Spill Response
Strategies For Oil Spill Cleanup
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.
What information is needed to help guide the response? What can be done
to promote any gains in environmental protection?
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:
1) the potential environmental impacts with the no-action alternative,
and 2) 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.
Natural Recovery
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.
Sorbents
Objective: To remove surface oil by using oleophilic
(oil-attracting) material placed in water or at the waterline.
Description: Sorbent material is placed on the floating
oil or water surface, allowing it to sorb oil, or is used to wipe or
dab stranded oil. Forms include sausage boom, pads, rolls, sweeps, snares,
and loose granules or particles. These products can be synthetically
produced or be natural substances. Efficacy depends on the capacity
of the particular sorbent, wave or tidal energy available for lifting
the oil off the substrate, and oil type and stickiness. All sorbent
material must be recovered. Loose particulate sorbents must be contained
in a mesh or other material.
Applicable Habitat Types: Can be used on any habitat
or environment type.
When to Use: When oil is free-floating close to shore
or stranded on shore. The oil must be able to be released from the substrate
and sorbed by the sorbent. As a secondary treatment method after gross
oil removal, and in sensitive areas where access is restricted. Selection
of sorbent varies by oil type: heavy oils only coat surfaces, requiring
use of sorbents with high surface areas to be effective (adsorbents);
lighter oils can penetrate sorbent material (absorbents).
Biological Constraints: Access for deploying and retrieving
sorbents should not adversely affect wildlife or be through soft or
sensitive habitats. Sorbents should not be used in a fashion that would
endanger or trap wildlife. Sorbents left in place too long can break
apart and present an ingestion hazard to wildlife.
Environmental Effects: Physical disturbance of habitat
during deployment and retrieval. Improperly deployed or tended sorbent
material can crush or smother sensitive organisms.
Waste Generation: Sorbents must eventually be collected
for proper disposal so care should be taken to select and use sorbents
properly, and prevent overuse and generation of large amounts of lightly
oiled sorbents. Because large amounts of waste may be generated, recycling
should be emphasized rather than disposal.
Use Dawg® Oil-Only
pads and rolls for petroleum spills on water and land.
Booms
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.
Barriers/Spill Berms
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.
Use our Silt
Fence to prevent erosion and keep sediment out of drains and waterways.
Storm
Wattles are an alternative to Silt Fence to minimize erosion and
stormwater runoff.
Install GullyGuard
across ditches and gulles where runoff is channeled. Trench
Filters reduce oil and sediment flowing through trench drains and
pipes.
Spill
Berm with Connectors allow you to connect two or more berms to custom
fit large spill areas.
Skimming
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 water’s 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.
Dispersants
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.
Solidifiers
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.
Aqueous
Polymer absorbs 300 times it's own weight in water based liquids.
Fuel
Solidifier encapsulates and solidifies hydrocarbon spills.
Sediment Reworking/Tilling
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 water’s 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.
Vacuum
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.
Shoreline Cleaning Agents (Surface Washing
Agents)
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.
