This Section presents the Air Quality Impact Assessment (AQIA) associated with the construction and operation of the proposed Project in accordance with Clause 3.4.4 of the EIA Study Brief.
The principal legislation for the management of air quality in Hong Kong is the Air Pollution Control Ordinance (APCO) (Cap. 311). Evaluation criteria for the AQIA will follow the prevailing Air Quality Objectives (AQOs) which stipulate the statutory limits of typical air pollutants in the ambient air and the maximum allowable number of exceedances over the specified periods under APCO. The prevailing AQOs are presented in Table 4.1.
Table 4.1 Hong Kong Air Quality Objectives
|
Air Pollutant |
Averaging Time |
Concentration (mg m-3) (a) |
No. of Exceedances Allowed per Year |
|
Sulphur Dioxide (SO2) |
10 minute |
500 |
3 |
|
|
24-hour
|
125 |
3 |
|
Respirable Suspended Particulates (RSP) (b) |
24-hour |
100 |
9 |
|
Annual
|
50 |
- |
|
|
Fine Suspended Particulates (FSP) (c) |
24-hour |
75 |
9 |
|
Annual
|
35 |
- |
|
|
Nitrogen Dioxide (NO2) |
1-hour |
200 |
18 |
|
|
Annual
|
40 |
- |
|
Carbon Monoxide (CO) |
1-hour |
30,000 |
0 |
|
|
8-hour
|
10,000 |
0 |
|
Ozone (O3) |
8-hour
|
160 |
9 |
|
Lead |
Annual |
0.5 |
- |
|
Notes: (a) Measured at 293K and 101.325 kPa. (b) Suspended particles in air with a nominal aerodynamic diameter of 10 μm or less (c) Suspended particles in air with a nominal aerodynamic diameter of 2.5 μm or less |
|||
In addition to the APCO, a maximum hourly average Total Suspended Particulates (TSP) concentration of 500µg m-3 at Air Sensitive Receivers (ASRs) is stipulated in Annex 4 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) to address potential construction dust impacts. The measures stipulated in the Air Pollution Control (Construction Dust) Regulation will be followed to ensure that potential dust impacts are properly controlled. Requirements stipulated in the Air Pollution Control (Non-road Mobile Machinery) (Emission) Regulation will also be followed to control potential emissions from non-road mobile machinery during construction phase.
The Study Area for the AQIA is defined as an area within 500m from the boundary of the Project. The Study Area considered in this AQIA is shown in Figure 4.1. No existing, planned and committed ASRs have been identified within the Study Area with reference to current land uses, relevant Outline Zoning Plans, Development Permission Area Plans, Outline Development Plans and Layout Plans. No ASRs are located within approximately 4km from the LNG Terminal. A number of representative ASRs beyond the Study Area for the GRS at the BPPS and the GRS at the LPS have been identified and they are listed in Table 4.2. The locations of the identified ASRs near the BPPS and the LPS are shown in Figure 4.2 and Figure 4.3, respectively.
Table 4.2 Identified Representative Air Sensitive Receivers
|
Area |
ASR |
Description |
Use |
Approximate Distance to nearest Project site (km) |
Approximate Maximum Height (m above ground) |
|
BPPS Study Area |
A1 |
Sludge Treatment Facilities (STF) Office |
GIC |
1.5 |
40 |
|
|
A2 |
Proposed WENT Extension Site Office |
GIC |
1.4 |
5 |
|
|
A3 |
Lung Kwu Tan |
Industrial |
1.7 |
10 |
|
|
A4 |
Planned Development in Lung Kwu Tan Reclamation Area |
Residential |
1.7 |
60 |
|
LPS Study Area |
A5 |
Village house at Tai Shan Central |
Residential |
1.3 |
10 |
|
|
A6 |
Village house at Wang Long |
Residential |
1.3 |
10 |
|
|
A7 |
Concerto Inn |
Hotel |
1.6 |
10 |
|
Note: (a) GIC = Government, Institutional or Community Uses |
|||||
The LNG Terminal is located in the southern waters of Hong Kong, while the GRS at the BPPS and the GRS at the LPS are located within the existing boundaries of the BPPS and the LPS, respectively. The local air quality of the sites of the GRS at the BPPS and LPS is primarily influenced by emissions from the BPPS and LPS, respectively.
The nearest EPD air quality monitoring station (AQMS) to the GRS at the BPPS is located in Tuen Mun. There are no AQMSs operated by EPD in the vicinity of the GRS at the LPS or the LNG Terminal.
CLP and HK Electric both operate a number of AQMSs in accordance with the requirements of their respective Specified Process (SP) licences. The CLP AQMSs that are the nearest to the GRS at the BPPS are located in Lung Kwu Tan and Tuen Mun Clinic, while the AQMS in Ap Lei Chau operated by HK Electric is the nearest to the GRS at the LPS. Table 4.3 to Table 4.6 provide the relevant time averaging concentrations of air pollutants measured at the above AQMSs in the most recent five years (i.e. 2013 to 2017) for comparison with the prevailing AQOs.
Table 4.3 Concentrations of Air Pollutants Measured at EPD’s Tuen Mun AQMS in the Recent Five Years (2013 - 2017)
|
Year |
Concentration of Pollutants (µg m-3) |
||||||||||
|
|
19th highest 1-hr NO2 |
Ann-ual NO2 |
4th highest 24-hr SO2
|
4th highest 10-min SO2 |
10th highest 24-hr RSP |
Ann-ual RSP |
10th highest 24-hr FSP |
Ann-ual FSP |
10th highest Daily Max 8-hr O3 |
Daily Max. 1-hr CO |
Daily Max. 8-hr CO |
|
2013 (a) |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
|
2014 |
184 |
53 (b) |
33 |
128 |
125 (c) |
47 |
83 (d) |
30 |
146 |
2,610 |
1,743 |
|
2015 |
184 |
48 (b) |
27 |
90 |
110 (c) |
45 |
76 (d) |
30 |
168 (e) |
2,400 |
2,058 |
|
2016 |
167 |
51 (b) |
28 |
75 |
103 (c) |
44 |
63 |
27 |
143 |
2,050 |
1,843 |
|
2017 |
188 |
46 (b) |
26 |
88 |
99 |
43 |
65 |
27 |
176 |
1,740 |
1,630 |
|
Prevail-ing AQOs |
200 |
40 |
125 |
500 |
100 |
50 |
75 |
35 |
160 |
30,000 |
10,000 |
|
Notes: (a) Tuen Mun AQMS in operation since 2014. (b) Exceedance of annual average NO2 criterion. (c) Exceedance of 24-hour average RSP criterion. (d) Exceedance of 24-hour average FSP criterion. (e) Exceedance of daily maximum 8-hour average O3 criterion. |
|||||||||||
Table 4.4 Concentrations of Air Pollutants Measured at CLP’s Tuen Mun Clinic AQMS in the Recent Five Years (2013 - 2017)
|
Year |
Concentration of Pollutants (µg m-3) |
|||
|
19th
highest |
Annual NO2 |
4th
highest |
4th
highest |
|
|
2013 |
228 (a) |
63 (b) |
26 |
- |
|
2014 |
195 |
55 (b) |
23 |
90 |
|
2015 |
198 |
57 (b) |
22 |
74 |
|
2016 |
150 |
35 |
26 |
57 |
|
2017 |
186 |
41 (b) |
34 |
74 |
|
Prevailing AQOs |
200 |
40 |
125 |
500 |
|
Notes: (a) Exceedance of 1-hour average NO2 criterion. (b) Exceedance of annual average NO2 criterion. (c) No 10-minute SO2 monitoring was conducted from 2012 to 2013 (i.e. before the 10-min SO2 AQO was in place in 2014). |
||||
Table 4.5 Concentrations of Air Pollutants Measured at CLP’s Lung Kwu Tan AQMS in the Recent Five Years (2013 - 2017)
|
Year |
Concentration of Pollutants (µg m-3) |
|||
|
19th highest |
Annual NO2 |
4th highest |
4th highest |
|
|
2013 |
149 |
28 |
34 |
- |
|
2014 |
149 |
27 |
24 |
131 |
|
2015 |
125 |
23 |
18 |
100 |
|
2016 |
131 |
24 |
33 |
163 |
|
2017 |
160 |
25 |
31 |
157 |
|
Prevailing AQOs |
200 |
40 |
125 |
500 |
|
Note: (a) No 10-minute SO2 monitoring was conducted from 2012 to 2013 (i.e. before the 10-min SO2 AQO was in place in 2014). |
||||
Table 4.6 Concentrations of Air Pollutants Measured at HK Electric’s Ap Lei Chau AQMS in the Recent Five Years (2013 - 2017)
|
Year |
Concentration of Pollutants (µg m-3) |
|||
|
19th highest |
Annual NO2 |
4th highest |
4th highest |
|
|
2013 |
173 |
29 |
44 |
- |
|
2014 |
130 |
17 |
53 |
251 |
|
2015 |
132 |
16 |
38 |
239 |
|
2016 (b) |
121 |
24 |
33 |
176 |
|
2017 |
135 |
16 |
35 |
247 |
|
Prevailing AQOs |
200 |
40 |
125 |
500 |
|
Note: (a) No 10-minute SO2 monitoring was conducted from 2012 to 2013 (i.e. before the 10-min SO2 AQO was in place in 2014). (b) Averaging values are based on measurement data from January to May 2016 as the operation of the Ap Lei Chau AQMS was suspended between June and December 2016 due to renovation work. |
||||
NO2
Exceedances of 1-hour average NO2 criterion were recorded at CLP’s AQMS in Tuen Mun Clinic in 2013. However, there was no exceedance from 2014 to 2017. No exceedance of 1-hour average NO2 criterion was recorded at EPD’s Tuen Mun AQMS from 2014 to 2017, or at CLP’s AQMS in Lung Kwu Tan and HK Electric’s AQMS in Ap Lei Chau in the past five years (2013-2017).
The annual average NO2 concentrations exceeded the relevant AQO criterion at EPD’s AQMS in Tuen Mun for the past four years (2014-2017). Exceedances of the annual average NO2 concentrations were also recorded at CLP’s AQMS in Tuen Mun Clinic from 2013 to 2015 and 2017. No exceedance of annual average NO2 criterion was recorded at CLP’s AQMS in Lung Kwu Tan and HK Electric’s AQMS in Ap Lei Chau in the past five years (2013-2017).
No exceedance of 24-hour average SO2 criterion was recorded at the AQMSs operated by EPD, CLP and HK Electric for the past five years (2013-2017). No exceedance of 10-minute average SO2 criterion was recorded at the AQMSs operated by EPD, CLP and HK Electric for the past three years (2013-2017).
Exceedances of 24-hour average RSP criterion were recorded at EPD’s AQMS in Tuen Mun from 2014 to 2016, but no exceedance of the annual average RSP criterion was recorded in the past four years (2014-2017).
No RSP monitoring was conducted at the CLP and HK Electric AQMSs.
Exceedances of 24-hour average FSP criterion were recorded at EPD’s AQMS in Tuen Mun in 2014 and 2015. No exceedance of the annual average FSP criterion was recorded at the EPD Tuen Mun AQMS in the past four years (2014-2017).
No FSP monitoring was conducted at the CLP and HK Electric AQMSs.
The measured daily maximum 8-hour average O3 concentrations at the EPD Tuen Mun AQMS complied with the relevant AQO criterion except in 2015.
No O3 monitoring was conducted at the CLP and HK Electric AQMSs.
The measured daily maximum 1-hour and 8-hour average CO concentrations at the EPD Tuen Mun AQMS were well within the respective criteria for the past four years.
No CO monitoring was conducted at the CLP and HK Electric AQMSs.
The background air pollutant concentrations predicted by the PATH-2016 model (i.e. Pollutants in the Atmosphere and their Transport over Hong Kong) in 2020 for the PATH grids of the identified ASRs (downloaded from EPD’s website) are presented in Table 4.7.
Table 4.7 Background Air Pollutant Concentrations Predicted by the PATH-2016 Model in 2020
|
PATH Grid |
Concentration of Pollutants (µg m-3) |
||||||||
|
19th highest 1-hour NO2 |
AnnualNO2 |
4th highest 24-hour SO2 |
4th highest 10-min SO2 (a) |
10th highest 24-hour RSP |
Annual RSP |
10th highest Daily Max. 8-hour O3 |
Daily Max. 1-hour CO |
Daily Max. 8-hour CO |
|
|
Area near the BPPS |
|
|
|
|
|
|
|
|
|
|
14, 42 |
106 |
24 |
35 |
150 |
83 |
36 |
154 |
973 |
826 |
|
15, 44 |
107 |
20 |
34 |
182 |
85 |
35 |
162 (b) |
984 |
830 |
|
Area near the LPS |
|
|
|
|
|
|
|
|
|
|
34, 23 |
117 |
19 |
33 |
157 |
79 |
34 |
149 |
1,008 |
807 |
|
35, 22 |
110 |
16 |
33 |
149 |
76 |
33 |
154 |
1,006 |
807 |
|
Prevailing AQOs |
200 |
40 |
125 |
500 |
100 |
50 |
160 |
30,000 |
10,000 |
|
Notes: (a) The multiplicative factor for the stability class calculated for each hour was applied to the 1-hour SO2 concentrations to estimate the 10-minute SO2 concentrations. (b) Exceedance of daily maximum 8-hour average O3 criterion. |
|||||||||
As shown in Table 4.7, the background air pollutant concentrations in the relevant PATH grids in 2020 are well below the relevant AQO criteria, except for a slight exceedance of the daily maximum 8-hour average O3 criterion in PATH grid (15, 44).
The construction site and all construction activities associated with the construction of the Project will be located within the existing boundaries of the BPPS and the LPS, as well as in marine waters where the LNG Terminal and the two subsea pipelines will be located. The construction of the Project will include the following key activities (see Section 3.4 for details):
· LNG Terminal Jetty and topsides construction;
· Construction of the BPPS Pipeline and LPS Pipeline; and
· Construction of the GRS at the BPPS and the GRS at the LPS.
No major earthworks or site formation works will be required during the construction of the Project. Piling activities at the LNG Terminal Jetty and pipeline trenching works are not expected to generate fugitive dust given the marine nature of these activities. Armour rock will be used for protection of the two subsea pipelines. Typically a derrick lighter or flat top barge will carry the armour rock stockpile and will move along the routes of the BPPS Pipeline and the LPS Pipeline. The stockpiling and handling of armour rocks has low potential to give rise to fugitive dust emissions.
The potential dust generating activities are expected to include soil excavation, materials handling, truck movements and wind erosion from open stockpiling of dusty materials during construction of the GRS at the BPPS and the GRS at the LPS.
The key air emissions associated with the operation of the LNG Terminal include the emissions from the FSRU Vessel and the Jetty during LNG unloading operation and LNG regasification process. For normal operation, the FSRU Vessel will provide natural gas fuelled power for the vessel itself and the Jetty and the associated emissions are expected to be continuous. On the Jetty, there will be a diesel-fired generator to provide backup power that will be used intermittently. The key air pollutants from these emissions are NO2, SO2, RSP and FSP.
LNG will be transported to the LNG Terminal by visiting LNGCs, the frequency of LNG deliveries (on average) will be one LNGC arriving every five to eight days (subject to actual gas demand). The LNGCs will be operated using boil off gas or low sulphur marine fuel, and the key air pollutants associated with these emissions include NO2, SO2, RSP and FSP.
The gas heaters of the GRS at the BPPS and the GRS at the LPS are the key air emission sources associated with the operation of the Project. The gas heaters of the GRS at the BPPS will be operated using regasified LNG from the LNG Terminal, while the gas heaters of the GRS at the LPS will be operated using gas from both the Guangdong LNG Terminal (existing source) and the LNG Terminal. The LNG will be well refined prior to supplying to the LNG Terminal and the regasified LNG sent to the GRS at the BPPS and the GRS at the LPS typically has very low content of sulphur or particulate matters. Similarly, the regasified LNG from the Guangdong LNG Terminal to the GRS at the LPS also has negligible content of sulphur or particulate matters. CO, which is produced as a result of incomplete combustion, is also not considered a key air pollutant from the gas heaters based on the operation experience of the existing GRSs at the BPPS and the LPS. The gas heaters will be operated under favourable conditions such that combustion efficiency is high to minimise CO emissions. Therefore, the key air pollutant from the stack emissions of the GRS at the BPPS and the GRS at the LPS is NO2, with negligible amount of CO, SO2, RSP and FSP.
The existing GRS gas heaters and the two stacks serving the existing eight combined-cycle gas turbine (CCGT) units (C1 to C8) are the key existing air emission sources within the BPPS. The existing auxiliary boiler (C18), which only operates during weekly routine testing or when the first BPPS unit is started after plant shutdown, has limited operational durations and is not considered a key emission source. At the BPPS, additional CCGT unit No. 1 served by one new stack is currently under construction. According to the tentative programme in the approved EIA Report of the Additional Gas-fired Generation Units Project, commercial operation of CCGT Unit No. 1 is anticipated by the end of 2019 and the commencement date for the construction of CCGT Unit No. 2 will be after 2019. The key air pollutant due to emissions from the existing GRS gas heaters, the existing CCGT units and the additional CCGT units during normal operation (gas-fired) is NO2.
At the LPS, the existing unit L1 has been retired in May 2017 while unit L3 is scheduled to be retired on 1 May 2018 ([1]). Therefore, stacks of existing units L2 and L4 to L8 (coal-fired) and L9 (gas-fired) as well as the converted CCGT unit (referred to as GT57) and the existing GRS gas heaters are the key existing air emission sources at the LPS during the operation of the Project. Existing gas turbines GT1, 2, 3, 4 and 6 only operate during peak lopping and emergency situation with limited operation durations and they are not considered key emission sources. Nevertheless, GT1, 2, 3, 4 and 6 have been included in the assessment as a conservative approach. Two new CCGT units (L10 and L11) are planned to be constructed within the LPS extension site. Tentatively, L10 and L11 will commence operation in 2020 and 2022, respectively. The existing stack housing the steel flue of L9 is designed to encase three steel flues including the two new ones of L10 and L11 during the future operation at the LPS extension. In addition, three additional CCGT units (i.e. L12, L13 and L14) may be constructed in the future with reference to the approved EIA report of 1800MW Gas-fired Power Station at Lamma Extension (AEIAR-010/1999), subject to future discussion and approval by the Environment Bureau. Although currently there is no plan or schedule for the construction of the potential L12 to L14, these three potential CCGT units have been included for a worst case assessment. The key air pollutant due to emissions from the GRS gas heaters, GT57, L9, the planned L10 and L11 and the potential L12 to L14 during normal operation (gas-fired) is NO2, while the key air pollutants arising from emissions from L2 and L4 to L8 (coal-fired), as well as GT1, 2, 3, 4 and 6 (oil fired), are NO2, SO2, RSP and FSP.
A number of major air emission sources (existing and planned) in the vicinity of the BPPS have been identified, including the STF, WENT Landfill (both existing landfill and future extension), marine emissions associated with the operation of the WENT Landfill, the proposed Integrated Waste Management Facilities (IWMF), Castle Peak Power Station (CPPS), Green Island Cement, Shiu Wing Steel Mill, Permanent Aviation Fuel Facility (PAFF) and EcoPark. In addition, a total of seven landfill gas power generation units (LFGPGUs) are proposed to be installed at the existing WENT Landfill. Two asphalt plants in Lung Kwu Sheung Tan have also been identified to be currently operating under a SP licence. The key air pollutants associated with these major air emission sources include NO2, SO2, RSP and FSP.
No other major emission sources have been identified in the vicinity of the LPS or the LNG Terminal.
It should be noted that additional traffic is not expected to be induced during operation of the Project. However, vehicular emissions from open roads may contribute to the cumulative air quality impact to identified ASRs in the vicinity of the BPPS (i.e. ASR A1 to A4). Key air pollutants from vehicular emissions include NO2, RSP and FSP. No open roads have been identified within 500m from the other identified ASRs in the vicinity of the LPS.
As discussed in Section 4.5.1, fugitive dust emissions may arise during the construction of the GRS at the BPPS and the GRS at the LPS, while the construction of the LNG Terminal as well as the two subsea pipelines are not considered to be dust generating activities. The construction activities at the GRS at the BPPS and the GRS at the LPS mainly include site clearance, foundation works and building works which will generate limited fugitive dust emissions. There are no ASRs within 500m from the construction sites at the BPPS and the LPS. In view of the nature of construction works and large separation distance between the construction sites and the nearest ASRs, no significant fugitive dust impact during the construction phase of the Project is anticipated. A quantitative assessment of the construction air quality impact arising from the Project is considered not necessary and the construction air quality impact is addressed qualitatively in Section 4.8.
Emissions are expected to be generated from the operation of the LNG Terminal (including FSRU Vessel and Jetty) and the visiting LNGCs. As no ASR has been identified within approximately 4 km from the LNG Terminal or from the Berthing Route of the visiting LNGCs as shown in Figure 3.7, no significant air quality impact associated with the operation of the LNG Terminal and the visiting LNGCs is anticipated. Potential air quality impact due to the operation of the LNG Terminal and LNGCs is addressed qualitatively in Section 4.9.1.
No ASR has been identified within 500m from the GRS at the BPPS and the GRS at the LPS. Nevertheless, a quantitative assessment has been undertaken to evaluate the potential air quality impacts arising from the operation of the gas heaters at the GRS at the BPPS and the GRS at the LPS. NO2 has been assessed quantitatively as it is the key air pollutant arising from the emissions of the gas heaters as discussed in Section 4.5.2.
A three-tier approach recommended in the EPD’s Guidelines on Assessing the 'TOTAL' Air Quality Impacts has been followed to assess the potential cumulative air quality impact at the identified ASRs.
The Project is expected to commence operation at the earliest the end of 2020 and that the Project emissions are expected to be consistent throughout the operation phase.
Although currently not planned, additional CCGT units (i.e. L12 to L14) may be constructed at the LPS in the future with reference to the approved EIA report of 1800MW Gas-fired Power Station at Lamma Extension (AEIAR-010/1999). L12 to L14, if constructed after 2020, will become the base load and serve as replacement for existing coal-fired power generation units at the LPS. Also, the future operation of the additional CCGT Unit No. 1 and No. 2 at the BPPS will also serve to displace power generation from the existing coal-fired power generation units at the CPPS and the existing gas-fired generation units at the BPPS; therefore, the overall emissions from the power plants are expected to reduce beyond 2020.
The Climate Action Plan 2030+ Report also requires an increase in the local gas-fired power generation to around 50% by 2020, and to phase down coal units and replace them by natural gas by 2030. This also suggests the emissions after 2020 will only get better, meaning the 2020 case represents the worst scenario.
As emissions are expected to be the highest in 2020 during the operation phase of the Project, 2020 has been selected as the assessment year for this assessment as a reasonably conservative approach.
Tier 1 contributions include emissions from the operation of the gas heaters at the GRS at the BPPS and the GRS at the LPS.
Tier 2 contributions include major emission sources in the vicinity of the Project that have the potential to contribute to cumulative impact with Project contributions. A number of existing and planned air emission sources have been considered as tier 2 contributions in the quantitative assessment in 2020, which include:
· Emissions from gas heaters in the existing GRSs at the BPPS;
· Main stack emissions from existing gas-fired generation units (C1 to C8) at the BPPS;
· Main stack emissions from the proposed additional CCGT units No. 1 and No. 2 at the BPPS;
· Emissions from gas heaters in the existing the GRS at the LPS;
· Main stack emissions from existing power generation units (GT57 and L9 (gas-fired), GT1, 2, 3, 4, 6 (oil-fired), L2 and L4 to L8 (coal-fired)) at the LPS;
· Main stack emissions from the proposed additional CCGT units (L10 and L11) at the LPS;
· Main stack emissions from the potential additional CCGT units (L12 to L14) at the LPS;
· Emissions from existing ash handling and disposal plant (36a&b, 37a&b and 38a&b) at the LPS.
· Other emissions from major emission point sources in the vicinity of the BPPS, including STF, WENT Landfill (both existing landfill and future extension), marine emissions associated with the operation of the WENT Landfill, the proposed IWMF, CPPS, Green Island Cement, Shiu Wing Steel Mill, PAFF, EcoPark, the proposed LFGPGUs at the existing WENT Landfill, and the two asphalt plants; and
· Vehicular emissions from open roads within 500m from ASRs A1 to A4.
For the assessment year 2020, all identified major emission point sources including the existing BPPS stacks (C1 to C8), existing LPS stacks (L1 to L9), STF, WENT Landfill (both existing landfill and future extension), the proposed IWMF, CPPS, Green Island Cement, Shiu Wing Steel Mill, PAFF and EcoPark have been included in the PATH-2016 model. To avoid double counting of the impacts from these emission sources, the PATH-2016 model for Year 2020 was re-run with the aforementioned major emission point sources removed. The predicted hourly background NO2 concentrations in 2020 obtained from the PATH-2016 model re-run were adopted as the Tier-3 contributions.
The cumulative NO2 concentrations ([2]) at the ASRs were estimated by adding together the hour-by-hour contributions from modelled results for Tier 1, Tier 2 and the PATH-2016 hourly background concentrations (in Year 2020). Different time-period averages of the 8,760 hourly results at each ASR were derived for comparison with the relevant assessment criteria (i.e. 1-hour NO2 and annual NO2).
Two gas heaters (BP1-1 and BP1-2) are proposed within the new GRS at the BPPS. For a conservative assessment, both gas heaters were assumed to be operating continuously in modelling. Each gas heater is equipped with two burners which are served by two separate stacks (A1 to A4). The locations of the two gas heaters and the associated stacks are shown in Figure 4.4. The stack design parameters and emission information for the gas heaters are presented in Table 4.8 and Annex 4A.
Table 4.8 Stack Design Parameters and Emission Information for the New Gas Heaters at the BPPS
|
Parameters |
BP1-1 |
BP1-2 |
||
|
Stack A1 |
Stack A2 |
Stack A3 |
Stack A4 |
|
|
No. of sources (stacks) |
1 |
1 |
1 |
1 |
|
Stack Diameter (m) |
0.6 |
0.6 |
0.6 |
0.6 |
|
Stack Height (mPD) |
21 |
21 |
21 |
21 |
|
Exit Velocity (m s-1) (b) |
10 |
10 |
10 |
10 |
|
Exit Temperature (ºC) (c) |
280 |
280 |
280 |
280 |
|
Emission Rate of NOx per stack (g s-1) |
0.2025 |
0.2025 |
0.2025 |
0.2025 |
|
Notes: (a) The stack design and emission information are provided by CLP. (b) Minimum exit velocity at full load condition. (c) Minimum exit temperature at full load condition. |
||||
There are a total of 10 gas heaters (BP2-1 to BP2-10) within the existing GRS complex at the BPPS. Gas heaters BP2-1 to BP2-7 are each equipped with an individual stack (stacks W1 to W7), while two stacks are connected to each of the gas heaters BP2-8 to BP2-10 (stacks W8 to W13). During operation, the BP2-1 to BP2-7 gas heaters as well as two of BP2-8 to BP2-10 gas heaters would be operating using natural gas continuously. One of BP2-8 to BP2-10 would be on stand-by. The locations of the existing gas heaters and the associated stacks are shown in Figure 4.4. The stack design parameters and emission information for the existing gas heaters are referenced from the current BPPS SP licence and are presented in Table 4.9 and Annex 4B.
Table 4.9 Stack Design Parameters and Emission Information for the Gas Heaters at the Existing GRSs at the BPPS
|
Parameters |
BP2-1 to BP2-7 |
BP2-8 to BP2-10 |
|
|
Stacks W1 – W7 |
Stacks W8 – W13 |
|
|
|
No. of sources (stacks) |
7 |
6 |
|
|
Stack Diameter (m) |
0.9 |
1.15 |
|
|
Stack Height (mPD) |
14.4 |
22 |
|
|
Exit Velocity (m s-1) (a) |
10 |
10 |
|
|
Exit Temperature (ºC) (b) |
300 |
280 |
|
|
Emission Rate of NOx per stack (g s-1) (c) |
0.64 |
0.57 |
|
|
Notes: (a) Minimum exit velocity at full load condition. (b) Minimum exit temperature at full load condition. (c) The maximum NOx emission rate per stack as per the current BPPS SP licence. |
|||
Following the same design philosophy as the existing GRS, facilities in the new GRS are designed on a unitised basis, i.e. a separate gas supply stream including gas heater will serve each CCGT unit. Four gas heaters (LP1-1 to LP1-4) are proposed within the new GRS at the LPS. The gas heaters are required in the unitised gas supply streams, i.e. one gas heater will serve one CCGT unit. Gas heaters LP1-1 to LP1-4 are each equipped with an individual stack (stacks B1 to B4). During operation, LP1-1 to LP1-4 gas heaters would be operating using natural gas continuously. The location of the gas heaters and the associated stacks are shown in Figure 4.5. The stack design parameters and emission information for the gas heaters are presented in Table 4.10 and Annex 4A.
Table 4.10 Stack Design Parameters and Emission Information for the New Gas Heaters at LPS
|
Parameters |
LP1-1 |
LP1-2 |
LP1-3 |
LP1-4 |
|
Stack B1 |
Stack B2 |
Stack B3 |
Stack B4 |
|
|
No. of sources (stacks) |
1 |
1 |
1 |
1 |
|
Stack Diameter (m) |
0.61 |
0.61 |
0.61 |
0.61 |
|
Stack Height (mPD) (b) |
18.9 |
18.9 |
18.9 |
18.9 |
|
Exit Velocity (m s-1) (c) |
2.6 |
2.6 |
2.6 |
2.6 |
|
Exit Temperature (ºC) (d) |
300 |
300 |
300 |
300 |
|
Emission Rate of NOx per stack (g s-1) (e) |
0.139 |
0.139 |
0.139 |
0.139 |
|
Notes: (a) The stack design and emission information are provided by HK Electric. (b) The stack height including base elevation is 18.9mPD. The actual stack height from ground level is 11.15m. (c) Minimum exit velocity at full load condition. (d) Minimum exit temperature at full load condition. (e) The maximum NOx emission loading from operation of each new gas heater is 0.5kg per hour. |
||||
For the assessment year 2020, there will be a total of four gas heaters within the existing GRS at the LPS, including two gas heaters (LP2-1 and LP2-2) for the GT57 at the LPS, one each for L9 (LP2-3) and L10 (LP2-4) at the LPS extension. Each of the four gas heaters is served by one individual stack (S1 to S4). During operation of the CCGT units, only three of the four gas heaters would be operating using natural gas continuously, while the remaining one in the converted CCGT unit gas supply stream would be on standby. The locations of the gas heaters and the associated stacks in 2020 are shown in Figure 4.5. The stack design parameters and emission information for the gas heaters as referenced from the current LPS SP licence with the same adopted for the gas heater (LP2-4) of L10 gas supply stream are presented in Table 4.11 and Annex 4B.
Table 4.11 Stack Design Parameters and Emission Information for the Gas Heaters at the Existing GRS at the LPS
|
Parameters |
LP2-1 |
LP 2-2 |
LP2-3 |
LP2-4 (d) |
|
|
Stack S1 |
Stack S2 |
Stack S3 |
Stack S4 |
|
|
|
No. of sources (stacks) |
1 |
1 |
1 |
1 |
|
|
Stack Diameter (m) |
0.61 |
0.61 |
0.61 |
0.61 |
|
|
Stack Height (mPD) |
18.9 |
18.8 |
15.2 |
18.9 |
|
|
Exit Velocity (m s-1) (a) |
2.6 |
2.6 |
4 |
2.6 |
|
|
Exit Temperature (ºC) (b) |
300 |
300 |
400 |
300 |
|
|
Emission Rate of NOx per stack (g s-1) (c) |
0.139 |
0.139 |
0.139 |
0.139 |
|
|
Notes: (a) Minimum exit velocity at full load condition. (b) Minimum exit temperature at full load condition. (c) The maximum NOx emission rate per stack is provided by HK Electric based on the current LPS SP licence. (d) The stack design parameters (i.e. stack diameter, exit velocity and exit temperature) and emission information adopted were referenced from LP2-1 and LP2-2, which are considered conservative assumptions for the assessment. The stack height of S4 is 18.9mPD based on the preliminary design information. The stack design parameters and emission information will be finalised during detailed engineering stage for L10 GRS in 2018-2019. |
|||||
Stack emissions due to the operation of the existing CCGT units (C1 to C8) and the proposed additional CCGT units at the BPPS were considered as Tier-2 contributions in the assessment. The existing auxiliary boiler with its limited operational durations would cause minimal air quality impact and are thus not included in the Tier-2 assessment. The stack design parameters and emission details for C1 to C8 have made reference to the current BPPS SP licence, while those for the proposed additional CCGT units were referenced from the approved EIA report for the Additional Gas-fired Generation Units Project (AEIAR-197/2016). All stacks were assumed to be operating continuously, for the purpose of a reasonably worst-case assessment. The stack locations are shown in Figure 4.6. The stack design parameters and emission information for the existing CCGT units and the proposed additional CCGT units at the BPPS are presented in Table 4.12 and Annex 4B.
Table 4.12 Stack Design Parameters and Emission Information for the Existing CCGT Units and the Proposed Additional CCGT Units at the BPPS
|
Parameters |
Existing Stack for C1 to C4 |
Existing Stack for C5 to C8 |
New CCGT Stack No.1 |
New CCGT Stack No.2 |
|
|
No. of sources (stacks) |
1 (a) |
1 (a) |
1 |
1 |
|
|
Stack Diameter (m) |
11.8 (b) |
11.8 (b) |
8 |
8 |
|
|
Stack Height (mPD) |
106 (c) |
106 (c) |
86 (d) |
86 (d) |
|
|
Exit Velocity (m s-1) |
15 |
15 |
15 |
15 |
|
|
Exit Temperature (ºC) |
80 |
80 |
80 |
80 |
|
|
Emission Rate of NOx (g s-1) |
188.9 |
188.9 |
4.66 (e) |
4.66 (e) |
|
|
Notes: (a) Each stack consists of four flues, each flue serves one CCGT unit. (b) Equivalent stack diameter. The diameter for each flue is 5.9m. (c) The stack height above ground (mAG) is 100m. (d) The stack height of the new CCGT units is between 80m to 100m above ground level. With reference to the approved EIA report for the Additional Gas-fired Generation Units Project (AEIAR-197/2016), the air quality impact at the identified ASRs arising from the new CCGT units is generally higher with a lower stack height of 80m above ground level. Therefore, the stack height of 80m is chosen for conservative assessment. (e) Emission rate is based on maximum allowable NOx emission limit of 5mg Nm-3 as per Best Practicable Means for Electricity Works (Coal-fired Plant, Gas-fired Gas Turbine, and Oil-fired Gas Turbine (Peak Lopping Plant)) (BPM 7/1 (2014)) and the highest proposed design capacity of 600MW per new CCGT unit. |
|
||||
Stack emissions due to operation of the existing power generation units (GT57, L2 and L4 to L9), the proposed additional CCGT units (L10 and L11) and the potential additional CCGT units (L12 to L14) at the LPS were considered as Tier-2 contributions in the assessment. Gas turbines GT1, 2, 3, 4 and 6 only operate during peak lopping and emergency situation with limited operation duration, while NOx emission from the existing ash handling and disposal plant, if any at all, is expected to be very minor. Nevertheless, as a conservative approach, emissions from GT1, 2, 3, 4, and 6 as well as the ash handling and disposal plant (36a&b, 37a&b and 38a&b) were included in the Tier-2 assessment. The stack design parameters and emission details for the existing power generation units (GT57, L2 and L4 to L9) were referenced from the current LPS SP licence, while those for the proposed additional CCGT units (L10 and L11) and the potential additional CCGT units (L12 to L14) are provided by HK Electric, with reference to the emission requirements as specified in BPM 7/1 (2014). All stacks as shown in Figure 4.7 were assumed to be operating continuously, for the purpose of a reasonably worst-case assessment. The stack design parameters and emission information for the key emission sources (i.e. GT57, L2, L4 to L14) at the LPS are presented in Table 4.13 and Annex 4B. Details for other emission sources (i.e. GT1, 2, 3, 4 and 6, 36a&b, 37a&b and 38a&b) at the LPS were referenced from the LPS SP licence and shown in Annex 4B.
Table 4.13 Stack Design Parameters and Emission Information for GT57, L2, L4 to L14 at the LPS
|
Parameters |
Existing Stack for L2 |
Existing Stack for L4 to L6 (a) |
Existing Stack for L7 and L8 (b) |
Existing Stacks for GT57 |
Stack of L9 – L11 (c)(d) |
Stack of L12 – L14 (e) |
|
Stack Diameter (m) |
5.11 |
9.73 |
7.83 |
5.6 |
10.39 |
10.39 |
|
Stack Height (mPD) |
215 |
215 |
215 |
86 |
110 |
110 |
|
Exit Velocity (m s-1) |
15 |
15 |
15 |
20 |
15 |
15 |
|
Exit Temperature (ºC) |
80 |
80 |
80 |
150 |
80 |
80 |
|
Emission Rate of NOx (g s-1) |
341.67 |
700.56 |
273.89 |
34.72 |
55.64 |
8.88 |
|
Notes: (a) The stack consists of 3 flues serving L4 to L6. The diameter of each flue is 5.62m. The equivalent stack diameter is 9.73m. (b) The stack consists of 2 flues serving L7 and L8. The diameter of each flue is 5.54m. The equivalent stack diameter is 7.83m. (c) The NOx emission rate for the proposed CCGT units (L10 to L14) is estimated based on the maximum allowable NOx emission limit of 5mg Nm-3 as per BPM 7/1 (2014) and the design maximum flue gas flow rate (i.e. 2,131,200Nm3/hour) per CCGT unit as provided by HKE. The NOx emission rate per CCGT unit is estimated to be 2.96g s-1 based on the following calculation: 2,131,200Nm3 hour-1 x 5mg Nm-3 /1000/3600 = 2.96 g s-1. (d) The stack consists of 3 flues serving L9 to L11. The diameter of each flue is 6m. The equivalent stack diameter is 10.39m. The NOx emission rate for L9 is 49.72g s-1 making reference to the LPS SP licence. The NOx emission rate for L10 and L11 is 2.96g s-1 each. (e) The stack consists of 3 flues serving L12 to L14. The diameter of each flue is 6m. The equivalent stack diameter is 10.39m. The NOx emission rate for L12, L13 and L14 is 2.96g s-1 each. |
||||||
Emissions from STF, WENT Landfill (both existing landfill and future extension), marine emissions associated with the operation of WENT Landfill, the proposed IWMF, CPPS, Green Island Cement, Shiu Wing Steel Mill, PAFF, EcoPark and the asphalt plants have been identified as the major emission point sources in the vicinity of the BPPS and were included as Tier-2 contributions in the quantitative assessment. These major emission point sources are shown in Figure 4.6 and the emission inventory is provided in Annex 4B.
In addition, emissions from the three stacks associated with the seven proposed LFGPGUs were included as Tier-2 contributions in the assessment. With reference to the Project Profile for the Landfill Gas Power Generation Project at the West New Territories (WENT) Landfill (DIR-251/2017) and information provided by CLP, the stack design parameters and emission details for the proposed LFGPGUs are presented in Table 4.14 and Annex 4B. The stack locations of the proposed LFGPGUs are shown in Figure 4.6.
Table 4.14 Stack Design Parameters and Emission Information for the Proposed LFGPGUs at WENT Landfill
|
Parameters |
Stack 1 (3 LFGPGUs)(b) |
Stack 2 (2 LFGPGUs) (b) |
Stack 3 (2 LFGPGUs) (b) |
|
Stack Diameter (m) |
0.5 |
0.5 |
0.5 |
|
Stack Height (mAG) |
20 |
20 |
20 |
|
Exit Velocity (m s-1) |
34 |
34 |
34 |
|
Exit Temperature (ºC) |
180 |
180 |
180 |
|
Emission Rate of NOx per stack (g s-1) |
0.36 (a) |
0.24 (a) |
0.24 (a) |
|
Notes: (a) NOx emission rate for each LFGPGU is 0.12g s-1. The total NOx emission rate for the seven LFGPGUs is 0.84g s-1. (b) Stack arrangement provided by CLP. |
|||
Vehicular emissions from open roads within 500m from ASR A1 to A4 as shown in Figure 4.8 and Figure 4.9 were assessed as Tier-2 contributions in the quantitative assessment. Projected hourly vehicle speed, hourly traffic flows and vehicle breakdown of 16 vehicle types for 24 hours for the identified open roads in 2020 (assessment year) were provided by the Project’s traffic consultant and are presented in Annex 4C.
One reasonably worst-case scenario under normal operating condition has been assessed in accordance with Clause 4(i) of Appendix A of the EIA Study Brief. The emission sources considered in the reasonably worst-case scenario for the assessment of cumulative impact are summarised in Table 4.15.
Table 4.15 Emission Sources Considered in the Reasonably Worst-case Scenario
|
Type of Source |
Details of Emission Source |
Remark |
|
Tier 1 |
Ÿ Stack emissions (A1 to A4) from two proposed gas heaters of the new GRS at the BPPS |
Ÿ Emission rates as shown in Table 4.8 were based on information from CLP. Ÿ The two new gas heaters at BPPS were assumed to be operating continuously for conservative assessment. |
|
|
Ÿ Stack emissions (B1 to B4) from four proposed gas heaters of the new GRS at the LPS |
Ÿ Emission rates as shown in Table 4.10 were based on information from HK Electric. Ÿ The four new gas heaters at LPS were assumed to be operating continuously for conservative assessment. |
|
Tier 2 |
Ÿ Stack emissions (W1 to W11) from gas heaters of the existing GRSs at the BPPS during normal operation |
Ÿ Emission rates as shown in Table 4.9 were referenced from the current BPPS SP licence. Ÿ It is assumed that BP2-1 to BP2-9 would be operating during normal operation while BP2-10 would be on standby. |
|
|
Ÿ Stack emissions (S1, S3 and S4) from gas heaters of the existing GRS at the LPS during normal operation |
Ÿ Emission rates as shown in Table 4.11 were based on information from HK Electric and the current LPS SP licence. Ÿ It is assumed that LP2-1, LP2-3 and LP2-4 would be operating during normal operation while LP2-2 would be on standby. |
|
|
Ÿ Main stack emissions from the proposed additional CCGT units (CCGT No. 1 and No. 2) at the BPPS |
Ÿ Emission rates as shown in Table 4.12 were based on the emission limit stipulated in BPM 7/1 (2014). |
|
|
Ÿ Main stack emissions from the existing CCGT units (C1 to C8) at the BPPS |
Ÿ Emission rates as shown in Table 4.12 were referenced from the current BPPS SP licence. |
|
|
Ÿ Main stack emissions from the proposed additional CCGT units (L10 and L11) and the potential additional CCGT units (L12 to L14) at the LPS |
Ÿ Emission rates as shown in Table 4.13 were based on the emission limit stipulated in BPM 7/1 (2014). |
|
|
Ÿ Main stack emissions from the existing units (GT1, 2, 3, 4 and 6, GT57, L2 and L4 to L9) at the LPS |
Ÿ Emission rates as shown in Annex 4B were referenced from the current LPS SP licence. |
|
|
Ÿ Emissions from the existing ash handling and disposal plant (36a&b, 37a&b and 38a&b) |
Ÿ Emission rates as shown in Annex 4B were referenced from the current LPS SP licence. |
|
|
Ÿ Other major emissions in the vicinity of the BPPS |
Ÿ Emission rates for the identified major emission sources and their references are provided in Annex 4B. Ÿ Stack emissions from the proposed LFGPGUs at WENT landfill as shown in Table 4.14 are referenced from the Project Profile for the Landfill Gas Power Generation Project at the West New Territories (WENT) Landfill (DIR-251/2017) supplemented with information provided by CLP. |
|
|
Ÿ Vehicular emissions from open roads within 500m from ASR A1 to A4 |
Ÿ Vehicular emissions based on traffic forecast in 2020 provided by Project’s traffic consultant. The traffic forecast is provided in Annex 4C. |
|
Tier 3 |
Ÿ PATH-2016 predicted background NO2 concentration in Year 2020 |
Ÿ Major emission sources included in Tier 2 were removed. |
An EPD recommended air dispersion model, AERMOD, was used to assess the air quality impact at the identified ASRs due to emissions from the GRS at the BPPS and the GRS at the LPS as well as the key existing and planned emission point sources as identified in Table 4.15. The quantitative assessment has been conducted following the latest EPD’s Guidelines for Local-scale Air Quality Assessment Using Models.
The relevant PATH grids in which the identified ASRs are located have been identified. The predicted meteorological data for the relevant PATH grids were used for model input. The relevant PATH grids for the identified ASRs are shown in Table 4.16.
Table 4.16 Relevant PATH Grids for the Representative ASRs
|
Area |
ASR |
Description |
Relevant PATH Grid |
|
BPPS Study Area |
A1 |
STF Office |
15, 44 |
|
A2 |
Proposed WENT Extension Site Office |
15, 44 |
|
|
A3 |
Lung Kwu Tan |
14, 42 |
|
|
A4 |
Planned Development in Lung Kwu Tan Reclamation Area |
14, 42 |
|
|
LPS Study Area |
A5 |
Village house at Tai Shan Central |
34, 23 |
|
A6 |
Village house at Wang Long |
34, 23 |
|
|
A7 |
Concerto Inn |
35, 22 |
AERMET was run to generate AERMOD-ready meteorological data for AERMOD model input. The land use parameters, including albedo, bowen ratio and surface roughness are required inputs for AERMET. The land use of 1km from the identified ASRs within each PATH grid has been evaluated to determine the PATH-grid specific surface roughness values. The land use of 10km x 10km from the GRS at the BPPS and the GRS at the LPS has also been evaluated to determine the values of albedo and bowen ratio for the PATH grids. Detailed calculations of albedo, bowen ratio and surface roughness are presented in Annex 4D. Land use maps illustrating the determination of the albedo, bowen ratio and surface roughness are also shown in Annex 4D.
The AERMOD model input parameters and assumptions for the assessment are summarised in Table 4.17.
Table 4.17 Model Input Parameters and Assumptions for Assessment
|
Input Parameters & Assumptions |
Descriptions |
|
Air dispersion model |
AERMOD |
|
Type of source |
· Point sources |
|
Assessment parameter |
· 1-hour and annual average NO2 |
|
Assessment Heights |
· 1.5m, 5m, 10m, 20m, 30m and 40m above ground (for ASR A1 and A2); · 1.5m, 5m, 10m, 20m, 30m, 40m, 50m and 60m above ground (for ASR A3 and A4); · 1.5m, 5m and 10m above ground (for ASR A5, A6 and A7); |
|
Meteorological data |
· Weather Research and Forecasting Model (WRF) data in 2010 from PATH-2016 to be used to input into AERMET to produce AERMOD-ready meteorological data · PATH Grid – (14,42), (15,44), (34,23) and (35,22) · Actual mixing heights recorded by the Hong Kong Observatory (HKO) in 2010 were in the range of 121m to 1667m. Mixing heights from WRF data which are lower than 121m or higher than 1667m to be adjusted to 121m and 1667m, respectively · Wind direction of 0º to be adjusted to 360º · Wind speed smaller than 1m/s to be adjusted to 1m/s · Anemometer height of WRF data = 9m |
An EPD recommended model, EMFAC-HK v3.3, was used to predict the vehicular emission factors of NOx for the 16 vehicle types in 2020. “EMFAC” model was used for the model run and the average ambient temperature (23ºC) and relative humidity (80%) recorded at the Hong Kong Observatory (HKO) Tuen Mun weather station in 2016 were used. The NOx emission factors for the 16 vehicle types and the calculation of the composite emission factors are presented in Annex 4C.
An EPD recommended air dispersion model, CALINE4, was used for predicting the NO2 impacts due to vehicular emissions from the identified open roads. Since the highest road height allowed in the input into CALINE4 model is limited at 10m, any road with road height greater than 10m was set at a height of 10m in the CALINE4 model. Details of the road configurations are provided in Annex 4C. The land use types have been examined within an area of 3km radius from the concerned PATH grid (i.e. 14, 42 and 15, 44). As industrial, commercial and residential land uses account for less than 50% of the examined area, rural area was assumed and the surface roughness height of 100cm for rural area was adopted for the CALINE4 model run. Wind directional variability was calculated based on the following formula according to the stability class with reference to Irwin, J.S., 1980 ([3]).
So = S × (Zo/15cm)0.2
Where
Zo = is the surface roughness length (in cm) of the PATH grid;
So = is the standard deviation of the horizontal wind direction Fluctuations (in degrees)
S = is the standard deviation of the horizontal wind direction fluctuations (in degrees) for an aerodynamic surface roughness length of 15cm with reference to Irwin, J.S., 1980. S is a function of Pasquill stability class.
Table 4.18 shows the standard deviations of the horizontal wind direction fluctuations under different Pasquill Stability categories for the concerned PATH grid.
Table 4.18 The Standard Deviation of the Horizontal Wind Direction Fluctuations under Different Pasquill Stability Categories
|
Pasquill Stability Class |
Standard Deviation of the Horizontal Wind Direction Fluctuations (in degrees) |
|
PATH Grid (14,42), (15,44) |
|
|
A |
32.9 |
|
B |
32.9 |
|
C |
25.6 |
|
D |
18.3 |
|
E |
11.0 |
|
F |
5.6 |
The CALINE4 model input parameters and assumptions are summarised in Table 4.19.
Table 4.19 Model Input Parameters and Assumptions for Assessment of Vehicular Emissions
|
Input Parameters & Assumptions |
Descriptions |
|
Air dispersion model |
Ÿ CALINE4 |
|
Year of traffic flow |
Ÿ Year 2020 |
|
Vehicle emission factors |
Ÿ EMFAC-HK emission factors for 2020 |
|
Assessment parameter |
Ÿ 1-hour and annual average NO2 |
|
Assessment Heights |
Ÿ 1.5m, 5m, 10m, 20m, 30m and 40m above ground (for ASR A1 and A2); Ÿ 1.5m, 5m, 10m, 20m, 30m, 40m, 50m and 60m above ground (for ASR A3 and A4); |
|
Meteorological data |
Ÿ Weather Research and Forecasting Model (WRF) data in 2010 from PATH-2016 Ÿ PATH Grid – (14,42) and (15,44) Ÿ Actual mixing heights recorded by the Hong Kong Observatory (HKO) in 2010 were in the range of 121m to 1667m. Mixing heights from WRF data which are lower than 121m or higher than 1667m to be adjusted to 121m and 1667m, respectively Ÿ Wind speeds smaller than the 0.5ms-1 recommended by the CALINE4 model were adjusted to 0.5ms-1. Ÿ Stability class calculated by PCRAMMET (version 99169) Ÿ Calculation of wind directional variability based on stability class and surface roughness length of 100cm for rural areas. |
The hourly concentrations of NOx were predicted at the relevant assessment heights of the identified ASRs. Ozone Limiting Method (OLM) was adopted for the conversion of NOx to NO2.
The initial NO2/NOx ratio for stack emissions was assumed to be 0.1 ([4]). The conversion of NOx to NO2 for stack emissions was calculated as follows:
[NO2]pred = 0.1x[NOX] pred + MIN {0.9x[NOX] pred, or (46/48)x[O3] bkgd}
where
[NO2] pred = the predicted NO2 concentration
[NOX] pred = is the predicted NOX concentration
MIN means the minimum of the two values within the brackets
[O3]bkgd = the representative O3 background concentration; (46/48) is the molecular weight of NO2 divided by the molecular weight of O3
The initial NO2/NOx ratio for vehicular emissions was conservatively assumed to be 0.28 with reference to EPD’s Guidelines for Local-scale Air Quality Assessment Using Models. The conversion of NOx to NO2 for vehicular emissions was calculated as follows:
[NO2]pred = 0.28x[NOX] pred + MIN {0.72x[NOX] pred, or (46/48)x[O3] bkgd}
where
[NO2] pred = the predicted NO2 concentration
[NOX] pred = is the predicted NOX concentration
MIN means the minimum of the two values within the brackets
[O3]bkgd = the representative O3 background concentration; (46/48) is the molecular weight of NO2 divided by the molecular weight of O3
The hourly background NO2 concentrations in 2020 predicted by the PATH-2016 model were used to establish the background contributions for the cumulative impact assessment. The identified major emission point sources which were included as Tier-2 contributions have been removed from the PATH-2016 model to avoid double counting of these emission sources. The predicted PATH-2016 background NO2 concentrations from the PATH-2016 model re-run in 2020 specific to the PATH grids that cover the locations of the identified representative ASRs were adopted.
The predicted NO2 results (Tier 1 and Tier 2 contributions) at each ASR were added up with the PATH-2016 predicted background NO2 concentrations on an hour-by-hour basis. The relevant time period averages for NO2 (i.e. 1-hour NO2 and annual NO2) were calculated and compared with the relevant NO2 criteria to evaluate the cumulative air quality impact at the identified ASRs.
The LNG Terminal Jetty with mooring facilities for the FSRU Vessel and the visiting LNGCs will be constructed at the Site as shown in Figure 4.1. The FSRU Vessel will be constructed outside of Hong Kong. Jackets method will be used for construction of the Jetty and is not expected to generate fugitive dust.
Once all of the piles for a Jetty structure have been installed, the construction of the Jetty Platform, or the decks of the Mooring Dolphins, Walkways, Vent Stack structures and various topsides equipment will take place, using either pre-cast concrete beams / panels or concrete poured in-situ to form slabs. No concrete batching facilities will be established at the worksite of the LNG Terminal and only very limited fugitive dust emission is expected.
No ASR has been identified within approximately 4km from the LNG Terminal. Due to large separation distance between the worksite and the nearest ASR, adverse dust impact arising from the construction activities of the Project is not anticipated.
The construction of the two subsea pipelines will involve dredging, pipelaying, jetting, rock armour placement, testing and commissioning. These activities are not expected to generate fugitive dust. Rock armour may be required to be placed at various locations along the pipelines to achieve adequate protection of the pipelines against anchor drop and drag. The armour rock stockpile on the floating storage barge will be kept wet to limit potential fugitive dust emissions. Typically, a derrick lighter, fall-pipe barge or side dump vessel will be used to place rock armour onto the pipelines and no fugitive dust emission is expected.
As there is no ASR within 500m along the subsea pipeline routes, no adverse dust impact is anticipated.
The construction of the GRS at the BPPS and the GRS at the LPS involve minor site clearance, building works (i.e. construction of new gas receiving facilities), trenching and installation of pipe racks, fences and a blast wall for the GRS at the BPPS. These construction activities would not require significant land excavation works, and the quantity of construction and demolition materials (including excavated materials) generated is expected to be insignificant. Due to the generation of small quantities of waste materials that require off-site disposal, the number of additional truck trips generated per day would be very limited. The potential air quality impact due to vehicular emissions from additional trucks during the construction phase of the Project is minimal.
As there is no ASR within 500m from the Project, no adverse dust impact is anticipated.
The FSRU Vessel will be permanently moored at the Jetty during the operation of the Project (except under adverse weather conditions). During normal operation, the FSRU Vessel and the Jetty will be fueled by natural gas. A diesel-fired generator is also provided at the Jetty for backup power that will be used intermittently.
No ASR has been identified within approximately 4km from the LNG Terminal. Due to large separation distance between the LNG Terminal and the nearest ASR, adverse air quality impact associated with the operation of the LNG terminal is not anticipated.
LNG will be transported to the LNG Terminal by visiting LNGCs. The indicative Berthing Route of visiting LNGCs to the LNG Terminal is shown in Figure 3.7. The LNG deliveries are infrequent (on average one LNGC arriving every five to eight days, subject to actual gas demand). The visiting LNGCs will be operated using boil off gas or low sulphur marine fuel. In addition, while berthed at the LNG Terminal, the fuel used shall have sulphur content of not exceeding 0.5% in accordance with the Air Pollution Control (Ocean Going Vessels) (Fuel at berth) Regulation.
No ASR has been identified within at least 4km from the Berthing Route of the visiting LNGCs. Due to large separation distance between the LNGC Berthing Route and the nearest ASR, adverse air quality impact associated with the marine emissions from visiting LNGCs is not anticipated.
As discussed in Section 4.7, cumulative NO2 impacts on the identified ASRs in the vicinity of the GRS at the BPPS and the GRS at the LPS have been assessed, taking into account emissions from the proposed new GRSs, other emissions in the vicinity of the Project, as well as PATH-2016 predicted background NO2 concentrations in 2020.
The predicted cumulative 19th highest 1-hour average and annual average NO2 concentrations at the worst affected height of the identified ASRs are presented in Table 4.20. The predicted maximum NO2 (project contributions only) are also presented in Table 4.20. Detailed results of all relevant assessment heights of each ASR are provided in Annex 4E.
Table 4.20 Predicted Cumulative 19th Highest Hourly Average and Annual Average NO2 Concentrations at the Worst Affected Height at Identified ASRs
|
ASR |
Description |
Cumulative NO2 Concentration (mg m-3) |
NO2 Concentration (Project Only) (mg m-3) |
||
|
19th Highest Hourly Average (a) |
Annual Average |
Maximum Hourly Average (b) |
Annual Average |
||
|
A1 |
STF Office |
137.2 |
36.2 |
65.5 |
0.18 |
|
A2 |
Proposed WENT Extension Site Office |
128.8 |
30.9 |
8.3 |
0.05 |
|
A3 |
Lung Kwu Tan |
153.7 |
35.5 |
7.4 |
0.05 |
|
A4 |
Planned Development in Lung Kwu Tan Reclamation Area |
146.7 |
37.7 |
34.2 |
0.13 |
|
A5 |
Village house at Tai Shan Central |
133.4 |
24.9 |
19.5 |
0.10 |
|
A6 |
Village house at Wang Long |
124.7 |
22.8 |
20.5 |
0.08 |
|
A7 |
Concerto Inn |
118.6 |
18.2 |
19.4 |
0.09 |
|
NO2 Criterion (mg m-3) : |
200 |
40 |
- |
- |
|
|
Notes: (a) The AQO allows 18 exceedances over a year, therefore, the results presented are in the 19th highest. (b) The maximum hourly average project contribution does not correspond to the same hour as the cumulative 19th highest hourly average concentration. |
|||||
The assessment results show that the cumulative 19th highest hourly average and annual average NO2 concentrations at all relevant assessment heights of all identified ASRs comply with the relevant AQO criteria. For BPPS, contour plots for the assessment heights at which the highest cumulative impact is likely to occur have been prepared. For ASR A1 and A2, the highest cumulative hourly and annual NO2 impacts were identified at 40m above ground and the contour plots are presented in Figure 4.10 and Figure 4.12. For A3 and A4, the highest cumulative hourly and annual NO2 impacts were identified at 60m and 50m, respectively, and the contour plots are shown in Figure 4.11 and Figure 4.13. For LPS, contour plots for cumulative 1-hour and annual NO2 impacts at 10m above ground in the LPS area are shown in Figure 4.14 and Figure 4.15. For BPPS, as shown in Figure 4.10 to Figure 4.13, there is no existing or planned air sensitive use located within the predicted area of exceedances of cumulative 1-hour and annual NO2 at high levels (i.e. 40m, 50m or 60m above ground). No exceedance of cumulative 1-hour or annual NO2 impacts was identified from the contour plots for LPS. Therefore, adverse air quality impact due to the operation of the GRS at the BPPS and the GRS at the LPS is not anticipated.
The following dust control measures stipulated in the Air Pollution Control (Construction Dust) Regulations and good site practices will be incorporated into the Contract Specifications and implemented at the land-based construction sites at the BPPS and the LPS throughout the construction period:
· Impervious sheet shall be provided for skip hoist for material transport;
· The area where dusty work takes place should be sprayed with water or a dust suppression chemical immediately prior to, during and immediately after dusty activities as far as practicable;
· All dusty materials should be sprayed with water or a dust suppression chemical immediately prior to any loading, unloading or transfer operation;
· Dropping heights for excavated materials should be controlled to a practical height to minimise the fugitive dust arising from unloading;
· During transportation by truck, materials should not be loaded to a level higher than the side and tail boards, and should be dampened or covered before transport;
· Wheel washing device should be provided at the exits of the work sites. Immediately before leaving a construction site, every vehicle shall be washed to remove any dusty material from its body and wheels as far as practicable;
· Road sections between vehicle-wash areas and vehicular entrance shall be paved;
· Haul roads shall be kept clear of dusty materials and will be sprayed with water so as to maintain the entire road surface wet at all times;
· Temporary stockpiles of dusty materials shall be either covered entirely by impervious sheets or sprayed with water to maintain the entire surface wet all the time;
· Stockpiles of more than 20 bags of cement, dry pulverised fuel ash and dusty construction materials shall be covered entirely by impervious sheeting sheltered on top and 3-sides;
· All exposed areas shall be kept wet to minimise dust emission;
· Ultra-low sulphur diesel (ULSD) will be used for all construction plant on-site, as defined as diesel fuel containing not more than 0.005% sulphur by weight) as stipulated in Environment, Transport and Works Bureau Technical Circular (ETWB-TC(W)) No 19/2005 on Environmental Management on Construction Sites;
· The engine of the construction equipment during idling shall be switched off;
· Regular maintenance of construction equipment deployed on-site shall be conducted to prevent black smoke emission; and
· In accordance with the Air Pollution Control (Marine Light Diesel) Regulation, all marine vessels fuelled in Hong Kong are required to operate using marine light diesel with sulphur content lower than 0.05%.
· In accordance with the Air Pollution Control (Non-road Mobile Machinery) (Emission) Regulation, non-road mobile machinery (NRMMs), e.g. mobile generator and air compressor, shall comply with the prescribed emission standards and approved with a proper label by EPD.
Natural gas should be used during normal operation of the FSRU Vessel and the Jetty to minimise the associated emissions. The operation of the visiting LNGCs shall comply with the fuel restriction requirement under the Air Pollution Control (Ocean Going Vessels) (Fuel at berth) Regulation. Emissions from the proposed new gas heaters at the GRSs during operation should be kept at or below the assumed emission rates as presented in Section 4.7. Provided that the mentioned measures are implemented and relevant regulations are complied with, additional measures during the operation phase of the Project is not required.
As discussed in Section 4.8, no adverse fugitive dust impact arising from the construction of the Project is expected. Hence, no adverse residual dust impact is anticipated during the construction of the Project.
As discussed in Section 4.9, no adverse air quality impact is expected to arise from the operation of the Project. Hence, there would be no adverse residual impact during the operation phase of the Project.
No adverse fugitive dust impact is anticipated during the construction phase, and so dust monitoring is considered not necessary. However, it is recommended to conduct regular environmental site inspections, i.e. on a monthly basis, at the GRSs at the BPPS and the LPS to check the implementation of the dust control measures and good site practices as recommended in Section 4.10.1 throughout the construction phase.
No adverse air quality impact is anticipated during the operation of the Project. Environmental monitoring and audit during the operation phase is considered not necessary.
All construction works associated with the Project are expected to generate limited fugitive dust emissions. No ASR has been identified within 500m from the boundary of the Project. Due to large separation distance between the worksite and the nearest ASR as well as the nature of the construction works, unacceptable dust impact is not anticipated to arise from the construction activities of the Project.
Proper dust control measures, site management and good housekeeping shall be implemented to further minimise any potential fugitive dust emissions arising from the construction of the Project. Regular environmental site audits on a monthly basis shall be conducted to ensure that dust control measures and good site practices are properly implemented throughout the construction period.
The operation of the LNG Terminal and visiting LNGCs will follow the requirements of all relevant regulations and recommended measures to minimise potential emissions. There is no ASR identified within approximately 4km from the LNG Terminal or the Berthing Route of visiting LNGCs. No unacceptable air quality impact is expected to arise from the operation of the LNG Terminal and from visiting LNGCs.
No ASR has been identified within 500m from the GRS at the BPPS and the GRS at the LPS. A quantitative assessment has been carried out to evaluate the potential NO2 impacts from the operation of the proposed GRSs on identified ASRs beyond the BPPS and the LPS Study Areas in 2020. A number of existing and planned key emission sources identified in the vicinity of the project sites at the BPPS and the LPS have also been considered for assessing cumulative impacts. The assessment results show that the predicted cumulative 1-hour average and annual average concentrations at the identified ASRs comply with the relevant AQO criteria. Hence, there would be no unacceptable air quality impact during the operation of the GRS at the BPPS and the GRS at the LPS.
([1]) 2014 – 2018 Development Plan and 2014 Tariff Review https://www.hkelectric.com/en/OurOperations/Documents/edev1210cb14545e.pdf
([2])
NO2 is the key air pollutant to be emitted from the operation of the GRS during
the operation phase.
([3])
Dispersion Estimate Suggestion #8:
Estimation of Pasquill Stability Categories. U.S.
Environmental Protection Agency, Research Triangle Park, NC. (Docket Reference
No.II-B-10), Irwin, J.S., 1980.