This section presents the assessment of potential air quality impacts
from the construction and operation of the proposed LNG terminal at Black
Point. Dust generated from the
construction activities and gaseous emissions from construction plant are
potential concerns during the construction phase. Air emissions from the LNG terminal
equipment and the LNG carrier are the principal concerns during the operational
phase. Representative Air Sensitive
Receivers (ASRs) and emission inventories have been identified and a
quantitative assessment of the air quality impacts has been conducted.
4.2
Legislation Requirement and Evaluation Criteria
The
principal legislation for the management of air quality in
Table 4.1
Air Pollutant |
Averaging
Time |
||||
|
1 Hour (b) |
8 Hour (c) |
24 Hour (c) |
3 Months (d) |
1 Year (d) |
Total
Suspended Particulates (TSP) |
- |
- |
260 |
- |
80 |
Respirable Suspended Particulates (RSP) (e) |
- |
- |
180 |
- |
55 |
Sulphur
Dioxide (SO2) |
800 |
- |
350 |
- |
80 |
Nitrogen
Dioxide (NO2) |
300 |
- |
150 |
- |
80 |
Carbon
Monoxide (CO) |
30,000 |
10,000 |
- |
- |
- |
Photochemical
Oxidants (as ozone (O3)) (f) |
240 |
- |
- |
- |
- |
Lead
(Pb) |
- |
- |
- |
1.5 |
- |
Notes: (a)
Measured at 298K (25°C)
and 101.325 kPa (one atmosphere) (b)
Not to be exceeded more than three times
per year (c)
Not to be exceeded more than once per
year (d)
Arithmetic means (e)
Suspended airborne particulates with
a nominal aerodynamic diameter of 10 micrometres or smaller (f)
Photochemical oxidants are determined
by measurement of ozone only |
A maximum
hourly level of TSP of 500 mgm-3
at ASRs is also stipulated in the Technical
Memorandum on Environmental Impact Assessment Process (EIAO-TM) to assess potential construction dust impacts.
The measures stipulated in the Air Pollution Control (Construction Dust)
Regulation 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 for equipment which consumes more than 1,150 megajoules
of gaseous fuel per hour or 25 litres 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 should be submitted not less than
28 days prior to the commencement of such work.
Should the processes listed in Table 4.2 exceed the respective
regulatory thresholds under the Air
Pollution Control (Specified Process) Regulations, a Specified Process (SP)
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
Specified Process |
Regulatory Thresholds for
Apply Licence from the EPD |
Concrete
Batching Plant |
·
Works
in which the total silo capacity exceeds 50 tonnes |
Rock
Crushing Plant |
·
Works
in which the processing capacity exceeds 5,000 tonnes per annum |
During the operation of these
processes, the dust control measures in the Guidance
Note on the Best Practicable Means for Cement Works (Concrete Batching Plant)
(BPM 3/2) 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 site is located to the northwest of the Black Point Headland and to
the west of the existing Black Point Power Station (BPPS). The area has a very low population
density and the local air quality is influenced by industrial emissions from
the existing BPPS, Castle Peak Power Station (CPPS) and other industrial
facilities, vehicle emissions from Lung Kwu Tan Road,
marine vessels and regional pollutant fluxes.
Background
Air Quality
There
is currently no Air Quality Monitoring Station (AQMS) operated by the EPD in
the immediate vicinity of Black Point.
The nearest EPD AQMS is located at Tung Chung (TC). The annual average concentrations of air
pollutants measured at EPD’s AQMS at Tung Chung in
2004 are summarized in Table 4.3.
Table 4.3 Background
Air Quality at Tung Chung (2004)
Air Pollutant |
Background
Concentration (mg
m-3) |
Total
Suspended Particulates (TSP) |
72 |
Respirable Suspended Particulates (RSP) |
62 |
Nitrogen
Dioxide (NO2) |
52 |
Sulphur
Dioxide (SO2) |
27 |
Carbon
Monoxide (CO) |
799 |
Ozone
(O3) |
108 (a) |
Note: (a)
The ozone concentration is the annual
average of the daily hourly maximum concentrations measured in 2004. |
The
measured annual averages at the Tung Chung AQMS give an indication of the
regional air quality.
Contribution
of Emissions from BPPS and CPPS
Air
quality in the vicinity will also be influenced by local emission sources,
including BPPS and CPPS.
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 NO2 and SO2 emissions from BPPS and CPPS
to local air quality. It should be
noted that there are no SO2 emissions from BPPS gas-fired units.
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, Ha Pak Nai/Nim Wan and Sheung Pak Nai 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 installed in CPA and CPB.
A further NOx reduction is
anticipated for CPB and the indicative date of the implementation of the
further NOx reduction measure is over the
period of 2009 to 2011, according to the approved EIA for Emission Control Project to CPPS “B” Units. In addition, a flue gas desulphurization
(FGD) system will be installed to further reduce SO2 emissions. The indicative date of the FGD
implementation is similar to that for NOx
reduction.
Taking into consideration the latest
information for BPPS and CPPS, as well as the higher ozone level of 108 µgm-3,
the adjusted NO2 and SO2 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, Ha Pak Nai/Nim Wan and Sheung Pak Nai areas.
Detailed
calculations are provided in Annexes 4-A and
4-B.
Table
4.4 Adjusted
Maximum Hourly, 2nd Highest Daily and Annual NO2 and SO2
Concentrations in 2004 based on Wind Tunnel Test Results
Location |
Adjusted
Concentration in 2004 (mgm-3) |
|||||
|
NO2
(a) |
SO2 |
||||
|
Maximum
Hourly |
Daily
(d) (e) |
Annual
(d) (e) |
Maximum
Hourly |
Daily
(d) (e) |
Annual
(d) (e) |
Sheung
Pak Nai |
99 (b) |
22 (f) |
0.6 (f) |
170 |
60 (f) |
1.5 (f) |
Ha Pak Nai
/ Nim Wan (g) |
108 (b) |
22 |
0.6 |
170 |
60 |
1.5 |
Lung Kwu
Tan |
54 (c) |
22 |
0.6 |
- (h) |
60 |
1.5 |
Notes: (a) Adjustment
is based on the annual average of the daily hourly maximum ozone
concentration (108 mgm-3) in 2004. (b) BPPS
and CPPS contributions are included.
Current power generating capacity of BPPS (2,500 MW) has been
accounted for. NOx reduction has been considered for CPA and
CPB, respectively (refer to Annex 4-A). (c) Only the BPPS contribution is
considered. A factor of 0.5 is
applied to adjust for the current power generating capacity of BPPS. (d) Both BPPS and CPPS contributions are
considered, no adjustment has been made to account for the reduced power
generation capacity of BPPS, the existing licence limit requirement or the
future NOx and SO2 reduction
at CPB due to the implementation of the Emission Control Project. (e) Since
the adjusted 2nd highest daily and annual average NO2
and SO2 concentrations at Lung Kwu Tan
and Ha Pak Nai are similar, the adjusted 2nd
highest daily and annual average NO2 and SO2
concentrations at Lung Kwu Tan are adopted for the
cumulative long-term impact assessment. (f) Sheung Pak Nai
was not included in the wind tunnel testing in BPPS EIA Study; however, the
worst wind angle for Sheung Pak Nai
is similar to that for Ha Pak Nai. As it is located further away from the
BPPS and CPPS than Ha Pak Nai, the Ha Pak Nai predictions were adopted as a worst case assumption. (g) In
accordance with Figure 2.3a of the BPPS EIA Study, the assessment point
in Ha Pak Nai was identified at Nim
Wan which is close to ASR A2 (EPD Office at WENT Landfill). Therefore, the wind tunnel testing
results at Ha Pak Nai in the BPPS EIA Study will be
used directly without any adjustment. (h) No
SO2 contribution from BPPS due to negligible SO2
emissions from gas-fired units. |
4.3.2
Air
Sensitive Receivers
In accordance with the Study Brief, the study area for the air quality
assessment is defined by a distance of 500 m from the boundary of the Project
site. Within 500 m of the Project
site boundary, no ASR was identified.
The nearest identified ASRs in the surrounding environment, as
identified by site visits, are summarized in Table 4.5 and shown in Figure 4.1.
Table 4.5 Identified
Air Sensitive Receivers
ASR |
Location |
Approximate
Distance from LNG Terminal (m) |
Type of Uses |
Maximum
Height (m above ground) |
A1 |
Sheung Pak Nai |
7,500 |
Residential |
10 |
A2 |
EPD Office at WENT Landfill |
3,200 |
Office |
10 |
A3 |
Black Point Power Station – Administration Building |
600 |
Office |
6 |
A4 |
Karting Track |
1,700 |
Recreational |
1.5 |
A5 |
Concrete Batching Plant – Site Office |
1,050 |
Site Office |
6 |
A6 |
Open Storage – Site Office |
1,170 |
Site Office |
1.5 |
A7 |
Hong Kong Oil - Site Office |
1,300 |
Site Office |
6 |
A8 |
Open Storage – Site Office |
1,500 |
Site Office |
1.5 |
4.4
Potential Sources of Impact
4.4.1
Construction
Phase
Nuisance from dust generating
activities and gaseous emission from diesel-driven plant has the potential to
arise during construction. The major
construction works include slope cutting, site clearance, dredging, reclamation
and civil works. Excavation and
filling, materials handling, wind erosion of open areas, rock crushing and
blasting are the major dust generating activities during site formation works.
Site Clearance and Blasting
Site clearance and blasting are planned
to be undertaken within the first 18 months 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 the submarine gas pipeline
protection works 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 impact. Mobile rock crushers will be employed
onsite to crush the excavated rock into a suitable size for
transportation. The processing
capacity of the mobile rock crushers is not yet confirmed at this stage. 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 the BPM 11/1.
Any dust impact during site clearance
and blasting is expected to be localized.
The separation distance between the nearest identified ASR (A3) and the
construction site is approximately 600 m, which satisfies the Hong Kong Planning & Standards Guideline
(HKPSG) recommended buffer distance of 100 m. Together with the implementation of the
dust control measures stipulated in Air
Pollution Control (Construction Dust) Regulation and the Guidance Note of Best Practicable Means for
Mineral Works (Rock Crushing Plant) BPM 11/1, the potential dust impact
arising from site clearance and blasting works is predicted to be minor and is
not anticipated to exceed the dust criterion.
Dredging and Reclamation Works
Dredging works will be required for
seawall construction, reclamation, approach channel and turning basin. Dredging is planned to be undertaken
within the first 2.5 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 therefore, anticipated during the works.
During reclamation, rocks will be
imported for seawall construction.
Marine sand and public fill will be imported for the reclamation
works. No fugitive emissions are
expected from rock and marine sand 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 ASRs and with the implementation of the dust control measures
stipulated in Air Pollution Control
(Construction Dust) Regulations, the dust impact from filling activities is
very limited.
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), are proposed at an offsite area. Fugitive dust emissions are expected
from the operation of the concrete batching plants. The potential sites of the concrete
batching plants include the CLP Ash Lagoon area, within the existing Black
Point Power Station (BPPS) or at STT lots outside the BPPS site.
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 emission limits. With the implementation of the dust
control measures recommended in the BPM
3/2, an adverse air quality impact is not anticipated at the ASRs.
On-site Sewage Treatment Works
A small sewage treatment works (STW) is
proposed for on-site sewage treatment during the construction phase. The STW shall be designed to meet the
Hong Kong standards ([2])
and reduce the odour nuisance and will comply with the regulatory requirements.
Gaseous Emissions from Construction
Plant
Gaseous emissions from 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), LNG terminal facility construction works and civil works will
involve the highest number of diesel-driven PMEs
including a total of 39 items of diesel-driven PMEs,
including 2 backhoes, 3 drill rigs, 9 generators, 16 air compressor, 9 crawler
cranes; 4 trucks and 14 barges/tug boats.
The engine power of the generators 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, the emissions from barges/tugboats will not be
continuous.
Oxides
of nitrogen (NOx) and respirable
suspended particulates (RSP) are the major air pollutants emitted from 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 construction plant
items 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
Plant Design
|
NOx |
RSP |
Total
worksite area |
230,000 m2 |
|
Total
no. of generators |
9 |
|
Average
Engine Power of generator (kW) (a) |
500 |
|
Total
no. of diesel-driven equipment (including backhoe + drill rig + air
compressor + crawler crane + trucks) |
34 |
|
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) |
20.2 |
1.19 |
Total
emission rate per area (g/m2/s) |
8.8x10-5 |
5.2x10-6 |
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) (i.e., 600 m between site
boundary and ASR A3), 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, jetty and other marine works.
Referring to the construction plant inventory in Section 5.4.1 and Annex 5-C, a total of 17
dredgers/barges/tugboats are required for reclamation and a total of 7
dredgers/barge/tugboats are required for marine works. These dredgers, barges and tugboats are
located at different marine works areas; 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 impacts
include:
·
emissions from submerged combustion
vaporizers (SCVs);
·
emissions from the LNG carrier and
tugboats during the unloading of LNG;
·
emissions from the pipeline gas
heaters;
·
emissions from on-site vehicles;
·
emissions from the emergency
generators;
·
emissions from diesel-driven firewater
pumps;
·
fugitive hydrocarbon releases from
Boil-off Gas (BOG) compressors seal leakage.
Emissions
from Submerged Combustion Vaporizers (SCVs)
Five
submerged combustion vaporizers (SCVs) will be operated in the event that the
Open Rack Vaporizer (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. 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 LNG Carrier and Tugboats during Unloading of LNG
LNG will be delivered to the LNG
terminal by LNG carrier. The LNG
will 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 or 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 Part 2, 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 during LNG unloading and to provide power for other ship
services. Three auxiliary engines
with at total capacity of approximately 9.35 MW running at 75% load will be
operated to pump the LNG to the terminal’s storage tanks. The generators 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 ([6]).
The MDO/HFO has been assumed to contain a maximum 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 at 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 flue; 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
generators are emitted continuously.
CAPCO
will ensure that the LNG carriers berthing at the Black Point Terminal will
comply with IMO Marpol Annex VI and have the on-board
electric generators which have total air emissions equal to or less than those
stipulated in this assessment, particularly the fuel quality (1.5% sulphur in
MDO or HFO), NOx emission rate (13.88
g/kWh) and peak hourly engine load (9,350 kW).
Emissions
from Pipeline Gas Heaters
Four pipeline gas heaters are proposed
for heating the send-out gas to 57 °C. The heaters use pipeline gas as their
fuel source. 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.
Emissions
from On-site Vehicles
As the delivery of diesel, LNG and materials are marine-based, the use
of on-site vehicles will be limited to those required for staff transportation
and maintenance works only. The
emissions from on-site vehicles will be negligible and no adverse air quality
impact from this source is anticipated.
Emissions
from Emergency Generator
The LNG terminal will be operated by
the imported electricity from the existing power plant. The on-site emergency generator (with
capacity of 500 kW) will only be used to generate electric power during
startup, emergency situations or routine testing, i.e. 3 hours per week on
average. The generator will be
driven by diesel and NOx, SO2 and CO are the principal
air emissions. In view of its
infrequent operation and the separation distance from ASRs, adverse air quality
impacts are not anticipated.
An approval for the chimney
installation will be obtained from the EPD, in accordance with the Air Pollution Control (Furnaces, Ovens and
Chimneys) (Installation and Alteration) Regulations.
Emissions from Diesel-driven Firewater Pumps
Four firewater pumps (two diesel-driven
and two electric-driven) will be provided and located beside 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-driven firewater pump is about 0.108 m3/hr. 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.
Summary
In view of the emission characteristics
of these sources and the frequency of operation, the SCVs,
LNG carrier generators and pipeline gas heaters 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 Figure
4.2.
CAPCO
is willing to accept a permit condition limiting NOx
emission from LNG terminal related onshore combustion sources of SCVs and gas heaters to no more than 3.88 g/s.
4.5.1
Emission
Rate Estimation
SCVs and pipeline gas heaters are
operated by natural gas and hence NOx and
CO are the principal
air emissions. During the LNG unloading
process, the LNG carrier generators are operated by MDO or HFO and so NOx, SO2 and CO are the principal air emissions.
As discussed in Section 4.4.2,
the SCVs, LNG carrier generators and pipeline gas
heaters are assumed to be operating continuously throughout 24 hours and 365
days in the modeling assessment and hence this is the worst-case approach.
The estimated emission rates of NOx, SO2 and CO are summarized in Table 4.7 and detailed calculations are
presented in Annex 4-C.
Table 4.7 Summary
of Emission Rates of NOx, SO2
and CO based on Preliminary Design Estimates
|
SCV |
LNG Carrier – Auxiliary Engine
(a) |
Pipeline Gas Heater |
Stack height (m) |
13 |
41 |
15 |
Stack diameter (m) |
1.2 |
0.78 |
1.07 |
Exit temperature (°C) |
30 |
320 |
280 |
Exit velocity (m/s) |
7.09 |
25 |
11.56 |
No. of emission sources |
5 |
1
(b) |
4 |
NOx
emission rate of each source (g/s) |
0.32 |
36 |
0.57 |
SO2 emission rate of each
source(g/s) |
- |
15.6 |
- |
CO emission rate of each source (g/s) |
1.63 |
1.56 |
0.36 |
Notes: (a) The total capacity of LNG carrier
generators is 9,350kW. (b) Three individual emission sources are
modelled 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 impacts.
The SCVs,
LNG carrier generators and pipeline gas heaters have been assumed to be
operated continuously in the modeling assessment for a worst case
assessment.
As
the site area is 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. In addition, the local terrain has been incorporated
into the model to account for terrain-induced impacts to dispersion.
It has been assumed that the background
ozone present in the vicinity of the Project site is elevated, and so the Ozone
Limiting Method (OLM) was used to estimate the hourly conversation ratios of NOx to NO2. As a worst case assumption, the annual
average of daily hourly maximum ozone concentrations measured at EPD’s Tung Chung AQMS in 2004 (i.e., 108 mgm-3) was utilized.
Since
most of the emissions are from elevated sources, air pollutant concentrations
were predicted at 1.5 m above ground at all identified ASRs and at 10 m for the
elevated ASRs.
A worst case assumption of continuous
emissions from all the identified sources was made, a high background ozone
level and a whole year of meteorological data were 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
Condition
Representative
hourly meteorological data from the Hong
Kong Observatory (HKO) station located at Sha Chau, for the year 2004, were used in the model. The meteorological data included hourly
wind speed, wind direction, stability class, air temperature and mixing height
information.
4.5.4
Cumulative
Impact
The
Black Point Power Station (BPPS) is considered the nearest existing air
emission source, contributing to the air quality within the study area. In addition, the Castle Peak Power
Station (CPPS) also contributes to the local air quality. The 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 the 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 time frames of these developments are unknown at this
stage and hence they are not 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)
The predicted worst-case
concentrations at all identified ASRs are well within the respective AQOs.
Isopleths
of predicted maximum hourly, daily average and annual average NO2
concentrations at 1.5 m and 10 m above ground are presented in Figures
4.3 to 4.8, respectively. Exceedance of
maximum hourly and daily NO2 concentrations was predicted at the
Black Point Headland, an area in the firing range and in an area of rough
terrain between Black Point and Nim Wan due to plume
impingement.
4.6.2
Cumulative
Impacts
The emissions from
the existing BPPS and CPPS together with the background air quality would
contribute to the cumulative air quality impacts in the vicinity during the
operation of the LNG Terminal.
Cumulative Short-Term (Hourly) NO2
Impact
The
existing BPPS is the closest emission source affecting the Nim
Wan and Sheung Pak Nai
areas. There is possibility that a
south-westerly wind may bring emissions from the LNG Terminal and BPPS towards
ASRs A1 and A2 and hence cumulative NO2 impacts may arise ([9]). The assessment has also taken emissions
from the CPPS into consideration.
Cumulative maximum hourly NO2 and SO2 impacts at
ASRs A1 and A2 were assessed taking into account the background air quality
(shown in Table 4.3) and the adjusted
maximum hourly NO2 and SO2 concentrations attributable to
the BPPS and CPPS, as shown in Table 4.4. The NO2 and SO2
concentrations predicted at ASRs A1 and A2 are summarized in Table 4.9.
A3 is located
within the BPPS site. The emission
height of the BPPS is about 100 m and hence due to high efflux temperature and
efflux velocity, the plume will not reach ground level at A3. In addition, no impact from the CPPS is
considered due to the opposing worst case wind angle. Hence, short-term cumulative NO2
and SO2 impacts due to BPPS and CPPS are not expected.
For those ASRs
(A4 to A8) located at Lung Kwu Sheung
Tan, the worse case wind angles for emissions from the LNG Terminal and the
BPPS are similar and therefore the contribution from BPPS is considered. No impact from the CPPS is considered
due to the opposing worst case wind angle.
The cumulative
maximum hourly NO2 and SO2 concentrations at the
identified ASRs are summarized in Table
4.9.
Table 4.9 Cumulative
Maximum Hourly NO2 and SO2 Impacts (Emissions from LNG Terminal
+ BPPS + CPPS + Background Air Quality)
ASR |
Cumulative Maximum Hourly
Concentration (mgm-3) (a) |
|||
|
NO2 |
SO2 (g) |
||
|
1.5 m above ground |
10 m above ground |
1.5 m above ground |
10 m above ground |
A1 |
227
(b) |
227
(b) |
225
(f) |
225
(f) |
A2 |
228
(b) |
228
(b) |
224
(f) |
224
(f) |
A3
(c) |
181 |
221 |
76 |
76 |
A4
(d) (e) |
209 |
- |
64 |
- |
A5
(e) |
229 |
229 |
91 |
91 |
A6
(d) (e) |
286 |
- |
91 |
- |
A7
(e) |
222 |
222 |
77 |
77 |
A8
(d) (e) |
224 |
- |
78 |
- |
Hourly NO2 Criterion |
300 |
300 |
800 |
800 |
Notes: (a) Background NO2 and SO2
concentration of 52 mgm-3 and 27 mgm-3,
respectively, measured at EPD’s AQMS at Tung Chung
is included. (b) Adjusted maximum hourly NO2
concentration (99 mgm-3 for A1 and 108 mgm-3
for A2) due to the contribution of BPPS and CPPS is added (refer to Table 4.4). (c) No contribution from CPPS and BPPS. (d) No contribution from CPPS due to
opposing worst wind angle.
Adjusted maximum hourly NO2 concentration (54 mgm-3
for A4 to A8) from the contribution of BPPS is also added (refer to Table 4.4). (e) As A4, A6 and A8 are not elevated
ASRs and therefore, no assessment was performed at 10 m above ground at these
ASRs. (f) Adjusted maximum hourly SO2
concentration of 170 mgm-3 for A1 and A2 due to
the contribution of CPPS is added. (g) No
SO2 contribution from BPPS is taken into account due to very
negligible emission from gas-fired units with reference to the BPPS EIA
Study, Annex B – Source Emissions and Characteristics. |
The
results indicate that the worst case cumulative hourly NO2 and SO2
impacts at all ASRs meet the AQOs. It should be noted that the cumulative
maximum hourly NO2 and SO2 concentrations at all ASRs
attributable to the LNG terminal emissions are predicted assuming continuous
emissions from all sources. The
actual cumulative maximum hourly NO2 and SO2
concentrations are expected to be lower than those presented in Table 4.9.
Isopleths
of cumulative hourly NO2 and SO2 concentrations were
plotted and are shown in Figures 4.9 to 4.12. The predicted worst case cumulative
hourly NO2 and SO2 concentrations exceeded the respective
assessment criteria at the Black Point Headland, the rough terrain area between
Lung Kwu Sheung Tan and Nim Wan and at the firing range.
In
reality, the frequency of LNG carrier berthing at the LNG terminal is low
(i.e., 6 carriers per month) and the SCVs will be
operated in the event that the ORVs run below their
capacity. Therefore, the potential
impact to these uninhabited areas will be lower than that presented in the
figures.
It
is noted that the designation of a Consultation Zone would impose development
constraints. 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. In
addition, no development is allowed within the firing range and no planned or
proposed developments are known in the area of rough terrain near Nim Wan.
Nevertheless,
should development be proposed in these areas in the future, the air quality
constraints would have to be accounted for.
Cumulative Daily and Annual NO2
and SO2 Impacts
Emissions
from BPPS and CPPS together with the background air quality have the potential
to create cumulative daily and annual average air quality impacts during the
operation of the LNG Terminal. The
predicted daily NO2 concentrations attributable to BPPS and CPPS are
22 mgm-3
and 0.6 mgm-3,
respectively. The predicted daily
SO2 concentrations attributable to BPPS and CPPS are 60 mgm-3
and 1.5 mgm-3,
respectively (refer to Table 4.4) ([10]). The cumulative daily and annual average
NO2 and SO2 concentrations at the ASRs are summarized in Table 4.10.
Table 4.10 Cumulative Daily
and Annual Average NO2 and SO2 Impacts (Emissions from
LNG Terminal + BPPS + CPPS + Background Air Quality)
ASR |
Cumulative Daily Concentration (mgm-3)
(a) (b) |
Cumulative Annual Average
Concentration (mgm-3) (b)
|
||
|
1.5 m above ground |
10 m above ground |
1.5 m above ground |
10 m above ground |
NO2 (c) (d) |
||||
A1 |
77 |
77 |
52.6 |
52.6 |
A2 |
76 |
76 |
52.6 |
52.6 |
A3 |
79 |
81 |
52.7 |
52.7 |
A4
(e) |
81 |
- |
53.2 |
- |
A5 |
85 |
85 |
53.6 |
53.6 |
A6
(e) |
89 |
- |
53.3 |
- |
A7 |
83 |
83 |
53.4 |
53.4 |
A8
(e) |
85 |
- |
53.4 |
- |
NO2 Criteria |
150 |
150 |
80 |
80 |
SO2
(f) (g) |
||||
A1 |
88 |
88 |
28.5 |
28.5 |
A2 |
88 |
88 |
28.5 |
28.5 |
A3 |
89 |
89 |
28.5 |
28.5 |
A4
(e) |
90 |
- |
28.8 |
- |
A5 |
93 |
93 |
29.0 |
29.0 |
A6
(e) |
93 |
- |
28.8 |
- |
A7 |
91 |
91 |
28.9 |
28.9 |
A8
(e) |
91 |
- |
28.9 |
- |
SO2
Criteria |
350 |
350 |
80 |
80 |
Notes: (a) It
should be noted that these values are the second highest daily averages (b) Background NO2 and SO2
concentrations (52 mgm-3 and 27 mgm-3,
respectively) as presented in Table 4.3
is included. (c) Adjusted daily NO2 concentration
of 22 mgm-3
is included (refer to Table 4.4). (d) Adjusted annual average NO2
concentration of 0.6 mgm-3 is included (refer to Table 4.4). (e) As A4, A6 and A8 are not elevated
ASRs and therefore, no assessment was performed at 10 m above ground at these
ASRs. (f) Daily SO2 concentration of
60 mgm-3
is included (refer to Table 4.4). (g) Annual average SO2
concentration of 1.5 mgm-3 is included (refer to Table 4.4). |
The
results indicate that the cumulative daily and annual average NO2
and SO2 impacts at all identified ASRs are well within the AQOs. The
contribution from the LNG terminal emissions is very minor, even under the
worst case scenario.
Isopleths
showing the cumulative daily and annual average NO2 and SO2
concentrations at 1.5 m and 10 m above ground are plotted and shown in Figures
4.13 to 4.20. Although exceedances
of the daily NO2 criterion are predicted at a small area on the
Black Point Headland located close to the LNG Storage Tanks, the small affected
area will be within the PHI Consultation Zone and development constraints will
be imposed.
It
should be noted that the cumulative air quality 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
([11]) in
which the NO2 and SO2 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 exceedances of the AQO criteria are anticipated at the ASRs
but the hourly NO2 and SO2 concentration was predicted to
exceed the criterion in some unpopulated areas including Black Point Headland,
firing range and the area of rough terrain near Nim
Wan . Exceedances
of the daily NO2 criterion are predicted at a small area on the
Black Point Headland located close to the LNG storage tanks. 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 constraints would have to be accounted for.
4.8.1
Construction
Phase
With the
implementation of the recommended dust control measures, no adverse 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
Dust
monitoring is recommended at the Administration Building of the existing Black
Point Power Station as a counter check to this assessment. 24-hour TSP measurement will be
conducted by High Volume Sampling (HVS) once every 6 days throughout the site
formation works.
A weekly site
audit will be conducted to ensure the implementation of the dust control
measures.
4.9.2
Operational
Phase
No operational
air quality monitoring is required.
Potential
nuisance from dust generating activities and gaseous emission from construction
plant during construction of the LNG terminal have been considered. With the implementation of standard
mitigation measures, no adverse impact is anticipated. The gaseous emissions from the
construction equipment are also minimal and no adverse impact is
anticipated. Dust monitoring is
recommended at the Administration Building of the Black Point Power Station to
ensure no exceedance of the dust criteria ([12]) is
encountered during site formation and reclamation works.
During the
operation of the LNG terminal, air emissions from submerged combustion
vaporisers (SCVs), LNG carrier auxiliary engines
during unloading and pipeline gas heaters are potential sources of air quality
impacts. For worst case assessment,
it was assumed that all three sources were operating continuously. With this set of assumptions, the
assessment indicated no exccedances of the AQOs at the ASRs.
Cumulative
maximum hourly NO2 and SO2 concentrations were predicted
to exceed the respective criteria at the uninhabited Black Point Headland,
firing range and the area of rough terrain near Nim
Wan (refer to Figures 4.9
to 4.12). Cumulative
daily NO2 concentrations were predicted to exceed the criterion at a
small area near the LNG storage tanks on the Black Point Headland assuming
continuous emissions and the worst case meteorological condition (refer to Figures
4.13 to 4.14). 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
constraints would have to be accounted for.