4
Air
Quality Assessment
This section presents the assessment of
potential air quality impacts from the construction and operation of the
proposed LNG terminal at
4.2
Legislation Requirement and Evaluation Criteria
The principal legislation for the
management of air quality in
Table 4.1
A maximum
hourly TSP concentration 500 mgm-3
at ASRs is also stipulated in the Technical
Memorandum on Environmental Impact Assessment Process (EIAO-TM) to control potential construction dust impacts.
The
measures stipulated in the Air Pollution
Control (Construction Dust) Regulations
should be followed to ensure that any dust impacts are reduced.
In
accordance with the Air Pollution Control
(Furnaces, Ovens and Chimneys) (Installation and Alteration) Regulations,
an installation of a chimney/flue which consumes more than 1,150 megajoules of gaseous fuel per hour or 25 litre of
conventional liquid fuel per hour requires an approval from the Environmental Protection Department
(EPD) prior to the commencement of the installation work. Engineering plans showing the elevations
and plan views of the chimney/flue together with the specification should be
submitted for approval not less than 28 days prior to the commencement of such
work.
Should
a process listed in Table 4.2 exceed
the respective regulatory thresholds under the Air Pollution Control (Specified Process) Regulations, it is
classified as a Specified Process and hence, a licence should be obtained from
the EPD prior to their operation.
Table 4.2 Specified
Process and Its Regulated Capacity under the Air Pollution Control (Specified
Process) Regulations
During
the operation of these processes, the air/dust control measures in the Guidance Note on the Best Practicable Means
for Cement Works (Concrete Batching Plant) (BPM 3/2), Electricity Works
(Coal-fired Plant, Gas-fired Gas Turbine and Oil-fired Gas Turbine (Peak
Lopping Plant)) (BPM 7/1) and Mineral
Works (Stone Crushing Plants) (BPM 11/1) should be implemented to meet the
respective emission limits.
4.3
Baseline Conditions and Air Sensitive Receivers
4.3.1
Baseline
Conditions
The proposed LNG terminal is located on
the South Soko Island. The North Soko
Island is located approximately 1 km away from the site. The island has no population and there are
no major sources of atmospheric emissions in the vicinity.
The proposed GRS is located to the west
of the BPPS (see Figure
4.3b).
The Black Point Headland is located to the west of the GRS. The Black Point area has a very low
population density. Air emissions
from the BPPS and the Castle Peak Power Station (CPPS) are major sources of air
emissions in the vicinity.
There is currently no Air Quality
Monitoring Station (AQMS) operated by the EPD in the immediate vicinity. The nearest EPD AQMS is located in Tung
Chung (TC), which is to the north of Sunset Peak and Lantau
Peak. The air quality data from the
AQMS at Tung Chung in 2004 are adopted as the background in this Study. These data are summarized in Table 4.3.
Table 4.3 Background
Air Quality at Tung Chung
|
Air Pollutant |
Background
Concentration (mg
m-3) |
|
Total
Suspended Particulates (TSP) |
72 (a) |
|
Respirable Suspended Particulates (RSP) |
62 (a) |
|
Nitrogen
Dioxide (NO2) |
52 (a) |
|
Sulphur
Dioxide (SO2) |
27 (a) |
|
Carbon
Monoxide (CO) |
799 (a) |
|
Ozone
(O3) |
108 (b) |
|
Notes: (a)
Annual Average Concentrations
measured at EPD’s Tung Chung AQMS in 2004 (b)
The ozone concentration is the annual
average of the daily hour maximum concentration measured in 2004 |
|
Contribution
of Emissions from BPPS and CPPS
Air quality in the vicinity will also
be influenced by local emission sources, including BPPS and CPPS during the
operation of GRS.
An EIA
of the Proposed 6,000 MW Thermal Power Station at Black Point: Key Issue
Assessment – Air Quality (hereafter referred to as the BPPS EIA Study) has been used as the basis for quantifying the
contribution of emissions from BPPS and CPPS to local air quality.
The BPPS
EIA Study included wind tunnel testing to assess the near-field air quality
impacts of six gas-fired units, each with a design generating capacity of 800
MW (Phases I and II) (i.e., a total generating capacity of 4,800 MW) for BPPS
and the CPPS “A” and “B” Units (CPA and CPB). The findings of the wind tunnel tests
indicated that nitrogen dioxide (NO2) is the major air pollutant and
that higher NO2 impacts occur at higher wind speeds (refer to Annex D of BPPS EIA Study) ([1]).
NO2 concentrations under different averaging times at Lung Kwu Tan were calculated based on the wind tunnel testing
results, the reported ozone level (i.e. 70 µgm-3) and the NOx/NO2
ratio estimation approach as described in “A
Classification of NO Oxidation Rates in Power Plant Plumes based on Atmospheric
Conditions”, by Janssen, 1983.
Since the assessment was completed,
there have been a number of changes to both the installed generating capacity
and the regional air quality.
Compared to the ozone level in 1993 (70
µgm-3), the annual average of the daily one-hour maximum
concentrations has increased to 108 µgm-3 in 2004 (see Table 4.3).
For assessing the contribution of the
BPPS, an adjustment was made to account for the current generating capacity
which is 2,500 MW. There is no
confirmed programme for the Phase II expansion, as was assumed in the BPPS EIA Study.
For assessing the contribution of the
CPPS, an allowance was made for the fact that low NOx
burners are now operating in the CPA and CPB. A further NOx
reduction is anticipated for CPB and the indicative date of the implementation
of the further NOx reduction measures will
be over the period of 2009 to 2011 according to the approved EIA for Emission Control Project to CPPS “B”
Units.
Taking into consideration the latest
information for BPPS and CPPS as well as the higher ozone level of 108 µgm-3,
the adjusted NO2 concentrations are summarized in Table 4.4 and were utilised in the
assessment of the cumulative air quality impacts in the Lung Kwu Sheung Tan area.
Detailed calculations are provided in Annex 4-A.
Table
4.4 Adjusted
Maximum Hourly, 2nd Highest Daily and Annual NO2
Concentrations in 2004 based on Wind Tunnel Test Results
|
Location |
Adjusted
NO2 Concentration in 2004 (mgm-3) (a) |
||
|
|
Maximum
Hourly |
Daily
(c) |
Annual
(c) |
|
Lung Kwu
Tan |
54 (b) |
22 |
0.6 |
|
Notes: (a) Adjustment
is based on the annual average of the daily hourly maximum ozone
concentration (108 mgm-3) in 2004. (b) Only the BPPS contribution is
considered. A factor of 0.5 is
applied to adjust for the current power generating capacity of BPPS to
current capacity. (c) Both BPPS and CPPS contributions are
considered, no adjustment has been made to account for the reduced power
generation capacity of BPPS, existing licence limit requirement or the future
NOx reduction at CPB due to the
implementation of the Emission Control Project. |
|||
4.3.2
Air
Sensitive Receivers
In accordance with the Study Brief, the
study area for the air quality assessment is generally defined by a distance of
500 m from the boundary of the Project site. Air Sensitive Receivers (ASRs) were
identified in accordance with the criteria in EIAO-TM Annex 12.
No ASRs were identified on the South Soko Island.
The nearest ASR is the Staff Quarters of Shek Pik Prison (A1), which is approximately 6.4 km away. In the Lung Kwu
Sheung Tan area, six ASRs were identified by site
visit. A description of the
identified ASRs is summarized in Table
4.5 and their locations are shown in Figures 4.1a and
4.1b.
Table 4.5 Identified
Air Sensitive Receivers
|
ASR |
Location |
Approximate
Distance from LNG Emission Source (m) |
Type
of Uses |
Maximum
Height (m above ground) |
|
Soko
Island |
||||
|
A1 |
Staff Quarters of Shek
Pik Prison |
6,400 |
Prison |
10 m |
|
Black Point |
||||
|
A2 |
Black Point Power Station –
Administration Building |
510 |
Office |
6 |
|
A3 |
Karting
Track |
1,800 |
Recreational |
1.5 |
|
A4 |
Open Storage – Site Office |
1,390 |
Site Office |
6 |
|
A5 |
Concrete Batching Plant – Site Office |
1,440 |
Site Office |
1.5 |
|
A6 |
Hong Kong Oil – Site Office |
1,550 |
Site Office |
6 |
|
A7 |
Open Storage – Site Office |
1,680 |
Site Office |
1.5 |
4.4
Potential Sources of Impact
4.4.1
Construction
Phase
Nuisance
from dust generating activities and gaseous emissions from diesel-driven plant
has the potential to arise during construction. The major construction works include
slope cutting, site clearance, dredging, reclamation, gas pipeline installation
works and civil works. Excavation
and filling, materials handling, wind erosion of open areas and blasting are
the major dust generating activities during the construction of the LNG
terminal.
Site Clearance and Blasting
Site
clearance and blasting are planned to be undertaken within the first year of
the works. Due to the limited space
available onsite, excavated soil will be temporarily stockpiled offsite for reuse
within the project or other concurrent construction projects. Excavated rocks will be taken to a
quarry in Mainland China for processing and the processed rock will be
subsequently reused within the project for protection of the submarine pipeline
or within the reclamation. Suitable
stockpile sites are currently being sought. Details of the disposal arrangements for
the excavated materials are presented in Section
7 (Waste Management).
Blasting
works will be carried out during the site formation works. During the blasting works, the control
measures stipulated in the Air Pollution
Control (Construction Dust) Regulations will be implemented to reduce the
dust impacts. Mobile rock crushers
will be employed onsite to crush the excavated rock into a suitable size for
transportation. During the rock
crushing activities, the dust control measures recommended in the Guidance Note on the Best Practicable Means
for Mineral Works (Stone Crushing Plants) (BPM 11/1) will be implemented to
meet the emission limit in BPM 11/1.
Any
dust impact during site clearance and blasting is expected to be
localized. The separation distance
between the identified ASR and the construction site is approximately 6.4 km, which satisfies the HKPSG recommended buffer distance of
100 m. Together with the
implementation of the dust control measures stipulated in the Air Pollution Control (Construction Dust)
Regulations and in the Guidance Note
on the Best Practicable Means for Mineral Works (Stone Crushing Plants) (BPM
11/1), the potential dust impact arising from site clearance and blasting
works at the ASR is predicted to be minor and within the dust criteria.
Dredging and Reclamation Works
Dredging
works will be required for construction of seawall, approach channel and
turning basin, submarine water main, gas pipeline, cabling and gas receiving
station. Such dredging is planned
to be undertaken within the first two years of the works depending on the
programme for the Foreshore and Seabed
(Reclamations) Ordinance (FSRO) approval. Marine sediment will be dredged and
disposed of at designated marine disposal sites by barge. The moisture content of dredged
materials is very high, therefore, no fugitive dust emissions are anticipated
during the works.
During
the reclamation works, rocks will be imported for seawall construction from the
designated stockpile site or quarries whereas soil will also be imported from
the designated stockpile site or public filling area for filling works. No fugitive emissions are expected from
rock filling; however, fugitive dust emissions are possible from the handling
of public fill. In accordance with
the construction method, the filled area will be compacted immediately after
filling and therefore, fugitive dust emissions will be reduced. Furthermore, due to the large separation
distance from the ASR and with the implementation of the dust control measures
stipulated in Air Pollution Control
(Construction Dust) Regulations, no dust impact is anticipated.
Terminal Facility Construction Works
and Civil Works
Terminal
facility construction works and civil works will be carried out. Two concrete batching plants with
concrete production rates of 110 m3hr-1 and 60 m3hr-1
(as backup) each, are proposed on site for the concreting work and
fugitive dust emissions are expected.
However, during the concreting activity, the dust control measures
recommended in the Guidance Note on the
Best Practicable Means for Cement Works (Concrete Batching Plant) (BPM 3/2)
will be implemented to meet the respective emission limits. With the implementation of the dust
control measures recommended in the BPM
3/2 and large separation from the ASR, an adverse air quality impact is not
anticipated at the ASR.
On-site Sewage Treatment Works
The
sewage generated from the workforce during the construction phase will be
either conveyed to a public sewage treatment works (STW) or treated
onsite. The daily generation rate
of sewage is about 240 m3, assuming a workforce of up to 1,600
people. If
a small STW is proposed on-site it will be designed to meet the Hong Kong
standards ([2])
and will minimise the potential of odour nuisance.
Gaseous Emissions from Construction
Plant
Gaseous
emissions from diesel-driven construction plant will arise during the
construction phase. With reference
to the construction programme and the powered-mechanical equipment (PME)
inventory (see Section 5.4.1 and
Annex 5-B), LNG terminal facility construction works and civil works
will involve the highest number of diesel-driven PMEs
(a total of 54 PMEs) including 2 backhoes, 3 drill
rigs, 18 engines, 16 air compressors, 15 crawler cranes; 4 trucks and 14
barges/tug boats. The engine power
of the engines is about 500 kW. For
other diesel-driven PMEs, the average engine power is
similar to a truck engine, i.e., 100 kW.
The barges/tugboats will normally be berthing for unloading/loading of
equipment or materials and therefore, their emissions will not be continuous.
Oxides
of nitrogen (NOx) and respirable
suspended particulates (RSP) are the major air pollutants emitted from
diesel-driven PMEs. The emission factors for non-road
diesel engines, as recommended in the USEPA
Tier 1 Non-road Engine Emission Factors ([3]),
are used to estimate the emission quantities. Assuming that all diesel-driven equipment
are operated simultaneously, the estimated emission rates are summarized in Table 4.6.
Table 4.6 Emission
Factors and Emission Rates for Construction Plant based on the Preliminary
Design Estimates
|
|
NOx |
RSP |
|
Total
worksite area |
230,000 m2 |
|
|
Total
no. of engines |
18 |
|
|
Average
Engine Power of generator (kW) (a) |
500 |
|
|
Total
no. of diesel-driven equipment (including backhoes + drill rigs + air
compressor + crawler crane + trucks) |
40 |
|
|
Average
Engine Power of diesel-driven equipment (kW) (b) |
100 |
|
|
USEPA
Tier 1 Non-road Engine Emission Factor (g/kWh) (c) |
9.2 |
0.54 |
|
Total
emission rate (g/s) |
33.2 |
1.95 |
|
Total
emission rate per area (g/m2/s) |
1.4x10-4 |
8.5x10-6 |
|
Notes: (a)
Reference
to the engine power provided by the Design Engineer (b)
Typical
engine power of truck is 100 kW and it is assumed that the engine power of
stationary source is also about 100 kW. (c)
Reference
to USEPA Non-road Engine Emission
Factor (http://www.dieselnet.com/standards/us/offroad.html) |
||
Air
emissions will disperse very rapidly over the large construction area and the number
of construction plant items adopted in the above estimation is the worst
case. It should also be noted that
not all items of construction plant will be operated continuously. Taking into account the large separation
distance between the site boundary and the nearest ASR (see Table 4.5), no adverse air quality
impacts are anticipated.
Offshore
PMEs such as grab dredgers, barges and tugboats will
be distributed at the area of dredging, reclamation, turning basin, pipeline
works, jetty and other marine works.
Referring to the construction plant inventory in Section 5.4.1 and
Annex 5-C, a total of 9 dredgers/barges/tugboats are required for
reclamation; a total of 12 dredgers/barge/tugboats are required for marine
works and a total of 5 are required for the installation of water main and
cable. These dredgers, barges and tugboats are located at different marine
works area, therefore, the air emissions from the offshore PMEs
over an overall large marine works area will be low. With the consideration of large
separation from the ASR, no adverse air quality impact due to offshore PMEs is anticipated.
4.4.2
Operational
Phase
During the operation of the LNG
terminal, potential sources of air quality impact include:
South Soko
Island
·
emissions from the submerged combustion
vaporizers (SCVs);
·
emissions from the gas-turbine
generator;
·
emissions from the LNG carrier and
tugboats during the unloading of LNG;
·
emissions from the on-site vehicles;
·
emissions from the diesel-driven
firewater pumps;
·
fugitive hydrocarbon release from
boil-off gas (BOG) compressors seal leakage; and
Black Point
·
emissions from gas heaters at the Gas
Receiving Station (GRS) at the Black Point Power Station.
Emissions
from Submerged Combustion Vaporizers (SCVs)
Five submerged combustion vaporizers (SCVs) will be operated in the event that the Open Rack
Vaporizers (ORVs) run below their capacity (i.e., the
ambient seawater temperature is too cold, breakdown of the seawater intake pump
or an increase in gas sendout is required).
Natural gas will be used as fuel for
the SCVs.
An individual stack is connected to each of the SCVs
and has a preliminary design diameter of 1.2 m and a height of 13 m above
ground. As the operating frequency
of the SCVs is not known at this stage, for the
purposes of the assessment, it has been assumed that all five of the SCVs are in continuous operation. Based on the continuous operation of SCVs, the exhaust gas flowrate of
each SCV is approximately 26,000 Nm3hr-1 ([4]).
The exhaust gas will be emitted at about 30 to 50°C. Oxides of nitrogen (NOx)
and carbon monoxide (CO) are the principal air emissions and about 51 tonnes of
NOx and 257 tonnes of CO may be emitted
from the SCVs a year. It has been conservatively assumed that
the exhaust gas will be emitted at 30 °C.
Emissions
from Gas-turbine Generators
The on-site gas-turbine generators may
be used to generate electric power for the LNG terminal. According the preliminary design, four
units of gas-turbine generators are proposed to provide a total capacity of 23
MW. These generators are fuelled by
natural gas. An individual stack is
connected to each generator and has a preliminary designed exhaust area of 2.3m
x 2.3m and a height of 8 m above ground.
NOx and CO are the principal air
emissions. Assuming that the
gas-turbine generators are operated continuously, about 128 tonnes of NOx and 156 tonnes of CO will be emitted a
year. The total exhaust gas will be
emitted at an estimated flowrate of 382,800 Nm3hr-1
and at a temperature of 500 °C.
A specified process licence will be
obtained from the EPD in accordance with the Air Pollution Control (Specified Process) Regulations and the
requirements for operational monitoring, including in-stack, process and ambient
monitoring in BPM 7/1 ([5]) , will be followed.
Emissions
from LNG Carrier and Tugboats during Unloading of LNG
LNG will be delivered to the LNG
terminal by LNG carrier. The LNG
will then be transferred from the LNG carrier to the storage tanks at the
terminal at a preliminary design rate of 14,000 m3hr-1. The unloading time will be approximately
18 hours. Approximately 75 LNG
carrier deliveries are expected each year
(i.e., approximately one LNG carrier transit into and out of Hong Kong waters
every 5 days). While within Hong
Kong waters, the LNG carrier will be guided by a pilot, with two to four
tugboats available to assist as necessary.
While
the LNG carrier is alongside the jetty, two tugboats will remain in close
proximity, but the engines of the tugboats will be shut down.
The proposed LNG carrier transit route
(refer to Figure
4.2), is very short in
When moored in required position
alongside the jetty, the main engine will be switched off and the auxiliary engines
will operate for LNG unloading and to provide power for other ship
services. Three auxiliary engines
with a total generator capacity of approximately 9.35 MW running at 75% load
will be operated to pump the LNG to the terminal’s storage tanks. The auxiliary engines are assumed to be
fuelled by Marine Diesel Oil (MDO) or Heavy Fuel Oil (HFO) and NOx, SO2 and CO are the principal air
emissions. The MDO or HFO has been
assumed to contain a maximum of sulphur content of 1.5%. Approximately 13.88 g/kWh of NOx, 6 g/kWh of SO2 and 0.6 g/kWh of
CO will be emitted from the auxiliary engine at 75% load ([7]).
The exhaust gas velocity is estimated to be 25.0 ms-1 through
a stack of approximately 41 m above sea level. The stack diameter is about 0.45 m. The three individual stacks of the
auxiliary engines are enclosed in a single chimney, therefore the three
individual emission sources are modeled as an
equivalent source with an equivalent diameter of 0.78 m.
For the worst case assessment and to
allow for the flexibility in the LNG carrier unloading process, it has been
assumed that exhaust emissions from the auxiliary engines are emitted
continuously.
Emissions
from On-site Vehicles
As the delivery of diesel, LNG and
materials are marine-based, the number of on-site vehicles will be limited to
those required for staff transportation and maintenance works only. The emissions from on-site vehicles will
therefore, be negligible and no adverse air quality impact from this source is
anticipated.
Emissions
from Diesel-driven Firewater Pumps
Four firewater pumps (two diesel-driven
and two electric-driven) will be provided and located besides the utility
area. They will be used in
emergency situations and during routine testing only, i.e., an average of 1.5
hours per week on average. The fuel
consumption rate of each diesel-fired firewater pump is about 0.108 m3hr-1. NOx,
SO2 and CO are the principal air emissions. The air emissions are infrequent and
minor and hence, adverse air quality impacts are not anticipated.
An approval for the chimney
installation for diesel-driven pumps will be obtained from the EPD, in
accordance with the Air Pollution Control
(Furnaces, Ovens and Chimneys) (Installation and Alteration) Regulations.
Fugitive
Hydrocarbon Release from Boil-off Gas (BOG) Compressors Seal Leakage
Fugitive hydrocarbon may be released
from a leakage of the boil-off gas (BOG) compressors seal,
releasing a quantity of boiled-off vapours of about 53 tonnes of hydrocarbon per
annum. Typically
about 90% of the hydrocarbon will be methane. This is equivalent to only 0.02% of the
total annual emission of methane in Hong Kong ([8]).
Emissions will be minimised through
the design process and the ongoing maintenance programme,
which will incorporate a leak detection and repair monitoring programme.
The safety implications of accidental
leaks are discussed in Section 13.
Emissions
from Gas Heaters at Gas Receiving Station at Black Point Power Station
The pipeline from
Natural gas will be used as fuel for
the gas heaters and NOx and CO are the
principal air emissions. Approximately
72 tonnes of NOx and 45 tonnes of CO will
be emitted a year. The total flowrate of the exhaust gas is estimated to be 73,900 Nm3hr-1
and the exhaust gas temperature will be about 280°C. An individual stack is connected to each
of the gas heaters. The stack
diameter is 1.07 m and the stack height is approximately 15 m above ground.
Summary
In view of the emission characteristics
of these sources and the frequency of operation, the SCVs,
gas-turbine generators and LNG carrier auxiliary engines on South Soko and gas heaters at new GRS at Black Point are included
in the detailed assessment. The
other sources have been excluded from the modelling assessment on the basis
that they are of a small scale and /or are operated very infrequently. The locations of the major emission
sources are shown in Figures
4.3a
and 4.3b.
4.5.1
Emission
Rate Estimation
SCVs and gas-turbine generators at
As discussed in Section 4.4.2, the SCVs, gas-turbine
generators, LNG carrier auxiliary engines and gas heaters at GRS are assumed to
be operating continuously throughout 24 hours and 365 days in the modeling assessment as a conservative approach.
The emission rates of NOx, SO2 and CO are estimated and
summarized in Table 4.5 and detailed
calculations are presented in Annex 4-B.
Table
4.7 Summary
of Emission Rates of NOx, SO2
and CO based on Preliminary Design Estimates
|
|
South Soko |
Black Point |
||
|
|
SCV |
Gas Turbine Generator |
LNG Carrier – Auxiliary Engine
(b) |
Gas Heaters at GRS |
|
Stack height (m) |
13 |
8 |
41 |
15 |
|
Stack diameter (m) |
1.2 |
2.6
(a) |
0.78 |
1.07 |
|
Exit temperature (°C) |
30 |
500 |
320 |
280 |
|
Exit velocity (m/s) |
7.09 |
14.2 |
25 |
11.56 |
|
No. of emission source |
5 |
4 |
1
(c) |
4 |
|
NOx
emission rate of each source (g/s) |
0.32 |
1.01 |
36 |
0.57 |
|
SO2 emission rate of each
source (g/s) |
- |
- |
15.6 |
- |
|
CO emission rate of each source (g/s) |
1.63 |
1.24 |
1.56 |
0.36 |
|
Notes: (a)
The
stack diameter is an equivalent diameter in which the stack emission area is
2.3 m x 2.3 m. (b)
The
total capacity of LNG carrier auxiliary engines is 9,350 kW. (c)
Three
individual emission sources are modeled as an
equivalent source. |
||||
4.5.2
Modelling
Approach
An air dispersion model, Industrial Source Complex Short Term
(ISCST3), recommended in the EPD’s Guideline of
Choice of Models and Model Parameter, was employed to predict the air
quality impact.
The SCVs,
gas-turbine generators, LNG carrier auxiliary engines and gas heaters were
assumed to be operated continuously in the modeling
assessment for a worst case assessment.
As the site areas of LNG terminal and
GRS are classified as “rural” in accordance with the EPD’s
Guidelines on Choice of Models and Model Parameter, the “rural”
dispersion mode was used in the model run.
In addition, the local terrain has also been incorporated into the model
to account for terrain-induced impacts to dispersion.
Due to the high background ozone level
as presented in Table 4.3 (108 mgm-3),
the Ozone Limiting Method (OLM) was therefore used to estimate the hourly conversion
ratios of NOx to NO2.
Since most of the emissions are from
elevated sources, air pollutant concentrations were, therefore, predicted at
1.5 m and 10 m above ground level for the identified ASRs.
A worst-case assumption of continuous
emissions from all of the identified sources was made and a whole year of
meteorological data was used in the air dispersion model. Maximum hourly, daily and annual average
NO2, SO2 and CO concentrations were predicted at the
identified ASRs.
4.5.3
Meteorological
Conditions
Representative hourly meteorological
data from the Hong Kong Observatory
(HKO) station located at Cheung Chau, for the year
2004, were used for the assessment of the air quality impact in the vicinity of
South Soko.
Whereas the hourly meteorological data from the HKO station located at Sha Chau for the year 2004 were
used for the assessment of the air quality impact in Black Point. The meteorological data included hourly
wind speed, wind direction, stability class, air temperature and mixing height
information.
4.5.4
Cumulative
Impacts
Within the vicinity of the South Soko Island, there is no major air emission source and only
the background air quality (presented in Table
4.3) would contribute to the cumulative air quality impacts during the
operation of the LNG Terminal.
Within the vicinity of the GRS at Black
Point, the Black Point Power Station (BPPS) is the nearest existing air
emission source. In addition, the
Castle Peak Power Station (CPPS) also contributes to the local air
quality. The cumulative assessment
considers the background air quality, as presented in Table 4.3, and these two main emission sources.
In the future,
atmospheric emissions may arise from additional facilities in the vicinity,
including Animal Carcass Treatment Facilities (ACTF), Sludge Treatment
Facilities (STF), Waste-to-Energy Facilities (WEF) and the landing point of the
Ling Ding Yang Bridge, would also contribute to the cumulative air quality
should they be developed. The
status and the timeframes of these developments are unknown at this stage and
hence they are not be considered in the cumulative air quality impact
assessment for this project.
4.6.1
Results
(Emissions from Operation of LNG Terminal Only)
The
worst case maximum hourly, daily average and annual average concentrations of
NO2 and SO2 and the worst case maximum hourly and 8-hour
average concentrations of CO were predicted due to the operation of the LNG
Terminal. The predictions are
summarized in Table 4.8.
Table 4.8 Predicted
Maximum Hourly, Daily Average and Annual Average Concentrations of NO2
and SO2 and Hourly and 8-hour Average Concentrations of CO
(Emissions from the Operation of the LNG Terminal and GRS)
The
predicted worst-case concentrations at all identified ASRs are very low and
well within the respective AQOs.
4.6.2
Cumulative
Impacts
South Soko
Within
the vicinity of the South Soko Island, there is no
major air emission source and only the background air quality (presented in Table 4.3) would contribute to the
cumulative air quality impacts during the operation of the LNG Terminal.
Isopleths
of cumulative maximum hourly, daily and annual average NO2 and SO2
concentrations at 1.5 m and 10 m above ground are plotted (including the
background NO2 and SO2 concentrations of 52 mgm-3
and 27 mgm-3,
respectively) and are presented in Figures 4.4 – 4.15.
The
isopleths indicate exceedances of the NO2
and SO2 AQOs at the headlands of South Soko based on the worst case approach assuming that the
emissions from the SCVs, gas-turbine auxiliary
engines and LNG carrier auxiliary engines were operating continuously and that
high concentrations of ozone were present.
In
reality, the frequency of LNG carrier berthing at the LNG terminal is low
(i.e., 6 carriers per month) and the SCVs will only
be operated in the event that the ORVs run below
their capacity. Therefore, the
potential impact to this uninhabited area will be lower than that presented in
the figures. It should be noted
that development in these areas will be constrained by the designation of a
Consultation Zone. The area of the
Consultation Zone is not yet defined; however, with reference to Consultation
Zones for other PHIs, it can be expected to have a
radius of not less than 500 m. This
would impose development constraints in the area and prohibit the development
for Air Sensitive Uses.
Black Point
The
air emissions from existing BPPS and CPPS together with the background air
quality would contribute to the ambient air quality in Black Point during the
operation of the GRS.
Cumulative
Short-term (Hourly) Air Quality Impact
The
existing Black Point Power Station (BPPS) is the largest single emission source
in the Lung Kwu Sheung Tan
area. There is a possibility that a
north-westerly wind may bring emissions from the GRS and BPPS towards the ASRs
in the Lung Kwu Sheung Tan
area. No impact from the CPPS is
considered due to the opposing worst case wind angle. Therefore, the short term cumulative
maximum hourly NO2 concentrations at the identified ASRs are
summarized in Table 4.9.
Table 4.9 Cumulative
Maximum Hourly NO2 Impacts (Emissions from GRS + BPPS + Background
Air Quality)
|
ASR |
Predicted
Cumulative Maximum Hourly NO2 Concentration (mgm-3) at Black
Point (a) |
|
|
|
1.5
m above ground |
10
m above ground |
|
A2 |
112 |
112 |
|
A3 (b) |
110 |
- |
|
A4 |
111 |
111 |
|
A5 (b) |
110 |
- |
|
A6 |
109 |
109 |
|
A7 (b) |
110 |
- |
|
Hourly
NO2 Criterion |
300 |
300 |
|
Note: (a) Background NO2
concentration of 52 mgm-3 measured at EPD’s AQMS at Tung Chung in 2004 and the adjusted maximum
hourly NO2 concentration attributed to the BPPS (54 mgm-3)
are included. (b) As A3, A5 and A7 are not elevated
ASRs and therefore, no assessment was performed at 10 m above ground level at
these ASRs. |
||
The results indicate that the
contribution of NO2 from the operation of GRS is very low and the cumulative
maximum hourly NO2 concentrations in the Lung Kwu
Sheung Tan area comply with the respective AQOs. No
adverse cumulative short-term air quality is predicted.
Isopleths of cumulative maximum NO2
concentrations were plotted and are shown in Figures
4.16 and 4.17. No offsite exceedance
is predicted. Hence, no adverse
cumulative short-term air quality impact is anticipated within the Lung Kwu Sheung Tan area due to the
operation of the GRS.
Cumulative Long-term (Daily and Annual)
Air Quality Impacts
Emissions from BPPS and CPPS together
with the background air quality have the potential to cause cumulative
long-term air quality impacts during the operation of the GRS. The predicted daily and annual average
NO2 concentrations attributable to the BPPS and CPPS are 22 mgm-3
and 0.6 mgm-3, respectively (refer to
Table 4.4) ([9]).
The cumulative daily and annual average NO2 concentrations in
the Lung Kwu Sheung Tan
area are summarized in Table 4.10.
Table 4.10 Cumulative Daily
and Annual Average NO2 Impacts (Emissions from GRS + BPPS + CPPS +
Background Air Quality)
|
ASR |
Cumulative
Long-term NO2 Concentration (mgm-3) at Black
Point |
|||
|
|
Daily
Average (a) (b) |
Annual
Average (a) (c) |
||
|
|
1.5
m above ground |
10
m above ground |
1.5
m above ground |
10
m above ground |
|
A2 |
77.1 |
77.7 |
52.9 |
53.0 |
|
A3 (d) |
75.9 |
- |
52.7 |
- |
|
A4 |
75.2 |
75.2 |
52.7 |
52.7 |
|
A5 (d) |
75.5 |
- |
52.8 |
- |
|
A6 |
75.6 |
75.6 |
52.7 |
52.7 |
|
A7 (d) |
76.1 |
- |
52.8 |
- |
|
NO2
Criteria |
150 |
150 |
80 |
80 |
|
Notes: (a) Background of NO2
concentration of 52 mgm-3 measured at EPD’s AQMS at Tung Chung is included. (b) Adjusted daily NO2
concentration of 22 mgm-3 is included (refer to
Table 4.4). (c) Adjusted annual average NO2
concentration of 0.6 mgm-3 is included (refer to
Table 4.4). (d) As A3, A5 and A7 are not elevated
ASRs are therefore, no assessment was performed at 10 m above ground at these
ASRs. |
||||
Compared to Table 4.8, the results indicate that the contribution of NO2
from the operation of GRS is very low and the cumulative daily and annual
average NO2 concentrations in the Lung Kwu
Sheung Tan area comply with the respective AQOs. No
adverse cumulative long-term (daily and annual) air quality is predicted.
Isopleths of cumulative daily and
annual average NO2 concentration at 1.5 m and 10 m above ground are
plotted and shown in Figures 4.18 to 4.21. No off site exceedance
is predicted.
It should be noted that the cumulative
long-term air quality impact assessment does not account for the fact that
CAPCO has obtained an approval for the Emission Control Project for the
Castle Peak Power Station “B” Units ([10]) in which the NOx
emissions will be further reduced.
4.7.1
Construction
Phase
Dust
control measures stipulated in the Air
Pollution Control (Construction Dust) Regulation will be implemented during
the construction of the LNG terminal to control the potential fugitive dust
emissions.
Good
site practices such as regular maintenance and checking of the diesel powered
mechanical equipment will be adopted to avoid any black smoke emissions and to
minimize gaseous emissions.
The
dust control measures for the operation of the concrete batching plant
recommended in the Guidance Note of Best
Practicable Means for Cement Works (Concrete Batching Plant) BPM 3/2 will
be implemented.
The
dust control measures for the operation of the rock crushing plant recommended
in the Guidance Note of Best Practicable
Means for Mineral Works (Rock Crushing Plant) BPM 11/1 will be implemented.
4.7.2
Operational
Phase
No exceedance of the AQO criteria is anticipated at the ASRs
but the cumulative maximum hourly, daily and annual NO2
concentrations and maximum hourly and daily SO2 concentrations were
predicted to exceed the respective AQO criteria at the headlands on South Soko Island (refer to Figures 4.4 to
4.13). In
reality, the frequency with which the worst case emissions would coincide with
the worst meteorological conditions is low. It should be noted that any future developments
in the vicinity of the LNG terminal will be tightly controlled following the
designation of a Consultation Zone.
Should development be proposed in these areas, the air quality
constraint would have to be accounted for.
The
air control measures for the operation of the gas turbine generator recommended
in the Guidance Note of Best Practicable
Means for Electricity Works (Coal-fired Plant, Gas-fired Gas Turbine and
Oil-fired Gas Turbine (Peak Lopping Plant)) (BPM 7/1) will be implemented.
With
the implementation of the recommended dust control measures, no residual
impacts are anticipated.
4.8.2
Operational
Phase
No
adverse residual operational air quality impact is anticipated.
4.9
Environmental Monitoring and Audit
4.9.1
Construction
Phase
A
weekly site audit will be conducted to ensure the implementation of the dust
control measures.
4.9.2
Operational
Phase
The
requirement of the operational monitoring of the gas-turbine auxiliary engines
including in-stack, process and ambient monitoring described in BPM 7/1 ([11])
will be followed.
Potential
dust nuisance from dust generating activities and gaseous emission from
construction plant during construction of the LNG terminal and Gas Receiving
Station (GRS) have been considered.
With the implementation of standard mitigation measures, no adverse impact
is anticipated. The gaseous
emissions from the construction plant are also minimal and no adverse impact is
anticipated.
During
the operation of the LNG terminal, air emissions from submerged combustion
vaporisers (SCVs), gas-turbine generators and LNG
carrier auxiliary engines during LNG unloading and gas heaters at GRS are
potential sources of air quality impacts.
As a worst-case assumption, it was assumed that all four sources were
operating continuously. With this
set of assumptions, the assessment indicated no exceedances
of the AQOs at the identified ASRs.
Cumulative
maximum hourly, daily and annual average NO2 and maximum hourly and
daily SO2 concentrations were predicted to exceed the respective AOQ
criteria at the uninhabited South Soko headlands
based on continuous emissions and the worst case meteorological condition. In reality, the probability of this set
of worst case emissions and meteorological conditions arising simultaneously is
low. Any future developments in the
vicinity of the LNG terminal will be tightly controlled following the
designation of a Consultation Zone.
Should development be proposed in these areas, the air quality
constraint would have to be accounted for.
The
cumulative NO2 concentrations due to the operation of the GRS taking
into account the BPPS and CPPS contribution and the background air quality are
within the AQO criteria and no adverse air quality impact is anticipated.