6
Waste management
6.1
Introduction
The Project involves the demolition of existing
facilities and retrofitting of emissions control facilities to four existing
677MW generating units of CPB. This
section identifies the potential wastes arising from the Project and assesses
the potential environmental impacts associated with waste handling and
disposal. The main issues are:
· disposal of
dredged sediments;
· handling and
treatment of contaminated soil;
· disposal of
construction and demolition (C&D) materials () arising from the
demolition, excavation and construction works; and
· management of
by-products produced from the FGD process.
Opportunities for waste minimisation, recycling,
storage, collection, transport and disposal have been examined and procedures
for waste reduction and management have been proposed.
6.2
Legislative
Requirements and Evaluation Criteria
The following discussion on legislative
requirements and evaluation criteria applies to both the construction and
operational phases of the Project.
The criteria and guidelines for evaluating
potential waste management implications are laid out in Annexes 7 and 15 of the EIAO-TM under the EIAO.
The following legislation covers, or has some
bearing upon, the handling, treatment and disposal of wastes in Hong Kong, and will also be considered in the assessment.
· Waste Disposal Ordinance (Cap 354);
· Waste Disposal (Chemical Waste) (General) Regulation (Cap 354C);
· Land (Miscellaneous Provisions) Ordinance (Cap 28);
· Public Health and Municipal Services Ordinance (Cap 132) - Public Cleansing and Prevention of Nuisances Regulation; and
· Dumping at Sea Ordinance (Cap 466).
6.2.1
Waste Disposal Ordinance (Cap
354)
The Waste
Disposal Ordinance (WDO) prohibits the unauthorised disposal of wastes,
with waste defined as any substance or article, which is abandoned. Under the WDO, wastes can only be disposed of at a licensed site. A breach of these regulations can lead
to the imposition of a fine and/or a prison sentence. The WDO
also provides for the issuing of licences for the collection and transport
of wastes. Licences are not,
however, currently issued for the collection and transport of construction
waste or trade waste.
The Waste
Disposal (Charges for Disposal of Construction Waste) Regulation defined
construction waste as any substance, matters or things 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, screening
or matter removed in or generated from any desludging,
desilting or dredging works.
The Construction Waste Disposal
Charging Scheme entered into operation on 1 December 2005. Starting from 1 December 2005, the main
contractor who undertakes construction work under a contract with value of $1
million or above is required to open a billing account solely for the
contract. Application should be
made within 21 days after the contract is awarded.
For construction work under a contract with value less than $1 million,
such as minor construction or renovation work, any person such as the owner of
the premises where the construction work takes place or his/her contractor can
open a billing account; the account can also be used for contracts each with
value less than $1 million. The
premises owner concerned may also engage a contractor with a valid billing
account to make arrangement for disposal of construction waste.
Under the new construction waste charging scheme, charging for disposal
of construction waste started on 20 January 2006 and therefore will apply to
this Project.
Depending on the percentage of inert materials in the construction
waste, construction waste can be disposed at public fill, sorting facilities, landfills
and outlying islands transfer facilities where different disposal cost would be
applied. The scheme encourages
reducing, reusing and sorting of construction waste such that the waste
producer can minimise their disposal fee.
Table 6.1 presents a summary
of the government construction waste disposal facilities, types of waste
accepted and disposal cost.
Table 6.1 Government
Waste Disposal Facilities for Construction Waste
|
Government Waste Disposal Facilities
|
Type of Construction Waste Accepted
|
Charge Per Tonne
|
|
Public fill reception facilities
|
Consisting entirely of inert construction
waste
|
$27
|
|
Sorting facilities
|
Containing more than 50% by weight of
inert construction waste
|
$100
|
|
Landfills
|
Containing not more than 50% by weight of
inert construction waste
|
$125
|
|
Outlying Islands
Transfer Facilities
|
Containing any percentage of inert
construction waste
|
$125
|
6.2.2
Waste Disposal (Chemical Waste)
(General) Regulation (Cap 354C)
Chemical waste as defined under the Waste Disposal (Chemical Waste) (General)
Regulation includes any substance being scrap material, or unwanted
substances specified under Schedule 1
of the Regulation, if such a substance
or chemical occurs in such a form, quantity or concentration so as to cause
pollution or constitute a danger to health or risk of pollution to the
environment.
A person should not produce,
or cause to be produced, chemical wastes unless he is registered with the
EPD. Producers of chemical wastes
must treat their wastes, utilising on-site plant licensed by the EPD or have a
licensed collector take the wastes to a licensed facility. For each consignment of wastes, the
waste producer, collector and disposer of the wastes must sign all relevant
parts of a computerised trip ticket.
The system is designed to allow the transfer of wastes to be traced from
cradle-to-grave.
The Regulation
prescribes the storage facilities to be provided on site including labelling
and warning signs. To minimise the
risks of pollution and danger to human health or life, the waste producer is
required to prepare and make available written procedures to be observed in the
case of emergencies due to spillage, leakage or accidents arising from the
storage of chemical wastes as well as provide employees with training in such
procedures.
6.2.3
Land (Miscellaneous
Provisions) Ordinance (Cap 28)
The inert portion of C&D materials (also
called public fill) may be taken to public filling facilities. Public filling areas usually form part
of land reclamation schemes and are operated by the Civil Engineering and
Development Department (CEDD) and others.
The Land (Miscellaneous
Provisions) Ordinance requires that individuals or companies who deliver
public fill to the public filling facilities obtain Dumping Licences from the
CEDD.
Under the licence conditions, public filling
areas will accept only inert building debris, soil, rock and broken
concrete. There is no size limit on
rock and broken concrete, and a small amount of timber mixed with inert
material is permissible. The
material should, however, be free from marine mud, household refuse, plastic,
metal, industrial and chemical wastes, animal and vegetable matter and any
other materials considered unsuitable by the public filling supervisor.
6.2.4
Public Health and Municipal
Services Ordinance (Cap 132) - Public Cleansing and Prevention of Nuisances
Regulation
This Regulation
provides a further control on the illegal dumping of wastes on unauthorised
(unlicensed) sites. The illegal
dumping of wastes can lead to a fine and imprisonment.
6.2.5
Dumping at Sea Ordinance (Cap
466)
This Ordinance
came into operation in April 1995 and empowers the Director of
Environmental Protection to control the disposal and incineration of substances
and articles at sea for the protection of the marine environment. Under the Ordinance, a permit from the Director of Environmental Protection
is required for the disposal of regulated substances within and outside the
waters of the Hong Kong SAR. The
permit contains terms and conditions that includes the following
specifications:
· Type and quantity
of substances to be dumped;
· Location of the
disposal grounds;
· Requirements of
equipment for monitoring the disposal operations; and
· The need for
environmental monitoring.
Management of
Dredged/Excavated Sediments for Marine Disposal
Marine disposal of any dredged/excavated sediment is subject to control
under the Dumping at Sea Ordinance
1995. The Ordinance has replaced the Dumping
at Sea Act 1974 (Overseas
Territories) Order 1975
(App. III p. DK1) in its application in Hong Kong SAR. In addition, dredged/excavated sediment destined
for marine disposal is classified based on its contaminant levels with
reference to the Chemical Exceedance Levels (CEL), as stipulated in ETWBTC No. 34/2002: Management of Dredged/Excavated Sediment. This Technical Circular includes a set
of sediment quality criteria, as presented in Table 6.2, which includes heavy metals and metalloids, organic
pollutants and a class of contamination level for highly contaminated sediment
not suitable for marine disposal.
Table 6.2 Dredged/Excavated
Sediment Quality Criteria for the Classification under the ETWBTC No 34/2002
|
Contaminants
|
Lower Chemical
Exceedance Level (LCEL)
|
Upper Chemical
Exceedance Level (UCEL)
|
|
Metals
(mg kg-1 dry weight)
|
|
Cd
|
1.5
|
4
|
|
Cr
|
80
|
160
|
|
Cu
|
65
|
110
|
|
Hg
|
0.5
|
1
|
|
Ni (a)
|
40
|
40
|
|
Pb
|
75
|
110
|
|
Silver (Ag)
|
1
|
2
|
|
Zinc (Zn)
|
200
|
270
|
|
Metalloid
(mg kg-1 dry weight)
|
|
Arsenic (As)
|
12
|
42
|
|
Organic-PAHs (mg
kg-1 dry weight)
|
|
Low Molecular Weight (LMW) PAHs
|
550
|
3,160
|
|
High Molecular Weight (HMW) PAHs
|
1,700
|
9,600
|
|
Organic-non-PAHs (mg
kg-1 dry weight)
|
|
Total PCBs
|
23
|
180
|
|
Organometallics
(mgTBT l-1 in interstitial water)
|
|
Tributyl-tin (a)
|
0.15
|
0.15
|
|
Note:
(a)
The
contaminant level is considered to have exceeded the UCEL if it is greater
than the value shown.
|
In accordance with ETWBTC 34/2002, the sediment is classified
into three categories based on its contamination levels:
Category L : Sediment
with all contaminant levels not exceeding the LCEL. The material must be dredged,
transported and disposed of in a manner which minimises the loss of
contaminants either into solution or by re-suspension.
Category M : Any one or more contaminants in the sediment exceed the - the LCEL
and none exceeding the UCEL. The
material must be dredged and transported with care, and must be effectively
isolated from the environment upon final disposal unless appropriate biological
tests demonstrate that the material will not adversely affect the marine
environment.
Category H : Any one or more contaminants in the sediment exceed the
exceeding the UCEL. The material
must be dredged and transported with great care, and must be effectively
isolated from the environment upon final disposal.
Figure 6.1 summarises the sediment classification and disposal
arrangements. EPD will base on the
sediment and biological test results to determine the most appropriate disposal
site (eg open sea or confined marine disposal site).
Figure 6.1 Management
Frameworks for Dredged/Excavated Sediment
Notes:
(a) Most open
sea disposal sites are multi-user facilities and as a consequence their management
involves a flexibility to accommodate varying and unpredictable circumstances.
Contract documents should include provisions to allow the same degree of
flexibility should it be necessary to divert from one disposal site to another
during the construction period of a contract.
(b) Dedicated
Sites will be monitored to confirm that there is no adverse impact.
(c) For
sediment requiring Type 2 or Type 3 disposal, contract documents should state
the allocation conditions of Marine Fill Committee (MFC) and DEP. At present,
East Sha Chau Mud Pits are
designated for confined marine disposal.
(d) If any
sediment suitable for Type 3 disposal (Category H sediment failing the
biological dilution test) is identified, it is the responsibility of the
project proponent, in consultation with DEP, to identify and agree with
him/her, the most appropriate treatment and/or disposal arrangement. Such a
proposal is likely to be very site and project specific and therefore cannot be
prescribed. This will not preclude treatment of this sediment to render it
suitable for confined marine disposal.
(e) The
allocation of disposal space may carry a requirement for the project proponent
to arrange for chemical analysis of the sediment sampled from 5% of the vessels
en-route to the disposal site. For Category M and certain Category H sediment,
the chemical tests will be augmented by biological tests. Vessel sampling will
normally entail mixing five samples to form a composite sample from the vessel
and undertaking laboratory tests on this composite sample. All marine disposal
sites will be monitored under the general direction of the CEDD. However,
exceptionally large allocations might require some additional disposal site
monitoring. These will be stipulated at the time of allocation.
(f)
Trailer suction hopper dredgers disposing
of sediment at the East Sha Chau
Mud Pits must use a down-a-pipe disposal method, the design of which must be
approved in advance by Director of the CEDD. The dredging contractor must
provide equipment for such disposal.
Source: Appendix C, ETWBTC 34/2002
6.2.6
Other Relevant Guidelines
Other ‘guideline’ documents, which detail how
the works contractor should comply with the WDO and its associated regulations,
are as follows:
· Waste Disposal Plan for Hong Kong (December 1989),
Planning, Environment and Lands Branch Government Secretariat, Hong Kong Government;
· Chapter 9 Environment (1999), Hong Kong Planning
Standards and Guidelines, Hong Kong
Government;
· New Disposal Arrangements for Construction Waste (1992), EPD &
CEDD, Hong Kong Government;
· Code of Practice on the Packaging, Labelling and
Storage of Chemical Wastes (1992), EPD, Hong Kong
Government.
· Works Branch Technical Circular (WBTC) No. 32/92, The
Use of Tropical Hard Wood on Construction Site; Works Branch, Hong Kong Government;
· WBTC No. 2/93, Public Dumps. Works Branch, Hong Kong Government;
· WBTC No. 2/93B, Public Filling Facilities, Works Branch, Hong Kong Government;
· WBTC No. 16/96, Wet Soil in Public Dumps; Works Branch, Hong Kong Government;
· WBTC Nos. 4/98 and 4/98A, Use of Public Fill in Reclamation and Earth Filling Projects;
Works Bureau, Hong Kong SAR Government.
· Waste Reduction Framework Plan, 1998 to 2007, Planning,
Environment and Lands Bureau, Government Secretariat, 5 November 1998;
· WBTC Nos. 25/99, 25/99A and 25/99C, Incorporation of Information on Construction and Demolition
Material Management in Public Works Sub-committee Papers; Works Bureau, Hong Kong SAR Government;
· WBTC No. 12/2000, Fill Management; Works Bureau, Hong Kong SAR Government;
· WBTC No. 19/2001, Metallic Site Hoardings and
Signboards; Works Bureau, Hong Kong SAR Government;
· WBTC Nos. 6/2002 and 6/2002A, Enhanced Specification for Site Cleanliness and Tidiness. Works
Bureau, Hong Kong SAR Government;
· WBTC No. 11/2002, Control of Site Crusher. Works Bureau, Hong Kong SAR Government;
· WBTC No. 12/2002, Specification Facilitating the Use
of Recycled Aggregates. Works Bureau, Hong Kong
SAR Government;
· ETWBTC No. 33/2002, Management of Construction and
Demolition Material Including Rock; Environment,
Transport and Works Bureau, Hong Kong SAR
Government;
· ETWBTC No. 34/2002, Management of Dredged/Excavated
Sediment; Environment, Transport and Works
Bureau, Hong Kong SAR Government;
· ETWBTC No. 31/2004, Trip Ticket System for Disposal of
Construction & Demolition Materials, Environment, Transport and
Works Bureau, Hong Kong SAR Government; and
· ETWBTC No. 19/2005, Environmental Management on
Construction Sites; Environment, Transport and Works Bureau, Hong Kong SAR Government.
6.3
Expected
Waste Sources
6.3.1
Construction Phase
During the construction phase, the main activities,
which will result in generation of waste, include demolition, site formation,
dredging, filling and concreting.
The typical waste types associated with these
activities include:
· Dredged marine sediment;
· Contaminated soil;
· C&D materials;
· Chemical waste;
· Sewage; and
· General refuse.
Proper waste management is important to prevent and
mitigate potential environmental impacts.
6.3.2
Operational Phase
The following wastes are expected to be generated
during the operational phase:
· Gypsum generated from FGD
processes;
· Sludge from FGD wastewater
treatment;
· Industrial waste; and
· General refuse.
6.4
Assessment
Methodology
The potential environmental impacts associated
with the handling and disposal of waste arising from the construction and
operation of the Project are assessed in accordance with the criteria presented
in Annexes 7 and 15 of the EIAO-TM, which
are summarised as follows:
· estimation of the
types and quantities of the wastes to be generated;
· assessment of the
secondary environmental impacts due to the management of waste with respect to
potential hazards, air and odour emissions, noise, wastewater discharges and
traffic; and
· assessment of the
potential impacts on the capacity of waste collection, transfer and disposal
facilities.
6.5
Waste
Management Assessment
6.5.1
Construction Phase
Dredged Marine Sediment
The existing Heavy Load Berth along the north-western
waterfront of the Castle Peak Power Station will be extended to form a
multi-purpose wharf and to provide the additional berthing facility required
for future loading and unloading of the reagent and by-products of the new
emission control system. Dredging
will be required for the development of the additional berthing facility. The dredging works are
expected to be carried out within about six weeks in early to mid 2007. The exact extent and boundary of the dredging works
is still being streamlined but the total area required to be dredged is
currently estimated to be approximately 30,000 m2. Due to the small dredging area, one
dredger is expected to be employed for the dredging works. The existing seabed level is about -6 mPD and the dredged level is
expected to be up to a depth of –8.2 mPD with the
estimated total dredged volume to be about 80,700 m3. The proposed dredged area is shown in Figure 2.3.
Based on the existing sediment quality data published by EPD for the
monitoring stations at Pillar Point and Urmston Road (NS3 and NS4), the
sediment quality in the area is considered to be not contaminated. To confirm no contamination of the
marine sediment, vibrocore samples of sediment were
taken at three locations evenly distributed within the area to be dredged based
on the total area expected to be dredged.
The sampling locations are presented in Figure 2.3. Detailed sampling plan and
sampling method are presented in Sediment Quality Plan (SQP) which has been
submitted to EPD (Annex D).
The results of the chemical analyses of the marine sediment are
presented in Table 6.3.
As shown in Table
6.3, all the results are below their respectively LCEL/reporting limit at
all sampling locations and all sampling depths. The findings indicate that the marine
sediment within the dredged area is likely to be uncontaminated but further
sampling and testing in accordance with the detailed requirements of ETWBTC No. 34/2002 will be required for
the actual allocation of sediment disposal site and the application for a dumping
permit under the Dumping at Sea Ordinance
(Cap 466) prior to the commencement of the dredging activities. In the event that these further tests
show the sediment to be uncontaminated, it would be suitable for disposal at
open sea. Should the sediment be
found to be contaminated, confined marine disposal would be appropriate. Based on a maximum daily dredging rate
of about 5,200m3, about 8 barge trips per day will be required,
assuming a carrying capacity of about 700 m3 per barge, for the
disposal of the dredged sediment.
Contaminated Soil
To accommodate the new development, demolition
works are required to demolish or relocate a number of existing facilities
including:
· CPB Fuel Oil Day
Tank (FODT);
· Dangerous Goods
(DG) Store to the south of the FOPH;
· Oil interceptor
for FODT and APS Transformer Compound (West & East Ends);
· Pipe works in
trenches connecting between FODT to FOTPH;
· Pipe works
connecting with FOPH and oil interceptor;
· Intermediate
pressure reduction station (IPRS), LPG compound and CO2 storage
tanks.
Potential leakage and/or spillage (if any) of
oil from the operation of these facilities may cause land contamination to the
underlying soil.
A Contamination Assessment Plan (CAP) has been prepared, submitted to
and was approved by EPD in April 2006 (see Annex E). It
reviewed the historical land uses and existing conditions of the site and
recommended a site investigation programme to determine if the site is
contaminated and if so, the types and degree of contamination. Site investigation was conducted at four
trial pits and eight drillholes. Based on the finding of the site
investigation, total petroleum hydrocarbon (TPH) was found at 0.9 m below
ground level at TP3. However, since
no contamination were found at the adjacent trail pits/boreholes, it is
anticipated that the TPH contamination is localized at TP3. The estimated amount of potentially
contaminated soil within the Project boundary is 50 m3 (with a
bulking factor of 1.2 applied to the in-situ
volume). Details of the finding of
the site investigation were reported in the Annex E1 – Contamination Assessment Report (CAR).
The excavated contaminated soil will be treated
onsite using bioremediation method.
The remediation actions involve excavation, testing, on-site treatment
(i.e., biodegradation) and verification sampling and analysis. The treated soils will be reused within
the Project as far as possible or disposed of at the public fill bank at Tuen Mun Area 38.
The Remediation
Action Plan (RAP) in Annex E details
the measures required.
C&D Materials
Demolition
Materials
Facilities to be demolished to provide space for
installing FGD plants in this Project have been discussed above.
The demolition and relocation works will take about
6.5 months and are scheduled to commence in the first half of 2007.
A total of about 835 tonnes of scrap metals will
be produced from the demolition of FODT, LPG and CO2 tanks, pumps
and the associated fixtures/ appendages such as pipeline, spiral stair and
catwalk attached to the oil tanks.
The steel sheet of the circular roof and sidewall will be cut into small
panels in regular size for easy transportation. All the scrap steel will be transported
off-site by barge/trucks for recycling.
A total of about 1,830 m3
uncontaminated reinforced concrete (after applying a bulking factor of 1.4)
will be generated from demolition of the retaining walls of FODT, DG stores,
LPG switch room and vaporiser room and LPG tank foundation. These materials are not contaminated and
will be separated from other wastes to avoid contamination. The reinforced concrete (public fill)
can be reused on-site or sent to public filling area at Tuen
Mun Area 38 and/or other reclamation site for reuse.
Excavated
Materials
Excavation works would be
required for the construction of the foundations to support the new
facilities. A total of
approximately 30,000 m3 (with a bulking factor of 1.2 applied) of
non-contaminated excavated materials (assumed to be mainly soft materials) will
be generated from the excavation for the foundations of new facilities. The excavated soil will be temporarily
stockpile onsite at the existing coal yard located to the north of the Stacker Reclaimer and is expected to be reused for the filling
activities in this Project.
The portion of the existing coal yard to be used
for the new FGD facilities (located south of existing ash sump and ACP Plant
House) will need to be raised from the existing level of +5 to +6mPD to an
approximate level of +7mPD. Public fill
material will still need to be imported even after reusing the excavated
materials generated from the Project and therefore no surplus excavated
materials is expected from the Project.
C&D Materials Arising from New Building
Construction
C&D materials consisting of packing
materials, plastics, metal, concrete, wood etc will be generated from the new
building construction. The main
structures to be constructed at the site would be the CO2 tank, LPG
tank, IPRS, FGD and SCR equipment, limestone and gypsum storage facilities and
urea storage area. The majority of
these new facilities are steel structures and also pre-fabricated, and
therefore the quantity of C&D materials generated is expected to be small. These materials should be sorted on-site
in order to minimise the amount of construction waste to be disposed of at
landfills and the cost for disposal of the C&D materials arising from the
Project. Recyclables could be
reused on site or sold to recyclers/recycling facilities. Construction waste will be disposed of
at the refuse transfer station at North
West New Territories or directly to the WENT
landfill by trucks.
Chemical Wastes
Chemical waste, as defined under the Waste Disposal (Chemical Waste) (General)
Regulation, includes any substance being scrap material, or unwanted
substances specified under Schedule 1
of the Regulation. A complete list of such substances is
provided under the Regulation;
however, substances likely to be generated from the construction of the SCR and
FGD plants and the associated building will, for the most part, arise from the
maintenance of construction plant and equipment. These may include, but need not be
limited to the following:
· Scrap batteries or
spent acid/alkali from their maintenance;
· Used paint, engine
oils, hydraulic fluids and waste fuel;
· Contaminated oily
water from the flushing and cleaning of the light oil tanks and the oil/water
separation sump prior to their demolition;
· Spent mineral
oils/cleaning fluids from mechanical machinery; and
· Spent
solvents/solutions, some of which may be halogenated, from equipment cleaning
activities.
Chemical wastes may pose environmental, health
and safety hazards if not stored and disposed of in an appropriate manner as
outlined in the Waste Disposal (Chemical
Waste) (General) Regulation and the Code
of Practice on the Packaging, Labelling and Storage of Chemical Wastes. These hazards may include:
· Toxic effects to
workers;
· Adverse effects on
air, water and land from spills; and
· Fire hazards.
Oily water and oily sludge will be generated
from the cleaning of the FODT and oil transfer pipelines to be demolished. The amount of chemical waste that will
arise from other construction activities will be highly dependent on the
Contractor’s on-site maintenance activities and the quantity of plant and
equipment utilised. With respect to
the nature of construction works, the number of construction plant and
equipment to be used on site, it is estimated that about a few hundred litres
of used lubricant oil will be generated during the construction period. It is anticipated that the quantities of
waste solvent and waste paint will be minimal.
With the incorporation of suitable arrangements
for the storage, handling, transportation and disposal of chemical wastes under
the requirements stated in the Code of
Practice on the Packaging, Labelling and Storage of Chemical Waste, no
adverse environmental and health impacts will result from the handling,
transportation and disposal of chemical waste arising from the Project.
Sewage
Sewage will arise from the construction
workforce and site office’s sanitary facilities. These wastes should be managed properly
to avoid any adverse water quality impact, odour and potential health risks to
the workforce by attracting pests and other disease vectors.
It is estimated that about
900 construction workers will be working on site at the peak of the construction programme. With a sewage generation rate of 0.15 m3
per worker per day, about 135 m3 of sewage will be generated per
day. It is expected that portable
toilets will be provided for site workers and the existing sanitary facilities
at the CPPS will not be used by any of the site workers. A licensed contractor should be employed to remove
the sewage and dispose of it to sewage treatment works operated by Drainage
Services Department. With the
implementation of these waste management practices on-site, adverse
environmental impacts are not expected.
General Refuse
The presence of a construction site with workers
and associated site office will result in the generation of a variety of
general refuse requiring disposal.
General refuse will mainly consist of food waste, aluminium cans and
waste paper.
The storage of general refuse has the potential
to give rise to adverse environmental impacts. These include odour if the waste is not
collected frequently (for example, daily), windblown litter, water quality
impacts if waste enters water bodies, and visual impact. The site may also attract pests, vermin,
and other disease vectors if the waste storage areas are not well maintained
and cleaned regularly. In addition,
disposal of wastes at sites other than approved landfills, can also lead to
similar adverse impacts at those sites.
During the peak of construction programme, about
900 construction workers will be worked on site at any one time and the amount
of general refuse to be generated is expected be about 585 kg per day based on
a general refuse generation rate of 0.65 kg per worker per day.
Recyclable materials (i.e. paper, plastic bottle
and aluminium can) should be separated and disposed of at the recycling bins in
order to minimise the amount of general refuse to be disposed of at
landfills. General refuse generated
from the construction workforce will be collected together with other general
refuse generated from the existing CPB by contractor and subsequently sent to
the refuse transfer station in North
West New Territories or directly to WENT landfill
for disposal. With respect to the
small quantity of general refuse to be generated, it is anticipated that no
additional traffic will be generated due to its disposal.
Provided that the mitigation measures
recommended in Section 6.6 are adopted, the environmental impacts caused by the storage, handling,
transport and disposal of general refuse are expected to be minimal.
Summary
Table
6.4
summarised the waste arising during construction of the Project.
Table 6.4 Waste
Arising During Construction Phase
|
Type
|
Estimated Quantity
|
Disposal / Treatment Site
|
|
Dredged Sediment
|
·
80,700 m3
(likely to be uncontaminated)
|
·
Disposal to open
sea (if confirmed by further tests in accordance with ETWBTC No. 34/2002 to be uncontaminated); or
·
confined marine
disposal (if confirmed by further tests to be contaminated)
|
|
Contaminated Soil
|
·
50 m3
(bulk)
|
On-site treatment
(bioremediation) and the treated soil will be reused as fill materials with
the Project or disposal of at public fill bank in Tuen
Mun Area 38
|
|
Scrap Steel
|
·
835 tonnes
|
Off-site recycling
|
|
Public Fill
|
·
1,830 m3
(uncontaminated concrete)
·
30,000 m3
(bulk) (excavated soil)
|
Reuse on-site for site
formation and backfilling
|
|
Construction Waste
|
·
minor
|
Refuse transfer station in North West New Territories
or WENT Landfill
|
|
Chemical Waste
|
·
fuel oil day tank
and oil separator sump demolition.
·
Less than one
hundred litres per month from all construction activities.
|
Chemical Waste Treatment
Centre and/or other licensed lube oil recycling facility
|
|
Sewage
|
·
135 m3/day
(on average)
|
Provision of portable toilets
and regular collection by contractor for off-site treatment
|
|
General Refuse
|
·
585 kg/day (on
average)
|
Transported together with
other general refuse generated from the existing CPPS to refuse transfer
station in North West
New Territories
or WENT Landfill
|
6.5.2
Operational Phase
Gypsum Generated from FGD
Processes
The limestone FGD processes will generate two
principal types of by-product or waste.
They are the gypsum and the sludge from treatment of the FGD wastewater.
Gypsum is a non-hazardous and non-toxic
substance. It is produced in the
form of fine, white, crystalline powder consisting predominantly of calcium
sulphate. The quantity of gypsum
generated will depend on a number of factors including the sulphur content of
the fuel used and the operational profile of CPB.
Gypsum is a useful construction material in
building industry and the demand for gypsum is high in both Hong Kong and
Mainland China.
About 240,000 tonnes of commercial grade gypsum
will be produced per year in addition to a small amount of lower grade gypsum
at about 17,000 tonnes per year (i.e., 6.6% of the total gypsum generated).
Commercial
Grade Gypsum : The commercial grade gypsum produced could be used for a number of
purposes such as the production of plasterboard, cement, etc. CAPCO can liaise with the overseas
limestone supplier to take back the gypsum generated from the limestone FGD
system at CPB. Currently, the Hongkong Electric Company has entered into a
buyback agreement with the overseas limestone supplier to take back the gypsum
generated from the FGD process at the Lamma Power
Station. It is likely that the
buyback agreement could also be feasible for the limestone FGD system at CPB.
Another feasible way to reuse the gypsum is to
sell to cement manufacturers in PRD and East-Asia region. The demand for gypsum from the cement
and plasterboard sectors in Guangdong
Province is likely to
exceed the supply. Many
multi-national cement manufacturers have acquired sizable cement production plants
in the East-Asia region and their potential demand for gypsum is therefore well
in excess of the level of supply by CAPCO.
It is therefore likely that multi-national cement manufacturers could
take all the FGD gypsum to be produced at CPB under a long-term arrangement to
supply various cement plant around the region.
Barges will be employed to transport the
commercial grade gypsum offsite.
One to two barge trips per week are anticipated for gypsum transport.
Lower Grade Gypsum: A small amount of lower
grade gypsum (about 17,000 tonnes per year or 6.6% of the total gypsum
generated) will also be generated as a result of the FGD process. Despite its lower grade, the gypsum can
still be reused for cement production.
Similar to the case of commercial grade gypsum, CAPCO can liaise with
the limestone supplier to take back also the lower grade gypsum. As a fallback option in the rare event
of the lack of demand for lower grade gypsum, it can be disposed of at a
designated area of the Tsang Tsui Ash Lagoons. The dewatered gypsum will be transported
by trucks. Assuming 365 working
days per year, 47 tonnes of lower grade gypsum (or about 20 m3 of
lower grade gypsum based on a density of 2.3 tonne per cubic metre) will be
generated per day. Based on a carrying
capacity of 7 m3 for each truckload, about three additional truck
trips will be generated per day from the Project on the Lung Kwu Tan Road
and Nim
Wan Road for the transportation of lower grade
gypsum.
Sludge from FGD Wastewater
Treatment
The dewatered gypsum cake will need to be washed
with fresh water to remove the soluble chlorides to meet the specification for
commercial grade gypsum. The wash
water, containing excessive chlorides, will be treated in a chloride purge
treatment system to remove the suspended solids and trace elements, to reduce
the residual COD and to adjust the pH before it is discharging with the cooling
water of the CPB to Urmston Road.
About 60 tonnes of sludge dry solids per day (or
about 180 tonnes per day at 30% dry solids) will be generated from the chloride
purge treatment system. The typical
quality of the sludge is presented in Table
6.5.
Table 6.5 Typical
Chemical Composition of Chloride Purge Treatment Sludge
|
Component
|
Content
|
|
Calcium sulphate
|
40%
|
|
Calcium sulphite
|
1%
|
|
Calcium carbonate
|
4%
|
|
Inerts
|
20%
|
|
Flyash
|
5%
|
|
Others (surplus
sludge from biological treatment system)
|
30%
|
Design optimisation of the FGD wastewater
treatment system has commenced. One
of the key design optimisation objective is to minimise the influent throughput
to the wastewater treatment system which would result in a lower quantity of
sludge arising. This would help to
reduce the amount of sludge requiring disposal. In addition, the feasibility of other
disposal options such as off-take by the limestone supplier and gypsum
off-taker to minimise the quantity of sludge to be disposed of at landfills
would be further explored in the detailed design stage.
Industrial
Waste
Most of the industrial waste generated from the
maintenance of the limestone FGD system will be scrap metal, which can be
recycled. It is therefore
anticipated that no adverse environmental impacts will result from the handling
and disposal of the industrial waste to be generated from the operation of the
FGD system.
General
Refuse
CAPCO will deploy the existing CPB staff to
manage the new emission control system and it is not anticipated to have
significant increase of number of staff.
Hence, no additional general refuse will be generated from the
workforce.
Summary
Table
6.6
summarises the waste arising during the operation of the Project.
Table 6.6 Waste
Arising During Operational Phase
|
Type
|
Estimated Quantity
|
Disposal / Treatment Site
|
|
Gypsum
|
·
Commercial grade
gypsum : 240,000 tonnes per year
·
Lower grade
gypsum : 17,000 tonnes per year
|
·
Commercial grade
gypsum : To be collected by the limestone supplier or sold to plasterboard
and/or cement manufacturers
·
Lower grade
gypsum : To be collected by the limestone supplier or sold to cement
manufacturers. As a fall-back
option, disposal at a designated area of Tsang Tsui
Ash Lagoons may be considered
|
|
Sludge
|
·
60 tonnes dry
solid per day or about 180 tonnes per day at 30% dry solids
|
·
Minimising the
influent throughput to the wastewater treatment system which would result in
a lower quantity of sludge arising;
·
Feasibility of
other disposal options to be further explored in detailed design stage
|
|
Industrial waste
|
·
Few kg of scrap
metal per month
|
·
To be collected
by recyclers/recycling facilities
|
6.6
Mitigation
Measures
There are no major waste management issues
associated with the operation of the new emission control system. This section recommends the mitigation measures
to avoid or minimize potential adverse environmental impacts associated with
handling, collection and disposal of waste arising from the construction of the
new emission control system.
It is the Contractor’s responsibility to ensure
that only licensed chemical waste collectors are used for collection and
transportation of chemical waste to the licensed disposal facility and that
appropriate measures are taken to minimize adverse environmental impacts,
including windblown litter and dust from the transportation of wastes. In addition, the Contractor must ensure
that all the necessary waste permits are obtained for the construction and
operational phases.
6.6.1
Dredged Sediments
According to the requirements stipulated in ETWBTC No. 34/2002, the dredged sediment
should be disposed of only at designated disposal sites allocated by the Marine
Fill Committee (MFC) based on the findings of further sediment quality
tests. A dumping licence should
also be obtained from EPD prior to the commencement of the dredging works.
Regardless of the sediment disposal method and
site, the Contractor should:
· Dredge the
sediments using closed grabs;
· Use split barges
of not less than 750 m3 capacity when transporting the sediment to
the disposal site;
· Regularly maintain
the barge hoppers to ensure that they are capable of rapid opening and
discharge at the designated disposal site; and
· Monitor the barge
load against loss of materials during transportation.
6.6.2
Contaminated Soil
For excavated contaminated soil, mitigation
measures recommended in the RAP, Annex E should be implemented.
6.6.3
Excavated Materials
Wherever practicable, excavated materials should
be segregated from other wastes to avoid contamination thereby ensuring that it
can be re-used onsite avoiding the need for disposal at landfills.
Management
of Waste Disposal
Construction Waste Disposal Charging Scheme was
launched on 1 December 2005 and the charging for disposal of construction waste
was commenced on 20 January 2006.
The Contractor should open a billing account
with EPD in accordance with the Waste
Disposal (Charges for Disposal of Construction Waste) Regulation for the
payment of disposal charges. Every
waste load transferred to Government waste disposal facilities such as public
fill, sorting facilities, landfills or transfer station would required a valid
“chit” which contains the information of the account holder to facilitate waste
transaction recording and billing to the waste producer. A trip-ticket system will be established
in accordance with the ETWBTC No. 31/2004
to monitor the reuse of surplus excavated materials offsite and disposal of
C&D waste and general refuse at transfer station/landfills, and to control
fly-tipping. The billing “chit” and
trip-ticket system will be included as one of the contractual requirements and
implemented by the contractor.
CAPCO will also conduct regular audits of the waste management measures
implemented on site as described in the Waste Management Plan.
A recording system (similar to summary table as
shown in Annex 5 and Annex 6 of Appendix G of ETWBTC No. 19/2005) for the amount of waste generated, recycled and
disposed of (including the disposal sites) should be established during the
construction stage.
Measures
for the Reduction of C&DM Generation during Planning and Design Stages
The various waste management options can be
categorized in terms of preference from an environmental viewpoint. The options considered to be more
preferable have the least impacts and are more sustainable in the long term. Hence, the waste management hierarchy is
as follows:
· Avoidance and
minimization, that is, reduction of waste generation through changing or
improving practices and design;
· Reuse of
materials, thus avoiding disposal (generally with only limited reprocessing);
· Recovery and
recycling, thus avoiding disposal (although reprocessing may be required); and
· Treatment and
disposal, according to relevant law, regulations, guidelines and good practice.
This hierarchy should be used to evaluate the
waste management options, thus allowing maximum waste reduction and reduced
disposal costs. Records of
quantities of wastes generated, recycled and disposed (locations) shall be
kept.
Measures
for the Reduction of C&DM Generation during Construction
All C&D materials will be reused within the
Project. Public fill and
construction waste should be segregated and stored in different containers or
skips to facilitate reuse or recycling of materials and their proper disposal
of construction waste. Specific areas
of the work site should be designated for such segregation and temporary
storage if immediate use is not practicable.
The construction waste should be collected by
Contractor and transported to landfills for disposal.
The use of wooden hoardings
should not be allowed. An
alternative material, which can be reused or recycled, for example, metal
(aluminium, alloy, etc) should be used.
To reduce the potential dust
impact, C&D materials should be wetted as quickly as possible during
excavation works.
6.6.4
Chemical Waste
The Contractor should register as a chemical
waste producer with the EPD.
Chemical waste, as defined by Schedule
1 of the Waste Disposal (Chemical
Waste) (General) Regulation, should be handled in accordance with the Code
of Practice on the Packaging, Handling and Storage of Chemical Wastes as
follows:
Containers used for storage
of chemical wastes should:
· be suitable for
the substance they are holding, resistant to corrosion, maintained in a good
condition, and securely closed;
· have a capacity of
less than 450 L unless the specifications have been approved by the EPD; and
· display a label in
English and Chinese in accordance with instructions prescribed in Schedule 2 of
the Regulations.
The storage area for chemical wastes should:
· be clearly labelled
and used solely for the storage of chemical waste;
· be enclosed on at
least 3 sides;
· have an
impermeable floor and bunding, of capacity to
accommodate 110% of the volume of the largest container or 20% by volume of the
chemical waste stored in that area, whichever is the greatest;
· have adequate
ventilation;
· be covered to
prevent rainfall entering (water collected within the bund must be tested and
disposed of as chemical waste, if necessary); and
· be arranged so
that incompatible materials are appropriately separated.
Disposal of chemical waste should be:
· via a licensed
waste collector; and
· to a facility
licensed to receive chemical waste, such as the Chemical Waste Treatment Centre which also offers a chemical
waste collection service and can supply the necessary storage containers.
6.6.5
Sewage
The sewage sludge from
the portable toilet should be collected by a reputable collector on a regular
basic.
6.6.6
General Refuse
General refuse should be stored in enclosed bins
or compaction units separately from construction and chemical wastes. General refuse should be removed from
the site, separately from construction and chemical wastes, on a daily basis to
minimise odour, pest and litter impacts.
Burning of refuse on construction site is prohibited by law.
Aluminium cans are often recovered from the
waste stream by individual collectors if they are segregated and made easily
accessible. As such, separate,
labelled bins for their deposit should be provided if feasible. Materials recovered will be re-used on
site or sold for recycling.
6.6.7
Staff Training
Training will be provided to workers on the
concepts of site cleanliness and on appropriate waste management procedures,
including waste reduction, reuse and recycling at the beginning of the
Contract.
6.7
Residual Environmental Impacts
With the implementation of the recommended
mitigation measures, no residual impacts are anticipated from the construction
and operation of the Project.
6.8
Environmental Monitoring and Audit
6.8.1
Construction Phase
Joint site audits by the CAPCO and the contractor should be undertaken
on a weekly basis. Particular
attention should be given to the contractor’s provision of sufficient spaces,
adequacy of resources and facilities for on-site sorting and temporary storage
of C&D materials. The C&D
materials to be disposed of from the site should be visually inspected. The C&D waste to be disposed of at
refuse transfer stations or landfills should contain no as practicable
observable inert or reusable/recyclable C&D materials (e.g. soil, broken
rock, metal, and paper/cardboard packaging, etc). Any irregularities observed during the
weekly site audits should be raised promptly to the contractor for
rectification.
6.8.2
Operational Phase
No adverse environmental impact will arise with the implementation of
good waste management practices and therefore, no environmental monitoring and
audit programme is required.
6.9
Conclusion
6.9.1
Construction Phase
The key potential impacts during the construction
phase are related to management of dredged sediments, demolition materials,
excavated materials and construction waste.
About 80,700 m3 of
marine sediment will be dredged in connection with the provision of the
additional berthing facility. The
final disposal site for the material will be determined by the MFC and a
dumping licence will be obtained from EPD prior to the commencement of the
dredging works with reference to the results of further tests to be undertaken
in accordance with the detailed requirements of ETWBTC No. 34/2002.
An estimated total of 50 m3
total petroleum hydrocarbon (TPH) contaminated soil will be excavated and the material should be remediated by using bioremediation method, as discussed in Section 7 and the RAP in Annex E. The treated soil will be reused within
the Project or disposed of at the public fill bank in Tuen
Mun Area 38.
A total of about 835 tonnes of scrap steel will
be produced during demolition of oil tanks and the associated fixtures/
appendages. All the scrap steel
will be delivered off-site by barge/truck for recycling.
A total of about 30,000 m3
of uncontaminated excavated soil will be generated from the demolition and
construction works. All excavated
soil will be reused for the backfilling on-site.
Small quantities of chemical
wastes (less than 100 litres per month), sewage (a maximum of 135 m3
per day) and general refuse (a maximum of 585 kg per day) will be generated
during the construction phase.
With the implementation of the recommendations
in Section 6.6, the potential
environmental impacts arising from storage, handling, collection, transport and
disposal of wastes should be able to meet the criteria specified in the EIAO-TM. No unacceptable waste management impact
is anticipated.
6.9.2
Operational Phase
Commercial grade gypsum (about 240,000 tonnes
per year) can be recycled in PRD and East-Asia regional market. Similarly the lower grade gypsum (about
17,000 tonnes per year) can also be reused for cement production. The sludge from FGD wastewater treatment
(about 180 tonnes at 30% dry solids per day) will be generated. Design optimization of FGD wastewater
system has been commenced and one of the key objectives is to minimize the
influent throughput to the wastewater treatment system as a result in lowering
the quantity of sludge arising.
This would help to reduce the amount of sludge requiring disposal. Alternative disposal options such as
off-take by the limestone supplier and gypsum off-taker and incineration of the
sludge will be explored in the detailed design stage.
With the implementation of the recommended
mitigation measures, the potential environmental impacts associated with the
storage, handling, collection, transport and disposal of a small quantity of
industrial waste and general refuse arising from the operation of the Project
will meet the criteria specified in the EIAO-TM
and no unacceptable waste management impact is anticipated.