Notes
A memo summarizing three alternative dilution modeling methods for evaluating reasonable potential for exceedence of State water quality standards at proposed Port of Seattle stormwater outfalls. The methods include a static single-event approach based on Ecology’s Permit Writer’s Manual, a dynamic continuous simulation approach using HSPF hydrologic models, and an EPA-funded probabilistic model developed by Dominic Di Toro. The memo also outlines considerations for proceeding, including client expectations, Ecology’s involvement, and available budget.