We used a variety of oil spill response techniques to try to prevent oil from reaching the shore, including skimmers, controlled in situ burning, and dispersants
In efforts to prevent the oil from reaching shore, we used large-scale offshore skimmers and shallow water equipment to skim the oil from the surface of the water. Where weather, sea conditions, distance from shore and other conditions made it safe and appropriate, the Unified Command also conducted controlled in situ burning of oil. According to the Unified Command, between 220,000 and 310,000 barrels of oil were destroyed through controlled burnings and use of fire boom.
Dispersants were one of the tools used to reduce the amount of oil reaching the Gulf shoreline. Dispersants act like dishwashing detergent, breaking up oil into smaller droplets that are more easily dispersed and can be consumed more quickly by microbes. The dispersants used in the Deepwater Horizon response degrade naturally in the environment.
The dispersants used in the Gulf were, and still are, on the National Contingency Plan Product Schedule, which is a list of dispersants pre-approved by the Environmental Protection Agency (EPA) for use in oil spill response efforts. Use of these dispersants during the Deepwater Horizon oil spill response was coordinated with and approved by federal agencies including the US Coast Guard and EPA. Approximately 1.84 million gallons of dispersant were applied altogether. With one exception in the case of an emergency, no dispersants were applied closer than three nautical miles offshore and 98% of the aerial dispersant applications occurred more than 10 nautical miles offshore. And, with the exception of five gallons that were applied on 4 September 2010 within the moon-pool of a recovery vessel that brought the capping stack to the surface of the Gulf of Mexico, no dispersants were used for the response after 19 July 2010.
Dispersants and seafood
To address concerns about the potential effect of oil and dispersants on seafood, in June 2010, the National Oceanic Atmospheric Administration (NOAA) and the US Food and Drug Administration (FDA), in consultation with the EPA and the Gulf states agreed to an extensive sampling and testing procedure. Areas once closed to fishing were reopened only when all seafood sampled in the area passed both the established sensory and chemical testing. While initial testing was focused on oil contaminants, in October 2010, the FDA and NOAA created a new test that could detect traces of dispersant constituents in fish tissue. To date, none of the seafood tested by the FDA, NOAA and the Gulf states has exceeded the FDA’s human health thresholds.