Uncertainty analysis of ocean outfalls

Variability and uncertainty are inherent in an ocean outfall system and wil l cause variation in estimated initial dilution and bacterial concentration at areas of interest near the discharge. Uncertainty analysis is therefore useful in evaluating the likely performance of the outfall and in determin ing if it will comply with relevant government regulations. This paper iden tifies the uncertainty in outfall design parameters for an outfall involvin g a single, horizontal, round buoyant jet discharging into an unstratified seawater environment. A case study based on data from the Spaniard's Bay ou tfall in Newfoundland, and using a Monte Carlo simulation, is presented and compared with some, limited, site data that are available. It is shown tha t the analysis adequately describes the probabilistic nature of the initial dilution and bacterial concentration and that it would be useful for pract ical design purposes.