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During emergency response operations, available information may be highly uncertain and fragmented at best, as will forecasts of environmental conditions or evaluations of response equipment needs. Nonetheless, the response community must sort out what is actually known about the spill, and select and deploy equipment as soon and as effectively as possible.
Because the goal of oil spill response is to minimize the overall impacts on natural and economic resources, some resources will be of greater concern than others; and response options offering different degrees of resource protection will be selected accordingly. Decisions regarding cleanup method(s) must balance two factors:
the potential environmental impacts with the no-action alternative, and
the potential environmental impacts associated with a response method or group of methods.
Potential impacts can be determined before considering the need for, or type of, response strategies. For example, evaluating a gasoline spill in an exposed seawall environment might lead to the conclusion that, due to evaporation and low habitat use, minimal environmental effects will occur and further evaluation is unwarranted. On the other hand, assessing a spill of a middle-weight crude oil in a soft intertidal area would likely indicate a high potential for environmental effects; therefore, response methods would need to be evaluated.
The decisions to select response methods should consider the potential of each possible method for reducing the environmental consequences of the spill and the response (including a natural recovery alternative). The method, or combination of methods, that most reduces consequences effectively, should be the preferred response strategy. A method that increases impacts in the short term can be the preferred alternative if it speeds up recovery. (Recovery cannot be defined as pre-spill conditions since natural changes in biological communities will introduce variability to organisms affected by the spill.)
The environmental consequences of a spill and the response will depend on the specific spill conditions, such as the type and amount of oil, weather conditions, habitat where the spill occurred, and effectiveness of the response methods. It is imperative that planners and responders discuss and develop resource protection priorities during contingency planning so that valuable time is not lost during an actual response.
Objective: No attempt to remove any stranded oil either to minimize impacts to the environment or because there is no effective method for cleanup. Oil is left in place to degrade naturally.
Description: No action is taken, although monitoring of contaminated areas may be required.
Applicable Habitat Types: All habitat types.
When to Use: When natural removal rates are fast (e.g., gasoline evaporation, high-energy coastlines), when the degree of oiling is light, or when cleanup actions will do more harm than natural removal.
Biological Constraints: This method may be inappropriate for areas used by high numbers of mobile animals (birds, marine mammals) or endangered species.
Environmental Effects: Same as from the oil alone.
Waste Generation: None.
Objective: To prevent oil from contacting resources at risk, and to facilitate oil removal.
Description: A boom specially designed for pollution response is a floating, physical barrier, placed on the water to contain, divert, deflect, or exclude oil. Containment is deploying a boom to contain and concentrate the oil until it can be removed. Deflection is moving oil away from sensitive areas. Diversion is moving oil toward recovery sites that have slower flow, better access, etc. Exclusion is placing boom to prevent oil from reaching sensitive areas. Booms must be properly deployed and maintained, including removing accumulated debris.
Applicable Habitat Types: Can be used on all water environments (weather permitting). Booms begin to fail by entrainment when the effective current or towing speed exceeds 0.7 knots perpendicular to the boom. Waves, wind, debris, and ice contribute to boom failure.
When to Use: When preventing oil from contacting sensitive resources is important. Most responses to spills on water involve deploying boom to help remove floating oil. Containment booming of gasoline spills is usually not attempted, because of fire, explosion, and inhalation hazards. However, when public health is at risk, gasoline can be boomed if foam is applied and extreme safety procedures are used.
Biological Constraints: Placing and maintaining boom and anchoring points should not cause excessive physical disruption to the environment, and both must be maintained so they do not fail nor tangle and cause more damage. Vehicle and foot traffic to and from boom sites should not disturb wildlife unreasonably, and booms in very shallow water should be monitored so they do not trap wildlife (such as migrating turtles returning to sea or fish coming in at high tide).
Environmental Effects: Minimal, if disturbance during deployment and maintenance is controlled.
Waste Generation: Cleaning booms will generate contaminated wastewater that must be collected, treated, and disposed of appropriately. Discarded booms will need to be disposed of according to appropriate waste disposal regulations.
Click on the links for more information on Dawg Oil Absorbent Booms that will skim and absorb oil from streams, settling ponds and other waterways.
Our selection of Oil Containment Booms are ideal for a variety of applications, such as; Simplex Boom for marinas and inland waterways, Optimax Containment Boom for rough waters in streams and oceans, inflatable Air Max Boom is easy to deploy and retrieve quickly, Swamp Boom is ideal for calm waters, MiniMax Containment Boom for inner harbor use, and the Silt Max Boom for turbidity control in protected waterways.
Objective: To prevent entry of oil into a sensitive area or to divert oil to a collection area.
Description: A physical barrier (other than a boom) is placed across an area to prevent oil from passing. Barriers can consist of earthen berms, trenching, or filter fences. When it is necessary for water to pass because of water volume, underflow or overflow dams are used.
Applicable Habitat Types: At the mouths of creeks or streams to prevent oil from entering, or to prevent oil in the creek from being released into offshore waters. Also, on beaches where a berm can be built above the high-tide line to prevent oil from overwashing the beach and entering a sensitive back-beach habitat (e.g., lagoon).
When to Use: When the oil threatens sensitive habitats and other barrier options are not feasible.
Biological Constraints: Responders must minimize disturbance to bird nesting areas, beaver dams, or other sensitive areas. Placement of dams and filter fences could cause excessive physical disruptions, particularly in wetlands.
Environmental Effects: May disrupt or contaminate sediments and adjacent vegetation. The natural beach (or shore) profile should be restored (may take weeks to months on gravel beaches). Trenching may enhance oil penetration and quantity of contaminated sediments.
Waste Generation: Sediment barriers will become contaminated on the oil side and filter fence materials will have to be disposed of as oily wastes.
A silt fence can be used to prevent erosion and keep sediment out of drains and waterways. EcoBlok is reusable, lasts for years, is made of 100% recycled tires, interlocks for increased support, minimizes erosion and acts as an alternative to messy sandbags. Use our EcoBag also as a replacement for sandbags, for reusable erosion resistance.
Spill Berm with Connectors allow you to connect two or more berms to custom fit large spill areas.
Objective: To recover floating oil from the water surface using mechanized equipment. This includes specifically designed pollution equipment called skimmers, and other mechanical equipment such as draglines and dredges.
Description: There are numerous types of skimming devices, described in the annually published World Catalog of Oil Spill Response Products (Schulze 1998): weir, centrifugal, submersion plane, and oleophilic. They are placed at the oil/water interface to recover, or skim, oil from the waters surface and may be operated independently from shore, be mounted on vessels, or be completely self-propelled. Because large amounts of water are often simultaneously collected (incidental to skimmer operation) and treated, efficient operations require that floating oil be concentrated at the skimmer head, usually using booms. Adequate storage of recovered oil/water mixtures must be available, as must suitable transfer capability. Skimmers are often placed where oil naturally accumulates in pockets, pools, or eddies.
Applicable Habitat Types: Can be used on all water environments (weather and visibility permitting). Waves, currents, debris, seaweed, kelp, ice, and viscous oils will reduce skimmer efficiency.
When to Use: When sufficient amounts of floating oil can be accessed. Skimming spilled gasoline is usually not feasible because of fire, explosion, and inhalation hazards to responders. However, when public health is at risk, gasoline can be skimmed if foam is applied and extreme safety procedures used.
Biological Constraints: Vehicle and foot traffic to and from skimming sites should not disturb wildlife unreasonably.
Environmental Effects: Minimal if surface disturbance by cleanup work force traffic is controlled.
Waste Generation: Free-floating oil can be recycled. Emulsions formed during the process must be treated (broken) before recycling. Oil-contaminated waste from the treatment phase should be treated as wastewater.
Use Dawg Oil Skimmer Socks for selectively removing oil, not water from sumps, bilges and tanks. Dawg Oil Skimmer Pillows are used to absorb heavy oil spills on water and Dawg Oil Sweeps allow you to quickly and easily sweep and absorb broad sheens or surface spills on water.
Objective: To reduce impact to sensitive shoreline habitats and animals that use the water surface by chemically dispersing oil into the water column.
Description: Dispersants reduce the oil/water interfacial tension, thereby decreasing the energy needed for the slick to break into small particles and mix into the water column. Specially formulated products containing surface-active agents are sprayed (at concentrations of 1-5 percent by volume of the oil) from aircraft or boats onto the slicks. Some agitation is needed to achieve dispersion.
Applicable Habitat Types: Water bodies with sufficient depth and volume for mixing and dilution.
When to Use: When the impact of the floating oil has been determined to be greater than the impact of dispersed oil on the water-column community.
Biological Constraints: Use in shallow water could affect benthic resources. Consideration should be made to avoid directly spraying any wildlife, especially birds or fur-bearing marine mammals.
Environmental Effects: Until sufficiently diluted, the dispersed oil can adversely impact organisms in the upper 30 feet (10 meters) of the water column. Because dispersion may be only partially effective, some water-surface and shoreline impacts could occur
Waste Generation: None.
Objective: To change the physical state of spilled oil from a liquid to a solid.
Description: Chemical agents (polymers) are applied to oil at rates of 10-45 percent or more, solidifying the oil in minutes to hours. Various broadcast systems, such as leaf blowers, water cannons, or fire suppression systems, can be modified to apply the product over large areas. Can be applied to both floating and stranded oil. Can be placed in sorbent booms and used like sorbents.
Applicable Habitat Types: All water environments, bedrock, sediments, and artificial structures.
When to Use: To immobilize the oil or prevent refloating from a shoreline, penetration into the substrate, or further spreading. However, the oil may not fully solidify unless the product is well mixed with the oil, and may result in a mix of solid and untreated oil. Generally not used on heavy oil spills that are already viscous.
Biological Constraints: Must be able to recover all treated material.
Environmental Effects: Products are insoluble and have very low aquatic toxicity. Unrecovered solidified oil may have longer impact because of slow weathering rates. Physical disturbance of habitat is likely during application and recovery.
Waste Generation: If skimming efficiency is increased, solidifiers may reduce the volume of water collected during oil recovery. Oil treated with solidifiers is typically disposed of in landfills.
Objective: To break up oily sediments and surface oil deposits, increasing their surface area, and mixing deeper subsurface oil layers, thus enhancing the rate of degradation through aeration.
Description: The oiled sediments are roto-tilled, disked, or otherwise mixed using mechanical equipment or manual tools. Along beaches, oiled sediments may also be pushed to the waters edge to enhance natural cleanup by wave activity (surf washing). The process may be aided with high-volume flushing of gravel.
Applicable Habitat Types: On any sedimentary substrate that can support mechanical equipment or foot traffic and hand tilling.
When to Use: On sand to gravel beaches with subsurface oil, where sediment removal is not feasible (due to erosion or disposal problems). On sand beaches where the sediment is stained or lightly oiled. Appropriate for sites where the oil is stranded above the normal high waterline.
Biological Constraints: Avoid use on shores near sensitive wildlife habitats, such as fish-spawning areas or bird-nesting or concentration areas because of the potential for release of oil and oiled sediments into adjacent bodies of water. Should not be used in clam beds.
Environmental Effects: Due to the mixing of oil into sediments, this method could further expose organisms that live below the original layer of oil. Repeated reworking could delay re-establishing of these organisms. Refloated oil from treated sites could contaminate adjacent areas.
Waste Generation: None.
Objective: To remove oil pooled on a shoreline substrate or subtidal sediments.
Description: A vacuum unit is attached via a flexible hose to a suction head that recovers free oil. The equipment can range from small, portable units that fill individual 55-gallon drums to large supersuckers that are truck- or vessel-mounted and can generate enough suction to lift large rocks. Removal rates from substrates can be extremely slow.
Applicable Habitat Types: Any accessible habitat type. May be mounted on vessels for water-based operations, on trucks driven to the recovery area, or hand-carried to remote sites.
When to Use: When oil is stranded on the substrate, pooled against a shoreline, concentrated in trenches, or trapped in vegetation. Usually requires shoreline access points.
Biological Constraints: Special restrictions should be established for areas where foot traffic and equipment operation may be damaging, such as soft substrates. Operations in wetlands must be very closely monitored, and a site-specific list of procedures and restrictions developed to prevent damage to vegetation.
Environmental Effects: Minimal, if foot and vehicular traffic are controlled and minimal substrate is damaged or removed.
Waste Generation: Collected oil and or oil/water mix will need to be stored temporarily before recycling or disposal. Oil may be recyclable; if not, it will require disposal in accordance with local regulations. Large amounts of water are often recovered, requiring separation and treatment.
Objective: To increase the efficiency of oil removal from contaminated substrates.
Description: Special formulations are applied to the substrate, as a presoak and/or flushing solution, to soften or lift weathered or heavy oils from the substrate to enhance flushing methods. The intent is to lower the water temperature and pressure required to mobilize the oil from the substrate during flushing. Some agents will disperse the oil as it is washed off the beach, others will not.
Applicable Habitat Types: On any habitat where water flooding and flushing procedures are applicable.
When to Use: When the oil has weathered to the point where it cannot be removed using ambient water temperatures and low pressures. This approach may be most applicable where flushing effectiveness decreases as the oil weathers.
Biological Constraints: When the product does not disperse the oil into the water column, the released oil must be recovered from the water surface. Use may be restricted where suspended sediment concentrations are high, near wetlands, and near sensitive nearshore resources.
Environmental Effects: The toxicity and effects on dispersability of treated oil vary widely among products. Selec-tion of a product should consider its toxicity.
Waste Generation: Because treated oil must be recovered, waste generation is a function of recovery method, which often includes sorbents.