Engineering Risk Assessments and Risk Engineering Risk Assessments and Risk CommunicationCommunication

Sarah Arulanandam, Hazard and Risk Group RWDI West Inc.

DISCLOSURE OF MATERIAL ENVIRONMENTAL EXPOSURES: What should investors expect?January 20, 2005

Definitions of RiskDefinitions of Risk

Risk = frequency x consequence Frequency: accidental releases, upset conditions Consequences: short-term, acute

Risk = exposure x effect Exposure: low-level, continuous emissions Effect: long-term chronic

Risk = frequency x consequence x outrage Outrage: stakeholders, media, public, government

Risk = attractiveness of target x consequence Attractiveness: likelihood of attack

Risk = ???

TECHNOLOGY SELECTION

• Design & Construction Standards

• Control Options• Accident, Mitigation &

Recovery Options

RISK BASED DECISIONS

RISK ASSESSMENT• Public Involvement• Guidelines & Standards• Risk Utility• Risk Acceptability• Risk Communication

RISK ANALYSIS• Employee and Worker

Safety • Public Safety • Environmental• Financial

HAZARD ANALYSIS• Hazard Identification• Source Term Modelling• Dispersion Modelling &

Forecasting• Receptor Response

Modelling

FREQUENCY ANALYSIS• Historical Accident

Incident Data• Predictive Failure Models• Event Tree Analysis• Fault Tree Analysis

RISK RISK MANAGEMENTMANAGEMENT

Steps Involved in Steps Involved in Hazard and Risk ManagementHazard and Risk Management

Identify the hazards Define the system and characterize the

source Conduct dispersion modelling Estimate the consequences

Compare hazard results to accepted public health and safety criteria

Review the options for managing the hazards Examine failure frequencies and event

probabilities Estimate the risk

Compare risk results to accepted risk criteria Review the options for managing and

reducing the hazards and risks (i.e., alternate design and operating parameters, and accident control, reduction and mitigation strategies)

Hazard Analysis

RiskAnalysis

RiskManagement

Hazard Assessment

Risk Assessment

Hazard Management

Threat SpectrumThreat Spectrum(Courtesy of DND)(Courtesy of DND)

Least

Greatest

• Most Likely: High Yield Explosive (HYE)Most Likely: High Yield Explosive (HYE)

• Most Dangerous: Nuclear WeaponsMost Dangerous: Nuclear Weapons ----------------------------------------------------------------------------------• Greatest Threat: Contagious Biological PathogenGreatest Threat: Contagious Biological Pathogen

HYE

BiologicalToxins

Industrial Chemicals

Biological Pathogens

Radio-Isotopes

Chemical Weapons

NuclearWeapons

Example: Hazard IdentificationExample: Hazard Identification

Jet Fire:• Exposure to flame• Exposure to heat • Exposure to products

Flash Fire: • Initial exposure

(toxicity)• Exposure to flame• Exposure to heat• Exposure to products

Dispersing plume:• Exposure (toxicity)

Uncontrolled release

Immediate ignition

No immediate ignition

Delayedignition

No ignition

Safety Design and OptimizationSafety Design and Optimization

Compare alternative designs

Assess control systems and operational parameters

Compare risks to accepted standards

Generate alternatives and implementation strategies

Emergency PlanningEmergency Planning Recommendations

for emergency planning zones and land-use

Understand the nature and extent of the hazard

Select the level of protection required

Define an emergency planning zone (EPZ)

Communicate findings

Example: Example: Health and Safety Planning Health and Safety Planning

PrioritiesPriorities

Advance warning of an accident?

Accident occurs

Plume disperses

Exposure to dispersing plumeArea where acute effects may be experienced: • Emergency Response Plan

(responsibility of company)• Selection of EPZ criteria

Area where chronic effects may be experienced:• Public health response area

(shared responsibilities)• Selection of health criteria

Area where other impacts may be experienced

Potential release source

Public Involvement and Public Involvement and CommunicationsCommunications

Present an understanding of the hazards and risks at public meetings

Preparation of materials for presentation to stakeholders

Regulatory applications and expert testimony

Corporate due-diligence and policy development

Forensic Incident AnalysisForensic Incident Analysis

Accident investigation and reporting Describe the system Evaluate the

meteorology during the event

Recreate the incident What happened? Who was affected?

Applications: Hazard and Risk Applications: Hazard and Risk AssessmentsAssessments

Safety design and optimization Recommendations for emergency

planning zones and land-use Public involvement and communications Regulatory applications and expert

testimony Corporate due-diligence policy Accident investigation and reporting

Incidents

Accidents

The Heinrich PyramidThe Heinrich Pyramid

Unreported Occurrences