Estimating the potential size and impact of an oil spill is crucial for several reasons such as Emergency Response Planning, Risk Assessment, Environment Protection, Public Safety & Health, and Resource Allocation.
A rough estimate of spill volume can be generated from observation of the oil slick’s size and thickness (1st figure) and the appearance, and light condition (2nd figure).


Example
Estimate the area impact of oil 100-gallon leakage from the offshore platform to the sea surface and spreading with dull colors.

Since the oil slick thickness is unknown, the area covered after 24 hours is between 0.0004 to 0.8 sq. miles. The more conservative area that needs to be investigated shall be as big as possible.

From the table, interpolate 2,500,000 + (100-61.7)*2,500,000/(123.4-61.7) = 4,051,863 sq. ft. or 0.145 sq. miles.