The objective of the Slacks Creek Optimization project was to evaluate a range of capital improvement alternatives to resolve wet weather overflows for a range of calibrated model design storm frequencies. The optimized solution was compared to a baseline solution developed based on the traditional planning approach of considering only conveyance improvements and a steady-state wet weather design flow of 1,300 liters per person per day.

The optimization process demonstrated that the improvements needed to contain the 1-year design storm differed significantly from those selected for the baseline solution.  By selecting cost-effective combinations of storage, I/I reduction and conveyance improvements, the optimization not only achieved significant cost savings but also significantly reduced the frequency and volume of manhole flooding and emergency overflow discharge.