The PORTS-based hazardous spill trajectory modeling concept was (unfortunately) tested on August 10, 1993, when a collision occurred at 0600 hours in Tampa Bay between two inbound fuel barges and an outbound phosphate freighter. One of the barges leaked No. 6 fuel oil into the water, eventually spilling approximately 300,000 gallons. Using a simple vector analysis routine and the PORTS wind and current data, a trajectory for the spill was calculated using wind direction as a cardinal direction, wind speed in knots, current direction in degrees true, and current speed in meters per second. At each hour, speed and direction for the oil movement were computed based on these data using a generic Minerals Management Service algorithm. Movement of the oil spill over the next hour at this speed and direction were entered on an electronic chart to locate the next point on the trajectory. This resulted in a rudimentary trajectory prediction in 1-hr increments (a progressive vector diagram).

Despite the limitations of the model, the simple trajectory calculation based on real-time wind and current observations proved adequate for predicting the movement of the spill in Tampa Bay over short (6-8 hr) time periods. The two oil spill maps indicate the modeled trajectory for 0600-1200 EDT and 1600-2000 EDT on August 10, 1993. The prevailing winds (from the S-SE; up to 23 knots) combined with slack water conditions indicated that oil located near the Sunshine Skyway Bridge would be driven northwest by winds towards the shallow seagrass beds and mangrove islands. This predicted trajectory was verified by both aerial and vessel surveys as well as by the distribution of No. 6 fuel oil in sediment samples taken September 1, 1993 from the seagrass beds and mangrove islands.

[PORTS at USF]--[OMPL]--[Tampa Bay Sites]