Notes
Email chain dated July 30, 2000 from Kelly R. Whiting, PE, King County Department of Natural Resources, Water and Land Resource Division, Drainage Services Section, to David Masters and Tom Luster (WDOE), forwarding water quality specialist Kate Rhoads’ notes on copper (Cu) levels in Seattle-Tacoma International Airport (STIA) runway stormwater runoff. Whiting discusses KCSWDM (King County Stormwater Design Manual) compliance, NPDES and 401 permit conditions, IWS redirects, and storm water management plan (SMP) review. Attached document (POS-Cu.doc) contains Rhoads’ analysis: median total recoverable Cu concentration of 37 ug/l from STIA runways exceeds the assumed acute toxicity standard of 15 ug/l (at hardness 100); Whole Effluent Toxicity (WET) testing per WAC 173-205 used daphnia and flathead minnows rather than salmonids; dissolved Cu in WET test was 13 ug/l; comparisons with NUPR freeway and other stormwater data; concerns about TSS, hardness, dissolved fraction, and chronic toxicity effects on salmon habitat.