Type of Presentation

Oral

Session Title

General Pollution Topics

Description

The Washington State Department of Ecology (Ecology) evaluated the potential transport, dispersion and dilution of potential vessel sewer discharges within the draft proposed Puget Sound No Discharge Zone (NDZ). These model simulations included potential vessel sewer discharges at six locations in Puget Sound along major shipping routes. Results are presented as virtual animations of surface concentrations, allowing us to visualize the transport, circulation, and dilution of these discharges over the course of several days.

Ecology and Pacific Northwest National Laboratory jointly developed a three-dimensional hydrodynamic FVCOM (Finite Volume Coastal Ocean Model) computer model of the Salish Sea. This model is forced by tides at the mouth of the Strait of Juan de Fuca, meteorological boundary conditions, and freshwater inputs from the US and Canada that induce estuarine circulation. The model has been calibrated to water surface elevations and profiles for the year 2006.

Potential discharges were simulated using the sediment module of the model, with zero settling velocity. The model allows us to evaluate connectivity between points of discharge and other parts of Puget Sound, and calculate the degree of dilution that has occurred before discharges reach specific geographic points of interest. Model simulations show the strong influence of tidal cycles on the movement of vessel sewer discharge. At some locations, freshwater inflows into Puget Sound from rivers also influence the movement and dilution. We found that there are several periods when fecal coliform bacteria concentrations typical of raw sewage would not meet the water quality standard based on dilution alone.

Since its development, Ecology has used the model for a number of applications to evaluate how potential point and nonpoint source discharges (e.g. wastewater facilities, vessel sewage discharges, and rivers) circulate once released into marine waters.

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Virtual simulations of potential vessel discharges in Puget Sound and the Puget Sound No Discharge Zone

2016SSEC

The Washington State Department of Ecology (Ecology) evaluated the potential transport, dispersion and dilution of potential vessel sewer discharges within the draft proposed Puget Sound No Discharge Zone (NDZ). These model simulations included potential vessel sewer discharges at six locations in Puget Sound along major shipping routes. Results are presented as virtual animations of surface concentrations, allowing us to visualize the transport, circulation, and dilution of these discharges over the course of several days.

Ecology and Pacific Northwest National Laboratory jointly developed a three-dimensional hydrodynamic FVCOM (Finite Volume Coastal Ocean Model) computer model of the Salish Sea. This model is forced by tides at the mouth of the Strait of Juan de Fuca, meteorological boundary conditions, and freshwater inputs from the US and Canada that induce estuarine circulation. The model has been calibrated to water surface elevations and profiles for the year 2006.

Potential discharges were simulated using the sediment module of the model, with zero settling velocity. The model allows us to evaluate connectivity between points of discharge and other parts of Puget Sound, and calculate the degree of dilution that has occurred before discharges reach specific geographic points of interest. Model simulations show the strong influence of tidal cycles on the movement of vessel sewer discharge. At some locations, freshwater inflows into Puget Sound from rivers also influence the movement and dilution. We found that there are several periods when fecal coliform bacteria concentrations typical of raw sewage would not meet the water quality standard based on dilution alone.

Since its development, Ecology has used the model for a number of applications to evaluate how potential point and nonpoint source discharges (e.g. wastewater facilities, vessel sewage discharges, and rivers) circulate once released into marine waters.