Aquaveo performed the majority of the hydrologic and hydraulic analysis which involved building a calibrated hydrologic model of each basin to determine the current 1 percent annual-chance flow rates in each channel. Stormwater was routed throughout the watershed using channel and storm drain information obtained from County as-built plans. The existing conditions models were then used to evaluate the impact of potential mitigation projects and identify those most suitable for reducing peak flow rates in the channels.
The County also exercised several optional tasks to develop design level models using County hydrologic methods for surface runoff and XPSWMM for subsurface conveyance. The models were used to quantify the local impact of several high priority mitigation projects in the basins.