15.1.1
According to the EIA Study Brief, the
hazard to life associated with the proposed Dangerous Goods Vehicles Ferry Pier
(hereinafter referred to as proposed DGVFP) at Cha Kwo Ling should be assessed
in accordance with the risk guidelines set out in Annex 4 of the EIAO TM. The proposed DGVFP was planned under
Agreement No. CE32/99, Comprehensive Feasibility Study for the Revised Scheme
of South East Kowloon Development, and the hazard to life was assessed under
that project. However, in the current
project additional risk could result from modifications of the access road to
the vehicle queuing area of the proposed DGVFP due to the two slip roads for
the Trunk Road T2 proposed in this project.
15.1.2
The assessment is based on the best and
latest information available during the course of the EIA study, although the findings
of the South East Kowloon Development Comprehensive Planning and Engineering
Review (SEKD Comprehensive Planning and Engineering Review) regarding the proposed
DGVFP was not available at the time of assessment.
15.1.3
A quantitative risk assessment (QRA)
is not conducted in this assessment.
This is because the occurrence of the scenario considered in the current Study
is uncertain with the following two reasons:
·
proposed
relocation of the
existing DGVFP to Cha Kwo Ling near the two slip roads is based on the assumption that the sea area
near the Kai Tak Airport Runway is reclaimed. However, the need of relocating the existing DGVFP is still
uncertain and would depend on the outcome of the ongoing SEKD Comprehensive
Planning and Engineering Review by Planning Department
·
the Trunk Road T2, part
of the components of SEKD, is subject to review under the SEKD Comprehensive Planning and
Engineering Review, the status of Road T2 alignment is therefore
uncertain. Alteration of Road T2
alignment may have a knock-on effect on the WCR alignment and its associated
road network, in particularly the connection between WCR and Road T2
15.1.4
Therefore, a qualitative approach is
adopted in this assessment to assess the feasibility of the Project in view of
hazard to life, based on the latest information available during the course of
the assessment. A QRA should be carried out by the
project proponent of SEKD to confirm the compliance of risk guidelines,
if it is proposed that
the existing DGVFP is to be relocated.
15.2.1
As set out in Annex 4 of the EIAO TM,
the risk guidelines comprise two components as follows:
·
Individual Risk Guideline: the maximum level of
off-site individual risk should not exceed 1 in 100,000 per year, i.e. 1 x 10-5
/ year
·
Societal Risk Guidelines: it can be presented
graphically as in Figure 15.1.
The Societal Risk Guideline is expressed in terms of lines plotting the
frequency (F) of N or more deaths in the population from accidents at the
facility of concern. There are three
areas shown:
- Acceptable where risks are so low that
no action is necessary;
- Unacceptable where risks are so high that
they should usually be reduced regardless of the cost or else the hazardous activity
should not proceed;
-
ALARP (As
Low As Reasonably Practicable) where the risks associated with the hazardous
activity should be reduced to a level “as low as reasonably practicable”, which
the priority of measures is established on the basis of practicability and cost
to implement versus risk reduction achieved.
15.3.1
The hazard to life associated with the
proposed DGVFP has been assessed under the EIA Study under Agreement No.
CE32/99 (hereinafter referred to as the Previous Assessment). The assessment was undertaken for the
‘current situation’ (at 2001, where the DGVFP is located at the existing pier
in Kwun Tong) and the
‘future scenario’ (at 2012, for the proposed DGVFP at Cha Kwo Ling, with the
consideration of developments nearby in future). The assessment was based on data including population near the
proposed DGVFP, the traffic flow/road population close to the proposed DGVFP,
ignition sources and the number of dangerous goods vehicle (DGV)
movements.
15.3.2
The relevant data used in the Previous
Assessment for the ‘future scenario’ (proposed DGVFP at Cha Kwo Ling) is
briefly described below:
·
Population near the proposed DGVFP: 11
individual populated areas including open spaces, residential areas, sewage
treatment plant and commercial land use were modelled. The total estimated population of these 11
areas in the future scenario were 23,924 and 41,371 at daytime and nighttime respectively.
·
Traffic flow/road population close to the
proposed DGVFP: 5 roads near
the proposed DGVFP were considered as presented in Table 15.1
below. It should be noted that the two proposed slip roads of WCR were
not considered in the Previous Assessment.
·
Number of DGV movements: for the future
scenario, the estimated annual vehicle movements were: LPG road tanker (7,665),
LPG cylinder wagon (4,745), petrol road tanker (6,935), diesel road tanker
(4,380) and chlorine cylinder wagon (24).
·
Ignition sources:
roads were considered as line ignition sources. The presence factor for line sources was determined based on
traffic densities, average speed along the roads and the length of the roads. The traffic densities on roads were the
daytime traffic flows as presented in Table 15.1.
Table 15.1 Traffic Flow/Road Population close to the
Proposed DGVFP estimated in the Previous Assessment
|
Location
|
Daytime Traffic Flow (per hour)
|
Total Population in Area
|
|
Cont. & Inst. Release
|
BLEVEa
|
|
Cha Kwo Ling Road
|
888
|
7
|
2
|
|
|
|
22
|
|
|
Wai Fat Road
|
984
|
18
|
5
|
|
WCR
|
1824
|
21
|
5
|
|
Kwun Tong Bypass
|
3000
|
68
|
17
|
a BLEVE denotes as Boiling
Liquid Expanding Vapour Explosion
15.3.3
The risk results of the future
scenario determined in the Previous Assessment are presented below:
·
Individual
Risk: the maximum level of individual risk was less than the ‘acceptable limit’
of the Individual Risk Guideline.
·
Societal
Risk: the FN curves for the combined trade (including all the dangerous goods
involved) commenced with 1 fatality at a frequency of 3.94 x 10-6
per year, moves through 5 fatalities at a frequency of 3.42 x 10-7
per year and 50 fatalities at a frequency of 1.14 x 10-9 per year,
which all lie in the ‘acceptable region’ of the Societal Risk Guidelines with a
considerable margin for safety.
Location of the Proposed DGVFP
15.4.1
The findings of the SEKD Comprehensive
Planning and Engineering Review are currently not available and therefore this
assessment is based on the assumption that the proposed DGVFP would be located
at the same location as assessed in the Previous Assessment.
Proposed Slip Roads of WCR and the Proposed DGVFP
15.4.2
The location of the two proposed slip
roads of Road T2 and the modification of the access road to the vehicle queuing
area due to these slip roads are shown in Figure 15.2. Slip Roads S1 and S2 would be located
northwest and southeast of the vehicle queuing area respectively. Also, the planned access road to the vehicle
queuing area was modified 25 m southward (compared with the design under
Agreement CE32/99) due to the two proposed slip roads.
Hazard to Life
Implications of the Proposed Slip Roads
15.4.3
It can be noted that the proposed slip
roads introduced three changes to the surrounding environment of the proposed
DGVFP from that modelled in the Previous Assessment, as listed below:
·
The access road to
the vehicle queuing area would be modified 25m southward;
·
The population surrounding
to the proposed DGVFP would increase;
·
The presence of two
new line ignition sources, Slip Roads S1 and S2.
15.4.4
The implications of the above three
changes to the risk levels associated with the proposed DGVFP are discussed in
the following paragraphs.
Modifications of the Access Road
15.4.5
The modifications of the access road
to the vehicle queuing area would not significantly increase the length of the
DGV transport route from the existing DGVFP at Kwun Tong to the proposed DGVFP
and in turn, would not affect the transport failure frequencies. Moreover, since the access road would be
modified 25m southward, the DGVs travelling along the access road would be
farther away from the populated areas.
15.4.6
Based on the fact that transport
failure frequencies would not increase and the DGVs would travel farther away
from the populated areas with the access road modifications, it is considered
that the modifications would not induce increase of risk levels associated with
the proposed DGVFP.
Increase of Surrounding Population
15.4.7
There would be no significant increase
of surrounding population to the DGVFP due to the two proposed slip roads of
the Project. The surrounding population
consists of two types, namely static population (i.e. population at the
buildings) and transient population (i.e. traffic population on roads). For static population, there would not be
significant change due to the two proposed slip roads while for transient
population, there would be an increase but the increase is not expected to be
significant because the slip roads are not major roads with busy traffic and
are relatively short.
15.4.8
Moreover, the Societal Risk associated
with the DGVFP estimated in the Previous Assessment was well within the ‘acceptable
region’, with 50 fatalities being the largest fatality number can be observed
at the frequency of 1 x 10-9 per year or higher. The small increase of transient population
due to the slip roads is not expected to shift the Societal Risk level to the
‘unacceptable region’ (i.e. area of fatality > 1,000).
Changes in Line Ignition Sources
15.4.9
The Project will introduce two additional
line ignition sources, Slip Roads S1 and S2.
However, this change would not induce significant change in risk levels
associated with the proposed DGVFP because it would not alter the nature of the
environment, which contains a number of busy roads (i.e. a number of ignition
sources with high presence factors).
The probability of delayed ignition in accident events (except chlorine
incident as chlorine is not flammable) would not change sharply since there were
ignition sources with high presence factor located around at the first
place.
15.5
Conclusions and Recommendations
15.5.1
Due
to the occurrence of the scenario considered in the
current Study (additional risk results from modifications of the access road to
the vehicle queuing area of the proposed DGVFP due to the two slip roads of the
Road T2) is uncertain, a qualitative approach is adopted in this assessment to
assess the feasibility of the Project in view of hazard to life.
15.5.2
It is considered that the two proposed
slip roads would not induce significant change to the risk levels associated
with the proposed DGVFP due to the following conditions: (1) the existing nature (presence of
ignition sources with high presence factor) of locations near the proposed
DGVFP, (2) an insignificant increase of surrounding population arising from the
proposed slip roads when compared to that considered in the Previous
Assessment. Moreover, as assessed in
the Previous Assessment, the societal risk level is well within the ‘acceptable
region’, with 50 fatalities being the largest fatality
number can be observed at the frequency of 1 x 10-9 per year or
higher. Therefore, it is considered unlikely that
the risk guidelines would be breached due to the changes introduced by the two
proposed slip roads. This shows that the
Project is unlikely to be infeasible in terms of hazard to life implication.
15.5.3
A QRA should be carried out by the
project proponent of SEKD development to confirm the compliance of risk
guidelines should the existing DGVFP is to be relocated.