As political rivals battled at the polls Tuesday, the Hovensa oil refinery announced it finished testing and cleaning water cisterns in the wake of two September oil aerosol releases affecting a broad swath of St. Croix, noting that tests found no health hazard.
“Test results from all cistern samples were well below the drinking water guidelines of 10 milligrams per liter used by the Agency for Toxic Substances and Disease Registry (ATSDR),” wrote a Hovensa spokesperson in a statement from the refinery. The ATSDR is a division of the U.S. Department of Health and Human Services.
On Sept. 19, Hovensa sprayed a vapor cloud of oil into the atmosphere morning when a small line in a desulfurizing unit burst. Then, on Sept. 30, a mishap forced the refinery to flare-off a large amount of partially processed oil, some of which also flowed into a low-pressure elevated flare, where it sprayed out and was carried downwind over a number of neighborhoods.
Residents of those neighborhoods were advised to disconnect their water cisterns and avoid using cistern water until their tanks could be tested. Since that time, it has sent crews to collect water samples, under the oversight of the departments of Health and Planning and Natural Resources.
A total of 642 samples of cistern water were analyzed by an independent lab, according to Hovensa. Of those, 31 tested positive for the presence of hydrocarbons, six of which matched the type of oil released during the incident. Hovensa has cleaned and refilled 29 of 30 cisterns that tested positive and is in the process of cleaning the remaining cistern, according to the refinery. Hovensa set up several water-distribution sites during the cleanup, offering free drinking water for residents of affected neighborhoods. It gave out more than 450,000 gallons of drinking water and issued more than 600 vouchers for car washes.
Water distribution will end at 5 p.m. Saturday, once all cisterns scheduled to be cleaned are completed.
“We greatly appreciate the patience, understanding and cooperation that our neighbors have shown to Hovensa and its responders over the past six weeks,” said Hovensa Incident Commander Rob Campbell in the company’s statement.
Health Commissioner Julia Sheen confirmed in a statement Wednesday the ATSDR found no public health threat from either oil-vapor discharge, or two recent sulfur dioxide and hydrogen sulfide releases, which spurred complaints of a rotten-egg smell.
Sheen said the department’s Public Health Preparedness Division consulted with ATSDR about the risks posed by droplets of oil on resident’s roofs after the two oil releases. The federal agency reviewed the lab results from the cisterns that were tested by an independent lab and based on the levels – 4 milligrams per liter or less – said that the water was considered safe for non-consumption uses, and even if consumed, would not have posed any health hazard, according to Sheen.
For the sulfur and sulfide releases, the ATSDR says water is the best cleanser and recommends wiping down horizontal surfaces indoors, where particles may have settled, with a damp cloth and to hose down or bathe pets. Outdoor surfaces, such as outdoor furniture and cars, as well as farm animals, should also be hosed down.
According to Health, in any future smoke or oil vapor releases, ATSDR recommends the “shelter in place” approach, which is to stay indoors and close windows, if it is of relatively short duration. The release of hydrocarbon droplets is still under investigation by the Department of Health and the ATSDR and Sheen said Health will update residents when results come in.
Meanwhile, residents of the affected neighborhoods can reconnect their cisterns and resume using the water. If the cistern has tested positive and has yet to be cleaned, the Health Department recommends using the water for everything but cooking and drinking, but that drinking the water poses no health risk according to federal guidelines.
