This Environmental Impact
Assessment (EIA) Report addresses the potential environmental impacts
associated with the construction and operational phases of a project entitled
“Lamma Power Station Units L4&L5 Flue Gas Desulphurisation Plant Retrofit
Project” (hereinafter referred to as the Project).
The Project is classified under
EIAO as a material change to an exempted designated project, the Lamma Power
Station as a Public Utility Electricity
Power Plant (Item D.1 Part I Schedule 2 of the EIAO Chapter 499), because
of the changes induced by the FGD operations to the types and quantities of
emissions, wastes and effluents. In addition, the demolition of two existing
Light Oil Tanks is a designated project under item 16 Part II (Decommissioning Projects) Schedule 2 of
EIAO (i.e. a store for oil with a storage
capacity exceeding 200 tonnes).
This report has been prepared by
ERM-Hong Kong, Limited (ERM) in accordance with the EIA Study Brief (No. ESB-133/2005) ([1]) and the Technical Memorandum of the
Environmental Impact Assessment Process (EIAO-TM). The Study Brief was issued in October 2005, following submission by the
Hongkong Electric Co., Ltd (HEC) in September 2005 of the Project Profile (No. PP-261/2005) ([2]) for the retrofit.
The Study Brief stipulates the following objectives for this EIA:
·
to describe the Project and associated works together with
the requirements and environmental benefits for carrying out the Project;
·
to identify if there are other types of Designated Projects
under Schedule 2 of the EIAO to be covered in the Project;
·
to identify and describe the elements of the community and environment
likely to be affected by the Project and/or to likely cause adverse impacts to
the Project, including both the natural and man-made environment and the
associated environmental constraints;
·
to identify and quantify emission sources and determine the significance
of impacts on sensitive receivers and potential affected uses;
·
to identify and quantify any potential land contamination caused, to
determine the significance of the impact and to propose measures to mitigate
the impact;
·
to propose the provision of infrastructure or mitigation measures to
minimize pollution, environmental disturbance and nuisance during construction,
operation and decommissioning of the Project;
·
to investigate the feasibility, practicability, effectiveness and
implications of the proposed mitigation measures;
·
to identify, predict and evaluate the residual environmental impacts
(i.e. after practicable mitigation) and the cumulative effects expected to
arise during the construction, operation and decommissioning phases of the
Project in relation to the sensitive receivers and potential affected uses;
·
to identify, assess and specify methods, measures and standards, to be
included in the detailed design, construction, operation and decommissioning of
the Project which are necessary to mitigate these environmental impacts and
cumulative effects and reduce them to acceptable levels;
·
to investigate the extent of the secondary environmental impacts that
may arise from the proposed mitigation measures and to identify constraints
associated with the mitigation measures recommended in the EIA study, as well as
the provision of any necessary modification; and
·
to design and specify the environmental monitoring and audit
requirements to ensure the effective implementation of the recommended
environmental protection and pollution control measures.
As stated in the 2002 HKSAR
Government press release ([3]): The HKSAR
Government and the Guangdong Provincial Government have agreed to aim to
reduce, on a best endeavour basis, the regional emissions of sulphur dioxide,
nitrogen oxides, respirable suspended particulates and volatile organic
compounds by 40%, 20%, 55% and 55% respectively by 2010, using 1997 as the base
year. To achieve these targets, the two Governments will study and consider in
detail the various improvement measures recommended in the study, determine
work priorities and draw up action plans having regard to the feasibility of
the proposed improvement measures. The two Governments aim to strive to reduce
the emissions from their own sources by the same levels in 2010. Achieving the
emission reduction targets will enable Hong Kong to meet its current air
quality objectives. At the same time, cities in the Region will meet the
relevant national air quality objectives except for certain time periods and
locations. The problem of smog will also be significantly improved.
The Project is proposed in
response to the above Government emission reduction commitment with regard to
SO2 emissions and represents HEC contribution to that goal.
1.4.1
Background
The Hongkong Electric Company,
Limited (HEC) is planning to retrofit the two existing 350MW coal-fired
generating Units L4 and L5 of Lamma Power Station with Flue Gas
Desulphurisation (FGD) plant for reducing sulphur dioxide emissions in support
of Government policy to improve the air quality of the Pearl River Delta.
It is proposed to adopt the “Wet
Limestone-Gypsum” process for the FGD plants, a technology which is already
used in, and proved effective and reliable for the existing coal-fired units
L6, L7 & L8.
The proposed FGD process involves
directing the flue gas from the boilers of Units L4 and L5 to FGD plants, in
which limestone slurry is introduced to react with flue gas for removal of SO2,
before discharging to the chimney.
As a result, besides a significant reduction of the SO2
concentration in the flue gas, the temperature of flue gas entering the chimney
will be reduced, waste water from the FGD absorber will be produced and gypsum
will also be produced as a by-product.
1.4.2
Purpose and Nature of the Project
Lamma Power Station has an
installed capacity of 3,420MW comprising 3x250MW and 5x350MW coal-fire units,
1x365MW oil-fired combined cycle unit, and 1x55MW and 4x125MW oil-fired open
cycle gas-turbine units. The
latest three 350MW coal-fired units, Units L6, L7 & L8, are equipped with
FGD plants. The proposed retrofit
project will include the installation of FGD plants with flue gas
desulphurization efficiency of 90% for the two 350MW coal-fired Units L4 &
L5 to reduce the overall SO2 emissions from Lamma Power Station.
Location of the Project is
presented in Figure 1.1.
1.4.3
Consideration of Alternatives
A comprehensive study
on FGD technologies were carried out in the EIA Study for Units L7 & L8 at
Lamma Power Station in 1993 of which two study reports namely Selection of FGD Process and Detailed Comparison of FGD Processes for
Units L7 & L8 at Lamma Power Station were prepared and submitted to the
EPD. Various FGD technologies including
wet, semi-dry, dry processes have been updated and evaluated by HEC in house
studies and were considered less advantageous in both environmental and
economical considerations. Since
the “Wet Limestone-Gypsum” is already used in Lamma Power Station for more than
10 years which has proved effective and reliable for the existing coal-fired
units L6, L7 & L8, it is considered that Wet Limestone-Gypsum Process, in
terms of maturity, cost, SO2 removal performance, reagent
availability, by-product quality, synergy benefits, is the most suitable
process for the application in L4 & L5 FGD retrofit project.
1.4.4
Proposed Additions, Modifications and Alterations
As
stated in the Project Profile, at
present, the flue gas from Units 4&5 Boilers is directly discharged to the
atmosphere via a 210 m high chimney. The retrofit work will involve demolishing
the existing Nos. 4 & 5 Light Oil Tanks (each of 250m3 capacity)
and relocating some of the pipeworks located in front of the respective boiler
to provide areas for installing FGD plant for each of Units L4 & L5.
The
flue gas from the boiler will be directed to the FGD absorber inside which
removal of SO2 will take place by reaction with limestone slurry.
After passing through the absorber, the treated flue gas will be heated up by a
gas-gas heater to over 80ºC at boiler rated capacity and directed back to the
existing chimney for discharge to the atmosphere.
As majority of the existing
common limestone powder/gypsum handling and storage facilities for Units L6, L7
& L8 FGD plants have spare capacity to cater for two more FGD units, the
additional equipment required for Units L4 & L5 FGD retrofits will be
limited to the extension of the existing gypsum dewatering system.
Figure 1.2 shows
the additional equipment to be installed for the proposed retrofit project for
Units L4 and L5 which includes:
·
Two sets of FGD absorbers and
associated ductworks
·
Two sets of booster fans
·
Two sets of gas-gas heaters
·
FGD Switchgear and Equipment
Building
·
Gypsum dewatering system
comprising two sets of hydrocyclones and belt filters
Figure 1.3 shows the layout of the two existing Light Oil
Tanks to be demolished.
1.4.5
Project Programme
Based on the lead time required
for design, delivery and construction, the targeted key dates for the proposed
FGD retrofit project are as follows:
·
Commencement of demolition
of L.O. Tanks April 2006
·
Commencement of civil works September
2006
·
Commencement of plant erection
for L5 Unit October 2007
·
Commencement of plant erection
for L4 Unit August
2008
·
Commercial operation of L5 FGD
Plant July 2009
·
Commercial operation of L4 FGD
Plant April
2010
1.4.6
Interaction with Other Projects
No other major project was
identified to be carried out concurrently in the vicinity of the proposed
Project.
1.5
Outline of the FGD Process
The “Wet Limestone - Gypsum”
process being employed for Units L6, L7 and L8 of Lamma Power Station will be
adopted for the proposed retrofit project. This technology has been proved
reliable and effective, and the operating and maintenance (O&M) costs are
low. Adopting the same technology
for Units L4 & L5 will have synergy benefits on O&M and utilizing most
of the common limestone/gypsum storage and handling facilities already in place
for the existing FGD plants.
Figure 1.4 shows
the schematic diagram of the FGD plant.
Limestone powder is mixed with
water to form slurry and fed to the scrubber to absorb SO2 from the
flue gas. The by-product is
withdrawn for dewatering to produce saleable gypsum. The clean flue gas is reheated before entering the chimney
to regain buoyancy for better dispersion and to prevent acid condensation in
the chimney.
Boiler flue gas is directed to
the absorber tower inside which SO2 reacts with the limestone slurry
in the suspension to calcium sulphite which is oxidised to calcium sulphate in
the absorber sump. Recycle slurry in
the absorber sump is maintained in motion by agitators to enhance gypsum
crystal growth, achieve a high degree of sulphite oxidation and promote
limestone dissolution.
A booster fan is provided to
overcome the draft loss of the flue gas passing through the FGD system. Three sets of dampers and a pair of
guillotine shutters are used to bypass and isolate the FGD plant. Gas-gas heater is adopted to heat up
the clean gas leaving the absorber to minimise the effect of condensation of
flue gas and to ascertain its effective dispersion of the remnant pollutants to
the atmosphere.
The reacted limestone slurry in
the absorber sump, called gypsum slurry, which is no longer useful is bled off
to a set of hydrocyclones and vacuum belt filters located inside the existing
gypsum dewatering building for dewatering and gypsum in cake form is produced
as a result. The filtrate generated thereof is directed to the existing
wastewater treatment system.
Gypsum discharged from the belt
filters with a purity of 90%, moisture of 10% and chloride of 200ppm is carried
through a set of belt conveyors into the existing gypsum silo for off-site
industrial application/reuse by barges.
The FGD plants of the proposed
retrofit project are capable of removing 90% of the SO2 in the boiler
flue gas.
1.6
Scoping of Environmental Issues
The potential environmental
impacts associated with the Project are summarised in Table 1.1.
Table 1.1 Potential
Sources of Environmental Impacts
|
Type of Potential Impact |
Construction |
Operation |
Remarks |
|
Noise
generation |
P |
P |
See
Section 6 |
|
Impacts
on ecological resources |
X |
X |
|
|
Visual
aspects |
P |
P |
See
Section 7 |
|
Gaseous
emissions |
P |
P |
See
Section 3 |
|
Dust |
P |
X |
See
Section 3 |
|
Liquid
effluents |
P |
P |
See
Section 4 |
|
Disposal
of spoil material |
P |
X |
See
Section 5 |
|
Generation
of waste or by-products |
P |
P |
See
Section 5 |
|
Disruption
of water movement or bottom sediment |
X |
X |
|
|
Risk
of accidents which would result in pollution or hazard |
X |
X |
|
|
Endangerment
of cultural heritage resources |
X |
X |
|
|
Traffic
generation |
X |
X |
Minor
increase in marine traffic |
The
objective of the Project is to reduce the SO2 emissions
from the L4 and L5 units, which would lead to an improvement of environmental
performance of the Lamma Power Station with regard to Air
Quality. The Project may however create,
both in the operational and construction phases, some impacts in other areas
such as Water Quality or Waste Management. All the potential environmental impacts, of the Construction
and Operational Phases of the Project, as well as the Environmental Monitoring
and Audit (EM&A) requirements (where necessary) are addressed in detail in
the following sections which constitute the principal part of the main part of
this report of the Environmental Impact Assessment Study.
The remainder of this EIA Report
comprises the following sections.
|
Section 2 |
presents the findings of the
land contamination assessment. |
|
Section 3 |
presents the findings of the
air quality impact assessment. |
|
Section 4 |
presents the findings of the water
quality impact assessment. |
|
Section 5 |
presents the findings of the
waste assessment. |
|
Section 6 |
presents the findings of the
noise impact assessment. |
|
Section 7 |
discusses and illustrates the
landscape and visual aspects of the project. |
|
Section 8 |
addresses Environmental
Monitoring and Audit (EM&A) issues and includes the Implementation
Schedule for the proposed mitigation measures |
|
Section 9 |
provides a summary of the conclusions
and environmental outcomes drawn from the detailed assessment of the Project. |
|
Annexes |
provide supplementary
information |