Dr. Roberts’ is Professor of Civil and Environmental Engineering at the Georgia Institute of Technology. His professional interests are in environmental fluid mechanics, particularly the fluid mechanics of outfall diffuser mixing and the development and application of mathematical models of wastewater fate and transport.  He has extensive international experience in marine wastewater disposal including the design of ocean outfalls, review of disposal schemes, numerical modeling, and the design and analysis of oceanographic field study programs.  Dr. Roberts has lectured widely on outfall design and is presently Co-Chairman of the IAHR/IWA Committee on Marine Outfall Systems.
Dr. Roberts’ mathematical models and methods have been adopted by the U.S. EPA and are widely used around the world.  He is a regular lecturer at workshops for the U.S. EPA on mixing zone analyses and on the use of mathematical models and outfall design for the Pan American Health Organization.  He has developed innovative experimental techniques for research on diffuser mixing processes using three-dimensional laser-induced fluorescence and has published extensively in this area.  For this research he was awarded the Collingwood Prize of ASCE in 1980 and was UPS Foundation Visiting Professor at Stanford University in 1993-94.  He is presently one of only two Distinguished Scholars in the National Ocean and Atmospheric Administration (NOAA) Oceans and Human Health Initiative (OHHI) in which he is conducting research on the hydrodynamic aspects of bacterial and pathogen transport in coastal waters.
Outfalls and Coastal Engineering
Philip J. W. Roberts
School of Civil and Environmental Engineering, Georgia Institute of Technology
The design and construction of ocean outfalls and prediction of the fate and transport of their discharges involves many coastal processes and disciplines. Transport is affected by hydrodynamic phenomena that act over wide ranges of temporal and spatial scales.  Near field mixing occurs within a few minutes after which the plume drifts with the current and is diffused by oceanic turbulence in the far field by processes that occur on time scales of hours to days and length scales of hundreds of meters to kilometers. Numerical modeling of these processes has advanced considerably over the past few years and have especially benefited from advances in oceanographic instrumentation, particularly the ability to measure ocean currents and density stratification over the whole water column. Telemetry of the data to shore promises the development of real time dispersion models and potentially optimization of treatment, such as disinfection, with considerable savings in treatment costs. The design and construction of marine pipelines and intakes depends heavily on knowledge of wave and wave climates and sediment erosion and movement on the seabed. In this presentation, we review aspects of ocean outfalls of interest to the coastal engineering community, especially the use of new instrumentation and its interaction with modeling and the design process for outfalls and intakes.