The Project
involves the demolition of two existing light oil tanks and retrofitting of FGD
plant to two existing 350MW coal-fired generating units (L4 and L5) of Lamma
Power Station. 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:
·
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.
5.2
Legislation Requirement 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 (Cap 499).
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).
5.2.1
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 will come into operation
on 1 December 2005. Processing of
account applications by the EPD will start on the same day. Starting from 1 December 2005, 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 shall be
made within 21 days after the contract is awarded. Failing this will be an offence under the law.
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.
Charging for disposal of construction waste will start on 20 January 2006 and
from this day; any person before using waste disposal facilities for disposal
of construction waste needs to open an account.
Construction work contracts awarded or tenders of which closed before 1
December 2005 are eligible for exemption from charges. Application for
exemption account must be made on or before 22 December 2005. 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 reduce, reuse and
sorting of construction waste such that the waste producer can minimise their
disposal fee. Table 5.1 summarises the government construction waste disposal
facilities, types of waste accepted and disposal cost.
Table
5.1 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 |
5.2.2
Waste Disposal (Chemical Waste) (General) Regulation
Chemical waste as
defined under the Waste Disposal
(Chemical Waste) (General) Regulation includes any substance being scrap
material, or unwanted substances specified under Schedule 1 of the Regulation,
if such a substance or chemical occurs in such a form, quantity or
concentration so as to cause pollution or constitute a danger to health or risk
of pollution to the environment.
A person should not produce, or cause to be produced, chemical wastes
unless he is registered with the EPD.
Any person who contravenes this requirement commits an offence and is
liable to a fine and imprisonment.
Producers of chemical wastes must treat their wastes, utilising on-site
plant licensed by the EPD or have a licensed collector take the wastes to a
licensed facility. For each
consignment of wastes, the waste producer, collector and disposer of the wastes
must sign all relevant parts of a computerised trip ticket. The system is designed to allow the
transfer of wastes to be traced from cradle-to-grave.
The Regulation prescribes the storage
facilities to be provided on site including labelling and warning signs. To minimise the risks of pollution and
danger to human health or life, the waste producer is required to prepare and
make available written procedures to be observed in the case of emergencies due
to spillage, leakage or accidents arising from the storage of chemical wastes. He/she must also provide employees with
training in such procedures.
5.2.3
Land (Miscellaneous Provisions) Ordinance (Cap 28)
The inert portion
of C&D materials ([1]) (also called public fill) may be taken to
public filling areas. 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 areas obtain Dumping
Licences. The licences are issued
by the CEDD under delegated authority from the Director of Lands.
Individual
licences and windscreen stickers are issued for each vehicle involved. Under the licence conditions, public
filling 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.
5.2.4
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.
5.2.5
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.
5.2.6
Other Relevant Guidelines
Other 'guideline'
documents, which detail how the Contractor should comply with the regulations,
are as follows:
·
Waste Disposal Plan for Hong Kong (December 1989), Planning, Environment
and Lands Branch Government Secretariat, Hong Kong Government;
·
Chapter 9 Environment (1999), Hong Kong Planning Standards and Guidelines, Hong
Kong Government;
·
New Disposal Arrangements for Construction Waste (1992), EPD & CED, 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. 15/2003, Waste Management on Construction
Sites; Environment,
Transport and Works Bureau, Hong Kong SAR Government; and
·
ETWBTC No. 31/2004, Trip Ticket System for Disposal
of Construction & Demolition Materials, Environment, Transport and Works Bureau, Hong Kong
SAR Government.
5.2.7
Landfill Disposal Criteria for Contaminated Soil
Excavated
contaminated soil has to meet certain criteria before disposal to landfill is
allowed. The criteria presented in
the EPD’s Guidance Notes for
Investigation and Remediation of Contaminated Sites of Petrol Filling Stations;
Boatyards; and Car Repair/Dismantling Workshops are set primarily in terms
of Toxicity Characteristic Leaching Procedure (TCLP) limits, as shown in Table 5.2.
Table
5.2 Landfill
Disposal Criteria for Contaminated Soil
|
Parameters |
TCLP Limit (ppm) |
|
Cadmium (Cd) |
10 |
|
Chromium (Cr) |
50 |
|
Copper (Cu) |
250 |
|
Nickel (Ni) |
250 |
|
Lead (Pb) |
50 |
|
Zinc (Zn) |
250 |
|
Mercury (Hg) |
1 |
|
Tin (Sn) |
250 |
|
Silver (Ag) |
50 |
|
Antimony (Sb) |
150 |
|
Arsenic (As) |
50 |
|
Beryllium (Be) |
10 |
|
Thallium (Tl) |
50 |
|
Vanadium (V) |
250 |
|
Selenium (Se) |
1 |
|
Barium (Ba) |
1,000 |
5.3.1
Construction Phase
During the
construction phase, the main activities, which will potentially result in the
generation of waste, include demolition works, excavation, and construction of
FGD Plant. The typical waste types
associated with these activities include:
·
Contaminated
soil;
·
Construction
and Demolition (C&D) materials;
·
Chemical wastes
from the flushing/cleaning of two light oil tanks and oil/water separation sump
prior to their demolition;
·
Sewage; and
·
General
refuse.
If not properly
managed, the handling and disposal of these wastes may cause adverse
environmental impacts.
5.3.2
Operational Phase
The following
wastes/by-products will be generated from the operation of the FGD Plant:
·
Gypsum
produced from the new FGD plant;
·
Additional
sludge from existing WWTP;
·
Chemical
waste;
·
Sewage; and
·
General
refuse.
The potential
environmental impacts associated with the handling and disposal of waste
arising from the construction and operation of the Project were 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.
5.5.1
Construction Phase
(a) Contaminated Soil
Two light oil
tanks and the adjacent in-ground oil separator will be demolished and soil
materials around and underlying the tank and oil separator will be excavated
during the subsequent retrofit programme.
Leakage and/or spillage (if any) of oil from operation of these
facilities may cause land contamination to the underlying soil.
A Contamination Assessment Plan (CAP) has been prepared and agreed by
EPD (see Annex A). 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. Based on
the finding of the site investigation and the extent of the excavation works,
it is estimated that about 600 m3 of excavated soil materials (with
bulking factor ([2])) to be excavated near the No. 5 oil tank
are potentially contaminated with Total Petroleum Hydrocarbon (TPH)). Details of the findings of the site
investigation are reported in the Contamination Assessment Report (CAR) (see Annex
B).
The excavated contaminated soil
will be remediated in accordance with the EPD’s Guidance Notes for Investigation and Remediation of
Contaminated Sites of Petrol Filling Stations Boatyards, and
Car/Repair/Dismantling Workshops, May 1999. The remediation actions
could involve excavation, testing, on-site treatment (ie soil
venting/biopiling) and on-site reuse.
A Remediation
Action Plan (RAP), which has been submitted together with the Contamination
Assessment Report (CAR) for EPD endorsement, has detailed the site clean up
method (see Annex B).
(b) C&D Materials
Demolition
Materials
The Project
involved demolishing of the following existing facilities to provide space for
installing FGD plants for Generation Units L4 and L5.
·
2 existing
250m3 light oil tanks and the associated fixtures/appendages/
foundations;
·
An in-ground oil
separator; and
·
Bund walls
surrounding the two light oil tanks.
The demolition
works will take about 5 months and are scheduled to commence in April 2006.
A total of about
29 tonnes of scrap steel will be produced from the demolition of the oil tanks
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 barges
for recycling.
A total of 660 m3 uncontaminated reinforced concrete (after
applying a bulking factor of 1.4) will be generated from demolition of the oil
tanks foundation, concrete slabs, bund walls and oil separator structures. They are not contaminated and should be
separated from other waste to avoid contamination. The reinforced concrete (public fill) will be reused on-site
for reclamation of Lamma Power Station Extension or sent to public filling
facilities /other reclamation site for reuse.
Excavated
Materials
Excavation works would be required for the construction of the piled foundations
of FGD booster fans, gas-gas heaters, gas ducts supports and the shallow
foundation of the Switchgear and Equipment Building. A total of 2,860 m3 (with bulking factors ([3])) of excavation materials (mainly soft
materials, ie sand and clay) will be generated.
After excavating the in-ground oil separator, the area will be backfilled with the excavated
soil (about 190 m3) to original ground level. About 2,670 m3 of
surplus excavation materials will be generated. The surplus excavated materials (public fill) will be reused
on-site for reclamation of Lamma Power Station Extension or sent to public
filling facilities/other reclamation site for reuse.
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 switchgear &
equipment building for the L4 & L5 FGD plant with the gross floor area
(GFA) of 750 m2. Based
on a generation rate of 0.1 m3 per m2 of GFA constructed ([4]), it is estimated that a total of about 75
m3 of C&D materials will be generated. These materials should be sorted on-site for into public
fill (inert portion) (about 60 m3) and construction waste (15 m3)
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.
Public fill will
be reused on-site for reclamation works of the Lamma Power Station Extension or
sent to public fills area / other reclamation site for reuse. Construction waste will be transported
to public pier by barge and transported by trucks to landfills for disposal.
C&D Materials - Summary
In view of the relative small of quantity of surplus public fill([5])
(a total of 3,400m3) and construction waste (about 15 m3)
to be generated, the potential environmental (ie dust water quality and noise)
impacts arising from waste handling and disposal will be minimal. Detailed assessments of the potential
air, water quality and noise impacts associated with the construction works are
discussed in Section 3, 4 and 7, respectively. The
public fill will be reused on-site for the reclamation works of the Lamma Power
Station and the off-site traffic will be minimal. About 1 barge trip and two truck trips will be required for
the off-site disposal of the construction waste.
(c) 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 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.
It is estimated that
about 30 m3 of oily water and oily sludge will be generated from the cleaning
of the fuel oil tanks and oil separator sump. It is difficult to quantify the amount of chemical waste
that will arise from other construction activities as it will be highly
dependent on the Contractor’s on-site maintenance activities and the quantity
of plant and equipment utilized.
However, it is anticipated that amount of chemical waste generated
during the construction phase will be less than a hundred litres per month
(mainly consists of lubricant oil).
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, the potential
environmental impacts will be negligible.
(d) Sewage
Sewage will arise
from the construction workforce and site office’s sanitary facilities. If not properly managed, these
materials could cause odour and potential health risks to the workforce by
attracting pests and other disease vectors.
It is estimated that a maximum of about 60 construction workers will be
working on site at any one time and the maximum quantity of sewage to be
generated will be about 3.6 m3 per day. All site workers will use the existing sanitary facilities
at the Lamma Power Station. With
respect to the small quantity (about 0.4% of existing WWTP capacity) of
additional sewage to be generated, no adverse impacts are envisaged for the
existing on-site wastewater treatment plant during construction phase.
(e) 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.
It is estimated
that a maximum of about 60 construction workers will be worked on site at any
one time. The amount of general
refuse to be generated will be about 39 kg per day. Recyclable materials (ie 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 Lamma Power Station by contractor and subsequently sent to
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
5.6.4 are adopted,
the environmental impacts caused by the storage, handling, transport and
disposal of general refuse are expected to be minimal.
Table 5.3 summarised the waste arising during construction of
the Project.
Table
5.3 Waste
Arising During Construction
|
Type |
Quantity |
Disposal
/ Treatment Site |
|
Contaminated Soil |
600 m3 |
On-site treatment and reuse as fill
materials at Lamma Power Station or Lamma Extension. |
|
Scrap Steel |
29 tonnes |
Off-site recycling |
|
Public Fill |
3,400 m3 |
Reuse on-site for the reclamation of
the Lamma Power Station Extension or other reclamation /public filling
facilities |
|
Construction Waste |
15 m3 |
Landfills |
|
General Refuse |
39 kg/day |
Transported together with other general
refuse generated from the existing Lamma Power Station to landfills |
|
Chemical Waste |
30 m3 from fuel oil tanks and oil
separator sump demolition. Less than 100 L/month from
construction activities. |
Chemical Waste Treatment Centre and/or
other licensed lube oil recycling facility |
|
Sewage |
3.6 m3/day |
Existing on-site WWTP |
5.5.2
Operational Phase
Solid Waste By-product from
FGD Processes
Gypsum
The proposed retrofit works involves directing of the
flue gas from the boilers of Unit L4 and L5 to new FGD plants, in which
limestone slurry is introduced to react with flue gas for removal of SO2
before discharging to the atmosphere via the stack. During these processes, wastewater from the FGD absorber will
be produced and commercial gypsum will be generated as a by-product. It should be noted that high quality
commercial grade gypsum is produced from the operation of the existing FGD
plants at Lamma Power Station. The
gypsum to be generated from the new FGD units will also be commercial grade.
Gypsum is a
useful construction material in building industry and the demand for gypsum is
high in both Hong Kong and mainland China. Table 5.4 presents the specification of gypsum to be
generated from the new FGD plant.
Table
5.4 Expected
Gypsum Specification
|
Parameter
|
Value |
|
Purity |
more than
90% as CaSO4.2H2O (dry basis) |
|
Free Moisture |
less than
15% (as received basis) |
|
Chloride |
less than
0.02% (as received basis) |
A total of 46,000
tonnes gypsum will be produced per year during the operation of new FGD plants
(L4 and L5). Under existing
contract arrangement, the limestone suppliers are required to collect an
equivalent amount of gypsum produced from the FGD Plants and no gypsum will be
stored on-site. This arrangement
has worked satisfactorily for the existing FGD plant. The same contract arrangement will therefore be used for the
new FGD plant.
In line with the
current practice, 70% of gypsum produced from the Unit L4 and L5 FGD plants
will be sold to a local cement manufacturer and 30% will be taken back by the
limestone suppliers to mainland China for reuse. Currently the quantity of gypsum supplied by HEC cannot meet
the demand of the local user and mainland limestone supplier and they have to
import gypsum from overseas suppliers.
Therefore it is expected that the local and mainland users will be
capable of off-taking the additional gypsum produced and no disposal or storage
facilities is required.
Under normal
operation, there is no off-specification gypsum produced which will otherwise
cause operational problem such as chute blockage by wet gypsum. All FGD plants are under daily
monitoring to ensure that the gypsum produced will meet the above
specification.
Additional Sludge from WWTP
The existing WWTP has spare capacity to
handle the additional wastewater produced from the new FGD plants. It is expected that a maximum 12 m3
hr-1 of wastewater will be produced from the new FGD plants
and an additional 1,200 tonnes per year (or about 3.3 tonnes per day) of sludge
will be produced from the WWTP. It
is expected that the characteristics of the sludge will be similar to that
currently generated from the WWTP (see Table 5.5).
Table
5.5 Sludge
Characteristics
|
Parameter
|
Value |
|
Purity |
More than 80% as CaSO4.2H2O |
|
Free Moisture |
Less than 25 % (as received basis) |
In line with
current operation, the sludge generated from WWTP will be off-taken by the
limestone suppliers together with the gypsum by barges. All sludges will be reused for
production of building materials (ie plaster board) in China.
Industrial Waste
Industrial waste
will arise from maintenance activities at the new FGD plants. The materials may include scrap materials
from maintenance of plant and equipment and cleaning materials. Provided the scrap materials are
collected regularly, it is not expected that storage, handling, transport and
disposal of industrial waste will cause adverse environmental impacts. Scrap metal and plastics will be
separated for recycling. Other
industrial waste (woods, packaging materials, etc) will be collected together
with the general refuse disposed of at landfills. From the operational experience of the existing FGD plant, the
amount of waste generated from the maintenance of the FGD plant is minimal (in
the order of a few kg per month).
Chemical Waste
Chemicals such as
limestone and sodium hydroxide will be used during the FGD and wastewater
treatment processes. Based on the
operation experience of the existing FGD plants and WWTP information, the
quantity of additional chemicals to be used for the new FGD plants are
summarized in Table 5.6.
Table
5.6 Types
and Quantity of Chemical To Be Used for Unit L4 & L5 FGD
|
Chemicals
|
Facility
Used |
Quantity |
|
Limestone |
FGD Plant |
26,000 tonnes/ year |
|
30% HCl |
WWTP |
48,000 L/ year |
|
50% NaOH |
WWTP |
106,000 L/year |
|
Polymer |
WWTP |
500kg/year |
With the existing
chemical management system, there is no wastage chemical due to over-supply,
expired chemicals and off-spec chemicals.
No chemical waste was generated from the use of these chemicals. The management system will be extended
to include the operation of the new FGD plant.
With reference to
the operation of the existing FGD system at Lamma Power Station, a small
quantity (in an order of several litres per month) of chemical waste will be
generated from the maintenance of the FGD Plants. The chemical waste may include lubricants, engine oil, used
batteries, coolants and solvents.
The existing chemical waste management system, which is development
based on the Code of Practice on the
Packaging, Labelling and Storage of Chemical Waste, will be extended to include
the chemical waste to be generated from the new FGD plant. No adverse environmental impacts are
anticipated due to the handling and disposed of the small quantity of chemical
waste from the operation of the new FGD system.
With reference to
the operational experience of the existing FGD plant at Lamma Power Station,
the amount of chemical waste to be generated from the maintenance of the plant
is minimal (in the order of several liters per month)
Sewage
The operation of the
new FGD plant will be managed by the existing staff. Therefore no additional sewage will be produced from the
workforce.
General Refuse
The operation of
the new FGD plant will be managed by the existing staff. Therefore no additional general refuse
will be generated from the workforce.
Table 5.7 summarises the waste arising during operation of the
Project.
Table
5.7 Waste
Arising During Operation
|
Type |
Quantity |
Disposal
/ Treatment Site |
|
Gypsum |
46,000 tonnes per year |
To be collected by the limestone
supplier and used by users in Hong Kong and China. |
|
Sludge |
1,200 tonnes per year or about 3.3
tonnes per day |
To be collected by the limestone
supplier and used by users in China |
|
Industrial waste |
A few kg per month |
To be disposed of together with
other general refuse. |
|
Chemical Waste |
Several litre per month |
Chemical Waste Treatment Centre or
other licensed lube oil recycling facility |
5.6
Mitigation of Adverse Impacts
There are no major
waste management issues associated with the operation of the new FGD
plant. 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 FGD plants.
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.
5.6.1
Contaminated Soil
For excavated
soil confirmed to be contaminated, mitigation measures recommended in RAP,
Annex B should be implemented.
5.6.2
Excavated Materials
Wherever
practicable, excavated materials should be segregated from other wastes to
avoid contamination thereby ensuring that it can be used as fill for the
reclamation works of the Lamma Power Station Extension and avoiding the need
for disposal at landfills.
Measures taken in the
Planning Design Stages to Reduce the Generation of C&DM
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.
Recommended Construction
Phase Measures for the Reduction of C&DM Generation
The Contractor
should recycle as much of the C&DM as possible on-site. 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. Surplus public fill should be reuse
on-site for reclamation, or delivered to public fills area /other reclamation
site by barge for reuse. The
construction waste should be collected by Contractor and transported to landfills
for disposal.
The use of wooden hoardings shall not be allowed. An alternative material, which can be
reused or recycled, for example, metal (aluminium, alloy, etc) shall be
used.
5.6.3
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.
5.6.4
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.
Office wastes can
be reduced through the recycling of paper if volumes are large enough to
warrant collection. Participation
in a local collection scheme should be considered if available. In addition, waste separation facilities
for paper, aluminium cans, plastic bottles etc., should be provided.
5.6.5
Management of Waste Disposal
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 should also be established in accordance with Works Bureau Technical Circular No. 31/2004
to monitor the disposal of solid wastes 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.
A recording
system for the amount of waste generated, recycled and disposed of (including
the disposal sites) should be established during the construction stage.
5.6.6
Staff Training
Training should
be provided to workers on the concepts of site cleanliness and on appropriate
waste management procedures, including waste reduction, reuse and recycling at
the beginning of the Contract.
5.7
Residual Environmental Impacts
With the
implementation of the recommended mitigation measures, minimal residual impacts
are anticipated from the construction and operation of the Project.
5.8.1
Construction Phase
The key potential
impacts during the construction phase are related to management of demolition
materials, excavated materials and construction waste.
A total of 600 m3 contaminated soil will be excavated for
on-site treatment (in accordance with the EPD’s Guidance Notes for
Investigation and Remediation of Contaminated Sites of Petrol Filling Stations
Boatyards, and Car/Repair/Dismantling Workshops, May 1999) and reuse at the either Lamma Power
Station Extension or Lamma Power Station.
A total of about
29 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 for recycling.
A total of 3,400
m3 of surplus public fill will be generated from the demolition and
construction works. The public
fill will be reused as fill for the reclamation of the Lamma Power Station
Extension or other reclamation/public filling facilities. About 15 m3 of construction
waste will be disposed of at landfills.
Small quantities
of chemical wastes (less than 100 litres per month), sewage (a maximum of 3.6 m3
per day) and general refuse (a maximum of 39 kg per day) will be generated
during the construction phase.
With the
implementation of the recommendations in Section
5.6, 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.
5.8.2
Operational Phase
All the
additional gypsum (about 46,000 tonnes per year) and sludge (about 1,200 tonnes
per year) will be generated and reused in Hong Kong and/or in Mainland China
and no disposal is required.
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 and chemical wastes
arising from the operation of the two new FGD units will meet the criteria
specified in the EIAO-TM and no
unacceptable waste management impact is anticipated.
([5]) The total volume of surplus public fill is the
sum of demolition concrete, inert C&D waste and excavated soil, reduced by
the volume of on-site back filling and potentially contaminated materials.