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Existing Conditions Model without UICs This model was developed to represent existing conditions of the stormwater system without modeling the effects of UICs. All runoff from subbasins with UICs was assumed to drain into the piped and surface stormwater drainage system without infiltrating into the existing UICs. Existing Conditions with UICs This model was developed to represent existing conditions of the stormwater system while modeling the effects of the UICs. UICs were assumed to infiltrate runoff from up to the 5 -year storm event (3.6 inches). UICs were modeled as storage nodes that store runoff up to the 5 -year storm event. When the capacity of the storage node is reached (5 -year event) the subbasins with UICs begin contributing all additional runoff flows to the piped and surface stormwater drainage system. The storage nodes were sized using an iterative trial and error process until the 5 -year event filled the storage volume but did not contribute runoff flows to the piped and surface stormwater drainage system. Future Conditions Model without UICs This model was developed to represent future development conditions of the stormwater system without modeling the effects of the UICs. All runoff from subbasins with UICs was assumed to drain into the piped and surface stormwater drainage system without infiltrating into the existing UICs. Future Conditions with UICs This model was developed to represent future development conditions of the stormwater system while modeling the effects of the UICs. UICs were assumed to infiltrate runoff from up to the 5- year storm event (3.6 inches). UICs were modeled as storage nodes that store runoff up to the 5 -year storm event. When the capacity of the storage node is reached (5 -year event) the subbasins with UICs begin contributing all additional runoff flows to the piped and surface stormwater drainage system. The storage nodes were sized using an iterative trial and error process until the 5 -year event filled the storage volume but did not contribute additional runoff flows to the piped and surface stormwater drainage system. Results of Modeling Conditions Both With and Without UICs While it was anticipated that existing UICs might relieve some flooding issues, the comparison of model results between the models with and without UICs for the design storms required by the City (10 -year and 25 -year storm event) did not show significant differences with respect to flooding problems. It is assumed that this was the case for the following reasons: Ii