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Experts say pollution found near Winslow Ravine not coming from Unocal property
Pollution in the Winslow Ravine and nearby waters is not coming from the former Unocal property, experts told the Bainbridge Island City Council Wednesday.
A neon-rainbow colored sheen that was sighted by island residents had led to some speculation that the former gas station property was seeping pollution out of the hillside.
Not so, said consultants hired to test the area for pollution.
Kitsap Transit presented to the city council the results of tests regarding the former Unocal site, and the adjacent ravine, at Wednesday's council meeting.
According to Kitsap Transit, the sheen observed by members of the island community is most likely from a marine source. Eagle Harbor, where the ravine empties, is home to a ferry dock as well as other marinas and daily boat traffic.
Kitsap Transit, the Department of Ecology and the Kitsap Health District have received complaints from island residents about the sheen in the ravine. It has since lead to speculation that the former Unocal gas station site was seeping material left over from the gas station's underground tanks.
Citing a recent review by Parametrix and stream sampling conducted by Aspect Consulting in March, Kitsap Transit officials said the sheen that has been seen was not coming from the Unocal property.
Pollutants that were found were probably coming from runoff from nearby roads, from fresh paving on Winslow Way, or garbage that had been dumped in the ravine. Other potential sources include naturally occurring organic rot from cedar trees, or from an offsite marine source. Those marine sources could include the marina, the ferry and ferry terminal, the ferry maintenance facility, boat traffic and the Wyckoff site in Eagle Harbor.
"There's probably no pinning the tail on the donkey on this," said Bill Webb of Parametrix.
What was certain, he said, was the pollution that was found was from marine diesel fuel and oil, and not gasoline.
Tests further up the stream also indicate that the pollution was not coming from the former gas station property, but was more likely "marine wash-up."
"There's no contamination in the stream," he said.
Hillside seeps and freshwater sediments were also not contaminated, Webb said.
Webb also told city officials that groundwater contamination in the test wells on the Unocal property was less than what had been found in tests done in 2004-2009.
"The gasoline is going away," he said.
Webb also said the scale of any pollution coming from the Unocal site were "trivial" compared to other sources of pollution nearby.
Aspect Consulting, a local island company, was hired by Kitsap Transit to test the hillside behind the Unocal site and the surrounding area. Aspect provided raw data, and Kitsap Transit took the data to draw their own conclusions, according to Chip Goodhue with Aspect.
Goodhue also volunteers for the Citizens Park Task Force, the group promoting the placement of a park on the surface of the site.