Tables
of Assumptions
This
section summarizes the assumptions adopted in the hazard assessment. These are
broadly categorised as population, meteorological, frequency, consequence and
plant data assumptions.
1
Population
Table
1.1 Estimated
Residential Population Data
|
Location |
Approx. Distance from Terminal Site |
2011 Population |
2021 Population |
|
Lung
Kwu Tan village Ha Pak
Nai village Lung
Kwu Chau |
3km 3.7km 4km |
753 216 0 |
1,297 372 0 |
Table 1.2 Industrial Facility
Population
|
Location |
Approx. Distance from Terminal Site |
2011 Population |
2021 Population |
|
Black Point Site Surrounding WENT
Landfill Shui
Wing Steel Plant Siu Lang
Shui Landfill Site Office |
1km 3km 3.5km 4.5km 4.8km 4.9km |
100 194 1,102 177 390 7 |
100 194 1,102 177 390 7 |
Table 1.3 Road
Population
|
Location |
Approx. Distance from Terminal Site |
2011 Population |
2021 Population |
|
Lung |
1.2km |
22/km |
22/km |
Table 1.4 Population
Time Periods Definitions
|
Time Period |
Description |
|
Night
time Weekday Peak
hours Weekend
day |
7:00pm until 7:00am 9:00am till 5:00pm, Monday through Friday 7:00am to 9:00am and 5:00pm to 7:00pm, Monday to Friday 7:00am to 9:00am and 1:00pm to 3:00pm, Saturdays 3:00pm to 7:00pm Saturdays, and 7:00am to 7:00pm Sundays |
Table 1.5 Land
Population Occupancy and Indoor/Outdoor Fractions
|
Population |
Occupancy |
%
Outdoors |
||||||
|
Type |
Night |
Peak |
Weekday |
Weekend day |
Night |
Peak |
Weekday |
Weekend day |
|
Residential Prison Hospital School Road |
100 % 100 % 100 % 0 % 10 % |
50 % 110 % 120 % 10 % 100 % |
20 % 100 % 110 % 100 % 50 % |
80 % 110 % 120 % 10 % 20 % |
0 % 5 % 0 % 0 % 0 % |
30 % 100 % 30 % 100 % 0 % |
10 % 50 % 10 % 20 % 0 % |
20 % 50 % 30 % 20 % 0 % |
Table 1.6 Marine Vessel Population
|
Type of Vessel |
Average Population per Vessel |
% of Trips |
|
Ocean-Going
Vessel Rivertrade
Coastal vessel Fast
Ferries Tug
and Tow Others |
21 5 450
(largest ferries with max population) 350
(typical ferry with max population) 280
(typical ferry at 80% capacity) 175
(typical ferry at 50% capacity) 105
(typical ferry at 30% capacity) 35
(typical ferry at 10% capacity) 5 5 |
3.75 3.75 22.5 52.5 12.5 5.00 |
Figure
1.1 Marine
Population at Risk by Grid, Year 2011
Figure 1.2 Marine Population at
Risk by Grid, Year 2021
Figure 1.3 Number of Fast Ferries
Per Day*, 2011
* 75% in
daytime, 25% in night time
Figure 1.4 Number of Fast Ferries
Per Day*, 2011
* 75% in
daytime, 25% in night time
Table 17 Fast
Ferry Population Distribution for Day and Night Time Periods
|
Population |
Population at Risk |
% of Day Trips |
% of Night Trips |
% of All Trips (= 0.75 x day + 0.25 x night) |
|
450 350 280 175 105 35 |
135 105 84 53 32 11 |
5 5 30 60 - - |
- - - 30 50 20 |
3.75 3.75 22.5 52.5 12.5 5.0 |
Table 1.8 Fatality Factors
|
Population Type |
Fatality Probability |
|
Land
Population Indoor Outdoor Road vehicles Marine
Population Ocean-Going Vessel Rivertrade Coastal Vessel Fast Ferries Tug and Tow Others |
0.1 1 0.5 0.1 0.3 0.3 0.9 0.9 |
2
Meteorological
Data
Table 2.1 Data
for Sha Chau Weather Station (2003)
|
|
Day |
Night |
||||||
|
Wind
Speed (m/s) |
2.5 |
2 |
3 |
7 |
2.5 |
2 |
3 |
7 |
|
Atmospheric
Stability |
B |
F |
D |
D |
B |
F |
D |
D |
|
Wind
Direction |
Percentage of
Occurrence |
|||||||
|
0° |
2.48 |
0.92 |
1.37 |
13.75 |
0.00 |
2.08 |
0.89 |
9.93 |
|
30° |
0.72 |
0.61 |
0.76 |
4.38 |
0.00 |
1.78 |
0.84 |
7.12 |
|
60° |
0.55 |
0.61 |
0.59 |
0.55 |
0.00 |
1.89 |
0.76 |
0.95 |
|
90° |
2.00 |
1.57 |
2.43 |
6.07 |
0.00 |
6.69 |
2.97 |
9.53 |
|
120° |
1.68 |
0.90 |
1.32 |
15.98 |
0.00 |
3.82 |
1.84 |
20.08 |
|
150° |
1.06 |
0.61 |
0.36 |
3.12 |
0.00 |
2.28 |
0.60 |
3.83 |
|
180° |
2.43 |
0.71 |
0.65 |
3.64 |
0.00 |
1.81 |
0.74 |
3.88 |
|
210° |
3.35 |
0.86 |
1.39 |
9.04 |
0.00 |
2.06 |
1.01 |
6.91 |
|
240° |
0.07 |
0.16 |
0.05 |
0.02 |
0.00 |
0.23 |
0.02 |
0.04 |
|
270° |
0.08 |
0.09 |
0.01 |
0.01 |
0.00 |
0.11 |
0.00 |
0.01 |
|
300° |
1.58 |
0.35 |
0.21 |
0.07 |
0.00 |
0.62 |
0.04 |
0.05 |
|
330° |
3.78 |
0.74 |
1.09 |
5.22 |
0.00 |
1.59 |
0.53 |
2.45 |
3
Frequency
Analysis
Table 3.1 Ignition
Probabilities
|
|
Immediate Ignition |
Delayed Ignition 1 |
Delayed Ignition 2 |
Delayed Ignition Probability |
Total Ignition Probability |
|
Liquid small leak |
0.01 |
0.035 |
0.005 |
0.04 |
0.05 |
|
Liquid large leak/rupture |
0.08 |
0.18 |
0.02 |
0.2 |
0.28 |
|
Gas small leak |
0.02 |
0.045 |
0.005 |
0.05 |
0.07 |
|
Gas large leak/rupture |
0.1 |
0.2 |
0.02 |
0.22 |
0.32 |
* Small leak = 10 and 25mm. Large leak = 50 and 100mm holes
Table 3.2 LNG Storage Tank Release
Ignition Probabilities
|
|
Ignition Probability |
|
Immediate
ignition Delayed
ignition 1 Delayed
ignition 2 |
0.7 0.2 0.1 |
Release Size
For piping and equipment, a range of release sizes are
considered, including 10mm, 25mm, 50mm, 100mm holes and full bore ruptures.
For LNG storage tanks, all failures are modelled at
catastrophic failures.