Safety and Environmental Programs as a Mechanism for Establishing ALARP
Authors: Arnold Kenneth E. , McCafferty Denise B. 
Published: October 2008

Introduction

In the past 2S years, there has been a growing awareness of the need to identify, evaluate and manage risks associated with offshore drilling and producing operations. Such risksinclude blowouts, fires and explosions and ship collisions. The effort to manage risks has increased greatly since the1988 Piper Alpha accident in the North Sea and the 1989 South Pass Block 60 accident in the Gulf of Mexico. In the North Sea, there is a specific requirement of the regulatory bodies to manage risks by assuring that facilities are designed and operated to a level of risk that is " As Low as Reasonably Practicable" (ALARP). To achieve ALARP, it is necessary that operators examine not only risks associated with hardware systems but to also evaluate the effect of management systems on reducing the probability of accidents or mitigating their consequences.

On the surface, this is an eminently reasonable concept. Certainly, if the risk of loss of life can be substantially reduced by a marginal increase in cost, we would all agree that it would be prudent to make the additional investment. We can also agree that there are perhaps some designs and operations that could theoretically carry such a high risk of loss of life that the risk is clearly not reasonable and either thedesign must be changed or the project should not be implemented. On the other hand we probably can also agree that there is some level of risk which is so low that no further analysis of alternatives to reduce this risk needs to be conceived and evaluated.

The problem with this theoretical approach, however, is in the implementation of the concept to real life situations. Just as would-be O. J. Simpson jurors and various legal pundits might disagree as to what constitutes a 'reasonable doubt" ora "preponderance of evidence," what is a 'reasonable risk" and what mitigation steps are '''practicable" can lead to a wide difference of interpretation between knowledgeable evaluators if such persons could be found.

For this reason, the offshore oil and gas industry and the regulatory bodies concerned with North Sea operations have evolved a working hypothesis based on calculations of the risk of loss of life. In most cases, if the calculated estimatesfor the risk of loss of life on a North Sea offshore platform is higher than 10−3 per year, the risk is considered to be clearly unreasonable and mitigation is required. If the potential loss is less than 10−5 per year, then the level of risk is considered to be "ALARP" and no further analysis is required. If the risk is calculated to be between −3 and −5, further mitigation is required, unless it can be shown by quantified risk assessment (QRA) that the cost is too high (and thus not 'reasonably practicable') compared to the computed monetary benefit of the reduced risk of the loss of life. For this type of analysis, it is necessary to establish the value of a life, and although there is room for a wide variance in this number, the industry seems to have settled on a number of approximately $2 million.