Oil Spill Risk Assessment Research Articles

INCORPORATING CONSEQUENCE ANALYSIS INTO OIL SPILL RISK ASSESSMENT IN NEW ZEALAND

ABSTRACT This paper describes the New Zealand (NZ) approach used to define the likelihood and consequences of oil spills through the Maritime Safety Authority (MSA) Marine Oil Spill Risk Assessment process. A new methodology for consequence analysis was developed using 20 kilometre coastal cells established across the country for ranking and mapping sensitivity. For each cell, the resources present were evaluated under “environmental” categories (shoreline character, plants and animals, protected sites) and “human” categories (economic, cultural, and social, amenity & recreation). Factors within each category were allocated scores reflecting the sensitivity, vulnerability and reversibility of impacts at local, regional and national levels on a semi-quantitative 5-point score (very low / low / moderate / high or unknown / extreme). Qualitative descriptions (e.g. “no vulnerable plants or animals” ranging to “a number of vulnerable plants or animals of national importance, or at least one that is irreplaceable”) were used to ensure national consistency in scoring. Determining the presence or absence of environmental and human factors within each cell enabled individual scores to be summed for each category and graphically presented using diagonally split colour-coded squares on a map. This was overlain with the results of the regional oil spill likelihood analysis (e.g. how much, how often, where, what oil, and where from) providing an overall risk profile for NZ. The methodology was refined through national level multi-stakeholder meetings, and tested at two regional workshops to produce a data collection template for use by regional response agencies. The unique contribution of this work has been to incorporate consequence analysis into the assessment of regional and national risk profiles. Further quantifying the relative contribution of different activities and factors to the risk profile of each region, and nationally, will guide preventive and preparedness measures to lower the likelihood and impact of a spill. This in turn will determine the relative contribution each risk activity makes to the total risk profile which forms the basis for setting Oil Pollution Fund levies used to fund spill preparation in NZ.

Statmap—a 3-dimensional model for oil spill risk assessment

Stochastic oil spill models have traditionally focussed on the production of statistics for oil on the sea surface and along shorelines. Environmental risk analyses of potential spills therefore have tended to neglect potential risks to organisms in the water column. StatMap fills this void, supplying in addition statistics on the spatial distribution of hydrocarbon concentrations in the water column. This paper describes the model concepts and provides examples of model input and output.

A Maritime Oil Spill Risk Assessment Model

ABSTRACT Mantime oil transportation decision-making models that integrate with oil spill risk assessment methodologies are scarce. Recently, first time quantitative efforts have been developed for the maritime transportation of petroleum products. However, there still exists a serious gap in the literature concerning risk assessment models that provide a rather significant input to any maritime oil transportation model, namely the estimation and assignment of risk costs to the links of such a network. The authors first present a critical review of oil spill risk assessment efforts found in the literature and then the development of a novel oil spill risk assessment model. The goal of this risk assessment methodology is twofold: first, to determine and assign risk costs to the links of a maritime transportation network, and second, to provide insights into contributors that lead to spills. Such insights may further lead to guidelines for the prevention of future incidents leading to spills. A federal regulatory agency (such as the U.S. Coast Guard) and/or a commercial shipper may use the identification of the dominant contributors to oil spills to evaluate the merits of alternative regulatory and shipping policies that could lead to improved safety performance of the marine system. The authors finally exhibit the usage of the proposed methodology on a real case scenario.

ASSESSING ENVIRONMENTAL IMPACTS FROM A PUGET SOUND OIL SPILL

ABSTRACT An oil spill risk assessment determines the likelihood of accident occurrence and potential consequences of a spill when the spill occurs. An essential part of the risk assessment is an environmental impact assessment. The impact assessment identifies resources at risk and examines potential environmental contamination. Computer models can be used in conjunction with resource distributions to predict the impact of an oil spill. This paper provides an overview of the methodology used in assessing environmental impacts from an oil spill and examines various oil spill-modeling tools. The Regulatory Assessment: Use of Tug to Protect Against Oil Spills in the Puget Sound Area (USCG, 1999) includes a Qualitative Environmental Impact Assessment that serves as a case study demonstrating the environmental impact assessment process. The U.S. Coast Guard used this Regulatory Assessment to study the alternatives for improving maritime safety in the Puget Sound area. The following are elements and approaches adopted for the impact assessment:Problem formulation. Problem formulation is a planning and scoping process that establishes the goals, breadth, and focus of the risk analysis. A conceptual model is developed to identify environmental resources to be protected, data needed, and analysis to be used.Analysis. This analysis phase develops profiles of environmental exposure and effects of oil spills. The exposure profile characterizes the ecosystem that may be exposed and describes the magnitude and pattern of exposure.Validation. The validation process is a crucial step in defining the reliability of modeling environmental impacts. The use of several oil spill models can minimize the weakness and assumptions associated with each model. Actual spill incidents provide a range and magnitude of possible environmental damages, which further validate model results.

Panel recommendations on Oil Spill Risk Assessment

A technical panel was convened by the Minerals Management Services (MMS) of the Department of Interior to identify deficiencies and recommend improvements in their Oil Spill Risk Analysis (OSRA) model. Members of the panel were J. M. Bane, Jr. (University of North Carolina, Chapel Hill), G. S. Janowitz (North Carolina State University, Raleigh), T. H. Lee (University of Miami, Miami, Fla.), G. L. Mellor (Princeton University, Princeton, N.J.), M. L. Spaulding (University of Rhode Island, Kingston), and F. M. Vukovich (Research Triangle Institute, Raleigh‐Durham, N.C.).The present OSRA model uses climatologically derived near‐surface velocity fields on which are superposed oil trajectory velocities derived from the so‐called “3.5% rule”: this uses a wind series derived from a “transition probability matrix” statistical approach.

Judgment and Analysis in Oil Spill Risk Assessment

The risk of oil spills is a major environmental issue in the siting of proposed coastal refineries, oil terminals, deepwater ports, and in the leasing of offshore lands for oil exploration and development. As with any kind of risk, oil spill risk assessment is inherently judgmental and no analytic method can eliminate the need for judgment. This paper compares representative examples of oil spill risk assessments with regard to decisions about data, variables, functional relations, and uncertainty. The comparison emphasizes the judgmental basis of analytic methods.

APPROACHES TO OIL SPILL RISK ASSESSMENT FOR MARINE VESSEL OPERATIONS

ABSTRACT An oil spill risk assessment study should show the estimated relationship between the magnitude of an adverse environmental impact and the probability of an impact's equaling or exceeding that magnitude. Any unacceptably large impact must have an acceptably low probability of occurrence. Unless such probabilities are correctly estimated, no informed decision can be made about the acceptability of a proposed project. In this paper, we review the basic rules of the calculus of probabilities, demonstrate their application to oil spill risk calculations, and discuss the analysis of data for estimating very low probabilities and the role of computer simulation models to estimate environmental effects. Throughout, a case study is used to point out the pitfalls and errors one should try to avoid. In this example, the correction of a number of errors in the probability calculations resulted in a 37-fold reduction in the collision spill probability estimate and a 3,500-fold reduction in the grounding spill risk estimate. Grounding spills had been estimated to have by far the most adverse environmental impacts. The corrections substantially reduced the expected values of the impacts.

METHOD FOR CONDUCTING OIL POLLUTION LIABILITY INSURANCE SURVEY

ABSTRACT Oil pollution liability insurance surveys of oil handling installations are undertaken by insurance companies to qualitatively assess the chances that an oil spill will occur and the damage it could cause. By thus examining a facility, a basis is established on which to determine the premium for insurance coverage. In conducting such an oil spill risk assessment survey, many facets of oil handling and storage are considered, such as oil accounting, housekeeping, oil handling equipment, maintenance, outside contractor access and use, oil spill response equipment, and relationships with government agencies. Each facet must be addressed, and affects the final evaluation of the facility. Some of the procedures used for surface oil spills also can be applied to assess the risk of underground oil spills.

A COMPARATIVE RISK ASSESSMENT TECHNIQUE FOR TANKER OIL SPILLS

ABSTRACT The tanker oil spill risk assessment model (TRAM) allows a user to investigate the way in which oil spill probabilities, and amounts spilled, vary with such factors as fleet composition, navigational aids, or particular properties of the route. Such a comparison of alternatives is generally required for an environmental impact statement. TRAM operates through multiplication of a series of matrices: P, Q, R, and S. The rows and columns of all matrices are parameterized by accident type (such as collision or grounding) and location (such as at a pier, or in a harbor). The probability of an accident (P) and of a spill following an accident (Q) are based on world tanker fleet data. The matrix S expresses the conditional probability that if there is a spill, the vessel will be a total loss. This enables catastrophic spills in which spill size can be related to vessel size to be distinguished from minor spills in which vessel size is generally not a factor. The matrix R contains most of the unique features of the model. It accounts for vessel and route-specific features that reasonably may be expected to alter the world tanker fleet data. Examples are given from the literature for the elements of R corresponding to: fleet composition (domestic/foreign carrier); navigation aids such as vessel traffic system; vessel age, and construction (double hull, inerting system, segregated ballast, etc.); and various features of the tanker route, such as channel width and traffic density, based on Macduff's causation probability formalism. The practical usage of the model is demonstrated by applying it to a hypothetical project involving tanker oil transportation. The extension of this analysis technique to other forms of risk analysis studies (including operations other than oil transport) is also discussed.