MONTE-CARLO MODELING OF WATER AND SEDIMENT CONTAMINATION BY TOXIC METALS AT THE NORTH AVENUE DAM, MILWAUKEE, WI, USA

A deterministic water - sediment quality model was developed with a Mo nte Carlo interface and input generation. The model was used to simula te water and sediment (total and dissolved-pore water) quality of a re ach of Milwaukee River that includes an urban impoundment. The sedimen ts in the impoundments are contaminated by toxic metals and other prio rity pollutants. The sediment - water quality model was composed of th ree sequential segments each represented by three systems: water, uppe r sediment and lower sediment layers. The mass balance of the sediment contaminants was strongly affected by the direction of the groundwate r fluxes through the sediments. Steady state was assumed for the water column and the upper sediment layer while a dynamic mass balance mode l was used for the lower sediment layer. The inputs of the Monte Carlo simulation were ten years long time-series of upstream flows and Comb ined Sewer Overflow (CSO) discharges with corresponding Monte Carlo ge nerated concentrations. The model calculated output concentrations whi ch were statistically similar to the probability distribution of measu red concentrations.