Updated oil spill risk assessment for the Gulf of Suez

Transcription

1 Updated oil spill risk assessment for the Gulf of Suez G. Ghalwash & M. Elkawam Arab Academy for Science, Technology & Maritime Transport Abstract The Gulf of Suez (GOS) is an important and sensitive area of Egypt, which contains unique environmental ecosystems and biodiversity in addition to the attraction factors for tourism activities and rich fishing grounds. The GOS is an important source of natural resources and many modern ports are constructed in it. The GOS occupies a strategic position in the south entrance of the Suez Canal (SC), which is an important international waterway, linking east and west trades. Many oil activities are concentrated in the area exposing it to great danger of operational and accidental oil spills. Oil Spill Risk Assessment (OSRA) is a basic approach for Risk Management. An OSRA was established by the Egyptian National Oil Spill Contingency Plan (NOSCP) in 1998, which did not include all the sources of oil spills and whose results are considered as underestimates. This study introduces an updated OSRA for the GOS with a methodology based on practical, theoretical and applied approaches. The practical approach includes two types of field survey, coastal and sea field survey, the purpose of which are to record the features, activities and oil pollution of the area. The theoretical concept is based on identifying the criteria of utilizing the results of the field survey to establish an oil pollution depositary map and the criteria of using global models supported by local statistics to identify the high oil spill risk areas and plot the results on the available sensitive map of the GOS to implement OSRA and extract the Marine Environmental High Risk Areas (MHRAs). The applied approach includes a description of the computer software applications to calculate the oil spill risks, project the results on the sensitivity maps, implement the OSRA and extract MHRAs besides drawing the oil depositary map. It also includes the procedures of using an oil fate model to predict oil movement, spreading and weathering. The oil spill risks are categorized with respect to the spill size into Spill < 100 tonnes and Spill > 100 tonnes. In addition to the obtained OSRA maps, the study estimates a total probability of oil spill risk in the GOS of spill/year from the first category and spill/year from the second category, which are compatible with the actual statistics. The study also indicates that the highest oil spill risk sources are the Off-Shore Oil Facilities, whose estimated risk probabilities are and Spill/Year from the two categories respectively. Keywords: oil spill, risk assessment, risk probabilities, risk consequences, integrated ranking.

2 464 Risk Analysis IV 1 Introduction The GOS is a unique example of the integration between human and biological resources in Egypt. It contains most of the main tourist attractions besides unique marine preserved areas rich with rare types of corals and marine habitats. The wide variety of natural resources in the GOS like metals, raw materials, petroleum and natural gas resulted in high investments by national and international companies in exploration and production of such resources. The beauty of the sandy beaches and adjacent rich corals also encouraged a considerable number of investments in beach resorts, aqua sporting and diving activities, fig. 1. E1 W1 W2 E2 W3 E3 W4 E4 E5 W5 E6 W6 E7 E8 W7 W8 E9 W9 E10 W10 E11 E12 W11 W12 W Western Coast Station E Eastern Coast Station MHRA Figure 1: Gulf of Suez, with its sensitive areas from source: NOSCP [1], survay stations and MHRAs.

3 Risk Analysis IV Background The notion of OSRA for the GOS was first established by the NOSCP in 1996 which lasted for two years. The project resulted in the risk probability of oil spills represented in terms of spill/year given for five different spill categories according to spill size and mapped on the chart of Egypt. The NOSCP study showed only a sum of 1.75 spill/year due to neglecting some influencing elements such as: the offshore pipeline systems, the spills due to ramming accidents involving oil platforms, oil terminals and local traffic, table 1. Table 1: Estimated annual frequencies of accidental oil spills at the GOS According to NOSCP [1]. Element Probability of Spill (Sp/Y) Sum Return Type 0-100t 100-1,000t 1,000-10,000t 10, ,000t >100,0 00t (Sp/Y) Period Years Sea Elements Coastal Elements Sum Objectives of the study This specific study took into consideration all previous items and in order to attain more realistic results, it also considered: -The quantity of liquid cargo transported northbound and southbound in the Suez Canal and the nature of such convoys. -The dangerous areas for navigation due to heavy traffic and congestions of the TSS in the GOS. -The annual throughput of oil cargo for every oil terminal in the GOS. -The daily oil production of every off-shore oil platform. 4 Practical approach The practical approach included two types of field surveys; these are coastal field survey for all the coasts surrounding the GOS and sea field survey for the water areas including islands in the GOS. The number of coastal survey stations is 24 main survey stations, which represent the features of the coasts in the GOS. They are selected as 12 on the Eastern Coast and 12 on the Western Coast of the GOS with approximately average distance of 15 nm (28 Km) between each two survey stations, fig 1. The stations which lie on the Eastern coast of the GOS are prefixed by the letter "E", and those that lie on the Western coast are prefixed by

4 466 Risk Analysis IV the letter "W" to facilitate recording of data. The main objective of the coastal field surveys is to identify the high oil and floating litter depositary coasts in the GOS. In addition, the following features are recorded for the survey stations: - The nature of the coast (Sand, Rock, Gravel, Mud or others) - The width and steepness of the beaches and inter- tidal zones - Height above the mean sea level (MSL) - The human activities on the coasts Two sea field survey trips were conducted on the training ship of the Arab Academy for Science, Technology & Maritime Transport (AASTMT), (Aida IV). The ship crosses the SC and the GOS twice in every trip that is in the Southbound and Northbound direction. All the navigational equipment was used in the observations including GPS, ARPA Radar, thermometers, hygrometers, hydrometers and barometers. The objectives of the sea field survey can be summarized in achieving the following: - Determination of the difficulties of navigation in the GOS - Calculation of the estimated time period between the passage of vessels in different parts of the GOS to specify the areas of high density traffic - Estimation of the percentage of ship traffic in the Northbound and Southbound in the GOS - Estimation of the percentage of increasing the risk probability in the divergence and crossing areas of the Traffic Separation Schemes (TSS) - Conducting a questionnaire for personnel who have long experience in navigation in the GOS to support the calculated estimations. - Recording meteorological conditions, sea state and current 5 Applied approach The applied approach of the study includes description of the methodologies of application of the identified theoretical concepts and description of the used computer software to conduct these applications. 5.1 The concept of applying OSRA in the GOS The main approach of the applied OSRA is based on calculating the probabilities of oil spills due certain identified activities and integrates them with the severity of these oil spills to extract the level of risk, which is achieved in this study by conducting the following steps: - The risk probabilities (P) are calculated, using Global Models based on Romer [2] and Quon and Bushell [3], supported by local circumstances and statistics and represented as the estimated frequency or probability of occurrence of these oil spills in terms of Sp/Y or return period for two classes of oil spill quantities below and above 100 tonnes (SP < 100 t. and Sp > 100 t.). - The criteria of dividing these probabilities into five levels (From 1 to 5), for each class of oil spill quantity, are designed for this study to suite the comparison between the different sources as illustrated in Table 2. - The severity (S) is expressed as the level of each of the following:

5 Risk Analysis IV 467 A- Depositary Level of the Coast (From 1 to 5) B- In addition to the sensitivity or vulnerability (Obtained from the Integrated Ranking) of the different areas in the GOS. These criteria identify a weight for each type of ranking (Environmental, Economic and Beach priority) from 1 to 3. By multiplying the weight of the 3 types of ranking, the level of integrated ranking is obtained and categorized From 1 to 5, table 3. Table 2: Criteria of classifying the square elements of the GOS According to the estimated probability of oil spills. Level of Oil Spill Risk Probability of a Square Element Spill Size Sp < 100 tonnes Sp > 100 tonnes Class Code Criteria (Sp/Y) Criteria (Sp/Y) Probability 1 P1 Sp = 0 Sp = 0 Probability 2 P2 Sp < 0.01 Sp < Probability 3 P > Sp > Sp Probability 4 P > Sp > Sp Probability 5 P5 Sp 0.10 Sp Sp= the estimated risk probability of oil spill per annum Table 3: Integrated priority ranking criteria. Ranking R Pts Biological Resources & Environmental Sensitivity H 3 -Coral reefs, Mangroves and marshes -Protected areas & endangered species -Turtle nesting beaches -Sites of international and national importance for water birds M 2 - Sea grass beds - Spawning and nursery areas for fish & shellfish grounds L 1 -Open waters without sensitive resources -Sandy/muddy seabed Beaches with low productivity, easy to clean Criteria & Type of Ranking Human Use & Economic Importance Priority ranking of Beaches -Tourist -Difficult to access and clean the areas (dive beach sites; -High risk of inducing impact on marinas; adjacent ecosystems or human use beaches) features if oil is stranded on the beach -Fish farms -High impact due to shore clean-up -Oil procedures activities -Ports, harbors, TSS -Urban areas -Industrial areas -Fishing areas -Unused land -Open unused waters H: High, M: Medium, L: Low, Pts: Points, R: Ranking Based on the NOSCP [1]. -Medium difficulty to access and clean the beach -Medium risk of inducing impact on adjacent ecosystems or human use features if oil is stranded on the beach -Medium risks of impact due to shore clean-up procedures -Easy to access for cleaning -Low risk of inducing impact on adjacent ecosystems or human use features if oil is stranded on the beach -Low risks due to clean-up procedures

6 468 Risk Analysis IV - Each one of the two above mentioned criteria will be used as the severity in the risk matrix, then an integration of the two will be used also and the results will be compared to adjust the level of severity (S). - When combining the probability (P) with the severity (S) in a two dimensional Risk Matrix, the Risk levels are extracted, which can be categorized as Low (From 1 to 8), Medium (From 9 to 16) or High Risk (From 17 to 25), fig The ALARP Principle The expression ALARP used in the following risk analysis assessment matrix stands for "As Low as Reasonably Practicable", which is mainly a principle based on a cost benefit comparison of risks. The benefits from a given technology or management approach should be of a reasonable ratio with the costs of response precautions on the bases Queensland [4]. However, the scheme can be adopted on the bases of tolerance and precaution. The ALARP level of this study is considered as the Medium Risk Level (from 9 to 16). It should be noted that risk levels form 1 to 8 are to be monitored only. High Medium 3 Low Probability (P) Low Risk 5 (Acceptable with review) Low Risk 3 (Acceptable with review) Low Risk 1 (Acceptable) Level of Risk = Probability X Severity R = P X S Risk Medium 15 ALARP Risk Medium 9 ALARP Low Risk 3 (Acceptable with review) Risk Unacceptably High 25 (MHRA) Risk Medium 15 ALARP Low Risk 5 (Acceptable with review) Low Medium High Severity (S) Figure 2: Risk analysis and assessment matrix. Source: After Queensland [4]. 7 Calculations of oil spill risk probabilities To establish and implement a comprehensive OSRA for the GOS, this study has taken into account certain considerations and performed identified actions, which are summarized in the following steps: 1- Considering, in details, the following potential sources of oil spills and collect and establish information data base for the following sources:

7 Risk Analysis IV 469 Merchant ship Traffic, including Suez Canal Traffic, Ports Traffic and Oil Terminals Traffic according to EMDB [5]. Off-shore oil production facilities based on EGPC [6]. Ports & Oil terminals Activities. 2- Involving collaboration of data of the potential sources of oil spills due to off-shore pipeline systems based on BP [7]. The required information about location dimension and throughput of the pipeline systems in the GOS were insufficient to establish a real model. However, the off-shore pipelines drawn on the navigational Admiralty Chart 5501 [8] were used to supplement the risk model. 3- Considering Local Traffic such as: fishing vessels, sailing ships, cruising yachts, supply vessels, bunkering ships, tug boats, barges, petroleum service vessels and floating cranes as potential source of oil spill but not included in the risk probability due to insufficient data. 4- Utilizing the actual local conditions, observations and available statistics of oil spill incidents in the GOS by location, frequency and severity based on EMDB [5] to support and supplement the OSRA. 5- Considering additional types of ship accidents that may result in oil spill incidents such as the sinkage of ships and ramming accidents. Ships sinkage is considered only inside ports because no sufficient information is available outside the ports. Ramming accidents are defined as the accidents between vessels and fixed installations. Ramming accidents are categorized in this study as: a- Ramming with Off-shore oil production facilities b- Ramming with Oil Terminals c- Ramming with berths and buoys inside ports and harbors. 6- Finally, these vital inputs were added to the influencing factors such as: - The quantity of liquid cargo transported Northbound and Southbound at the Suez Canal, - The nature of the Northbound (NB) and Southbound (SB) Convoys - The dangerous areas of heavy traffic and congestions - The dangerous navigable areas of the TSS at the GOS such as the divergence and crossing areas - The annual throughput of oil cargo for every oil terminal at the GOS and - The daily oil production of every off-shore oil platform. Table 5 shows the final summary of the oil spill probabilities after consideration of all the previous aspects. 8 OSRA presentation The area of study in the GOS is divided into 161 square Elements on the chart number (5501) with side length of five minutes Latitude and five minutes Longitude (5' X 5'), which is considered suitable for this specific study. The chart is scanned and incorporated into the GIS to establish new themes for the

8 470 Risk Analysis IV different types of the necessary features of the GOS such as TSS, Ports, OPF, OT, coasts and sensitive areas. The elements are numbered from left to right, starting from the northern part (NP) of the GOS towards the southern part (SP). The element is identified by its number beside the letter S if it is in the sea and the letters (Ce, Cw and Ci) if it is on the east, west or an island coast respectively. The risk mapping will provide the user with a number of data for each element which are the following: Element Number and Identity (East Coast, West Coast, Island Coast or Sea Element) and if the Square Element is in the NP or SP Latitude and Longitude, Estimated Risk Probability of Sp < 100 t with its category (1-5), Estimated Risk Probability of Sp > 100 t with its category (1-5), Depositary level of Oil if it is a coastal element Sensitive or Vulnerability level of the element Length of TSS (NB & SB), Ports Approach, Oil Terminal Approach and submarine Pipelines in nautical miles Number of Ports, Oil Terminals and Off-shore Oil Facilities Table 4: Criteria of classifying square elements of the GOS according to the depositary level of oil. Depositary Code Total Weight of Criteria of Classification Classes Tar Balls on the Coast in Kg Class 1 O 1 Nil Nothing of the following (Tar Balls, Fresh Oil Residuals, Traces of oil at inter-tidal zone or pollution of oil on gravel, rock, sand and litter) Class 2 O 2 Nil Nothing of the following (Tar Balls, Fresh Oil Residuals, Traces of oil at inter-tidal zone) but there is oil pollution on gravel, rock, sand or litter or even black sand subsurface due to old oil Class 3 O 3 Wt < 5 Total Weight of Tar Balls < 5Kg and there is oil pollution on gravel, rock, sand or litter Class 4 O Total Weight of Tar Balls 6-10Kg and there is Fresh Oil Residuals, Traces of oil at inter-tidal zone and oil pollution on gravel, rock, sand and litter Class 5 O 5 Wt > 10 Total Weight of Tar Balls 11-15Kg and there are layers of oil in addition to Fresh Oil Residuals, Traces of oil at inter-tidal zone and oil pollution on gravel, rock, sand and litter

9 Risk Analysis IV Declaring MHRAs The study highlights the areas that classified as MHRAs, which should be declared as illustrated in Fig. 1, or Medium Risk Areas. The causes of the risk for each of these areas should be evaluated and prioritized in terms of overall importance. Some risks will require treatment and others can be accepted. The unaccepted high risks are passed to the treatment stage, which includes control, prevention and mitigation procedures. The OSRA for the GOS is conducted by Excel Spread Sheets, which enables easy presentation of data, change and updating of data, calculations and application of the formulae of risk contributing factors. The Estimated levels of risk probabilities are combined with the sensitivity level in the spread sheets to extract the MHRAs. The high risk probability areas that extracted from the results of the OSRA, are used as hypothetical oil spill sources in the Fate Model (S. L. Ross) providing the model with the same weather and sea conditions to estimate the depositary coasts of oil in the GOS. Then a comparison between the maps obtained from the two previous steps (Observations of the coastal field survey and results of the Fate Model) is conducted to adjust the estimation of the depositary coasts. The criteria of classifying the coasts with respect to accumulating oil are prepared for this study to enable comparison between the different sources of oil spills as illustrated in Table 4, while the final summary of OSRA is given in Table 5. Table 5: Final summery of oil spill risk probabilities in the GOS. Source of Risk Sp<100t /Year Sp>100t /Year Sum SC Traffic Pts Traffic OT Traffic Sum of TSS Traffic Ports Approach OT Approach Sum of Approach OPF OT Ports Pipelines Sum of Pipelines, OPF, OT, Ports Local Traffic 5 X 10 6 liter /Y not include in calculations of the OSRA Sum Total References [1] Egyptian Environmental Affairs Authority, Egyptian National Oil Spill Contingency Plan (NOSCP), NOSCP Committee, Cairo, 1998.

10 472 Risk Analysis IV [2] Romer, H. G., Risk Assessment of Marine Transport of Dangerous Goods, Ph. D. Thesis, Joint Research Center IPRA, Italy, 1996 (Report EUR EN). [3] Quon, K. A. & Bushell, G. E., Modeling Navigational Risk and Oil Spill Probabilities, Journal of Navigation, Vol. 47, No. 3, September [4] Queensland State, Queensland Transport, Oil Spill Risk Assessment Report for the coastal waters of Queensland and the Great Barrier Reef Marine Park, Australia, [5] Egyptian Maritime Data Bank (EMDB). Accidents in the Gulf of Suez, Statistical Annual Report. Alexandria, [6] Egyptian General Petroleum Corporation (EGPC), Ministry of Petroleum, Annual Report, Egypt, [7] British Petroleum (BP), [8] The UK Hydrographic Office, Admiralty Chart 5501, Taunton, Somerset, TA1 2DN, United Kingdom, 1997.