1                                            Introduction

1.1                                      The EIA Study

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.

1.2                                      Objectives of the Study

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.

1.3                                       Need for the Project

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                                      Project Description

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




Noise generation



See Section 6

Impacts on ecological resources




Visual aspects



See Section 7

Gaseous emissions



See Section 3




See Section 3

Liquid effluents



See Section 4

Disposal of spoil material



See Section 5

Generation of waste or by-products



See Section 5

Disruption of water movement or bottom sediment




Risk of accidents which would result in pollution or hazard




Endangerment of cultural heritage resources




Traffic generation



Minor increase in marine traffic

1.7                                       Structure of this Report

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.


provide supplementary information


([1])      http://www.epd.gov.hk/eia/register/study/latest/esb-133.doc

([2])      http://www.epd.gov.hk/eia/register/profile/latest/esb133.pdf

([3])      http://www.info.gov.hk/gia/general/200204/29/0429128.htm