EXH0636024622

t From: Dong Henderson / Linda Logan 556-2912-01 (61) Subject: Update on the Status of the Site-Specific WQC for Copper This memorandum summarizes our efforts to date to develop a site-specific water quality criterion for copper in Miller, Walker, and Des Momes Creeks. The need for such development is based on the assumption that the quality of stormwater from the third runway will be similar to that currently discharged from SDS-3. Prior to collecting any dad__mm__ was proposed to prevent unnecessary data collection (Figure 1). The-_6 recomm_n_¢xt methods for developing a site-specific "vVQCwere the Water-Effect Ratio (WER) and the site-specific metals translator. The WER approach uses toxicity tests to evaluate the relative toxicity of copper-spiked site water compared to copper-spiked laboratory water. The ratio of these results is used to adjust the state water quality criterion, which is based on copper-spiked laboratory tests. The site-specific metals translator approach uses m-stream momtormg data to estimate the ratio of dissolved to total copper in the receiving water. This ratio is then used to calculate a new total copper permit limit based on the dissolved state WQC. Although the site-specific metals a-anslmor is quicker and less expensive to develop than a WEP,, it is a less acourate estimate of copper bioavailability, as the bioavailable fraction •of a metal is generally less than the dissolved fraction. Therefore, a WER will likely result in higher permit limits than a site-specific metals translator. For example, if the dissolved copper concentrations are half of the total copper…

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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 [...]