Step 1 - Answers

Here's how the Dispersant Mission Planner should look, once you've entered all information and clicked Calculate:

Graphic: Program window snapshot

Answers

  1. How long will it take you to treat the entire slick with dispersant? This is the Total Time, 4.2 hours.
  2. What percentage of the total time will be spent spraying dispersant? This is the time spent spraying dispersant (Spray), divided by the Total Time (spent spraying, transiting, resupplying, repositioning, and so on), multiplied by 100%: (0.5 hours / 4.2 hours) * 100% = 12%
  3. How much dispersant will you need to treat the entire slick? Since DOR, the dispersant-to-oil ratio, is 1:20 for this scenario, you must apply 1 bbl of dispersant to every 20 bbl of oil in the slick. The total volume of oil in the slick is estimated to be about 1,000 bbl, so your answer is 1000 bbl / 20 = 50 bbl.
  4. What difference would it make if the transit distance was only half as far (i.e., 10 km)? To answer this question, just type in a new Transit Distance of 10 kilometers, then click Calculate (leave all other aspects of the scenario unchanged). You'll find that it would take 2.8 hours to treat the slick (Total Time), with about 18% of the time spent spraying dispersant ([Spray / Total Time] * 100%), and 100% - 18% = 82% of the time spent in transit, turning/repositioning, and resupply.
  5. Is applying dispersant a realistic option, given the time you have available? You have an estimated 10 hours before the slick is predicted to reach the sensitive site. Since treating the slick is estimated to take just 4.2 hours, applying dispersant is a realistic option, as long as

Compared with other application platforms, the Bell 212 helicopter has a relatively small cargo capacity and relatively narrow swath width (width of the area covered by dispersant during a pass). If you had available an aircraft with more capacity and a wider swath width, such as a C130, you would be able to apply dispersant to this entire slick sooner, using fewer sorties. To see this difference, try repeating this exercise using the C130 as your application platform.

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Revised: April 16, 2001
Office of Response and Restoration, National Ocean Service, National Oceanic and Atmospheric Administration