Cleanup of a roughly 200-gallon diesel fuel spill in Winlock continues as teams with the Washington state Department of Ecology say they have excavated all of the contaminated soil they can and will continue to mitigate the impact to nearby Olequa Creek.
In the last week, Cowlitz Clean Sweep and other crews contracted by the Department of Ecology have continued to excavate soil, vacuum up contaminated groundwater and soak up diesel fuel remnants still entering the creek. Along the way, teams have tested soil and groundwater contamination to evaluate the next steps forward for cleanup.
According to updates from the Department of Ecology, soil and groundwater below the source of the diesel spill tested at safe levels this week, and crews will begin filling in the large pit created by the cleanup efforts on Monday. The same day, crews will begin hauling away the collected contaminated soil.
Olequa Creek itself is still being cleaned using sorbents to soak up remnants of diesel fuel. Sorbents are special materials used to soak up harmful substances, and multiple layers remain in place in three sections of the creek with the first where the spill entered the creek. The second, which is just a little bit downstream of the spill site, is set to be removed to allow what the Department of Ecology refers to as “non-recoverable sheen” to dissipate naturally while the last layer of sorbents near the Fir Street Bridge will remain in place as a catch-all.
Moving forward, crews will continue testing soil closer to the creek and on its bank where excavation isn't an option due to the risk of the bank becoming unstable or possibly collapsing. According to the updates provided to Lewis County Public Health and Social Services, water flushed through the soil on the bank of Olequa Creek as well as water runoff from recent light rainfall is still producing some fuel sheen. That fuel is being soaked up as soon as it enters the creek.
Now that the source of the diesel fuel spill, including any fuel retained by the soil below the spill, has been removed, the spill team will continue flushing the soil and plants to clean up remaining contamination and mitigate impacts to the creek.
According to the official leading the response, fish have been seen in the creek and no fish kills have yet been reported. The status of the creek for recreation remains the same, with roughly a mile still closed off but sites further downstream and near Vader are safe to enter.
The saga of the local spill began with a report of discoloration and oil slick being spotted on the surface of Olequa Creek near the Winlock City Treatment Plant on Thursday, July 10.
A response and investigation by the state Department of Ecology led to confirmation of a fuel spill the following day. Lewis County first released a public announcement that day, July 11, warning residents of Winlock and Vader against recreating or in any way entering Olequa Creek.
The investigation by the Department of Ecology found 200 gallons of diesel fuel to be missing from an above ground fuel tank located near the creek on Northwest King Road. It also later found the concrete basin below the tank to be cracked. The tank sat on City of Winlock property that is currently used as a bus depot for the Winlock School District.
