::Cosmopolitan Engineering Group::

Cosmopolitan Engineering Group has been providing annual water quality sampling and modeling work for the City of Gig Harbor since 1997. The City's wastewater treatment plant outfall discharges within Gig Harbor, a shallow side embayment attached to the Tacoma Narrows in Puget Sound. In the first two years these studies included:

	Marine water quality testing for dissolved oxygen, pH, temperature, nutrients, chlorophyll and metals, both inside the harbor and in the narrows.
	Dye tracer and density studies to assess the flushing rate and reflux within the harbor.
	Mixing zone studies and modeling to assess dilution factors and compliance with water quality standards.

In 2000, Cosmopolitan Engineering Group conducted a siting study for a new deepwater outfall located in the Tacoma Narrows:
	Field studies included conductivity, temperature and depth (CTD) field surveys, circulation studies using drogues and current meters, and marine biological investigations.
	Dive surveys were conducted to assess geoducks and eelgrass within the shellfish harvest closure zone at the candidate outfall sites.
	Dilution modeling was conducted to assess water quality impacts and mitigate the shellfish impacts.
	Several stakeholder meetings including the state departments of Ecology, Health, Fish and Wildlife and Natural Resources were conducted to facilitate the siting study.
	Conceptual design tasks were conducted to support the outfall siting, including diffuser hydraulic analysis, preliminary alignment and profile, construction materials and methods, and cost estimates.
Cosmopolitan Engineering is proceeding with final design and permitting for the new outfall. The outfall improvement will consist of a new 9,000-foot, 24-inch-diameter HDPE pipeline with a 540-foot diffuser at a depth of 190 feet MLLW in Colvos Passage.