Thornton Creek Contaminated By Fuel Spill Accident

Yesterday’s semi-truck accidents on I-5 near Northgate Way that backed up traffic for miles on the southbound commute also released 40 gallons of spilled diesel fuel oil into the storm drain and the south fork of Thornton Creek. Though nobody was injured in the accidents, Thornton Creek, however, has been injured, and in the next few weeks and months we should get some idea of the extent of the damage.
Sound Transit contractors, JCM ULink, noticed the diesel smell at 5:45am and had the necessary emergency gear and training to put down booms and take other steps to control the spill at the culvert outflow on the east side of the freeway (1st Ave. NE and NE 100th).  Because of their actions authorities were able to send the Hazmat team to Beaver Pond Natural Area first.

Workers "vacuum and sweep" Thornton Creek to remove contaminates

Workers “vacuum and sweep” Thornton Creek to remove contaminates


Booms and ‘diapers’, or ‘sweeps’, are strewn across the creek at ten sites.  These materials both slow the flow and soak up contaminants.  Additionally a vacuum truck hosed up the brown slick in the separator basins and the creek.  The crew seemed to be doing the best job possible under the circumstances.
Sweeps and booms have been placed as far downstream as Kingfisher Natural Area at the site of the complex and expensive Knickerbocker Project where diesel fumes were detected (approximately 19th NE-21st NE and NE 98th –NE 100th).
Closer to the spill Beaver Pond Natural Area reeks of oil in some places, and there is a sheen all the way up to the beaver dam at NE 106th.  To some degree this is what will happen every time there is a punctured fuel tank on I-5 just north of Northgate because the separator basins can’t cope with more than the daily load.
The hazmat company, NRC, will continue to monitor the creek for 1-2 weeks.
There are two culverts serving each side of the freeway, and they combine both creek water and run-off.  They each have their own pair of separators in between the freeway and 1st Ave.  NE.  The culverts run parallel underground until they merge and flow into the Thornton Creek Water Quality Channel and then resurface at Beaver Pond NA.
Silver lining:  The weir that controls the water that runs from the I-5 drain to the Water Quality Channel was incorrectly turned off when the contractor completed the clean out this summer.  Turning on the waterfall – which happened after a vigilant Thornton Creek Alliance member contacted them – was only water runoff from Northgate, not I-5.  That water was drained into a pipe and diverted under 5th Ave. NE to the Beaver Pond NA project.
The Seattle Public Utilities’ Spill Response Team and the Washington Dept. of Ecology assisted with the containment and monitoring of the situation.  SPU environmentalist Nathan Hart was on the scene at Beaver Pond NA in the very early hours of the morning where Seattle Parks just last week completed a $500K restoration project.  He estimated that of the 40 gallons of fuel that spilled, perhaps 10 gallons ended up in the creek.
As a result of this event this Thursday’s Thornton Creek Alliance meeting will include a SPU representative who will give us an update and answer questions.
October 23, 2014; 7:15pm
Meadowbrook Community Center
10517 35th Ave NE
Seattle, WA

Ruth Williams and other members from the Thornton Creek Alliance contributed to this article.

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