or frequency of removal off-site.
9.118
Waste
hauliers holding appropriate permits should be used to collect and transport
wastes to the appropriate disposal points. The following measures should be
enforced to minimize adverse impacts:-
l
Handle and store wastes in a manner which ensures that they are held
securely without loss or leakage, thereby minimizing the potential for
pollution;
l
Licensed waste hauliers should only collect wastes prescribed by their
permits;
l
Remove waste in a timely manner;
l
Maintain and clean waste storage areas regularly;
l
Minimize windblown litter, dust or odour impacts during transportation
by either covering trucks or transporting waste in enclosed containers;
l
Obtain the necessary waste disposal permits from the appropriate
authorities, if required, in accordance with the Waste Disposal Ordinance (Cap
354), Waste Disposal (Chemical Waste) (General) Regulation (Cap 354) and the
Land (Miscellaneous Provisions) Ordinance (Cap 28);
l
Dispose of waste at licensed waste disposal facilities;
l
Develop procedures such as ticketing system to facilitate tracking of
loads, particularly for chemical waste, and to ensure that illegal disposal of
wastes does not occur; and
l
Maintain records of the quantities of wastes generated, recycled and
disposed.
9.119
C&D
materials should be disposed of at designated public filling reception
facilities or landfills. Disposal of these materials for use at other
construction projects is subject to the approval of the EPD, Engineer and/or
other relevant authorities, such as LandsD, PlanD, etc. Furthermore,
unauthorized disposal of C&D materials in particular on private
agricultural land is prohibited and may be subject to relevant enforcement and
regulating actions.
9.120
In order to
monitor the disposal of C&D materials and wastes and to control
fly-tipping, the disposal of public fill and C&D waste shall be controlled
through trip-ticket system in accordance with ETWB TCW No. 31/2004. A recording
system for the amount of waste generated, recycled and disposed, including the
disposal sites, should be established.
9.121
In addition
to the above measures, specific mitigation measures are recommended below for
the identified waste arisings to minimise environmental impacts during
handling, transportation and disposal of these wastes.
9.122
Good
quality reusable topsoil should be stockpiled for later landscaping works.
Stockpiles should be less than 2m in height, formed to a safe angle of slope
and covered with tarpaulin to prevent erosion during rainy season and to
minimize dust generation.
9.123
Control
measures for temporary stockpiles on-site should be taken in order to minimize
the noise, generation of dust, pollution of water and visual impact. These
measures include:
l
surface of stockpiled soil should be regularly wetted with water
especially during dry season;
l
disturbance of stockpiled soil should be minimized;
l
stockpiled soil should be properly covered with tarpaulin especially
when heavy rain storms are predicted;
l
stockpiling areas should be enclosed where space is available;
l
stockpiling location should be away from the water bodies; and
l
an independent surface water drainage system equipped with silt traps
should be installed at the stockpiling area.
9.124
In order to
minimise impacts resulting from collection and transportation of C&D
material for off-site disposal, the excavated materials arising from the SCS
construction, PTW upgrading works and SCISTW expansion should be reused on-site as far as practicable.
Surplus inert C&D material should be disposed of at public fill reception
facilities for other beneficial uses.
C&D waste, such as wood, steel and other metals should be reused or
recycled and, as a last resort, disposed of to landfill. It is recommended that
a suitable area be designated to facilitate the sorting process and a temporary
stockpiling area would be required for the separated materials. The Contractor
should identify these areas in the WMP.
9.125
Bentonite
slurries used in diaphragm wall construction should be reconditioned and reused
wherever practicable. The disposal of
residual used bentonite slurry should follow the good practice guidelines
stated in ProPECC PN 1/94 “Construction Site Drainage” and listed as follows:
l
If the disposal of a certain residual quantity cannot be avoided, the
used slurry may be disposed of at the marine spoil grounds subject to obtaining
a marine dumping licence from EPD on a case-by-case basis.
l
If the used bentonite slurry is intended to be disposed of through the
public drainage system, it should be treated to the respective effluent
standards applicable to foul sewers, storm drains or the receiving waters as
set out in the Technical Memorandum of Standards for Effluents Discharged into
Drainage and Sewerage Systems, Inland and Coastal Waters.
9.126
If
excavated material would be stockpiled
temporarily on-site, control measures as described in Chapter 3 (Air Quality
Assessment) and Chapter 6 (Water Quality Assessment) should be taken to prevent generation of dust and pollution
of stormwater drainage systems.
9.127
The
capacities of some existing facilities at PTWs are inadequate to handle the
projected flow under the ultimate development scenario. Instead of upgrading
the building structure, capacity of the following PTWs can be enhanced by
replacement of existing E&M equipment:-
l
Inlet pumping station and screening facilities of Wan Chai East PTW
l
Inlet pumping station of
l
Inlet pumping station of Aberdeen PTW
9.128
In order to
minimize C&D material (and other environmental impacts), it is proposed to
increase the capacities of the above facilities by replacement of existing
E&M equipment in addition to some minor civil modification works, such that
scale of the demolition and re-construction could be minimized.
9.129
It is
recommended to adopt a more compact treatment technology, e.g. vortex-type grit
trap instead of traditional detritor for grit removal. Due to smaller size of
the grit trap, the volume of excavation could thus be reduced.
9.130
By adopting
this upgrading approach, generation of about 30,000m3 (bulk volume)
of C&D materials (which would mainly
comprise waste concrete and non-inert C&D waste) could be avoided.
9.131
The workers
would be scattered along the proposed tunnel
alignment and different work sites. The most cost-effective solution is to provide
adequate number of portable toilets at temporary works areas or the PTWs to
ensure that sewage from site staff would be properly collected.
9.132
Depending on
site conditions, land availability, site activities and arrangement, locations
and number of portable toilets should be determined by the Contractor during
preparation of the Waste Management Plan (WMP).
9.133
General
refuse should be stored in enclosed bins, skips or compaction units separating from C&D material and disposed of at
designated landfill. A reputable waste
collector should be employed by the contractor to remove general refuse from
the site, separately from C&D material. A
temporary refuse collection point should be set up by the contractor to
facilitate the collection of refuse by licensed contractors. An enclosed and covered area shall be provided
to reduce the occurrence of ‘wind blown’ light material.
9.134
The removal
of waste from the site should be arranged on a daily or at least on every
second day by the Contractor to minimise any potential odour impacts, minimise
the presence of pests, vermin and other scavengers and prevent unsightly
accumulation of waste.
9.135
The
recyclable component of the municipal waste generated by the workforce, such as
aluminium cans, paper and cleansed plastic containers should be separated from
other waste. Provision and collection of recycling bins for different types of
recyclable waste should be set up by the Contractor. The Contractor should also
be responsible for arranging recycling companies to collect these materials.
9.136
The burning
of refuse on-site is prohibited under the Air Pollution Control Ordinance
(APCO) (Cap.311).
9.137
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, 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.
9.138
Suitable
containers should be used for specific types of chemical wastes, containers
should be properly labelled (English and Chinese in accordance with
instructions prescribed in Schedule 2 of the Regulations), resistance to
corrosion, stored safely and closely secure. Stored volume should not be kept
more than 450 liters unless the specification has been approved by the
9.139
Hard
standing, impermeable surfaces draining via oil interceptors should be provided
in works area compounds. Interceptors should be regularly emptied to prevent
release of oils and grease into the surface water drainage system after
accidental spillages. The interceptor should have a bypass to prevent flushing
during periods of heavy rain. Oil and fuel bunkers should be bunded and/or
enclosed on three sides to prevent discharge due to accidental spillages or
breaches of tanks. Bunding should be of sufficient capacity to accommodate 110%
of the volume of the largest container or 20% of the total volume of waste,
whichever is largest. Waste collected from any grease traps should be collected
and disposed of by a licensed contractor.
9.140
Lubricants,
waste oils and other chemical wastes are likely to be generated during the
maintenance of vehicles and mechanical equipment. Used lubricants should be
collected and stored in individual containers which are fully labelled in
English and Chinese and stored in a designated secure place. If possible, such
waste should be sent to oil recycling companies, and the empty oil drums
collected by appropriate companies for reuse or refill.
9.141
No
lubricants, oils, solvents or paint products should be allowed to discharge
into water courses, either by direct discharge, or as contaminants carried in
surface water runoff from the construction site.
9.142
As mentioned in Section 9.31, marine deposit would be mainly generated from excavation
works for upgrading of PTWs and expansion works of SCISTW. Prior to excavation
of the marine deposit layer, the deposit should be tested in accordance with
the ETWB TC(W) No. 34/2002 and
the results should be presented in a Preliminary Sediment Quality Report.
The marine deposit should be disposed of at the disposal site designated by the
Marine Fill Committee (MFC) or
Director
of Environmental Protection (DEP)
depending on the test results.
9.143
Silty or
clayey materials from alluvium and marine deposit shall be identified at
source. Non-contaminated alluvial and marine deposits should be transported by
leak proof trucks to eliminate water leakage during transportation to the
barging facility for open sea disposal.
9.144
Site visits
to existing SCISTW and the PTWs have been conducted to identify any mitigation
measures that can be incorporated into operation practice and design of the
future upgrading and extension works in order to reduce environmental nuisance
during loading, transportation and unloading process of sludge, grit and
screenings.
9.145
There are
some foreign examples in recycle and reuse of sludge as fertilizer or soil
conditioner. The sludge has to be pre-treated in order to produce a marketable
fertilizer or soil conditioner and the pathogen requirements. Heat drying and
composting are commonly adopted technologies for the pre-treatment works.
9.146
Nonetheless,
recycle and reuse of sludge generated from SCISTW is considered infeasible due
to the following considerations:-
l
Sea water is used for flushing. The sludge generated from SCISTW will
contain high levels of sodium and chlorides making the treated product
worthless as a fertilizer or soil conditioner;
l
Land spacing at SCISTW is already very limited. There is insufficient of
space at SCISTW to setup a pre-treatment plant and storage of end product.
Off-site treatment requires selection of a suitable land while a STF has
already been proposed next to WENT landfill Besides, odour problem could be a
concern during the pre-treatment process; and
l
There must be a demand of the end product to substantiate recycling and reuse
of the sludge.
9.147
During the
site inspections in 2006, significant distance was found between the discharge
openings and sludge tankers, thereby may cause odour release and sludge
spillage on the top of tankers. In design of the future sludge silos, the
discharge chute should be extended from the discharge openings down to the top
of sludge transfer tanks to prevent any spillage and odour emission during
sludge loading.
9.148
The sludge
tanks should be air-tight. Rotating
brushes or other alternative devises should be installed at the upper frame of
the sludge tank washing facilities to provide better cleaning of the surface around
the top loading opening of the sludge tanks. Prior to making such provision,
the top covers of the sludge transfer tanks should be water cleaned manually
after unloading. After the
implementation of these mitigation measures, it is expected that the odour
nuisance associated with sludge tanks during transportation from SCISTW to the
strategic landfills would be completely mitigated.
9.149
Sludge
transfer tanks should be equipped with the following features:-
l
Installation of rubber seals at the edges of sliding doors and their
frames to ensure air tightness; and
l
Installation of a 150 mm height stainless steel plate at the bottom of
unloading doors for preventing centrate leakage.
9.150
Since the
air tightness of tankers highly relies on the effectiveness of rubber seals at
the loading openings and unloading doors, odour leakage from tankers are
commonly resulted from the aging rubber seals. It is recommended to develop a
preventive maintenance programme for rubber seals of loading openings and
unloading doors of sludge transfer tanks to ensure the tightness of covers and
doors. Rubber seals should be regularly replaced within its design life as
specified by suppliers.
9.151
The
vehicles washing facilities should be able to brush the top of tankers.
Rotating brushes or other alternative devises should be installed at the upper
frame of vehicles washing facilities. If head space is insufficient for
installing additional brushes, manual cleaning and brushing the top of tankers
should be implemented in the first cleaning stage. Other current cleaning
practices for sludge transfer tankers should be continued.
9.152
A Waste
Management Plan is presented in Appendix
9.1. To ensure the appropriate handling of the C&D materials, the
Contractor shall be required to prepare
a WMP for submission to EPD. Apart from those conditions listed out in Appendix 9.1, this WMP shall also
contain:-
l
Details of the construction wastes such as location of the stockpile
sites, breakdown of different categories of waste, disposal routings and the
timing for peak disposal, etc; and
l
A trip-ticket system to monitor waste disposal arising from the Project.
9.153
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 Project.
9.154
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 shall form the basis of the site Waste
Management Plan to be developed by the Contractor in the construction stage.
9.155
Waste types
generated by the construction activities are likely to include C&D material
(from excavation and tunnelling works), general refuse from the workforce, and
chemical waste from the maintenance of construction plant and equipment. 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 phase.
9.156
The main
waste types to be generated during the operation phase would be grit and
screenings collected at the upgraded PTWs and the SCISTW, and sewage sludge
collected at the SCISTW. The collection,
transportation and disposal practices of the grit and screenings would follow
the existing arrangements currently in operation at the PTWs and SCISTW. The dewatered sludge from the SCISTW would be
disposed of
to the proposed Sludge Treatment
Facilities which would be commissioned in 2012 under the current planned
arrangement.
[1] Project Profile for “Sludge Treatment Facilities” (ESB-169/2007) submitted to EPD on 20 August 2007.