Annex 9.1: Case study for risk assessments
Petroleum terminal and distribution project
The project involves upgrading an operational oil terminal
facility through the addition of new storage tanks, improvement of tank
foundations, and construction of a new pipeline. The terminal receives various
petroleum products by ship. It stores the products and subsequently distributes
them to the domestic market by barge, tank trucks, drums, and cylinders. At
present, the main activities in the terminal include unloading of the products
from ships, loading of liquid products into barges, loading of liquid products
and liquefied petroleum gas (LPG) into tank trucks, blending and loading of
lubricating oils in drums, and filling of LPG cylinders.
The proposed 50 km pipeline will be used to transport LPG and
light petroleum products to a pumping station in another city, and then to
another terminal in a port. The pipeline will pass a populated area, highways,
rivers, a railroad, mangrove areas, and energy transmission lines.
The terminal is in a commercial/industrial area on the edge of an
island. Adjacent facilities include shipyards, other industrial plants, and
office buildings. Strong typhoons average two per year. The population around
the terminal consists mostly of about 2000 workers in the area. Similar
terminals operated by the same company can be found in many other countries,
although the distribution system varies in each case.
An EIA with ERA is proposed to be conducted for the project. The
EIA will assess the impact of the project to the population and the natural
ecosystem. EIAs for similar facilities have identified the following as the
major sources of environmental concerns: fuel spills and leakages, fires,
explosions, vapour clouds, and pollution from the storage or accidental spills
and leaks of the petroleum products. The ERA is expected to investigate these
concerns where significant consequences and uncertainties warrant. The major
hazard is large quantities of motor gasoline and LPG, which have low flash
points. Spills and leakages could cause fires, explosions, or vapour clouds and
could lead to catastrophic consequences, but the actual risk depends on how and
when the spills and leakages would occur and what their magnitudes or sizes are.
Potential spills during operations are most likely during the
transfer of products from one location or from one transport mode to another,
such as from barge to tank truck. Those transferred at temperatures below their
flash points may burn but will not create a flammable vapour cloud. Those
liquids with high flash points (e.g., in excess of 80° C) will be difficult
to ignite but may add fuel to a fire. The liquid products, which have flash
points lower than ambient temperature, could produce vapour clouds under normal
Calculation of risk and presentation
The usual method of calculation of individual risk is to calculate
the risk of a specified level of harm occurring to an individual who is assumed
to be at a particular point 100% of the time. The calculation is summed for all
hazardous events which can give that level of harm at that particular point, and
this gives the total individual risk at that point from the hazardous source. By
repeating the calculations for a series of points in a radial direction from the
source, a risk profile can be generated. If a grid of points is considered, a
series of contours can be produced around the source by interpolating between
the risk values in the grid.
The distance from the release point to the location of interest is
determined and then the concentration and cloud width at this downwind distance
from the release point is calculated from either the concentration or the
duration of exposure (release duration for a continuous release and the time for
the cloud to pass over for an instantaneous release) using a probit function.
Emergency planning - definition
A major emergency is one which has the potential to cause serious
injury or loss of life. It may cause extensive damage to property and serious
disruption both inside and outside the works. It would normally require the
assistance of outside emergency services to handle it effectively. While an
on-site plan will always be the responsibility of the works management,
different legislations may place the responsibility for the off-site plan
elsewhere. For example, the EC Seveso Directive requires the local authority to
prepare the off-site plan.
Emergency planning - objectives
The overall objectives of an emergency plan are: (a) to localize
the emergency and, if possible, eliminate it, and (b) to minimize the effects of
the accident on people and property. Elimination will require prompt action by
operators and works emergency staff using, for example, fire-fighting equipment,
emergency shut-off valves, and water sprays. Minimizing the effects may include
rescue, first aid, evacuation, rehabilitation, and giving information promptly
to people living nearby.
Identification and assessment of hazards
Overfilling of tanks could lead to large spills. The tanks are
equipped with liquid indicators and vents to prevent spillage. But the alarms
may fail or may be ignored by operators. Leakage from the pipeline may occur
from operational errors, faulty systems, or damage to the pipeline from external
sources. As the pipeline gets older, the frequency of leaks may increase.
Another possible catastrophic event is called BLEVE (boiling
liquid expanding vapour explosion). This is the sudden failure of a tank when
the contained liquid is at a temperature well above its atmospheric pressure
boiling point. The usual cause of a BLEVE is the exposure to fire of the dry
portions of a tank.
Additional matters that need further investigation are presented
in the risk screen report (see below).
Accidents while transporting petrochemical products have occurred
in many countries. Recent accidents in developing countries have caused many
fatalities. In 1983, a train transporting gasoline in Pojuca, near Salvador,
Bahia, derailed and caused the death of about 100 people. In the same year, a
big rock from the construction of a highway damaged an oil pipeline in the state
of Sao Paulo. The spilled oil polluted about 20 kilometers of estuarine
mangroves and several beaches. In 1984, leakage from a pipeline transporting
gasoline and other light petroleum products in Cubatao, Sao Paulo, caused a fire
that killed 100 people and destroyed houses.
Pipelines will be equipped with protection systems and instruments
for controlling internal conditions. Line pressure, temperature, flow rate alarm
system, and shutdown devices will be triggered if abnormal transmission
conditions occur. It will also have safety valves for the upstream and
downstream parts of the zone. In each of the populated areas it will pass
through, an emergency management system will be installed. This will include
warning signs with clear instructions to people on what to do in case of an
Tanks are fitted with fire extinguishers, external water spray
systems for exposure protection, and liquid level indicators and alarms. The
terminal is provided with a manually operated emergency shutdown system with
actuators strategically located in various areas in the terminal.
There is a need to evaluate probable accident scenarios with the
use of fault and event tree analysis, failure modes and effect analysis, and
common model failures. The contractor must identify probable initiating events.
The analysis must consider similar accidents already experienced in similar
facilities. The maximum credible spill, leakage, fire, and explosion and their
adverse consequences must be assessed.
Physical risk screen
The physical risk screen was conducted to identify hazards other
than those related to hazardous chemicals that could lead to impacts or public
and occupational safety, physical damage to ecosystems, or monetary and
disruptive impacts on project or community facilities. The following were
identified: transportation risks; ship traffic accidents near the terminal or
while docking; natural disasters; typhoon, which could cause some damage to the
terminal and the distribution system; other on-site and off-site hazards;
workers in the project, in general, may be compared with workers in a
petrochemical plant for which the British Standard of the Advisory Committee on
Major Hazards defines the total accident frequency rates (TAFR) to be equivalent
to a death risk probability of 3 × 105 per person-year; the
project involves use of barges, tank trucks, drums, and cylinders, and in
addition to the distribution pipeline, the terminal itself has a piping system;
the project does not involve complex human operations; the system within the
terminal and the distribution system is simple - some parts of the pipeline,
however, may be more difficult to monitor because they pass through rivers; the
island has been peaceful because the entire system is secured from trespassers;
the project is not highly dependent on the reliability of an electricity supply.
1 Categories of adverse events: accidents, spills, leakages,
fires, explosions, vapour clouds; natural disasters (typhoons) affecting the
2 Population at risk: workers in and around the terminal;
residents of communities where the pipeline will pass through; residents of
communities along the route of tank trucks; public within 500 m of the terminal.
3 Flow cycle: unloading of ships and barges; additional processing
(i.e., mixing of products, enhancing of products with additives); storage;
transport from the terminal to various distribution sites.
4 Geographic boundary: terminal project site, plus surrounding
5 Time period: the operating lifetime of the facility.
6 Human health endpoints: deaths.
7 Risk indicators: inventory; routine emissions and leaks.
Terms of reference for the contractor
The contractor is to conduct the ERA in accordance with the
following terms of reference.
1 The feasibility study for the project includes an EIA, which
covers all the environmental effects found by initial examination to be of
significant importance. This EIA will be performed simultaneously with the ERA.
2 The objective of the ERA is to advise management on the risks to
human health, the ecosystem, and welfare from the major hazards encountered in
the proposed petroleum terminal and distribution project. The consultant will
conduct studies sufficient to:
• identify major hazards, including those in the
attached screening checklist;
• construct plausible risk scenarios within the boundaries
suggested in the attached scoping summary;
• characterize the risks as quantitatively as possible;
• compare the risk with alternative means of accomplishing
the project or with abandonment of the project or of any aspect of it (e.g., the
• describe the feasible risk reduction actions and estimate
their costs; and
• recommend the most appropriate risk-reduction measures and
3 Description of the project.
4 The concerns of management centre on the risks from fuel spills,
leakages (mainly from the proposed pipeline), fires, explosions, and vapour
clouds, and their impact on populations within and around the terminal site and
distribution routes, on property, on other industrial facilities, and on
The screening process shows the following: significant quantities
of flammable products shall be stored, handled, and transported and increased
levels of transportation accident hazards. Scenarios include transportation
accidents from the terminal to the distribution sites using various
transportation routes and modes. These include accidents on highways, railroad
crossings, and in rivers, and spills and leaks of hazardous products stored. The
maximum credible accident (BLEVE) should be evaluated, including its likelihood
5 The scope of the ERA is detailed in the attached report of the
6 Constraints and opportunities for risk reduction are foreseen to
include the following.
• The terminal was moved only a year ago from a
previous site. The move required substantial investment. Hence it is unlikely
that any alternative terminal site will be considered at this point.
• Alternative transportation routes have been considered for
each of the destinations of the petroleum products and the ones proposed have
been found by the proponent to be the best, based on both economic and safety
considerations. The contractor must confirm this finding, as it may be possible
to reroute the pipeline to the least populated areas.
• Relocation of populations near the terminal and along the
chosen transportation routes will be expensive and politically unacceptable.
• Workers and engineers trained to prevent and handle spills
and leakages can be supplied as required by the project.
• Other possibilities for reducing risk from spills and
leakages are using equipment with low failure rates, redundancy in critical
equipment, installing spill detection and emergency shutdown systems to reduce
the size of spills, and using drainage and diking systems to reduce the spread
• Community emergency response plans have been designed and
may be reviewed further for additional improvements.
• Emergency response and safety features in the facility may
be strengthened further.
7 Risks should be characterized as:
• plot of frequency versus severity for
different designs and operations that would achieve the project objective;
• the severity should be measured in terms of deaths of
workers or residents;
• individual risk of premature death for workers and
residents in and around the terminal and near the transportation routes from
accidents involving spills, leakages, fires, explosions, and vapour clouds;
• damage to surrounding facilities from terminal or
8 Study constraints.
• The estimated cost of the ERA is ______, of
which ______% is allocated for technology transfer and training of local staff.
• The estimated time required to conduct the ERA is ______.
• The proposed payment schedule is as follows: ______.
• The specialist staff requirements are ______.
• The contractor is expected to coordinate closely with the
project proponent and the ADB project manager during the conduct of the