Seeing Red: City suspects asphalt sealer spill in pond near Snoqualmie Ridge IGA shopping center

A red-tinted stormwater detention pond, located on Kinsey Street behind the IGA shopping center property on Snoqualmie Ridge, caught the attention of residents this week, raising questions about what may have caused the very-apparent discoloration.

The City of Snoqualmie said via press release that it reported a spill to the Department of Ecology (DOE) on July 17, 2018 and then took samples from the Kinsey Pond catch basin, pond and equipment left by a contractor that had performed a parking lot seal in the nearby private lot. They added, “There is no impact to the public or to wildlife.”

Lab results from Amtest Laboratories of Kirkland revealed a trace amount of hydrocarbons (300 ug/L) or .3 parts per million (ppm). The city explained for comparison, 4 drops from a dropper in a 55-gallon barrel equals 1 ppm; this is .3 ppm or one (1) drop in a 55-gallon barrel.

The samples were tested for a clay component of the asphalt sealer, which the city said would contribute to the red coloration. The Department of Ecology will make a final determination on the contaminate after reviewing lab results.The city said it would then follow through with their recommendations.

According to the city, stormwater ponds like the Kinsey Pond are designed to catch all spills, asphalt, and brake dust from roads and treat it over time. The ponds were installed near impervious infrastructure throughout the City to provide protection for the Snoqualmie River and all local streams.


Kinsey Stormwater Detention Pond on August 7, 2018. Photo credit: Gary Anderson.

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