Dispersants and InSitu Burning A Brief Overview

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Dispersants and In-Situ BurningA Brief Overview
ED Levine NOAA Scientific Support Coordinator
RRT Two October 2008
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Dispersants

• Dispersants are specially designed chemicals
• Break oil into small droplets so it is dispersed
  into the water column.
• Dispersants do NOT change the physical
  characteristics of the oil. (if the oil floated
  before the application, it will float after the
  application)
• Eliminate/reduce surface oil.
• Enhance degradation of dispersed oil (physical
  and biological).
• Low toxicity. Toxic effects are a result of the
  oils toxicity, not the dispersant.

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Dispersant Mechanism

• Dispersable slick

Surfactant reduces interfacial tension, and
micelles of oil break off
Dispersant applied, surfactants penetrate slick
and align at oil/water interface
Mechanical energy limits recoalescence and
dilutes increased concentration of dispersed oil.
Increased surface area enhanced weathering and
biodegradation
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3 Dimensional Mixing
Convergences
Langmuir circulation
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3 Dimensional Mixing
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Dispersant effectiveness

• Effectiveness
• Effectiveness drops with oil weathering, and is
  also dependent on the oil and dispersant
• Spilled oil generally considered dispersable for
  one to several days
• Heavy crude oils and fuel oils (Bunker C) are
  less amenable to dispersal
• Different dispersants will have different
  effectiveness
• No lab test will determine field effectiveness,
  only provide relative results
• As with other methods, not 100 effective

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Dispersant- Lab Tests

• Heavy crude oils ----------------------------1
• Medium crude oils --------------------------10
• Light crude oils ------------------------------30
  
• Very light crude oils ------------------------90
  
• Weathered crude oils -- always lower than fresh

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Application Systems

• Dispersants must be applied at the right dosage
  (120 ratio, or 5 gal/acre) and right droplet
  size
• Large Aircraft
• C-130 with modular system
• DC-3/4 with dedicated system
• Air Force spray planes available to OSC on
  not-to-compete basis
• Small Aircraft
• Crop dusters (many cannot deliver right
  amount/drop size)
• Helicopter with application bucket
• Vessel
• Fire monitor
• Spray booms

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Large application systems

• Large spray aircraft are able to treat large
  slick areas in short periods of time, and can
  carry between 2,000 5,000 gallons of dispersant
  to treat about 100,000 gallons of oil)

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Dispersant Application
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Slick Breaking Up
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Boat Spraying System
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Toxicity Issues

• Pulse vs Short Term
• Even in large deployments, oil-dispersant
  combination is below the LC50 within hours, in
  less than a kilometer of application
• Dispersant companies and regulatory agencies are
  beginning to gather quantitative toxicological
  data on this issue

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Environmental Issues

• Tradeoffs
• Dispersed oil will have toxic effects on the
  water column and inhabitants
• These effects must be weighed against the effects
  eliminated by dispersal. Choose least harmful
  alternative!
• Typical restrictions / requirements
• Water depth - dispersants less controversial in
  areas where dispersed oil unlikely to reach
  bottom (gt10m)
• Special Consideration Areas - Areas of particular
  concern where use is limited
• Monitoring - for effectiveness, and possibly
  effects
• Concern about the unknown and perception

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Pros of dispersant use

• High areal coverage rates
• May compliment, not necessarily replace, other
  techniques to maximize removal
• Weather conditions not as restrictive as for
  mechanical and in-situ burning
• Environmental impacts may be reduced by trading
  long-term impacts for shorter-term water column
  impacts

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Cons of dispersant use

• Controversial decision
• Either decision will be debated
• Quantification of effectiveness and effects
  difficult
• Generally not useable (approved) in shallow
  waters, so as to minimize benthic impacts
• Current capability and expertise may be limiting
  factor
• Short window of opportunity

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Monitoring Programs

• S.M.A.R.T.
• Special Monitoring of Applied Response
  Technologies

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Smart Basics
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Tier II SMART Data HIPS
Note the patchy nature of a dispersed oil plume.
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Dispersant Approval

• Case-by-case decisions require
• Approval of
• Federal On-Scene Coordinator
• State On-Scene Coordinator
• EPA Regional Response Team (RRT) co-chair
• Consultation with Natural Resource Trusteesfrom
  DOI and NOAA

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Special Consideration Areas
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Special Consideration Areas
0.5 - 2 miles
Concurrence with DOI (1 hour deadline from
contact)
2 miles of DOI Managed islands Beyond 0.5 miles

• Concurrence with DOI
• May 15 - August 15
• January 1 - March 31

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Dispersant MOU approval areas in USCG
D1(additional conditions apply)
Maine
Maine and New Hampshire Area Committee FOSC and
State decision outside 0.5 nm
VT
N.H.
Massachusetts and Rhode Island Area
Committees FOSC decision outside 2nm and gt40
feet depth
Mass.
New York
R.I.
Conn.
Region II (NY/NJ) Offshore Areas FOSC decision
outside 3nm, trial application (110 gal) outside
0.5 nm and in Port of NY/NJ
N.J.
Long Island Sound will be separately addressed
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In Situ Burning of Spilled Oil
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In-Situ Burning
N.O.B.E. (Newfoundland Oil Burning Experiment)
New Carissa, Coos Bay, OR (1999)
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In Situ Burning Mechanism

• Burnable slick is concentrated in fire boom to
  5mm or greater (thickness necessary for
  vaporization to sustain burn)

Ignition is accomplished by helitorch or
hand-held igniters
Remaining residue (about 10 by volume) is
collected manually
Smoke plume is monitored visually and using
portable real-time particulate monitors
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Pros and Cons of ISB use

• Advantages
• Rapid oil removal
• Reduction of shoreline or other impacts
• Minimal equipment or labor necessary
• Easily controlled if oil thickness maintained by
  containment
• Disposal is reduced
• Disadvantages
• Large amount of highly visible smoke
• Safety concerns at burn location
• Concerns regarding public exposure to smoke
• Burn residue may sink if not collected
• Concerns regarding environmental impacts of smoke
  and at surface under burn

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Small In-Situ Burns
Minimum Oil Thickness 2 millimeters
Water Heat Transfer about 2 inches
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Coastal Burning(freshwater wetlands, Brunswick,
Maine)
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Katrina Oil SpillsChevron Site
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Katrina Oil SpillsChevron Site
Apr 20, 2006 6 months post-burn
Oiled/Burned
Unoiled/Unburned
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Stability Class A B Winds lt 5 knots
Wind
1 Mile
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Stability Class C Winds 5 - 15 knots
Wind
One Mile
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Stability Class D Winds gt15 knots
Wind
One Mile
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SMART In-Situ Burning
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New Carissa, Coos Bay, OR (1999)
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Mobile Bay 1998
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Actual Monitoring Data
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ISB Pre-Authorization ZonesNew England

• Zone A 6 miles from the coast
• OSC Approval Only
• Zone B 1 - 6 miles from the coast
• Unified Command
• Zone C 0 - 1 mile from the coast
• Full NCP subpart J concurrence
• Federal (USCG EPA)
• Potentially impacted states
• Trustees (consultation)

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In-situ Burning MOU areas in USCG D1(additional
conditions apply)
Maine
Region I, except Long Island Sound FOSC decision
beyond 6 mi FOSC/SOSC decision 1-6
mi Case-by-case elsewhere and in Special
Consideration Areas
VT
N.H.
Mass.
New York
R.I.
Conn.
Region II (NY/NJ) Offshore Areas FOSC decision
outside 6nm (or outside 3nm with offshore winds),
FOSC/SOSC between 3nm and 6nm with any wind.
N.J.
Long Island Sound will be separately addressed
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Discussion Action Items?