Chemical Dispersant Exercise¶
Incident¶
At 0700 on April 4th, 2017, a collision occurred between a shrimp boat and a freighter about 30 miles southeast of Galveston, Texas at 28° 55.9’N, 94° 21.5’W. Initial reports indicate 315 bbls of IFO 180 were lost. The National Weather Service marine forecast indicates that the winds will be from the southwest at 15 knots for the next 36 hours.
Approval has been given for the application of dispersants. Corexit 9500 has been loaded onto a DC-4, and the aircraft is on standby in Houma, Louisiana. Unfortunately, the aircraft has a mechanical problem with the dispersant equipment. The contractor indicates that they will be able to disperse the next day.
Commander Jones would like to know if the oil will emulsify to the extent that dispersants will not work.
Model Input¶
Begin on the home page by clicking “Oil Fate Wizard” under “Weathering Only”. Or, from the Setup View, click the “New” menu and select “Oil Fate Wizard”.
Scenario Settings¶
Click Scenario Settings
Give the incident a name
Set the start time: 0700 on April 4th, 2017
Set the model duration to 2 days
Click Save
Oil:¶
IFO 180.
Click Oil to open the ADIOS Oil Database
There are multiple ways to find an IFO-180 in the database. Here are a few options:
type “IFO” in the search box
type “180” in the search box
select Residual Fuel Oil in the “Type” selection
You probably want to select the oil with the highest score unless you know it’s a more specific oil.
Click the oil name to show you the details of the oil.
Click “Download” to select the oil to use in GNOME.
Spill:¶
Instantaneous release of 315 bbls.
Click “Spill” to set the spill properties
Select “Instantaneous Release”
Set Amount Released to 315
Make sure the units are set to “bbl”
Load the oil file that you downloaded from the ADIOS Oil Database
Click Save
Water:¶
Water temperature has significant effects on evaporation rates.
Ideally, you would find a field data value for water temp in the region, perhaps from the NDBC web site (for the US):
http://www.ndbc.noaa.gov/
As of April 4, 2017, the water temp south of Mobile is 75.6 F (station 42012).
Or use an approximation for the season
Click Water
Enter 75.6 and choose F from the popup menu.
Select 32 psu (avg. oceanic) from the Salinity popup menu
Select 5 mg/l (ocean) from the Water Sediment Load popup menu
Leave Wave Height at “Compute from Wind (Unlimited Fetch)”
Wind:¶
Winds will be from the southwest at 15 knots for the next 36 hours
Click Wind
Select the Constant Wind Tab
Set the direction to “SW”
Set the speed to 15 knots
Click Save
Run the model¶
Click “Solve”
Discussion¶
Commander Jones would like to know if the oil will emulsify to the extent that dispersants will not work.
IFO-180’s do not normally emulsify, however, the oil may weather and become very viscous so that dispersants may be less effective. You can address this issue by using the Oil Viscosity Graph.
Click the Weathering tab to see the oil properties graphs.
Click the Viscosity tab to see how the viscosity of the oil is changing with time.
Notice that after about 8 hours, dispersability is restricted. The effectiveness of dispersants will be questionable. Ask your SSC for further guidance.