The Kobuk River lies directly southeast of the bluff where a 15,000-gallon
diesel fuel spill occurred in 2020. The Kobuk River is the source of drinking
water for Shungnak, and the drinking water collection gallery for the municipal
water intake is located down gradient and downriver of the spill location. The
village of Shungnak also relies on the Kobuk River for subsistence fishing. Site
characterization efforts in 2020 and 2021 confirmed subsurface oil
contamination downgradient from the spill location. Oil- contaminated soil has
been excavated and stockpiled at the site but is not being managed in a manner
that prevents oil migration from the stockpile toward the Kobuk River. In June 2023,
oil just below ground surface was observed approximately 30 feet from the Kobuk
River. Contamination at the top of the hillside appears to be approximately
10ft below ground surface and may also be commingled with a previously
unreported historical spill that was discovered during 2020 assessment work. No
cleanup actions have taken place at the site since the initial spill response
removed approximately 350 cubic yards of oil contaminated soil and 250-500
gallons of pooled diesel fuel.
Oil migration toward the
Kobuk River is occurring via both surface and subsurface pathways. If
contaminants reach the intake pipeline fill material, the intake fill could be a
preferential pathway for contaminant migration to the Kobuk River Contaminants
could also migrate along the surface permafrost and in suprapermafrost
groundwater.
EPA initiated an oil removal evaluation and discharge mitigation activities in October 2023.
