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Spills of Emulsified Fuels: Risks and Response 4 Efficacy of Response: Summary and Evaluation of Available Information In this chapter the available information on response technologies is evaluated with respect to the likely efficacy of response in the six settings described in Chapter 2, namely, marine—open water; marine—nearshore; estuarine (brackish water); nontidal river; fresh water—quiescent; and on land near water. Most of the literature on response options for spills of emulsified fuels describes equipment and systems that are similar to those traditionally used to respond to spills but modified to have improved effectiveness for spills of emulsified fuels. However, because there have been no significant spills of emulsified fuels, the modified equipment and the strategies for their use have been untested in real cleanup situations. Therefore, no actual spill data for determining actual or measurable effectiveness are available. These response options and their modifications are evaluated to the degree possible in the following sections. It should be noted that the effectiveness of oil response in containment and recovery of spilled oil has been historically low. In the response community, recovery of 20 percent of the spill volume is considered to be a good effort. Where dispersants or in situ burning are used effectively there is little or no additional response or recovery. MARINE OPEN-WATER RESPONSE In recent years, alternative technologies have been accepted as response tools to be considered as part of the oil spill response arsenal in the United States. Alternative response technologies usually include, but are not limited to, the use of dispersants, in situ burning, and bioremediation. Since some emulsified fuels,
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Spills of Emulsified Fuels: Risks and Response such as Orimulsion-400, already have a dispersant added in the form of their emulsifying surfactant, at the instance of spillage they disperse into the upper part of the water column. Therefore, the aerial dispersant application operations that are normally considered the first response in many areas of the United States for most spilled oils in the open water, have already taken place with emulsified fuel products. Since 1989, BITOR and its subsidiaries, in conjunction with their primarily utility company clients and U.S. and international government agencies, have studied the response to and possible cleanup techniques for spills of Orimulsion-100 and Orimulsion-400. These studies provide a large volume of information regarding available cleanup techniques and the individual merits and failures of response for these emulsified fuel products. Table 4.1 summarizes the effectiveness of response options for spills of emulsified fuels in marine open-ocean environments. It is clear that in an open-water marine environment, the preferred response methodology would be to monitor the naturally dispersed bitumen plume using the Surveillance and Monitoring for Alternative Response Technology (SMART) protocols in place for monitoring chemically dispersed spills of other types of oil. This sampling and analysis approach could also be augmented with discrete water column sampling for separate dissolved and dispersed bitumen droplet phases (Payne et al., 1999), to provide calibration for the UV fluorescence approach of the SMART Protocols and validation of computer model predictions of dissolved- and dispersed-bitumen droplet PAH concentrations. The availability of existing sophisticated computer three-dimensional modeling programs will support and enhance required surveillance operations (French et al., 1997). If any of the spill re-floated and was found, cleanup would be initiated using existing cleanup technology developed and available for Orimulsion, as well as technologies available for other Group V oils that are presently being transported in the United States (National Research Council, 1999). Many of the tests for equipment specifically designed for response to spills of Orimulsion products have been carried out on the open-ocean to determine the ability of responders to recover dispersed bitumen in that environment (Hvidbak and Masciangioli, 2000). As is the case with most open-ocean oil spill response equipment, some equipment developed specifically for response to Orimulsion spills and evaluated during the documented tests, such as the Tar Hawg, the forced adhesion and floatation (FAF) system, the PNP Re-floater, and the deepskirted containment booms, can reasonably be deployed and perform to some degree of efficiency in calm, open-ocean conditions, especially during an intentional spill demonstration scenario (Bitor America Corporation, 1997). For persons not familiar with equipment that has been developed specifically for Orimulsion, the Tar Hawg is a belt skimmer that has teeth built into the belt to enhance bitumen adhesion. The FAF and PNP Re-floater systems are two different methods of pumping both water and Orimulsion from the dispersed plume and forcing air into the pumped material, causing the bitumen to float. As the
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Spills of Emulsified Fuels: Risks and Response TABLE 4.1 Effectiveness of Response Techniques for Spills of Emulsified Fuels in Marine Open-Water Environments Response Technique Effectiveness for Emulsified Fuels Special Issues Monitoring and tracking Similar to success of tracking intentionally dispersed oils SMART protocols should be used and augmented with large-volume water sampling systems to analyze dissolved and dispersed bitumen PAH concentrations Mechanical refloating and forced adhesion and flotation of dispersed emulsified oil Even under optimum conditions, amount of oil that could be found, contained, and re-floated would be minimal Very specialized equipment; not proven under spill conditions; little hands-on experience by responders. Logistics may be overwhelming to deploy Long-skirted containment boom Limited to upper 3 m of water column, difficult to be towed byboats, must be allowed to drift with current To be effective, must be deployed before the dispersed plume spreads in the water column Skimming Low overall because of limited amount of bitumen that will re-float in this environment Floating bitumen “clumps” are very sticky and viscous, requiring specialized skimmers and pumping systems Trawl nets Effective for containing and recovering weathered bitumen intests. Offloading in significant incidents may be an issue for this recovery technique Smaller mesh nets may be more effective but will increase drag for towing vessels. More testing required Pumping Moving recovered bitumen from skimmers to storage and offloading storage devices will require heavyoil pumping systems and perhaps heating systems Successful tests have been conducted on small amounts of spilled Orimulsion. However, the effectiveness and efficiency of tested devices may differ greatly for large uncontained spills On-water storage Disposable bladders or bags and tanks barges may be used Tank barges and tanks on skimming vessels, should have heating coils installed to facilitate offloading Disposal of recovered weathered bitumen Same as for other crude oil and oil products Shoreside recycling and incineration are probably best options available
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Spills of Emulsified Fuels: Risks and Response name suggests, the deep-skirted containment boom is a normal offshore-type oil spill containment boom with a 9- to 12-foot skirt. However, although responding to locate and recover any floating weathered bitumen is practical and reasonable, the notion that requiring an operation to be mounted with the goal of tracking, refloating, and then recovering a dispersed oil of any type in the open ocean would be unrealistic and unreasonable. The disposal of recovered weathered bitumen poses the same problems as the disposal of other recovered crude oil and oil products that are spilled (Bitor America Corporation, 1999). MARINE NEARSHORE RESPONSE In the nearshore marine environment, the surveillance and monitoring response action (Table 4.2) suggested for the open ocean will be more important because of the increased potential for the bitumen to re-float in sticky clumps. Any re-floated bitumen will provide a threat to wildlife due to the greater number of birds and marine mammals present in the nearshore environment. Furthermore, the potential for re-floated bitumen to come ashore as an oil slick or in the form of sticky tar patties and tar mats is much greater. Because shoreline cleanup is more costly and shoreline impacts increase the potential for natural resource and third-party damages, there should be an increased effort to respond to recover re-floated bitumen as quickly as possible. The containment and recovery of re-floated “clumps” will follow the same strategy and, to a large degree, will use the same equipment available in the openwater marine environment. Response times should be faster for spills in nearshore waters, potentially increasing the effectiveness of on-water containment and recovery operations. If available, the viscous oil recovery equipment developed for Orimulsion may enhance the recovery rate for resurfaced Group V oil (Garcia Tavel et al., 1997). However, in order to make a difference, equipment such as the Tar Hawg, Oriboom, and other devices must be stockpiled in sufficient quantity at locations where the greatest potential for emulsified fuel spills exists (Middleton et al., 1995). Furthermore, local responders need to become familiar with the effective operation of this equipment. While existing equipment resources serving other oil transporters and storage facilities will satisfy the containment and recovery of resurfaced Group V oil requirements under the Oil Pollution Act of 1990 (OPA-90), especially if enhanced with the specially designed equipment for Orimulsion, the concern will be for the special on-water storage requirements necessary for these types of oils. It would seem that the viscosity of this product will mandate that all tank barges and tanks on skimming vessels be heated if off-loading of filled tanks is considered during a continuing on-water response operation. Since there is greater potential for dispersed bitumen to re-float in the coastal zone, dispersants must be considered for this environmental scenario. Limited
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Spills of Emulsified Fuels: Risks and Response TABLE 4.2 Effectiveness of Response Techniques for Spills of Emulsified Fuels in Marine Nearshore Environments Response Technique Effectiveness for Emulsified Fuels Special Issues Monitoring and tracking Same as for open-water marine SMART protocols should be used and augmented with large-volume water sampling systems to analyze dissolved and dispersed bitumen PAH concentrations Dispersant application Product disperses when spilled; dispersant effectiveness on re-floated bitumen will be very low Application of dispersant in an attempt to redisperse re-floated bitumen may be ineffective. More study and field testing are required Mechanical re-floating of dispersed emulsified oil Because of faster response time for deployment of deep-skirted boom, this option may be more feasible than in open-ocean. However, low effectiveness levels would be expected Increased tidal currents and wave energy in nearshore areas may reduce effectiveness Long-skirted containment boom Because of faster response time, this may be more effective in containing bitumen prior to extensive lateral dispersion Recommended booming strategy for containing dispersed bitumen is a free-floating O-type configuration Skimming Faster response time for deep-skirted boom and skimmer deployment, increased potential for natural refloating, increased on-station time for spotter aircraft Same as for open-water marine On-water storage Same as for open-water marine Shoreline protection Same basic strategy as for heavy oils. Expanded use of geotech materials, deep-skirted boom, and other products such as visqueen to cover shorelines prior to impact Ability to carry out exclusion, deflection, and diversion of dispersed bitumen may require further study Shoreline cleanup Same basic strategy as for other heavy oils. Solvents or chemicals may enhance cleanup of some shoreline types Preferred use of salt water in pressure washing to remove bitumen from substrates will increase wear and tear on equipment
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Spills of Emulsified Fuels: Risks and Response Wildlife Same strategy as for other oils Studies required to determine the efficiency and toxicity of preferred cleaning agent Dredging Limited to submerged areas where sunken oil would accumulate Many operational issues in regard to water depth, storage, disposal of recovered oily water and sediments, sea conditions, and currents Diver-directed pumping and vacuum systems Limited to submerged areas where sunken oil would accumulate Visibility, water depth, storage and disposal of recovered oily water and sediments, sea conditions, and currents Disposal Same as for open-ocean studies have indicated that applying dispersant to re-floated bitumen will cause some redispersal (Oil Spill Response Limited, 1989). However, more work would have to be completed to determine if the dispersant application would be efficient and effective. Shoreline protection and cleanup must also be considered in the coastal environment. For the most part, shoreline protection and cleanup of emulsified fuels will be conducted in the same manner as for other oil products (Owens and Sergy, 1999). There may also be a need to protect sensitive areas from shoreline impact if possible. Presumably this can be achieved by using long-skirted booms to exclude the oil from the zone to be protected, diverting it to a less sensitive shoreline for recovery or deflecting it back to open water (Morgan and Fernie, 1995; Owens and Sergy, 1999). Once weathered bitumen is stranded on the shoreline, chemical agents enhance its removal (Guénette et al., 1998). However, further testing, particularly with agents accepted by the U.S. EPA for use in the United States, should be conducted to determine their efficiency in removing stranded bitumen coatings from various shoreline types and to study the fate and effects of the released bitumen. As with other types of heavy oil, mechanized beach cleaners and other types of mechanical or manual recovery equipment are efficient in cleaning up stranded weathered bitumen from certain shorelines (Clement et al., 1997). Dredging or other types of underwater recovery must also be considered as a response option,
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Spills of Emulsified Fuels: Risks and Response because oil-sediment tar mats may be deposited in offshore depressions. Again, these operations will be similar to those used for spills of other types of heavy oil (National Research Council, 1999). Because of the increased potential for contact with wildlife cleaning, of seabirds particularly, will become an issue. Even though a suitable agent has been proposed for cleaning wildlife (Gauvry and Miller, 1995), the effect of weathered Orimulsion on wildlife and the ability to clean contaminated wildlife for return to their habitat remain to be seen. The report by Gauvry and Miller (1995) called for more study to determine the ability of the preferred cleaning agent to remove Orimulsion from birds and other species and to determine the toxicity of the cleaning agent itself to various types of wildlife. ESTUARINE (BRACKISH WATER) RESPONSE Only a small fraction of the spilled emulsified fuel is expected to re-float in an estuarine environment. The response strategies for estuaries will follow very closely those strategies discussed for the open-ocean, because the majority of the bitumen droplets will remain in suspension or sink (Table 4.3). However, because many estuaries in the United States are also major port areas, the response time to spills should be much faster than for spills in the openocean or in coastal zones. Therefore, some of the response techniques discussed for the open-ocean and nearshore environments are appropriate for estuaries as well, and they may be more efficient because of the increased speed of response and access to shoreside support resources. Estuaries do have zones of low flow where suspended particles may settle out, increasing the potential need for dredging or underwater vacuum recovery operations. However, the issue would be whether there is enough accumulation of “oil” to warrant bulk oil removal. Dredging and diver-assisted pumping or other types of underwater recovery operations can be very effective; however, they are also very expensive and require handling of large volumes of potentially contaminated water and sediment. Furthermore, dredging is not a commonly used spill response technique, and the required equipment may not be readily available. NONTIDAL RIVER RESPONSE Because of the fresh water and current conditions in a river, an emulsified fuel spill is expected to remain in suspension and to become more dispersed as it spreads further downstream. Therefore, tracking of the plume will require water column monitoring, either with grab water samples (limited spatial coverage, very slow) or field detectors such as fluorometers. Even where trajectory models are available, they must be validated with field data on the location of the main body of the plume. Without preplanning that
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Spills of Emulsified Fuels: Risks and Response TABLE 4.3 Effectiveness of Response Techniques for Spills of Emulsified Fuels in Estuaries (Brackish Water) Response Technique Effectiveness for Emulsified Fuels Special Issues Monitoring and tracking With so little surface oil, it will be difficult to track the dispersed oil plume using overflights. Water sampling or remote sensing methods will be required, which have significant limitations Gradients in water salinity over space and time, will have significant influence on ability to model the dispersed oil plume Dispersant application Not applicable because so little bitumen is expected to float or refloat Mechanical refloating and FAF of dispersed emulsified oil Even though response times should improve, containing dispersed bitumen in tidal currents while attempting to re-float it will be difficult If suspended plume can be diverted to a quiet backwater, th Long-skirted containment boom Because of tidal currents, even tear-dropped boom drifting with the current may not be able to contain dispersed droplets for recovery. May consider diverting dispersed bitumen plume to quiet water for settling-dredging or re-floating operations Set and drift of vessels supporting re-floating and skimming operations will cause increased entrainment of bitumen from containment boom Skimming Because of improved response times and less area, skimming operations should be as effective for floating emulsified fuels as would be expected for other oils On-water storage Same as open-ocean or nearshore Shoreline protection Due to freshwater influence and less potential for “clumping” there may be less shoreline impact Shoreline cleanup Due to freshwater influence and less potential for “clumping” there may be less shoreline impact Dredging Same as nearshore Diver-directed pumping and vacuum systems Same as nearshore Disposal Same as open-ocean
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Spills of Emulsified Fuels: Risks and Response includes purchase, training, and maintenance of the necessary equipment, the monitoring of emulsified oil in rivers will be very difficult. There are at least 75 hazardous substances currently being transported in bulk on tankers and tank barges throughout the United States that present these same problems when spilled (U.S. Code of Federal Regulations). As discovered during a 1996 survey of resources available for response to releases of bulk hazardous substances transported by water, there may be a shortage of readily available equipment and personnel trained to monitor and sample products that either disperse, dissolve, or sink (Chemical Transportation Advisory Committee, 1996-1997). However, if and when the OPA-90 regulations for hazardous substances are finalized, they may include provisions that require transporters to have the ability to readily provide monitoring and sampling resources and expertise, and this situation will improve. There will be very little opportunity for suspended droplets to re-float in this environment; therefore, there will be little or no opportunity to recover bitumen from the water surface using skimmers (see Table 4.4). The droplets will remain in suspension until the surfactant degrades, so they will be widely distributed before they attach to other suspended matter and sink. Therefore, it is doubtful that there will be sufficient accumulations in depression and behind natural and man-made structures to substantiate a dredging or diver-directed pumping or vacuum system recovery. The most feasible response in this environment will be to deploy exclusion or deflection long-skirted booms or silt fences at water intakes and other sensitive sites downstream. Alternatively, downstream locations where the bitumen droplets might settle out (e.g. low-flow areas, backwater sloughs) and dredging-pumping-vacuum operations might be effective could be identified. If sufficient quantities of dispersed bitumen can be diverted to these quiet areas, then the PNP Re-floater or FAF principle could be considered as a response option. Based on limited experiments, the PNP Re-floater device is about 30 to 60 percent effective in re-floating dispersed bitumen in freshwater environments (Hvidbak and Masciangioli, 2000). Although recovery is lower than for salt water, laboratory testing indicates a good recovery of dispersed re-floated bitumen in fresh water. However, aeration is essential since recovery only occurs at the surface. If the sorbent or polymer material is delivered as part of the aeration process, efficiency may be increased even further (M3 Inc., 1996). FRESHWATER QUIESCENT RESPONSE A discharge of emulsified fuel in a freshwater, quiescent setting, such as a port facility, will offer the best opportunity for containing and recovering the spilled bitumen or oil. A facility that receives routine cargo of emulsified fuel can plan for spill events and provide the necessary equipment needed for containing and recovering it.
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Spills of Emulsified Fuels: Risks and Response TABLE 4.4 Effectiveness of Response Techniques for Spills of Emulsified Fuels in Nontidal Rivers Response Technique Effectiveness for Emulsified Fuels Special Issues Monitoring and tracking Visual techniques will not be effective in most rivers. Most effective would be fluorometers deployed on boats or at one location (e.g., water intake) Real-time river flow data are available to predict spread of the dispersed plume. Would require preplanning for use of water column monitors. May be shortage of readily available sampling equipment and qualified technicians Dispersant application Since emulsified fuels will remain in suspension in fresh water, dispersant will not be considered None Mechanical re-floating of dispersed emulsified oil In most cases, not a viable or efficient option. However, if dispersed bitumen can be diverted to a quiet water area, it may be tried Effectiveness of PNP Re-floater and FAF has to be validated for fresh water Long-skirted booming May consider diversion or exclusion booming to protect water intakes or sensitive areas. Can probably be effective only in slow-current environments Specially designed booms with semi-permeable skirts might be more effective than regular booms Skimming Use only in conjunction with PNP and FAF operations None Sorbents and polymers May be effective, if used with aeration Containment will be an issue using these techniques On-water storage Required for skimming conducted in conjunction with PNP and FAF operations None Shoreline protection Not applicable because no shoreline stranding should occur None Shoreline cleanup Not applicable because no shoreline stranding should occur None Dredging Low effectiveness because of low potential for accumulation of recoverable amounts of bottom oil River currents should keep particles in suspension and enhance spreading Diver-directed pumping and vacuum systems Low effectiveness because of low potential for accumulation of recoverable amounts of bottom oil Low visibility in rivers may make diver operations less effective Disposal Same as open ocean None
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Spills of Emulsified Fuels: Risks and Response Furthermore, although the equipment designed for Group IV and V oils may not be as efficient as specially designed equipment, it will be more available and perhaps more rapidly deployed in this environment. Because many transfer facilities are situated in at least semi-protected areas, it is likely that the berth will be pre-boomed (or can immediately be boomed) with a deep-skirted boom or silt curtain following a spill. In this case, the majority of the bitumen droplets will remain in suspension until they sink to the bottom of the berth or are re-floated. Although the PNP Re-Floater may achieve only 30 percent success in fresh water, a fully contained spill would provide more time to work the dispersed bitumen, and a greater percentage may be obtained (see Table 4.5). A fully contained spill at a shoreside facility would also allow greater opportunity for the use of FAF system technology. It would allow the dispersed plume to be pumped to shoreside tanks where FAF would allow separation, floatation, and recovery. This scenario also provides the best opportunity for carrying out dredging or diver-assisted pumping operations to recover the bitumen droplets that settle on the bottom. Once on the bottom the bitumen will likely remain until recovery can take place. The shallow water depths in a port area will also be conducive to dredging operations. ON LAND NEAR WATER RESPONSE When spilled on land, fresh Orimulsion will behave like a viscous liquid, with the potential for penetration into porous substrates. Response and cleanup methods would be similar to those for conventional heavy oils. As it weathers and becomes sticky, the degree of penetration will decrease, and cleanup will likely involve complete removal of the surface oil and oiled sediments. Even though the risk of groundwater contamination is low, groundwater cleanup methods would be needed for the water-soluble fraction contained in the water component. In this type of spill, the emulsified fuel will remain in suspension when in water. Containment booming using regular containment boom and filter-fencetype material should be possible (see Table 4.6), because of the reduced current and very shallow-water conditions expected in a wetland habitat. Dikes and berms could also be constructed to isolate the spill area from other waterways and reduce migration. Depending on the amount of product spilled, the size of the area impacted, and the sensitivity of the wetland, the area could be isolated and pumped dry for manual or heavy equipment recovery of oil or bitumen from the substrate. The spill site could then be treated by burning or land farming. To ensure that only clean water was discharged downstream the effluent from any pumping operation to a dry out area could be routed through a filter box arrangement, or FAF or a PNP Refloater pumping system could be used to pump out the marsh water. In areas where the land is alternately wet and dry, emulsified fuels,
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Spills of Emulsified Fuels: Risks and Response TABLE 4.5 Effectiveness of Response Techniques for Spills of Emulsified Fuels in Freshwater Quiescent Environments Response Technique Effectiveness for Emulsified Fuels Special Issues Monitoring and tracking Can be relatively effective because the point of exit can be the focus of water column monitoring None Dispersant application Not applicable because none of the oil will float None Mechanical re-floating of dispersed emulsified oil Tests indicate that only 30 percent effectiveness can be achieved in fresh water. However, logistics available in this scenario may make it a viable option None FAF system Shoreside facilities and ability to contain dispersed bitumen plumemake this a viable option for this scenario Oil water treatment facility and/or decanting authority would be necessary Long-skirted containment boom Predeployed deep-skirted boom should be considered for transfer facilities. For emulsified fuel that escapes the encapsulated area, river environment techniques would apply Facility response planning allows for advanced containment strategy and equipment staging Sorbents and polymers Same as rivers Containment should be improved in this environment Storage Should not be limiting because of many shoreside options Facility response planning allows for advanced containment strategy and equipment staging Shoreline protection Limited to areas where re-floating operations take place None Shoreline cleanup Limited to areas where re-floating operations take place None Dredging Oil or bitumen that sinks should be contained in the immediate vicinity of berth and readily recovered None Diver-directed pumping and vacuum systems Oil or bitumen that sinks should be contained in the immediate vicinity of berth and readily recovered Bottom topography can be highly variable, so divers may have to direct recovery to zones of higher accumulation
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Spills of Emulsified Fuels: Risks and Response TABLE 4.6 Effectiveness of Response Techniques for Spills of Emulsified Fuels on Land Near Water Response Technique Effectiveness for Emulsified Fuels Special Issues Monitoring and tracking Can be highly effective since plume is highly visible None Dispersant application Not applicable because none of the oil will float None Mechanical refloating of dispersed emulsified oil Dependent on water depth. May be considered part of any pumping operation intended to increase flow from marsh or to dry area for recovery of product that sinks None Containment boom Regular boom, filter fence, and deep-skirted boom should be considered depending on water depths Access will be an important consideration Berms or dikes Install berm or dike to contain spill within marsh area already impacted Environmental concern regarding impact of stopping flow of water through marsh Skimming Not effective because none of the bitumen is expected to float None Sorbents and polymers Could be moderately effective where plume can be concentrated to flow through a restricted area None Storage May be difficult in areas of limited access None Shoreline protection Minimal shoreline protection strategy required None Excavation or dredging Method dependent on water depth and soil conditions. Removal of contaminated sediments using heavy equipment or manual labor Disposal of large volumes of material Shoreline cleanup Shoreline cleanup will be required on any surface where the product flowed across soil or vegetation and dried. Normal oil shoreline cleanup techniques will apply Access will define type of cleanup technique to large extent
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Spills of Emulsified Fuels: Risks and Response Dredging Same as for estuarine environment. Amount spilled, area impacted, type of marsh environment, and water depth will be critical Access will be critical for defining type of dredging equipment that may be used Diver-directed pumping and vacuum system Same as dredging above None Excavation Pump impacted marsh or wetland area dry, and excavate oil or bitumen that has sunk and accumulated Environmental effect of pumping marsh dry In situ burning Pump impacted marsh or wetland area dry, and burn oil or bitumen that has sunk and accumulated Burning agent will have to be used to support in situ burn of bitumen. Environmental effect of pumping marsh dry Land farming or bioremediation Pump impacted marsh or wetland area dry, and land-farm or fertilize to enhance biodegradation Environmental effect of pumping marsh dry and bitumen in particular, are less likely to leach into the substrate than other heavy oils (Wood, 1996). SUMMARY Because emulsified fuels are essentially predispersed, the most likely response actions will be monitoring of the dispersed plume and recovery of any refloated bitumen. Recovery efforts are likely to be even lower than for traditional spills because so little of the oil is expected to re-float. Therefore, as for all types of spills, the most effective strategy, is prevention. Many of the proposed strategies for responding to spills of emulsified fuels are likely to have low initial effectiveness for the following reasons: They have not been tested under realistic conditions. The equipment may not be readily available at all necessary locations. Responders are not familiar with the equipment and strategies available for emulsified fuel spills
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Spills of Emulsified Fuels: Risks and Response There have not been spills where the proposed strategies could be tested and made more effective under field conditions. For example, mechanical re-floating of dispersed bitumen has been demonstrated in small intentional spill scenarios and is suggested as a practical response to a spill of emulsified fuel. However, only actual experience will determine if it is practical to re-float any type of dispersed oil and, if required, to determine whether the methodologies being suggested are logistical and practical for likely spill scenarios. Another proposed strategy is diversion or deflection of a dispersed plume using deepskirted booms; field tests should be conducted to validate this strategy and determine the physical and environmental limitations. Tests with trawl-type nets for containing and recovering floating weathered bitumen indicate that smaller-mesh nets might make the systems more effective. Further tests are needed to determine if towing smaller-mesh nets is practical. Realistic field tests1 and refinement of the more innovative methods for containment and recovery of emulsified fuels are required before these methods can be part of realistic response plans. 1 Environmental restrictions on the release of possibly toxic substances may contstrain certain types of field tests.
Representative terms from entire chapter: