Near-Field Observations of an Offshore Multiport Brine Diffuser under Various Operating Conditions

Abstract

A field experiment was conducted at an inclined multiport brine diffuser in an open-coastal embayment for plant operating capacities ranging 33–1%. A three-dimensional array of conductivity and temperature sensors captured high-resolution brine plume dynamics. Ambient velocity and wave characteristics were also measured. Measured localized outfall salinity concentrations did not exceed background levels by more than 1.9 g/kg, whereas deviations from time-averaged ambient salinity ranged from −4.3 to 2.83 g/kg over the 14-day sampling period. Plume trajectory and dilution were compared with commonly applied laboratory-based empirical methods. Although there was general agreement in time-averaged distributions for the 1% plant operation case, the effects of ambient hydrodynamic processes on plume dynamics were dominant. The results have implications for the application of empirical models in the design, regulation, and management of these outfalls.