6.1
Introduction
6.1.1
This section identifies the potential waste arising from
the construction and operation of the Project and assesses the potential
environmental impacts associated with waste handling and disposal. Options for
avoidance, minimization, reuse, recycling, treatment, storage, collection,
transport and disposal of such wastes are examined.
6.1.2
Where unacceptable impacts are identified, appropriate
mitigation measures and good site practices are recommended. Disposal options
will be outlined for each type of waste, and the responsibilities for disposal
or recycling discussed.
6.1.3
This section also identifies and assesses any potential
land contamination issues arising from the Project and to propose remediation
measures if required.
6.2
Relevant
Legislation, Policies, Standards and Criteria
Legislation, Circulars, Guidelines related to
Waste Management
6.2.1
The following legislation relates to the handling,
treatment and disposal of wastes and will be used in assessing potential
impacts:
·
Environmental Impact Assessment
Ordinance (Cap. 499);
·
Waste Disposal Ordinance (Cap. 354);
·
Waste Disposal (Chemical Waste)
(General) Regulation (Cap. 354C);
·
Waste Disposal (Charges for Disposal of
Construction Waste) Regulation (Cap. 354N);
·
Land (Miscellaneous Provisions)
Ordinance (Cap. 28);
·
Public Health and Municipal Services
Ordinance (Cap. 132) – Public Cleansing and Prevention of Nuisances Regulation;
and
·
Dumping at Sea Ordinance (Cap. 466).
6.2.2
The
following documents, circulars and guidelines which relate to waste management
and disposal will also be referred to during this study:
·
Technical Memorandum on Environmental Impact Assessment
Process (EIAO-TM) - Annexes 7 and Annex 15;
·
Code of Practice on the Packaging, Labelling and Storage of
Chemical Wastes, EPD (1992);
·
WBTC No. 2/93 - Public Dumps;
·
WBTC No. 2/93B - Public Filling Facilities;
·
WBTC No. 16/96 - Wet Soil in Public Dumps;
·
WBTC No. 4/98 & 4/98A - Use of Public Fill in Reclamation
and Earth Filling Projects;
·
WBTC No. 12/2000 - Fill Management;
·
WBTC No. 19/2001 - Metallic Site Hoardings and Signboards;
·
WBTC No. 12/2002 - Specifications Facilitating the Use of
Recycled Aggregates;
·
ETWB TCW No. 34/2002 - Management of Dredged/Excavated
Sediment;
·
ETWB TCW No. 24/2004 - Specifications Facilitating the Use of
Concrete Paving Units Made of Recycled Aggregates;
·
ETWB TCW No. 19/2005 - Environmental Management on
Construction Sites;
·
DEVB TCW No. 6/2010 - Trip-ticket System for Disposal of
Construction & Demolition Material;
·
DEVB TCW No. 8/2010 - Enhanced Specification for Site
Cleanliness and Tidiness;
·
DEVB TCW No. 2/2011 – Encouraging the Use of Recycled and
other Green Materials on Public Works Projects;
·
DEVB TCW No. 9/2011 – Enhanced Control Measures for
Management of Public Fill; and
·
Project Administration Handbook for Civil
Engineering Works (2014 Edition) – section 4.1.3 relating to Construction and
Demolition Materials)
6.2.3
The
following guidelines are related to land contamination:
·
Practice Guide for Investigation and Remediation of
Contaminated Land;
·
Guidance Note for Contaminated Land Assessment and
Remediation; and
·
Guidance Manual for Use of Risk-Based Remediation Goals
(RBRGs) for Contaminated Land Management.
6.3
Assessment
Methodology
6.3.1
Reference
has been made to the methodology laid out in the EIAO-TM (Annexes 7 and 15).
The assessment of potential waste management implications include the following
tasks:
·
Estimation of the types and quantities of waste arisings;
·
Evaluation of potential impacts from the handling,
collection, transportation and disposal of waste; and
·
Proposal of mitigation measures for the waste management.
6.3.2
In
order to identify and evaluate the potential contamination impacts associated
with the Project, a desktop study has been conducted to review the current and
historical land uses. Site inspections have been conducted to identify any
potential contamination hotspots and its current site condition.
6.4
Sources
and Types of Waste arising from the Project
Construction Phase
6.4.1
The
proposed sewerage works include the following construction activities:
·
site clearance and demolition works;
·
expansion of the Sha Tau Kok Sewage Treatment Works (STKSTW);
·
construction of a temporary sewage treatment plant (TSTP);
·
demolition of the existing Sha Tau Kok Sewage Pumping Station
(STKSPS) and decommissioning of the rising main between STKSPS and STKSTW;
·
construction of new
gravity sewers; and
·
decommissioning of the existing
submarine outfall and construction of a new one.
6.4.2
These
construction activities will result in the generation of a variety of
Construction and Demolition (C&D) materials. The C&D materials are
usually mixed consisting of inert C&D materials such as soil, rock, asphalt,
concrete, brick and bentonite slurry, etc. and non-inert C&D materials
comprising metal, timber, paper and plastic.
Sediment, chemical waste and general refuse may also arise as a result
of construction activities. The likely waste generated from the construction of
the Project can be classified into the following main categories:
·
site clearance / demolition materials;
·
excavated materials;
·
sediment;
·
bentonite slurry;
·
chemical waste; and
·
general refuse.
Operational Phase
6.4.3
The
following waste will be generated during operation of the TSTP and the expanded
STKSTW:
·
sludge;
·
solid waste ; and
·
chemical waste.
6.5
Impact
Assessment and Evaluation
Construction
Phase
Inert C&D Materials
Site Clearance / Demolition Works
6.5.1
Site
clearance and demolition works will be required for the works, thus generating
unwanted materials during construction.
6.5.2
Parts
of the existing STKSTW will need to be demolished to facilitate expansion
works. Upon completion of the expansion works of STKSTW, the existing sewage
pumping station at Shun Hing Street will be decommissioned and demolished. Site
clearance / demolition works will generate concrete rubble, plastics, metals,
glass, asphalts, wood, vegetation and refuse. In addition, existing road
surface for the gravity sewers will have to be broken up thus generating broken
concrete and asphalt. As these materials are likely to be in a deteriorating
condition, the potential for reuse of such materials on site is very limited. Approximately 4,885 m3 of inert C&D materials
consisting of concrete rubbles and broken asphalt and approximately 23 m3
of non-inert C&D materials will require disposal to public fill reception
facilities (either Tseung Kwan O (TKO) Area 137 Fill Bank or Tuen Mun (TM) Area
38 Fill Bank) and landfill (assume to be NENT Landfill) respectively.
Excavation Works
6.5.3
The
majority of C&D materials generated from the Project will be from
excavation works associated with the expansion of the STKSTW, gravity sewers
and from the HDD works for the new submarine outfall. It is noted from historic
aerial photos that some of the works areas are reclaimed land. According to
site investigation results and based on the proposed excavation depth, the excavated
materials will be mainly inert C&D materials consisting of general fill. The
excavated materials from HDD works for the new submarine outfall will also be
mainly inert C&D materials consisting of rock cuttings. The C&D materials will consist of about
45,795 m3 of soils and about 3,081 m3 of rocks.
Approximately 9,500 m3 and 1,609 m3 of soils and rocks could be reused in the STKSTW works and gravity sewers works
respectively. As such, the estimated inert C&D
materials requiring disposal to public fill reception facilities (either TKO
Area 137 Fill Bank or TM Area 38 Fill Bank) will be 37,767 m3
(consisting of 36,295 m3 of soils and 1,472 m3 of rocks).
An average of about 6 truck trips per day is envisaged. Disposal routing will
be via Sha Tau Kok Road, Fanling Highway, Tolo Highway, Tate’s Cairn Tunnel,
Kwun Tong Bypass, Tseung Kwan O Road and Wan Po Road to the TKO Area 137 Fill
Bank or via Sha Tau Kok Road, San Tin Highway, Yuen Long Highway and Lung Mun
Road to the TM Area 38 Fill Bank.
Non-inert C&D Materials
6.5.4
Non-inert
C&D materials from construction activities will generate waste from removal
of vegetation, metal and timber formwork, bamboo scaffolding and packaging
materials. Such waste should be sorted for reuse and recycling as far as
possible before disposal to landfill (assume to be NENT Landfill).
Approximately 275 m3 of non-inert C&D materials will be
generated of which about 23 m3 will be from site clearance /
demolition works and the remaining 252 m3 will be from other
construction works. Together with general refuse generated during construction,
about 1 truck trip every other day is envisaged. Disposal route will be via Sha
Tau Kok Road and Wo Keng Shan Road to the NENT Landfill.
Marine Sediment
6.5.5
To
minimize the generation of excavated marine sediments, various construction
methods for the new submarine outfall have been considered (see Section 2). With the use of HDD, the
need for sediment excavation during construction of the new submarine outfall
can be significantly reduced. Nonetheless, localised excavation of a small
seabed area will be necessary to facilitate the construction of the diffuser
for the new submarine outfall. Based on the engineering
design, the existing seabed will be exposed for a length of approximately 54m
by excavation method. The trapezoidal trench will be approximately 22m top wide
(3m bottom wide) and 4.5m deep. The volume of marine sediments to be excavated during
construction of the submarine outfall and requiring disposal is about 3,040 m3.
6.5.6
Reusing
the sediment at the outfall diffuser site is not possible as the void space
surrounding the diffuser will need to be backfilled with armour rock for
protection purpose. Reusing the sediment as backfill material in other parts of
this Project is also not possible as the works will generally require
exportation of fill rather than import of fill as well as the limited space
available on-site for handling and storage of the sediment. Furthermore, the
sediment to be reused will need to be transported by dump trucks from the Sha
Tau Kok public pier to the works site which could generate additional
environmental nuisance due to the handling/transport of sediment with high
water content. Disposal to the marine disposal site is therefore considered
more practical.
6.5.7
A Sediment Sampling and Testing
Plan (SSTP) in accordance with ETWB TCW No. 34/2002 was conducted and submitted
to EPD for approval. The SSTP was approved by EPD on 19 November 2015.
Rationale for sediment removal was approved by MFC/CEDD on 22 December 2015.
Copy of the relevant correspondences and the SSTP are enclosed in Annex 6A. Sediment
sampling and laboratory testing was undertaken on 12 February 2016 in the
proposed excavation area in accordance with the approved SSTP. At the sampling
location, surface grab sample was taken using Van Veen Grab Sampler lowered
from a boat. For sampling below seabed level, gravity coring was employed. The
sampling tube was manually driven from the boat into the seabed to obtain the
sediment sample at the required depth. Details of the sediment sampling and
results of the chemical test are presented in Annex 6B. From
the chemical testing results, only Category L sediment was identified. In
accordance with ETWB TCW No. 34/2002, Type 1 – Open Sea Disposal should be adopted
for Category L sediment. The disposal of marine sediment will be via sea route
by barge from the works site to the marine disposal site allocated by MFC/CEDD.
Approximate 5 barge trips is anticipated.
Bentonite Slurry
6.5.8
Drilling
fluid is used in HDD mainly to cool and lubricate the bit and drill string,
transport cuttings to surface and stabilize the borehole. The most common type
of drilling fluid is bentonite mixed with water to form a viscous, shear
thinning material often referred to as bentonite slurry. The amount of bentonite slurry for use during the drilling works and
requiring disposal is estimated to be approximately 6,500 m3 with
reference to the best available design information.
6.5.9
Bentonite
slurry is normally recycled and reused during the drilling process. Inadvertent
release of bentonite slurry or improper disposal may lead to contamination of
the nearby water bodies. The storage, treatment and recycling of the bentonite
slurry (drilling fluid) will only be conducted at the proposed launching site
in STKSTW. Spent bentonite slurry will be disposed to public fill reception
facilities (either TKO Area 137 Fill Bank or TM Area 38 Fill Bank) via land
route or sea route depending on Contractor’s proposal.
Chemical Waste
6.5.10
Wastes
classified as chemical waste are listed in the Waste Disposal (Chemical Waste)
(General) Regulation. Where the construction processes produce chemical waste,
the Contractor must register with EPD
as a chemical waste producer. In general, chemical waste would mainly arise
from maintenance of construction equipment. These may include the following
items:
·
scrap batteries or spent acid/alkali from their maintenance;
·
used engine oils, hydraulic fluids and waste fuel;
·
spent mineral oils/cleaning fluids from mechanical machinery;
and
·
spent solvents/solutions from equipment cleaning activities.
6.5.11
Chemical
wastes pose serious environmental and health and safety hazards if not stored
and disposed of in an appropriate manner as outlined in the Chemical Waste
Regulation. These hazards include:
·
toxic effects to works;
·
adverse effects on water quality from spills; and
·
fire hazards.
6.5.12
The
amount of chemical waste cannot be accurately predicted at this stage since it
largely depends on the Contractor’s housekeeping and equipment maintenance
requirement. The amount is anticipated to be small in the order of about 50
litres per month and will be disposed of at regular interval when sufficient
quantities warrant disposal (tentatively assume 1 trip per month). It is
recommended that the Contractors should implement good housekeeping measures to
minimise the amount of chemical waste generated. The amount of chemical waste
to be generated will be quantified in the monthly Waste Flow Table to be
prepared by the Contractor. Disposal
routing will be via Sha Tau Kok Road, San Tin Highway, Tai Lam Tunnel, Tsing
Long Highway and Tsing Yi Road to the Chemical Waste Treatment Centre.
General Refuse
6.5.13
General
refuse will be generated by the site staff and construction workers during the
construction period. This includes food scraps, waste papers, plastic
containers, packaging materials, etc. The amount of municipal waste that may be
produced is dependent on size of workforce at site.
6.5.14
It
is expected not more than 50 site staff and construction workers will be
working on site at any one time. With a general refuse generation rate of 0.65
kg per person per day, the amount of general refuse to be generated will be
about 32.5 kg per day. Together with non-inert C&D materials generated
during construction, about 1 truck trip every other day is envisaged. Disposal
route will be via Sha Tau Kok Road and Wo Keng Shan Road to the NENT Landfill.
6.5.15
The
storage of general refuse has the potential to give rise to a variety of
adverse environmental impacts. These include odour if putrescible food waste is
not collected frequently, water quality impacts if waste enters water bodies
and visual impact from windblown litter. The refuse may attract pests and
vermin if the storage areas are not well maintained and cleaned regularly. In
addition, disposal of waste at sites other than approved waste transfer or
disposal facilities can also lead to environmental impacts.
6.5.16
Handling
and disposal of general refuse should cope with the presence of peak workforce
during the construction period. Provided that the refuse is stored and
transported in accordance with proper practices and disposed at approved
disposal facilities, potential environmental impact is not expected.
6.5.17
A
summary of the main C&D materials and wastes expected to arise from the
Project and the estimated quantities is presented in Table 6.1.
Table 6.1 – Preliminary
Estimated Quantities of C&D Materials, Sediment and Different Types of
Waste during the Construction Phase
|
Types
|
Estimated Quantities*
|
|
Bentonite
|
6,500 m3 (see Note 1)
|
|
Inert C&D Materials (granitic
rock – Grade III or below)
|
3,081 m3 (see Note 2)
|
|
Inert C&D Materials (soft
public fill)
|
45,795 m3 (see Note 2)
|
|
Inert C&D Materials (artificial
hard material)
|
4,885 m3 (see Note 2)
|
|
Sediment
|
3,040 m3 (see Note 3)
|
|
Chemical Waste
|
50 litres/month (see Note 4)
|
|
Non-inert C&D Materials
|
275 m3 (see Note 5)
|
|
General Refuse
|
32.5 kg/day (see Note 5)
|
|
Approximate timing * : mid 2017 – mid2021
|
Notes:
* Tentative construction
programme of mid 2017 – mid 2021 may be subject to further changes.
The estimated quantities are based on preliminary design of the proposed works
and the best available ground investigation data. The waste arising will
largely depend on the contractor works programme and activities. The contractor
will be required to provide detailed estimation of all the C&D materials
and waste generated on-site using the Monthly / Yearly Summary Waste Flow Table
as required under ETWB TCW No. 19/2005.
1
The
amount of bentonite used and requiring disposal will depend on the Contractor
HDD works procedure. Bentonite should be recycled and reused during the
drilling process. Any spent bentonite unsuitable for reuse should be suitably
dewatered for disposal at public fill reception facilities.
2
Topsoil,
rocks and suitable materials should be stockpiled for later reuse in this or
other projects subject to approval by relevant parties in accordance with the
DEVB TCW No. 6/2010. The amount of materials that can be reused in this Project
will be examined further during the detailed design stage. Artificial hard
materials include concrete rubble and broken asphalt which are not suitable for
reuse in this Project.
3
According to the chemical testing results, the
sediment to be excavated is classified as Category L sediment.
4
The
amount of chemical waste will be dependent on the contractor’s on-site
maintenance programme and the number of equipment and vehicles used on-site.
Chemical waste should be collected by licensed contractor and properly disposed
of at approved chemical waste treatment facilities (e.g. the Chemical Waste
Treatment Centre at Tsing Yi). Chemical waste will be generated throughout the
construction period.
5
The
amount of non-inert C&D materials and general refuse will depend on the
contractor’s operating procedures and housekeeping practices as well as the
size of the workforce on-site. All such materials should be sorted, reused and
recycled before disposal at designated outlets. General refuse will be
generated throughout the construction period.
6.5.18
Out
of the total 53,761 m3 of inert C&D materials generated, it is
tentatively anticipated that about 20% of soft public fill can be reused in
this Project.
Operational Phase
Sludge
6.5.19
During
the operational phase, sludge will be generated after the sewage treatment
process. The sludge will be dewatered on-site at the TSTP / STKSTW before
delivered via Shek Wu Hui STW (SWHSTW) to the Sludge Treatment Facility (STF) at
Tuen Mun for disposal. The production rate for the TSTP, Phase 1 expanded
STKSTW and Phase 2 expanded STKSTW is expected to be about 1.7, 3.5 and 7 m3
per day respectively.
6.5.20
Sealed sludge tankers will be used to transport the
sludge at around 1 trip per day via Fanling Highway, Po Shek Wu Road, SWHSTW,
San Tin Highway, Yuen Long Highway, Lung Mun Road to the Tuen Mun STF. The holding area of the dewatered sludge and
loading of the sludge will be located in enclosed area of the STKSTW, in which
odourous air will be drawn to a deodourization unit for treatment before release
to the atmosphere. As the sludge holding and transfer process will be in
enclosed environment, no adverse odour impact is expected.
Solid Waste
6.5.21
Screenings
will be generated from the fine screens at the sewage inlet. These screenings
will be removed regularly to maintain efficiency of the screen. It will be
collected and stored in covered containers for disposal at landfill (assume to
be the NENT Landfill) at around 2-3 times per week. The membrane filters will
be replaced when worn, and will be disposed of at landfill. The amount of screenings is estimated to be approximately 1.3 m3
per day with reference to the best available design information.
6.5.22
In addition, small amount of general refuse will be
generated from the operators. General refuse may include food waste, plastic,
glass bottles, aluminium cans and waste paper. About 6 operators are expected
to be working at the STKSTW each day. With an estimated general refuse
generation rate of 0.65 kg per person per day, the amount of general refuse to
be generated will be about 4 kg per day. This will be collected for disposal at
landfill (assume to be the NENT Landfill) after
recyclable materials are separated, together with the screenings and worn
filters at around 2-3 times per week. Disposal routing will be via Sha Tau Kok
Road and Wo Keng Shan Road to NENT Landfill.
Chemical Waste
6.5.23
A small amount of chemical waste will be generated from
normal operation and maintenance of the STW. This may include spent UV lamps,
scrap batteries and lubricating oil. The chemical waste will be collected by
licensed waste collectors at regular interval when sufficient quantities
warrant disposal to the Tsing Yi Chemical Waste Treatment Centre. Disposal
routing will be via Sha Tau Kok Road, San Tin Highway, Tai Lam Tunnel, Tsing
Long Highway and Tsing Yi Road to the Chemical Waste Treatment Centre. All
chemical wastes should be properly stored, labelled and removed by licensed
waste collectors in accordance with the Waste Disposal (Chemical Waste)
(General) Regulation.
6.6
Mitigation
Measures
Construction
Phase
General
6.6.1
Upon
appointment, the main Contractor of each construction contract should prepare
and implement an Environmental Management Plan (EMP) in accordance with ETWB
TCW No. 19/2005 – “Environmental Management on Construction Sites” which should
describe the arrangements for avoidance, reduction, reuse, recovery, recycling,
storage, collection, treatment and disposal of different categories of waste to
be generated from the construction activities. The EMP should incorporate site
specific factors, such as the designation of areas for segregation and
temporary storage of reusable and recyclable materials. The waste management
plan now becomes part of the EMP. 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 (preferably monthly) by the Contractor. The EMP
should take into account the recommended mitigation measures in the approved
EIA report.
6.6.2
The
Contractor should refer to the estimated quantities in this EIA to facilitate
him in the preparation of the EMP.
6.6.3
The
Contractor should nominate an appropriate person, such as site agent or
environmental officer, to be responsible for good site practices, arrangement
for collection and effective disposal of all wastes generated at the site to an
approved facility. Training of construction staff should be undertaken by the
Contractor about the concept of site cleanliness and appropriate waste
management procedures. The Contractor should 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. Requirements for
staff training should be included in the EMP.
6.6.4
Good
planning and site management practices should be employed to eliminate over
ordering or mixing of construction materials to reduce wastage. Proper storage
and site practices will minimise the damage or contamination of construction
materials. Regular cleaning and maintenance of the waste storage area should be
provided.
6.6.5
Where
waste generation is unavoidable, the potential for recycling or reuse should be
rigorously explored. If waste cannot be recycled, disposal routes described in
the EMP should be followed. A recording system for the amount of wastes
generated, recycled and disposed (including the disposal sites) should be
implemented in accordance with DEVB TCW No. 6/2010. In order to monitor the
disposal of C&D materials and solid wastes at public fill reception
facilities and landfills and to control fly-tipping, a trip-ticket system should
be included.
6.6.6
Imported
soft fill and rocks, if required, should be sourced from CEDD’s fill bank,
other projects or other approved sources instead of using new materials.
Approval from the Engineer and all other relevant parties should be obtained by
the Contractor before importation of the fill materials.
On-site Sorting, Reuse and Recycling
6.6.7
All
waste materials should be segregated into categories covering:
·
inert C&D materials suitable for public filling
facilities;
·
recyclable materials / waste;
·
non-inert C&D materials for landfill;
·
spent bentonite for public filling facilities;
·
chemical waste; and
·
general refuse for landfill.
6.6.8
Proper segregation and disposal
of construction waste should be implemented. Separate containers should be
provided for inert C&D materials and non-inert C&D materials.
6.6.9
The reuse of excavated materials within this Project
should be adopted as far as practicable. The opportunity of reusing the
material in other projects in North District should also be explored.
6.6.10
Sorting
is important to recover materials for reuse and recycling. Specific areas
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 spoil, bricks / tiles and waste paper. If
the area is limited, all C&D materials should at least be sorted on-site
into inert and non-inert components. Non-inert C&D materials (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 a last resort. Inert C&D materials such as concrete, rock, clay,
brick, soil, asphalt and the like should be separated and reused in this or
other projects (subject to approval by the relevant parties) before disposed of
at public fill reception facilities operated by Civil Engineering and
Development Department (CEDD). Steel and other metals should be recovered from
demolition waste stream and recycled.
6.6.11
The
reuse of inert C&D materials such as soil, rock and broken concrete should
be maximised. Waste should be separated
into fine, soft and hard materials.
6.6.12
Prior
to export of material from the site, the potential for it to be reused should
be assessed. Most C&D materials can
easily be reused with minimum processing.
Waste separation methods should be followed to ensure that non-inert
C&D materials are separated at source.
Suitable soft materials should be used for landscaping and grading of
embankments. Fine material should be separated out and used as topsoil.
6.6.13
The
feasibility of using recycled aggregates in lieu of virgin materials should be
rigorously considered during the detailed design and construction phases. In
general, recycled aggregates are suitable for use as fill materials in
earthworks, road sub-base formation, and drainage works. Recycled aggregates
can also be used in concrete (up to Grade 35) for mass concrete walls and other
minor structures such as planter boxes, toe wall planters and pavement, etc.
Site Clearance / Demolition Works
Excavation Works
6.6.14
All
C&D materials should be sorted on-site into inert and non-inert components
by the Contractor. Non-inert C&D materials such as wood, glass and plastic
should be reused and recycled before disposal to a designated landfill as a
last resort (currently assume to be the NENT Landfill). Inert C&D materials
(should be reused on-site or in other projects approved by relevant parties
before disposed of at public fill reception facilities. Steel and other metals
if any should be recovered from C&D materials and recycled.
6.6.15
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 repose
and hydroseeded or covered with tarpaulin to prevent erosion during the rainy
season and to minimise dust generation.
6.6.16
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:
·
surface of stockpiled soil should be regularly wetted with
water especially during dry season;
·
disturbance of stockpiled soil should be minimized;
·
stockpiled soil should be properly covered with tarpaulin
especially when heavy rain storms are predicted;
·
stockpiling areas should be enclosed where space is
available;
·
stockpiling location should be away from the water bodies;
and
·
an independent surface water drainage system equipped with
silt traps should be installed at the stockpiling area.
6.6.17
The
identification of final disposal sites for C&D materials generated by the
construction works will be considered during the detailed design stage of the
Project when the volume and types of C&D materials can be more accurately
estimated. The Public Fill Committee and Marine Fill Committee of CEDD should
be consulted on designated outlets for inert C&D materials and
sediment, whilst EPD should be
consulted on landfills for non-inert C&D
materials . The inert C&D materials
to be disposed to public fill
reception facilities must consist entirely of inert construction materials.
Disposal of non-inert C&D
materials to landfill must not have more
than 50% by weight of inert material. The non-inert C&D materials delivered for landfill disposal should contain
no free water and the liquid content should not exceed 70% by weight.
6.6.18
In
order to avoid dust or odour impacts, any vehicles leaving a works area
carrying C&D materials should have their load covered up
before leaving the construction site.
6.6.19
C&D
materials should be disposed of at designated public fill reception facilities
or landfills. Reuse of inert C&D materials
at other construction projects
is subject to the approval of the relevant project proponents, 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. The Contractor shall refer and strictly follow the
trip-ticket system for the disposal of C&D materials as stipulated in the
DEVB TCW No. 6/2010. According to the Waste Disposal (Amendment) Ordinance
2013, to enhance the control of deposition or dumping of construction waste on private land, prior
acknowledgement from EPD must be obtained before the commencement of the
depositing activity. Furthermore, copy of the acknowledgment form must be
display in a conspicuous place on the land lot before depositing the waste.
Marine Sediment
6.6.20
With reference to the Sediment
Quality Report in Annex 6B, only Category L sediment was identified. In accordance with ETWB
TCW No. 34/2002, Type 1 – Open Sea Disposal should be adopted for the disposal
of 3,040 m3 excavated sediment during construction of the proposed
outfall diffuser. The location of marine disposal site should be sought with
MFC/CEDD. The Contractor shall obtain a Marine Dumping Permit
in accordance with the Dumping at Sea Ordinance. The Contractor should provide separate
submissions (e.g. Sediment Sampling and Testing Plan / Sediment Quality Report)
to EPD / DASO authority when applying for the Marine Dumping Permit under the
Dumping at Sea Ordinance.
Bentonite Slurry
6.6.21
Bentonite
slurry used in the drilling works should be treated and recycled at the works
area in STKSTW. Any bentonite that is not suitable for recycling should be
suitably dewatered before disposed of at public fill reception facilities.
Chemical Waste
6.6.22
Where
the construction processes produce chemical waste, the Contractor must register
with EPD as a chemical waste producer. Wastes classified as chemical wastes are
listed in the Waste Disposal (Chemical Waste) (General) Regulation. These
wastes are subject to stringent disposal routes. EPD requires information on
the particulars of the waste generation processes including the types of waste
produced, their location, quantities and generation rates. A nominated contact
person must be registered with EPD. An updated list of licensed chemical waste
collector can be obtained from EPD.
6.6.23
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 Wastes published by EPD, and
should be collected by a licensed chemical waste collector.
6.6.24
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, safely stored and securely closed. Stored volume should not be kept
more than 450 liters unless the specification has been approved by the EPD. Storage area should be enclosed by three sides
by a wall, partition of fence that is at least 2 m height or height of tallest
container with adequate ventilation and space.
6.6.25
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.
6.6.26
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.
6.6.27
The
registered chemical waste producer (i.e. the Contractor) has to arrange for the
chemical waste to be collected by licensed collectors. The licensed collector
should regularly take chemical waste to a licensed chemical waste treatment
facility (such as the Chemical Waste Treatment Centre in Tsing Yi). A trip
ticket system operates to control the movement of chemical wastes.
6.6.28
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.
Non-inert C&D Materials
6.6.29
All wooden materials used
on-site should be kept separate from other wastes to avoid damage and to
facilitate reuse. Timber which cannot be reused should be sorted out from other
waste and stored separately from all inert C&D materials before being disposed of to
landfill.
6.6.30
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. 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.
6.6.31
Only
waste material need to be taken to a landfill. It should be separated from
recyclable wood and steel materials. As for all waste types these materials
should be reused on-site or other approved sites before disposal is considered
as an option. Disposal to landfill
should only be considered as a final option.
Contractors are responsible for storage of re-useable materials on-site.
General Refuse
6.6.32
General
refuse generated on-site should be stored in enclosed bins or skips and
collected separately from other construction and chemical wastes and disposed
of at designated landfill. A temporary refuse collection point should be set up
by the Contractor at the works area to facilitate the collection of refuse by
licensed waste collector. 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.
6.6.33
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.
6.6.34
A
summary of the estimated C&D materials, sediment and different types of waste
and their disposal routes are tabulated in Table
6.2. The preliminary reuse / disposal programme breakdown is shown in Table 6.3.
Table
6.2 - Summary of the Quantities and Disposal Routes of C&D Materials,
Sediment and Different Types of Waste Arising from the Project during the
Construction Phase
|
Construction
Activity
|
Estimated
Quantities*
|
|
Inert
C&D Materials, m3
[A]
|
Inert
C&D Materials re-use in the Project, m3
[B]
|
Inert
C&D Materials for Disposal, m3
[C=A-B]
|
Non-inert C&D Materials (C&D Waste), m3
[D]
|
Bentonite, m3
[E]
|
Total C&D Materials generated and requiring Disposal, m3
[F=C+D+E]
|
Sediment, m3
|
Chemical
Waste
|
General
Refuse
|
|
Site
clearance and demolition works
|
3,552
|
0
|
3,552
|
18
|
-
|
3,570
|
-
|
50 litres/month
(see Note 6)
|
32.5 kg/day
|
|
Modification
and upgrading of STKSTW and construction of a TSTP
|
42,305
|
9,500
|
32,805
|
213
|
-
|
33,018
|
-
|
|
Construction
of submarine outfall
|
3,216
|
0
|
3,216
|
16
|
6,500
|
9,732
|
3,040
|
|
Laying of
gravity sewers
|
4,597
|
1,609
|
2,988
|
23
|
-
|
3,011
|
-
|
|
Demolition
of STKSPS
|
91
|
0
|
91
|
5
|
-
|
96
|
-
|
|
Total
|
53,761
|
11,109
|
42,652
|
275
|
6,500
|
49,427
|
3,040
|
|
Potential Disposal
Routes (see Note 1)
|
-
|
-
|
(see Note 2)
|
(see Note 3)
|
(see Note 4)
|
-
|
(see Note 5)
|
(see Note 6)
|
(see Note 3)
|
Notes:
* The
estimated quantities are based on the preliminary design of the proposed
sewerage works and the best available ground investigation data. The waste
arising will largely depends on the contractor works programme and activities.
The contractor will be required to provide detailed estimation of all the
C&D materials and waste generated on-site using a Monthly / Yearly Waste
Flow Table as required under ETWB TCW No. 19/2005.
1
All
suitable materials will be reuse and recycle before disposal. Reuse of C&D
materials in other projects is subject to approval by the relevant parties in
accordance with DEVB TCW No. 6/2010. Final disposal outlets subject to final
agreement with Public Fill Committee and Marine Fill Committee of CEDD for
public fill reception facilities and marine dumping sites, and EPD for landfills.
2
Suitable
inert C&D materials will be stockpiled for later reuse. The amount of
materials that can be reuse in this Project will be examined further during the
detailed design and construction phases. Surplus material will be disposed to
designated public fill reception facilities (either TKO Area 137 Fill Bank or
TM Area 38 Fill Bank). Disposal routing will be via Sha Tau Kok Road, Fanling Highway, Tolo
Highway, Tate’s Cairn Tunnel, Kwun Tong Bypass, Tseung Kwan O Road and Wan Po
Road to the TKO Area 137 Fill Bank or via Sha Tau Kok Road, San Tin Highway,
Yuen Long Highway and Lung Mun Road to the TM Area 38 Fill Bank.
3
The
amount of non-inert C&D materials and general refuse will depend on the
contractor’s operating procedures and housekeeping practices as well as the
size of the workforce on-site. All such wastes should be sorted, reused and
recycled before disposal at designated landfill (e.g. NENT Landfill). Disposal routing will be via Sha Tau
Kok Road and Wo Keng Shan Road to NENT Landfill.
4
Bentonite
will be used during the HDD works for the submarine outfall. The amount of
bentonite will depend on the Contractor’s working procedures for HDD works. All
bentonite will be recycle and reuse in the drilling process, spent bentonite
will be disposed to public fill reception facilities after dewatering. Spent bentonite slurry will be disposed to public fill
reception facilities (either TKO Area 137 Fill Bank or TM Area 38 Fill Bank)
via land route or sea route depending on Contractor’s proposal.
5
According to the chemical testing results, the
sediment to be excavated is classified as Category L sediment. The disposal
of marine sediment will be via sea route by barge from the works site to the
marine disposal site allocated by MFC/CEDD.
6
The
amount of chemical waste will be dependent on the contractor’s on-site
maintenance programme and the number of equipment and vehicles used on-site.
Chemical waste should be collected by licensed contractor and properly disposed
of at approved chemical waste treatment facilities (e.g. the Chemical Waste
Treatment Centre at Tsing Yi). Disposal routing will be via Sha Tau
Kok Road, San Tin Highway, Tai Lam Tunnel, Tsing Long Highway and Tsing Yi Road
to the Chemical Waste Treatment Centre.
Table 6.3 -
Preliminary Reuse and Disposal Programme during the Construction Phase
|
Reuse / Disposal Arrangement
|
Approximate Quantity (m3)
|
Estimated Frequency of Trucks /
Vessels Involved
|
|
2018
|
|
Reuse of inert C&D materials
|
393
|
~7 truck trips per day
|
|
Disposal of inert C&D materials
to public fill reception facilities
|
13,579
|
|
Disposal to landfill
|
64
|
~1 truck trip every other day
|
|
2019
|
|
Reuse of inert C&D materials
|
5,153
|
~8 truck trips per day
|
|
Disposal of inert C&D materials
to public fill reception facilities
|
10,017
|
|
Disposal to landfill
|
82
|
~1 truck trip every other day
|
|
2020
|
|
Reuse of inert C&D materials
|
5,161
|
~8 truck trips per day
|
|
Disposal of inert C&D materials
to public fill reception facilities
|
10,017
|
|
Marine disposal of sediment (see
Note 2)
|
3,040
|
~5 barge trips
|
|
Disposal to landfill
|
64
|
~1 truck trip every other day
|
|
2021
|
|
Reuse of inert C&D materials
|
402
|
~5 truck trips per day
|
|
Disposal of inert C&D materials
to public fill reception facilities
|
8,948
|
|
Disposal to landfill
|
60
|
~1 truck trip every other day
|
|
2022 (see Note 3)
|
|
Reuse of inert C&D materials
|
0
|
~1 truck trip per day
|
|
Disposal of inert C&D materials
to public fill reception facilities
|
91
|
|
Disposal to landfill
|
5
|
~1 truck trip
|
Notes:
1.
The
exact programme, quantities and frequency of the disposal will depend on the
Contractor’s programme after the contracts are awarded. Although the
construction contract is expected to be awarded in mid-2017, the actual major construction works
hence the generation of C&D materials is expected to commence in 2018.
2.
Marine
disposal site(s) to be allocated by MFC/CEDD.
3.
The
demolition of the STKSPS will be conducted upon completion of the main
construction works. This is tentatively programmed in 2022 subject to the substantial completion
of the main works.
Operational Phase
6.6.35
Dewatered sludge should be delivered by sealed sludge
tanker for disposal at the Sludge Treatment Facility in Tuen Mun.
6.6.36
Screenings should be collected and stored in covered
containers before disposed of at landfill. Likewise, worn membrane filters and
general refuse should be properly stored and disposed of at landfill.
6.6.37
All chemical wastes should be properly stored, labelled
and removed by licensed waste collectors
in accordance with the Waste Disposal (Chemical Waste) (General) Regulation and
the Code of Practice on the
Packaging, Labelling and Storage of Chemical Wastes.
6.6.38
No secondary impact is expected
from the mitigation measures proposed in the EIA report.
6.7
Land
Contamination
6.7.1
This
section identifies and assesses sites within the proposed works area which, due
to their past and present land uses and activities, will have potential land
contamination implications.
6.7.2
The
review of site historical information was conducted with reference to the
Practice Guide for Investigation and Remediation of Contaminated Land. A review
of historical aerial photos was undertaken to identify the past land uses of
the proposed works area (Annex 6C). During the 70s, the STKSTW, proposed
gravity sewer and STKSPS site was still vacant land and undeveloped with
village houses mainly congregated at the current market area. STKSTW was
constructed in the late 80s while Sha Tau Kok Chuen was progressively developed
during the 90s. No significant land use change was noted since then. The land
use in the area has been and up to now mainly residential uses with some
community and recreational uses. Indeed, as the Project is within Closed Area,
the presence of industrial land use and activity is not expected and not
observed. Photos showing the existing site conditions of the proposed works
area are shown in Annex 6D.
6.7.3
Relevant
authorities have been approached to obtain information on chemical waste
producer, dangerous goods license and possible incident on spillage / leakage
of chemicals / dangerous goods at the Project area. No records of dangerous
goods license and spillage / leakage incidents were noted from the reply.
Relevant correspondences are shown in Annex 6E. Based on a search of EPD’s
record, no records of registered chemical waste producers within the works area
were noted.
6.7.4
A
site walkover was conducted in May 2015 with DSD representatives at the STKSTW
and STKSPS. Part of the works are located within the existing STKSTW and
STKSPS, site walkover indicates the works area is generally paved, clean,
without stain or abnormal odour. Based on site observation (Annex 6D) and confirmation by DSD/ST1, there are no
oil / chemical storage areas or any contaminating activities in the proposed
works area of the STKSTW and STKSPS. The checklist is shown in Annex 6F and Annex 6G. The proposed works area for the gravity
sewers includes verge, road and open area. There are no contaminating
activities or landuse in the proposed gravity sewers works area.
6.7.5
Based
on the desk-top review and walkover, the presence of contaminated land in the
proposed works area is therefore not expected. A summary of the land
contamination review is presented in Table
6.4.
6.7.6
The
operation of the TSTP will not require the use of large amount of chemicals or
fuels that may potentially cause land contamination. Similar to the existing
STKSTW, all chemicals required for sewage treatment would be stored indoor. For
any spillage / leakage of chemical, the operator will clean up with appropriate
materials stipulated in the material safety data sheet. The resulting clean up
materials will be considered as chemical waste and properly disposed by
licensed waste collectors. In addition, the operator will be required to
properly store, label and remove all chemical wastes in accordance with the Waste Disposal
(Chemical Waste) (General) Regulation and the Code of Practice on the
Packaging, Labelling and Storage of Chemical Wastes. As such, no land
contamination issue is expected for the demolition of the TSTP after the
expanded STW comes into operation. Should any land contamination issue be
identified in the decommissioning of the TSTP, the project proponent (DSD)
should follow up in accordance with the prevailing guidelines.
Table 6.4 - Summary
of Land Contamination Review
Review of Information
|
STKSTW
|
STKSPS
|
Gravity Sewers
|
Historical
aerial photo interpretation:
|
1973
|
Undeveloped mudflat
|
Undeveloped land, bare ground
|
Partly undeveloped mudflat, partly
village area
|
1986
|
Undeveloped mudflat
|
Roundabout
|
Partly reclaimed land under construction,
partly village area
|
1987
|
Reclaimed land, STKSTW under construction
|
STKSPS under construction
|
Partly reclaimed land under construction,
partly village area
|
1995
|
STKSTW
|
STKSPS
|
Road
|
2003
|
STKSTW, no change
|
STKSPS, no change
|
Road, no change
|
2008
|
STKSTW, no change
|
STKSPS, no change
|
Road, no change
|
2012
|
STKSTW, no change
|
STKSPS, no change
|
Road, no change
|
Government
records:
|
EPD memo dated 13 May 2015
|
No record of accidents of
spillage/leakage of chemicals at the concerned location. A search of EPD’s
chemical waste producers record was conducted on 8 July 2015, no records of chemical
waste producers within the works area were found.
|
FSD memo ref. (114) in FSD GR 6-5/4 R Pt.
9 dated 3 June 2015
|
Neither records of dangerous goods
license nor incidents of spillage / leakage of dangerous goods were found at
the concerned location.
|
Site
walk:
|
10 June 2015
|
Existing sewage treatment works with
paved ground surface, no stain or abnormal odour. No polluting or land contaminating
activities nearby.
|
Existing pumping station with paved
ground surface, no stain or abnormal odour. No polluting or land
contaminating activities nearby.
|
Existing paved road, no stain or abnormal
odour. No polluting or land contaminating activities nearby.
|
6.8
Evaluation
of Residual Impacts
6.8.1
With
the implementation of proper waste management practices for storage, handling,
transportation and disposal of waste arisings, no residual impacts are expected
during the construction and operational phases of the Project.
6.8.2
As
no residual impact is identified, no additional study is required.
6.9
Environmental
Audit
6.9.1
Auditing
should be carried out periodically to determine if waste is being managed in
accordance with prescribed waste management procedures and the EMP. The audits
should examine all aspects of waste management including waste generation,
storage, recycling, treatment, transportation, and disposal. The general site
inspections including waste management issues will be undertaken weekly by the
Environmental Team to check all construction activities for compliance with all
appropriate environmental protection and pollution control measures, including
those set up in the EMP. Meanwhile, waste management audit will also be carried
out as part of the monthly audit by the Independent Environmental Checker.
6.9.2
No
EM&A is required for operational phase of the Project.
6.10
Summary
6.10.1
Construction
and demolition (C&D) materials, sediment, chemical waste and general refuse
will inevitably be produced during the construction phase of the Project.
6.10.2
Provided
that there is strict control of C&D materials generated from construction
works and that all arisings are stored, handled, transported and disposed of in
accordance with the recommended mitigation measures, no unacceptable impact due
to waste management is expected during construction phase. The recommended
mitigation measures can be enforced by incorporating them into the waste
management requirements as part of the Environmental Management Plan.
Environmental audit would be necessary to ensure the implementation of proper
waste management practices during construction
6.10.3
With the use of HDD, the need for sediment
excavation during construction of the new submarine outfall can be
significantly reduced. Nonetheless, localised excavation of a small seabed area
will be necessary to facilitate the construction of the diffuser for the new
submarine outfall. Sediment sampling and testing results indicated the
excavated sediment is Category L sediment which should be disposed of as Type 1
– Open Sea Disposal. The Contractor shall obtain a Marine Dumping Permit in accordance with
the Dumping at Sea Ordinance. The Contractor should provide separate
submissions (e.g. Sediment Sampling and Testing Plan / Sediment Quality Report)
to EPD / DASO authority when applying for the Marine Dumping Permit under the
Dumping at Sea Ordinance.
6.10.4
Operation
of the sewage treatment works will generate sludge, screenings, worn membrane
filters, chemical waste and general refuse. With the implementation of the
recommended mitigation measures, no unacceptable impact due to waste management
is expected during operational phase.
6.10.5
A review of the past and present land
use of the Project site area was conducted. Based on desk-top review and site
walkover, the presence of contaminated land is not expected.