Far field modelling of a submerged outfall

A three-dimensional hydrodynamic/pollutant transport model, is used for the far-field modelling of the proposed Waste Water Treatment Plant (WWTP) submerged outfall in order to address the potential impact of discharged effluent to the nearby municipal drinking water supplies. The modelling domain is the western part of Lake Ontario in Canada, that includes the WWTP outfall and the two nearby municipal drinking water intakes. Preliminary runs for a constant wind of 5 m/s and two wind directions under both stratified and isothermal lake conditions indicate that (a) the dilution at the water intakes is greater under stratified conditions and (b) the total dilution ranges between 137:1 to 285:1 while the far field dilution ratio varies within a factor of 2 amongst the different cases and ranges between 11:1 and 22:1.