EXH1120042316

To: Port of Seattle project files April 20, 2000 From: Doug Henderson / Linda Logan 556-2912-001 (61) Subject: Range-Finding Water-effect ratio results This memorandum summarizes results of range-finding toxicity tests conducted as part of the water-effect ratio (WER) study for copper in streams receiving STIA stormwater. The purpose of these range-finding WERs is to determine if the final WERs would be robust enough to warrant the expense of conducting definitive studies. Although range- finding WERs 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). In the event that mixing zones cannot be granted for the creeks, it was agreed that two additional.types of range-finding WERs be conducted, one without any mixing with stormwater (i.e., receiving water only) and the other one after complete mix, below outfall discharges. Sampling Samples were collected at five pre-determined locations during a qualifying storm on the afternoon of 13 April 2000. The storm started at 2:00 PM on 13 April and ended at 1:00 AM on 14 April 2000. The dry antecedent period preceding this storm was 74 hours. Approximately 0.34 inches of rain fell at STIA during 12 hour period of rainfall. Taylor Associates collected flow-weighted composite samples for 12 hours…

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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 [...]