EXH0741026666

To: Port of Seattleproject files April v2_,2000 From: Doug Henderson / Linda Logan 556-2912-001 (61) Subject: Range-Finding Water-effect ratio results _-OLtr_C__ . This memorandum summarizes results of range-finding toxici W tests conducted as part of the water-effect ratio (WER) study for copper in streams receiving STLA stormwater. _'l_nepurpose ofthese range-finding WERs is todetermine ifthe final WElLswould be robum enough to warram the expense of conducting definitive studies. Although range- finding WER.s were conducted in February 1999, these tests were conducted on simulated receiving water samples that were mixtures of outfall SDS3 stormwater and instream receiving water. Mixture ratios of these two samples were prepared in the laboratory by combining measured volumes of stormwater and upstream receiving water in proportions - estimated to occur in the receiving water (based on hydrographs generated using HSPF). the event tha_ mixing zones cannot be _anted for the creeks, it was a_eed that two additional _es of range-finding WERs be conducted, one without my mixing with storrnwater (i.e., receiving water only) and the other one after complete mix, below outfal] discharges. Sampling L Samples were collected at five pre-deterrnined locations during a qualifying storm event on the morning of 15 April 2000. This storm evem started at Xh on 15 April and ended at X_aon 15 April 2000. The dry antecedent period preceding this storm was at least 24 hours. Approximately X inches of ram fell at STIA during this x-hour storm. Taylor Associates collected flow-weighted composite samples for X hours during the storm event…

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PSCAA Advisory Council Meeting Agenda
Add to CalendarMWednesday Mar 11, 9:00am - 11:35am
1904 3rd Avenue, Suite 105, Seattle, WA 98101
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 [...]