On February 6, 1986, the barge St. Thomas struck a submerged piling in Crown Bay, St. Thomas, U.S. Virgin Islands. It is estimated that up to 70,000 gallons of an intermediate fuel oil were spilled from both this initial incident and a secondary spill which occurred the following day in Charlotte Amalie Harbor. The spilled oil threatened the island's primary source of drinking water: the desalination plant. St. Thomas' only alternative source of fresh water is rain water collected in cisterns. Due to its limited supply, potable drinking water is a precious commodity in the Caribbean Islands, and protection of the desalination plant became a crucial part of the spill response.

When officials in charge of the desalination plant believed that oil had entered the plant's intakes, they shut down the desalination plant. Residents were warned by local officials not to drink the water to avoid serious health effects. The island's hospital feared their water supply had become contaminated and began using emergency bottled water. The Commissioner of Public Works reported that the island had less than four days of water remaining in storage.

This paper discusses how the contaminated drinking water problem was resolved. Details are provided about the sampling methods and chemical analysis used in determining the water quality. Possible effects of oil on the two most common types of desalination plants are addressed. Monitoring and protection techniques are suggested for these desalination plants. Finally, a checklist is provided for oil spills which threaten desalination plants.

This content is only available as a PDF.