EXH0116017903

_ _, Comments on the Copper levels from SEATAC runways * Copper levels seem high (based on Table 4-8) - I think that they would exceed the numeric surfac _.water standard, but it is impossible to tell with the data presented. The data presented ., is total recoverable (TR) Cu and the st,_.ndardis based on the dissolved fraction. Based on the TSS levels for the runways, I expect that most of the Cu is in the dissolved form. Hardness levels are not presented and are needed to determine toxicity. Assuming a hardness of 24 (based on hardness data from WET testing), the acute toxicity standard for Cu is 4ug/l. The runway data presented has a median TR Cu concentration of 37 ug/l. I should also note that and excedance of the acute toxicity standard does not necessarily result in a fish kill, but there could be long term chronic effects. Also, the toxicity standard is an in-stream standard and (I think) the STIA data is stormwater runoff from the runways, prior to discharge to the creek. The comparisons in Table 4-8 show TR Cu concentrations within the same range of the runways. The TSS concentrations from these comparisons (NUPR, freeway, etc) are much higher than from the runways. Because of this, I would assume that the dissolved Cu fractions from the comparison data would be much less than the runway. Therefore, the dissolve fraction of Cu is probably higher for the runways and more of a toxicity issue than the…

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Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]