Figure 12D.1 Pipeline
Alignment and Trench Type
|
|
This section summarizes the assumptions
adopted in the QRA study. These are
broadly categorised as population, meteorological, frequency, consequence and
plant data assumptions.
12D.1.1
Segmentation of Route
Table 12D.1 Pipeline
Segmentation
|
|
Section |
Kilometre Post |
Length (km) |
Typ. Water depth (m) |
Trench type |
|
|
From |
To |
|||||
|
4 |
Boundary Section |
0 |
0.73 |
0.73 |
2-20 |
2 |
|
3 |
|
0.73 |
2.52 |
1.79 |
20 |
3 |
|
2 |
Black Point West |
2.52 |
4.78 |
2.26 |
5 |
2 |
|
1 |
Black Point Approach |
4.78 |
4.89 |
0.11 |
2 |
1 |
Figure 12D.1 Pipeline
Alignment and Trench Type
|
|
12D.1.2
Marine Vessel Classification
Table 12D.2 Vessel
Classes Adopted for Assessment
|
|
12D.1.3
Marine Traffic
Table 12D.3 Traffic
Volume across Gate Sections (Daily Average, 2003)
|
Vessel Class |
|
||||||||
|
Vessel
Speed (m/s) |
0-5 |
5-25 |
Others |
|
|||||
|
|
0-30 |
30-75 |
75+ |
0-30 |
30-75 |
75+ |
Total |
||
|
From Gate |
To Gate |
“A1”
Fishing Vessels and Small Craft |
“B1”
Rivertrade Coastal Vessels |
“C1”
Ocean-going Vessels |
“A2”
Fast Launches and Fast Ferries |
“B2”
Fast Ferries |
“C2”
Fast Ferries & Ocean-going Vessels |
||
|
0 |
1 |
250 |
265 |
45 |
150 |
110 |
40 |
5 |
865 |
|
1 |
2 |
40 |
5 |
1 |
50 |
50 |
5 |
10 |
161 |
Notes: Values
>5 are rounded to nearest 5
Daily values based on 9 day record.
Some rounding applies
Table 12D.4 Traffic
Growth Forecast
|
Vessel
Type |
20112 compared to 2003 |
20212 compared to 2003 |
|
Ocean-going Vessel* Rivertrade
Coastal Vessel Fast Ferry Fishing Vessel/ Small Craft/ Fast launch Others |
-5% +5% +10% +5% +5% |
+10% +15% +30% +15% +15% |
* The traffic growth forecasts for 20112 and 20212 does not take into account the development of the Tonggu Waterway.
This waterway is expected to shift ocean-going vessels away from
Table 12D.5 Traffic
Volume Assumed for Base Case 2011
|
|
Traffic volume (ships per day) |
|
|||||||
|
Section |
Fishing |
River-trade |
Ocean-going |
Fast Launch |
Fast ferry |
Other |
Total |
||
|
4 |
Boundary Section |
21 |
3 |
0 |
24 |
30 |
8 |
86 |
|
|
3 |
|
250 |
265 |
81 |
118 |
150 |
5 |
869 |
|
|
2 |
Black Point West |
12 |
16 |
0 |
5 |
8 |
2 |
43 |
|
|
1 |
Black Point Approach |
1 |
0 |
0 |
0 |
0 |
0 |
1 |
|
|
|
Total |
284 |
284 |
81 |
147 |
188 |
15 |
999 |
|
Table 12D.6 Traffic
Volume Assumed for Future Year 2021
|
|
Traffic volume (ships per day) |
|
|||||||
|
Section |
Fishing |
River-trade |
Ocean-going |
Fast Launch |
Fast ferry |
Other |
Total |
||
|
4 |
Boundary Section |
22 |
3 |
0 |
26 |
35 |
9 |
95 |
|
|
3 |
|
262 |
290 |
81 |
129 |
177 |
6 |
945 |
|
|
2 |
Black Point West |
12 |
17 |
0 |
6 |
9 |
2 |
46 |
|
|
1 |
Black Point Approach |
1 |
0 |
0 |
0 |
0 |
0 |
1 |
|
|
|
Total |
297 |
310 |
81 |
161 |
221 |
17 |
1087 |
|
12D.1.4
Marine Vessel Population
Table 12D.7 Vessel Population
|
Class |
Population |
|
|
|
Fishing vessels Rivertrade
coastal vessels Ocean-going vessels Fast launches Fast ferries Others |
5 5 21 5 450 (largest ferries in peak hours, 4
hours a day) 350 (average ferry in peak hours, 4 hours
a day) 280 (80% capacity, peak hours, 4 hours a
day) 175 (50% capacity, daytime operation, 9
hours a day) 105 (30% capacity, late evening, 4 hours
a day) 35 (10% capacity, night time, 7 hours a
day) 5 |
3.75% of trips 3.75% of trips 22.5% of trips 52.5% of trips 12.5% of trips 5% of trips |
|
12D.1.5
Frequency Analysis
Table 12D.8 Anchor
Damage Frequencies used in this Study
|
Pipeline
section |
Frequency |
Comment |
|
Boundary Section |
1´10-4 |
Medium marine traffic |
|
|
8.6´10-4 |
High marine traffic |
|
Black Point West |
1´10-4 |
Medium marine traffic |
|
Black Point Approach |
1.37´10-5 |
Low marine traffic |
Table 12D.9 Summary
of Failure Frequencies used in this Study
|
Pipeline
section |
Trench type |
Corrosion /defects (/km/year) |
Anchor/Impact |
Others /km/year |
Total* /km/year |
||
|
Frequency (/km/year) |
Protection factor (%) |
||||||
|
anchor<2 |
Anchor>2 |
||||||
|
Boundary Section |
2 |
1.18´10-6 |
1´10-4 |
99 |
50 |
1.34´10-6 |
3.5´10-6 |
|
|
3 |
1.18´10-6 |
8.6´10-4 |
99.9 |
99 |
1.34´10-6 |
4.1´10-6 |
|
Black Point West |
2 |
1.18´10-6 |
1´10-4 |
99 |
50 |
1.34´10-6 |
3.5´10-6 |
|
Black Point Approach |
1 |
1.18´10-6 |
1.37´10-5 |
99 |
50 |
1.34´10-6 |
2.7´10-6 |
* The calculation of total failure
frequency takes into account the size distribution of ships (based on 20122011 marine traffic) and the protection factors for
anchors
12D.1.6
Scenario Development
Table 12D.10 Hole Size Distribution Adopted for Corrosion and Other
Failures
|
Category |
Hole Size |
Proportion |
|
Rupture (Half
Bore) |
22" or
558mm |
5% |
|
Puncture |
4" or
100mm |
15% |
|
Hole |
2" or 50mm |
30% |
|
Leak |
<25mm |
50% |
Table 12D.11 Hole Size Distribution for Anchor Impact
|
Category |
Hole Size |
Proportion |
|
Rupture (Full
Bore) |
Full bore |
10% |
|
Major |
22" or 558mm
(half bore) |
20% |
|
Minor |
4" or 100mm |
70% |
Table 12D.12 Ignition
Probabilities used in Current Study
|
Release Case |
Ignition Probability |
|
|
|
Passing Vessels (1) |
Vessels in Vicinity (2) |
|
<25mm |
0.01 |
n/a |
|
50mm |
0.05 |
n/a |
|
100mm |
0.1 |
0.15 |
|
Half bore |
0.2 |
0.3 |
|
Full bore |
0.3 |
0.4 |
|
1.
Values
applied to passing vessels for all types of incidents, i.e. corrosion, others
and anchor impact. 2.
Values
applied only to scenarios where the vessel causing pipeline damage due to
anchor impact is still in the vicinity. |
||
12D.2.1
Population
Land Population
There is no land based population within 500m of the
proposed GRSs.
The security entrance to BPPS is more than 600m from
the GRS facilities. The nearest industrial facilities in Lung Kwu Sheung Tan are about 1.4km
away and
Marine Population
The marine study was based on 2003 data, extrapolated
to years 2011 and 2021.
Table 12D.13 Population
at Risk
|
Marine Vessel Type |
Population |
Fatality Probability |
Population at Risk |
|
Ocean-Going
Vessel Rivertrade Coastal Vessel Fast
Ferries Tug and
Tow Others |
21 5 450 350 280 175 105 35 5 5 |
0.1 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.9 0.9 |
2 2 135 105 84 53 32 11 5 5 |
Figure 12D.2 Marine
Population at Risk by Grid, Year 20112
Figure 12D.3 Marine Population at Risk
by Grid, Year 20212
Table 12D.14 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
× day + 0.25 × 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 |
Stationary Marine Population
Other stationary marine population such as that for
the
12D.2.2
Meteorological Data
Table 12D.15 Data
from Sha Chau Weather
Station (2004-2008)
|
|
Day |
Night |
||||||
|
Wind Speed
(m/s) |
2.5 |
3 |
7 |
2 |
2.5 |
3 |
7 |
2 |
|
Atmospheric
Stability |
B |
D |
D |
F |
B |
D |
D |
F |
|
Wind Direction |
Fraction of Occurrence |
|||||||
|
0° |
0.052 |
0.006 |
0.140 |
0.005 |
0.000 |
0.005 |
0.114 |
0.010 |
|
30° |
0.009 |
0.005 |
0.050 |
0.003 |
0.000 |
0.004 |
0.092 |
0.008 |
|
60° |
0.005 |
0.004 |
0.009 |
0.002 |
0.000 |
0.006 |
0.021 |
0.010 |
|
90° |
0.040 |
0.012 |
0.064 |
0.007 |
0.000 |
0.016 |
0.139 |
0.029 |
|
120° |
0.053 |
0.007 |
0.136 |
0.005 |
0.000 |
0.009 |
0.228 |
0.023 |
|
150° |
0.014 |
0.003 |
0.023 |
0.003 |
0.000 |
0.003 |
0.039 |
0.015 |
|
180° |
0.029 |
0.004 |
0.032 |
0.004 |
0.000 |
0.003 |
0.048 |
0.012 |
|
210° |
0.074 |
0.007 |
0.083 |
0.004 |
0.000 |
0.004 |
0.100 |
0.014 |
|
240° |
0.000 |
0.001 |
0.000 |
0.000 |
0.000 |
0.000 |
0.000 |
0.001 |
|
270° |
0.000 |
0.000 |
0.000 |
0.000 |
0.000 |
0.000 |
0.000 |
0.001 |
|
300° |
0.008 |
0.001 |
0.001 |
0.001 |
0.000 |
0.000 |
0.001 |
0.003 |
|
330° |
0.043 |
0.004 |
0.040 |
0.003 |
0.000 |
0.004 |
0.027 |
0.007 |
12D.2.3
Frequency Analysis
Table 12D.16 Gas
Release Event Frequencies
|
Piping Diameter (mm) |
Hole Size (mm) |
Initiating Event Frequency |
Unit |
Reference |
|
|
G01 |
7501067 |
10 25 50 100 FB |
1.00E-07 1.00E-07 7.00E-08 7.00E-08 3.00E-08 |
per metre per year |
Hawksley |
|
G02 |
700 |
10 25 50 100 FB |
1.00E-07 1.00E-07 7.00E-08 7.00E-08 3.00E-08 |
per metre per year |
Hawksley |
|
G03 |
400 |
10 25 50 100 FB |
3.00E-07 3.00E-07 1.00E-07 1.00E-07 5.00E-08 |
per metre per year |
Hawksley |
|
G04 |
700 |
10 |
1.00E-07 |
per metre per year |
Hawksley |
|
|
25 |
1.00E-07 |
|||
|
|
50 |
7.00E-08 |
|||
|
|
100 |
7.00E-08 |
|||
|
|
FB |
3.00E-08 |
|||
|
G05 |
700 |
10 |
1.00E-07 |
per metre per year |
Hawksley |
|
25 |
1.00E-07 |
||||
|
50 |
7.00E-08 |
||||
|
100 |
7.00E-08 |
||||
|
FB |
3.00E-08 |
||||
|
G06 |
350 |
10 |
3.00E-07 |
per metre per year |
Hawksley |
|
25 |
3.00E-07 |
||||
|
50 |
1.00E-07 |
||||
|
100 |
1.00E-07 |
||||
|
FB |
5.00E-08 |
||||
|
G07 |
700 |
10 |
1.00E-07 |
per metre per year |
Hawksley |
|
25 |
1.00E-07 |
||||
|
50 |
7.00E-08 |
||||
|
100 |
7.00E-08 |
||||
|
FB |
3.00E-08 |
||||
|
G08 |
700 |
10 |
1.00E-07 |
per metre per year |
Hawksley |
|
25 |
1.00E-07 |
||||
|
50 |
7.00E-08 |
||||
|
100 |
7.00E-08 |
||||
|
FB |
3.00E-08 |
12D.2.4
Scenario Development
Table 12D.17 Ignition
Probabilities Assumed
|
|
Immediate
Ignition |
Delayed
Ignition 1 |
Delayed
Ignition 2 |
Delayed
Ignition Probability |
Total
Ignition Probability |
|
Small leak |
0.02 |
0.045 |
0.005 |
0.05 |
0.07 |
|
Large
leak/rupture |
0.1 |
0.2 |
0.02 |
0.22 |
0.32 |
* Small leak = 10 and 25mm. Large leak = 50 and 100mm
holes
