Receiving water modeling in support of the design of an ocean outfall

A detailed investigation was performed to characterize the circulation patterns and water quality response of the receiving waters adjacent to Montevideo, Uruguay. The purpose of this study was to determine the best offshore location for a submerged diffuser outfall, to ensure adequate protection of bathing beaches from bacterial contamination. The study included an intensive 4-month oceanographic data collection program (current meters, drogue and drift studies, dye dispersion experiments, bacterial dieoff studies, and ambient water quality measurements. These data were used to calibrate and verify far-field circulation and water quality models to predict the bacterial concentrations in the receiving waters for submerged outfalls of various lengths. The modeling results showed that the minimum safe length of the outfall is 2,250 m, which is twice the length estimated from an earlier study that used simpler analyses.