COMPARATIVE COSTS OF OIL SPILL CLEANUP TECHNIQUES

Transcription

1 COMPARATIVE COSTS OF OIL SPILL CLEANUP TECHNIQUES T. H. Möller, H. D. Parker, J. A. Nichols The International Tanker Owners Pollution Federation Limited Staple Hall, 87-9 Houndsditch London EC3A 7AX, United Kingdom ABSTRACT: This paper examines the costs of various cleanup techniques, drawing mainly on information from recent oil spills from ships. Analyses of the costs for dispersant application and for the use of offshore mechanical recovery equipment are compared in relation to their effectiveness and scope for reducing shoreline cleanup costs and damage from oil pollution. Spill size, oil type, coastline character, and the extent of pollution all contribute to the observed differences in shoreline cleanup and disposal costs. The influence of these factors is evaluated and criteria are proposed for selecting the most appropriate cleanup response to suit the circumstancees of a particular oil spill. On occasions, a response at sea is both necessary and worthwhile, but for most spills shoreline cleanup, including protection of sensitive resources, is likely to be the most cost-effective option. The costs arising from oil spills fall into two broad categories: cleanup and damage. As a rule, cleanup is carried out to prevent or reduce damage. Most of the resources sensitive to oil pollution are situated on or very near the coastline, and on the principle of prevention being better than cure, attempts are frequently made to combat spills at sea. This paper specifically examines the effectiveness of this approach in relation to the costs incurred for shore cleanup and disposal. A more general discussion of cleanup costs and economic as well as environmental damage is given by White and Nichols. 3 It is an accepted premise that no two oil spills are identical, but nevertheless similarities do exist in some aspects of cleanup responses, although the problem of identifying them correctly is notoriously difficult. The circumstances of any particular spill are often poorly understood, so that such factors as costs are easily misinterpreted. In addition, any judgment on the effectiveness of oil spill cleanup techniques is of necessity subjective in part, but the bias can be minimized by a consistent approach followed during the evaluation of data. For this reason the analyses in this paper are largely confined to a core of 26 recent spills at which International Tanker Owners Pollution Federation (ITOPF) staff attended onsite (Table 1). The observations made by ITOPF staff at the time of an incident form the basis of estimates made particularly regarding performance of equipment and materials, and the effectiveness of cleanup techniques. Precise measures of these parameters are seldom, if ever, available. The cost figures presented in Tables 1 through 3 represent the best available data on costs incurred or compensation paid. To facilitate direct comparisons, all costs are expressed in US $ normalized to 1985 values by applying the appropriate Wholesale Prices Indexes published by the International Monetary Fund. Total cleanup costs Data from 26 oil spills are listed in Table 1 against an identifying number for ease of reference. All the spills occurred between 198 and Calculations of the cost of cleanup measures are expressed in $ per metric ton (t) or $ per barrel (bbl). The costs vary from $71 to $21, per t ($1 to $3,3 per bbl), with an average of $3,83 per t ($598 per bbl). To assess the merits of cleanup operations in such rough terms alone would clearly be misleading, but the table provides a good starting point for developing the more refined concept of cost-effectiveness. The data also serve to illustrate how several external factors influence cleanup costs, thereby causing some of the observed variability. The most important of these are reviewed below. Location. The location of the spill is significant in that if spilled oil does not come ashore, little or no cleanup response will be necessary. In the case of incidents 7 and 21 ($71 to $19 per t), this occurred due to the direction of winds and currents that kept much of the spilled oil offshore until it had broken up naturally. The impact of oil spills will also vary depending on the population density of the coastline affected. In uninhabited areas a spill can pass virtually unnoticed whereas a spill in a built-up area will create demands for thorough cleaning. Incidents numbered 4, 5, 23, and 24 ($856 to $21,298 per t) all occurred in the ports of large cities and resulted in cleanup operations lasting over six weeks. T^pe of oil. The composition and physical properties of the spilled oil affect its impact. Light and refined oils evaporate and disperse naturally to a large extent except when persistent water-in-oil emulsions are formed. The following seven oil spills extracted from Table 1 show that, with one exception, cleanup costs relative to quantity of oil spilled were lower than average. During incident 2, the spilled oil penetrated deeply into coarse-grained beaches and the exceptionally calm weather provided none of the natural scouring that normally takes place. Spill no. $ per t $ per bbl , , , ,4 2, The views here expressed are those of the authors and do not necessarily reflect those of the individual directors and members of the International Tanker Owners Pollution Federation Limited. In contrast, heavy s, heavy fuel oils (), and water-in-oil emulsions are highly persistent and viscous, causing widespread contamination, as well as difficulties in the use of dispersante, skimmers, and pumps. It is no coincidence that these heavy oils also generate 123

2 OIL SPILL CONFERENCE Table 1. Total cleanup costs of 26 oil spills Spill number, regioni 1. N.E. 6. N.E. 1. N.E. 12. N.E. 14. N.E. 15. S.E. 16. S.E. 27. S.E. 19. N.A. 21. S.A. 23. F.E. 24. F.E. Cost ($) 1,84, ,8 319, ,13 338, , , ,748 19, 158, 19,738 9,1 14,367 Cost of treatment of oil "at sea' " Percent of Oil quantity treated Unit costs total cost (metric tons) (barrels) ($/t) ($/bbl) ,148 1, ,391 2, ,18 22, , , , Cost ($) 21,968,737 1,82, , ,513 1,127,249,659 11,115 13,49 12,8 3,171,93 144,46 2,767,455 1,,26 Cost of cleanup on shorelines Oil quantity treated Percent of total cost (metric tons) (barrels) , , Regions: N.E., Northern Europe; S.E., Southern Europe; N.A., North America; S.A., South America; F.E., Far East 2. Unconfirmed estimate 3. Daily rate 29,25 2 2,925 3, , 16,25 2 3,25 2 Unit costs ($/t) ($/bbl) , , Table 2. Costs for cleanup at sea and on shorelines Spill number, regioni 1. N.E. 2. N.E. 3. N.E. 4. N.E. 5. N.E. 6. N.E. 8. N.E. 9. N.E. 1. N.E. 11. N.E. 12. N.E. 13. N.E. 14. N.E. 15. S.E. 16. S.E. 17. N.A. 18. N.A. 19. N.A. 2. N.A. 21. S.A. 22. F.E. 23. F.E. 24. F.E. 25. F.E. 26. F.E. Type of oil Heavy Heavy Heavy Heavy Heavy (t) 12, 1, 3 1,6 6, , 1, 6 2,3 2,8 3,34 76 Spill Quantity (bbl) 81,25 6, 2, 2,6 1, 4, 2,6 88 2,6 2, , 4, 65, 1, 3,9 16, 15, 22, 5, 3,25 Total cleanup costs (U.S. $) 23,89,48 868,618 4,465,184 3,613,213 8,519,26 2,759, , ,89 81,132 93,643 27,396 1,465,96 286,857 1,565,53 284,71 459,238 1,542,13 4,27,467 3,329,93 9,2, ,784 1,619,254 2,857,465 1,214,393 1,189, ,16 Unit cost (1985 US$) 2 ($/t) ($/bbl) 1,95 4,343 4,465 12,44 21,298 1, ,77 1,82 2, , ,827 4,38 3,62 2, ,379 15, ,598 5,948 1, ,87 3, , , Cleanup method 3 ON.ST.MA. ST. ON.ME.MA. ON.ST. ON. ST. OF.RE.ON.ME. OF.DI.ON.ME. ON.DI.MA. OF.RE.ON.ME.MA. ON.ME.MA. OF.RE.ON.ST.MA. ON.ME.MA. OF.RE.ON.ME. OF.RE.ON.ST.MA. OF.RE.ON.DI.MA. ON.MA. ON.DI.MA. 1. Regions: N.E., Northern Europe; S.E., Southern Europe; N.A., North America; S.A., South America; F.E., Far East 2. Averages: worldwide, $3,82/t ($598/barrel); Northern Europe. $4,564/t ($698/barrel); North America, $5,73/t ($768/barrel); Far East, $2,56/t ($313/barrel) 3. Cleanup methods: OF.RE., offshore recovery; OF.DL, dispersants; ON.ME., onshore mechanical; ON.MA., manual; ON.DL, dispersants; ON.ST., steam/hot water washing

3 CLEANUP OPERATIONS 125 Table 3. Costs of dispersant spraying operations Spill number, regioni 28. N.E. 29. N.E. 3. N.E. 31. N.E. 32. N.E. 9. N.E. 33. S.E. 34. S.E. 15. S.E. 16. S.E. 35. S.A. 36. M.E. 37. M.E. 38. M.E. 39. M.E. N.A. N.A. Type of oil spilled isö IFO IFO Dispersant Type,,, consumed L drums A 4,95 1, Application method Dispersant cost (US$) B 1,25, ,522 67,865 9,573 13, ,35 36,28 28,655 13,39 145,3 75, ,921 38,216 77, ,916 41,43 125, , 125, Cost of /vessel hire (US$) C 2,69, ,524 34,92 6,357 7,778 33,721 12,78 14,32 5,77 38,461 27, ,827 2,382 7,85 27,43 29,427 12, , 83, Cost per drum 2 (B + C)/A Regions: N.E., Northern Europe; S.E., Southern Europe; N.A., North America; S.A., South America; M.E., Middle East 2. Average cost of application (excluding estimates), $768/drum; average cost of vessel duplication, $536/drum. Average costs per drum by region: N.E., $69; S.E., $564; M.E., $7 3. Estimate for C14 4. Estimate for DC , ,95 4 some of the costliest cleanup operations, for example, incidents 4 and 5. Spill quantity. The correlation between spill quantity and total cleanup costs is poorer than might be expected. Such factors as location, weather conditions, and oil type occasionally lead to small spills being expensive to clean up, and conversely, cleaning up large spills can be relatively cheap. However, for roughly similar spills the unit cleanup costs are comparable. The following eleven incidents selected from Table 1 all occurred in Europe and involved spills of heavy fuel oil. With few exceptions, these spills cost $2, to $4, per t spilled ($3 to $7 per bbl). Spill No. $pert $ per bbl 1 1, , , , , , , ,827 1, , , Geographical area. Comparing incidents in different country groups gives some insight into the varying approach to oil spill cleanup in the five broad geographical regions represented (Tables 1 and 2). In many European countries, attempts have been made to combat spills both at sea and onshore, whereas the approach in North America and the Far East has been to on shoreline cleanup. The differences apparent in the corresponding average costs for the geographical regions are less significant than they seem because of the great spread in the data for the 26 spills in Table 1. A closer examination of cleanup response at sea compared with shore cleanup is made in the following sections. Cleanup costs at sea In Table 2, a smaller number of spills are listed for which reliable information exists on costs incurred both at sea and in shoreline cleanup. In addition, some indication is given of cleanup effectiveness in an estimate of the quantity of oil treated. The total spill quantity given in Table 1 is immaterial in this context since the greater portion of any spill is broken up by natural processes including wave action, dispersion, and biodegradation. While cost figures can be given with some precision, the data on oil treated is necessarily imprecise. Measuring the volume of skimmed or pumped liquids can be straightforward, providing the measurements are taken at the correct point, but it is more difficult to ascertain the true oil content in the mixture of oil and water collected. Similarly, any calculation of oil dispersed at sea, or oil quantities on a shoreline and in collected oily waste, will include errors since estimates are based more on judgment than measurement. In some cases no reliable figures are available or, alternatively, only a maximum figure can be quoted with any confidence. Accordingly, the interpretation of the unit costs ($ per t or bbl) must be made with care. Mechanical recovery. Mechanical recovery techniques were used in nine of the incidents listed in Table 2 (numbers 1,6,1,12,14,19,21, 23, and 24). In almost every case, the quantity of oil treated at sea is small compared with the amount of oil cleaned up on shorelines. A total of 1,152 t (7,532 bbl) were collected by containment and recovery at sea, while 9,28 t (6,875 bbl) were treated ashore. In other

4 OIL SPILL CONFERENCE words, 11 percent of all oil treated in these combined operations was cleaned up at sea, and 89 percent on shorelines. This pattern is the primary reason for the high unit costs that often characterize oil spill response at sea (Table 2). In addition, any work at sea will involve the use of or, which are inherently expensive to operate. The response at sea during incident number 1 was particularly wasteful of effort and resources since no oil was actually collected. Nevertheless, incident 6 is an example of successful offshore mechanical recovery. Approximately 1,61 of heavy fuel oil were spilled in calm sea conditions. Three fitted with weir skimming devices were used to recover 792 t (5,148 bbl) over 2 days, after which time the oil had fragmented and become too viscous to pass through the recovery pumps. A few days later the oil remaining at sea began to come ashore along many miles of sandy beach. It is estimated that 451 of oil was recovered during the subsequent beach cleanup. With the exception of incident 6, the attempts made at sea to combat the spills listed in Table 2 did not materially alter the pattern of shoreline impact, and in no case was shore pollution actually prevented. It is debatable whether shore cleanup costs would have been significantly increased if no response had been made at sea. Based on this record, the justification for conducting cleanup activities at sea in response to spills from ships has to be argued on grounds other than strict cost-effectiveness. Use of dispersante. Dispersante will only work on oils that are naturally dispersible, and the application of the chemical simply accelerates the natural dispersion rate. In practice it therefore becomes impossible to distinguish between dispersion attributable to natural water movement or to dispersant application. After a spill of 6, t of oil in 1983 (incident 7), a total of 647 drums of dispersants were applied from seven and eight, but although the oil was demonstrably dispersed, no reliable estimate can be given of how much floating oil was actually treated during the cleanup operation at sea (Tables 2 and 3). On this occasion the amounts of dispersant applied from and were 488 drums and 159 drums respectively. The aerial spraying was more accurate and less wasteful of dispersant, which more than compensated for the higher operating costs of the. Table 3 summarizes most of the major dispersant spraying operations carried out over an eight-year period (1978 through 1985). For reasons discussed above it is not possible to assess how much oil was actually treated by each dispersant application, and unit costs are therefore expressed relative to the number of L dispersant drums consumed ($ per drum). Spills in Europe are best reported, and on average, treated at a slightly lower cost than those occurring in the Middle East (Gulf States). The use of offers higher application rates and better control over spraying patterns, which, again, offsets their higher cost. Estimates for using large (C13 and DC4) are added to indicate the considerably higher costs involved. For the sake of realism, the estimates relate to an actual incident when aerial spraying was contemplated and the costs include callout fees, positioning charges, flying hours, fuel, and landing fees for applying 19 drums of dispersant. The estimates show that the use of large only becomes cost-effective when a large spraying operation is envisaged, thereby emphasizing the importance of a realistic evaluation of the scope for dispersant usage in relation to factors such as availability, flight distances, amenability of the oil to treatment within the time available, and cost-benefit analyses of other cleanup options. Dispersant application with and is discussed in more detail by Nichols and Parker. 2 Dispersants were also used on two spills of heavy fuel oil in the Mediterranean (incidents 15 and 16), but with no effect because of the high viscosity of the oil. Table 2 reveals a high penalty for such misuse of dispersant, with the combined costs exceeding $53, for two dispersant spraying operations, to no apparent benefit. Concentrating effort on shore cleanup is a more successful strategy on such occasions, since high viscosity oils often also severely reduce the efficiency of skimmers and pumping units of offshore recovery systems. Shore cleanup costs Unit costs. The unit costs for shore cleanup and disposal (Table 2) are much less variable than either the overall figures given in Table 1 or the unit costs for combating oil at sea. Shore cleanup costs for the incidents listed in Table 2 fall between about $65 and $6, per t of oil treated or collected ($1 to $1, bbl). Specifically selecting those eleven incidents on which information is available for both "at sea" and "onshore" responses allows some further analysis: Incidents: 1, 6, 1, 12, 14, 15, 16, 19, 21, 23, 24 Treatment of 1,151 t of oil at sea: $4,342,624 (3,773)j Cost of shore cleanup of 9,44 t: $34,497,558 (3,654) Totals: 1,592 t (69,447 bbl): $38,84,182 (3,667) 1. Unit cost, in U.S. dollars per ton The data does not allow the point to be argued with precision, but these figures suggest that the cost-effectiveness of shore cleanup and oil spill response at sea is about similar. Individual techniques. Examples of spills when dispersants and steam-cleaning techniques were used on shorelines are indicated in Table 1. During one incident (24), dispersants were applied on rocks to remove oil traces remaining after the bulk of the heavy oil had been removed manually. When worked into the oil with brushes the dispersant acted to loosen the oil sufficiently to be hosed or washed off with water. This operation cost about $3 per square meter of rock treated, compared with $4 per square meter for steam cleaning (incident 23, same location). In all, 151, L of dispersant were used to treat 92, m 2 of rocky shoreline at a total cost of $26,. When comparing experience from the two incidents, the cost-effectiveness of dispersant and steam cleaning seemed roughly equivalent when additional labor costs were taken into account: in both spills dislodged oil had to be collected manually to avoid renewed pollution. Also, the rate of progress of a three-man dispersant treatment team was similar to that of one steam lance operator. Manual cleanup. Records from spill 23 in the Far East also demonstrate how the efficiency of any shore cleanup activity decreases with time as oil becomes scarcer: Cleanup Effort Oil quantity Cost Unit cost period (man-days) collected (t) U.S. $ ($/t) Stage 1 136,8 2,27 1,56, 748 Stage 2 143, 748,22 4,69 Stage 3 12, , 712,835 Most of the effort during this spill was expended on manual cleanup of shorelines in consecutive stages, but some steam cleaning of rocks and sea walls was carried out during the second stage. It can be seen that the effort measured as the number of mandays was roughly constant but the oil quantity collected dropped by 99 percent over the cleanup period and the unit cost ($ per t) increased sharply toward the end. It is a well-known fact that the return on effort invested in cleaning decreases progressively with time and complete cleanup can never be achieved in practice. A vital point in any cleanup operation is deciding when it is reasonable to call a halt to further expenditure. Incident 27, listed in Table 2, is an example from a Mediterranean country where cheap manual labor rates resulted in modest shore cleanup costs. Conversely, the very high costs incurred in incidents 4, 5, 14, and 2 reflect the high labor charges of northern Europe and the United States (Table 1). Boat cleaning. Several incidents (2, 4, 7, 8, and 17) have given rise to numerous claims from owners of small boats. When yachts and other small craft become oiled, dispersants or suitable cleaning liquids may be used to clean the contaminated hull. However, some countries, notably the United States, impose such severe constraints on dispersant use that cleaning boats in the water using chemicals is practically impossible. The cleaning costs vary greatly depending on the degree of contamination and type of boat. Providing oil is not allowed to dry on to a glass reinforced plastic (GRP) or steel hull, it can be cleaned relatively easily at only $5 to $15 per boat. Any need to lift a boat out of the water to repaint or recoat the hull will more than double the basic cleaning cost, but only in rare cases is this really necessary.

5 CLEANUP OPERATIONS 127 Disposal of oily waste During oil spills the question of disposal often generates controversy and costs can escalate if collected oily waste has to be disposed of by an elaborate process or at great distance from the spill site. Several difficulties arise when attempting to compare disposal costs from different spills. The costs for transport and for disposal are often inextricably linked in cleanup claims. If candidate disposal sites are located at various distances from the site of the incident, the transportation costs may quickly overcome even quite significant differences in the basic costs of disposal options. For example, the cost for disposal alone at landfill sites can be as low as $3 to $7 per t of oily waste, which is comparable to typical transportation costs over a distance of 1 miles in Europe or the United States at $4 to $6 per t. In contrast, the charge for landfill disposal may in come countries reach $1 per t. The wide variation in the above examples, drawn from actual spills, is partly due to differences in the type of landfill site. A cheap landfill site may be little more than a dumping ground, whereas a controlled site may be constructed with impermeable membranes and leachate monitoring stations. Similarly, incineration plants can range from a simple brick kiln capable of processing oily waste at $3 per t, to a fully enclosed plant designed with smoke emission controls and other safety features required for disposal of hazardous chemical compounds. In one spill in Northern Europe the costs incurred to incinerate 1, t of oily waste in such a plant was $256,, 5 percent of the shoreline cleanup costs. Another reason for high disposal costs is the collection of very large volumes of sand from oiled beaches, particularly when road construction vehicles are employed for cleanup. In spill 6, the impact of 45 t of heavy fuel oil along many miles of sandy beaches led to the accumulation of 3, m 3 of oily sand with an average oil content of less than 1 percent. Conclusions If oil threatens a coastline, the primary aim should be to protect specific areas recognized to be most important, and to limit the extent of pollution damage elsewhere. The secondary aim should be to clean up stranded oil where necessary, giving priority to the most important areas. In reviewing measures suitable for achieving these aims, the consideration of cost-effectiveness should be one of the prime criteria. One simple test is to question whether a planned course of action, or an activity in progress, is an improvement on doing nothing and allowing natural processes to take their course. When it comes to oil spill response at sea, it is a fact that the natural spreading of spilled oil, the weather and sea conditions, and the physical properties of the oil may combine to thwart even the best equipped and trained team. In addition, the time available to respond at sea to spills from ships will be severely restricted, either because the properties of the spilled oil may alter with weathering, or the floating oil may quickly be carried ashore by winds and currents. Nevertheless, the incidents reviewed in this paper show that occasionally conditions may be favorable for particular techniques. The only way of maximizing the chances of success is to make a realistic evaluation of the circumstances of the incident, the aims to be achieved, and the capabilities and limitations of the equipment, materials, and manpower available. This evaluation must be done quickly. Any decision taken also needs reviewing from time to time in the light of changing circumstances. The record of past spills shows all too clearly that actions are often taken and then pursued both at sea and on shorelines without due regard to the real difficulties of the situation. The point is not so much that costs might be reduced by a more rational approach, but that the limited resources available to combat a spill may be better employed to achieve a quicker and more satisfactory result with less waste of effort and loss of morale. Acknowledgments In preparing this paper, the authors gratefully acknowledge the assistance of members of The International Group of P. & I. Clubs, The International Oil Pollution Compensation Fund, and Cristal Services, Ltd. References 1. International Monetary Fund, International Financial Statistics Yearbook. Volume 38. IMF, Washington, D.C. 683pp 2. Nichols, J. A., and H. D. Parker, Dispersante: comparison of laboratory tests and field trials with practical experience at spills. Proceedings of the 1985 Oil Spill Conference, American Petroleum Institute, Washington, D.C, pp White, I. C, and J. A. Nichols, The cost of oil spills. Proceedings of the 1983 Oil Spill Conference, American Petroleum Institute, Washington, D.C, pp

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