City of Edmonds Department of Public Works crews responded last week to a report of a privately-owned underground heating oil tank located in the parking lot behind 326 4th Ave S., that apparently had been leaking for some time into the soil below.

Here’s the information provided from the city:

With one of the rainiest Octobers on record, a rise in the groundwater level mobilized the oil in the soil and it found its way to the surface near the tank’s fill port. This mixture of heating oil and water flowed out of the privately-owned parking lot onto the city street then flowed south down 4th Avenue South and entered the City’s storm system just north of Dayton Street.

The oil/water mixture followed the City’s storm system in westerly direction on Dayton, then south on 3rd Avenue South, discharging into Shellabarger Creek north of Howell Street. A sheen was seen in the creek but no “free product” was seen. It takes very little product to make a noticeable coloration on the street and on standing water. A representative of the Department of Ecology’s spill response team was on site and evaluated the spill and its effect on the Creek. The Ecology representative indicated that the vegetation in the creek would help remove the sheen and reduce the amount that entered the Edmonds marsh and that it really didn’t look like a lot got in the creek.

The owner of the property was notified by the City not long after the spill came to our attention on Monday, October 27th. The owner was surprised to learn of an oil tank on his property and was very cooperative. He immediately called a tank removal/spill response firm. Meanwhile City personnel put oil collection material in some City catch basins and strung an oil boom across the entrance to Shellabarger Creek culverts that go under SR104 into Edmonds marsh.

Late that same day, Monday October 27th, the owner’s tank removal firm pumped the oil from the tank. The next day the tank was removed and the contaminated soil around the tank was excavated and hauled offsite for disposal. This is a very quick response by an owner. This firm also power-washed the street that was stained with the oil/water mixture and cleaned out the catch basins on 4th Avenue South that had been impacted by the spill.

The nature of the oil (oil, weathered oil) and the fact that it probably had been leaking over the weekend prior to its discovery, is the reason the road gutter appears to still have oil on it. The concrete is likely stained and the stain cannot be removed without damaging the concrete.