::Cosmopolitan Engineering Group::


Cosmopolitan Engineering was retained by the City of Raymond in 1993 to conduct a mixing zone study for their WWTP outfall in the Willapa Estuary. Ecology was concerned about the potential for reflux of effluent around the outfall due to reversing tides. Cosmopolitan conducted a dye tracer study using a 5-day continuous injection of Rhodamine WT to directly measure the quasi-steady effluent concentration at key locations in the estuary and near the outfall.
Cosmopolitan was hired again in 1998 by the Cities of Raymond and South Bend, Pacific County, and the Port of Willapa to assist Ecology in the development of a dissolved oxygen and fecal coliform TMDL. Field studies and modeling conducted by Cosmopolitan revealed significant errors in the draft TMDL model issued by Ecology. As a result, the modeling was completed by Cosmopolitan Engineering. Model development included extensive current studies using fluorescent dye to track the presence and concentration of wastewater discharges relative to critical areas of low oxygen and commercial shellfish resources.