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3.2 New Phase 2 nomenclature 3.21 Alternative 6 (Alt 6) As for Phase 1 nomenclature, Alternative 6 (Alt 6) refers to the number of active stormwater evacuation pumps. For this new alternative, it does not only refer to the pump station in watershed A but also the one in watershed BIC. • Alt 6 has an equivalent of 8 active unit pumps: 2 at pump station A (by lake 3), 68 (3 actual pumps) at Phase 2 pump station in watershed B/C (between lakes 12, 19 and 22). The pumps (for models with pumping) are modelled with pumps "Rated By Static Head" meaning that a pump that pumps according to the head at the upstream node using a multi-point pump curve and starting and stopping elevations. The pump rate was set to 12.5cfs for all static head values meaning that all pumps would pump 12.5cfs (each)whenever on9. The start and stop elevations for the pumps at all pump stations: • Pump 1: Start 5.3 Stop: 5.1 • Pump 2: Start 5.5 Stop: 5.1 • Pump 3: Start 5.7 Stop: 5.1 (Phase 2 pump station only) • Pump 4: Start 5.3 Stop: 5.1 (Phase 2 pump station only) • Pump 5: Start 5.5 Stop: 5.1 (Phase 2 pump station only) • Pump 6: Start 5.7 Stop: 5.1 (Phase 2 pump station only) 3.2.2 Lake L The designation "L" refer to the path the stormwater from watershed A/phase 1 is evacuated. • L: Water from lake 3 in watershed A is pumped into lake 25 located in watershed B. 3.2.3 Version 2.0(V20) The designation V20 refers to the finalized lake- and pump station connection pipes layout for phase 2. While this report only presents the results for this layout, the designation is included to differentiate between pervious model configurations presented in earlier revisions of the River Islands Phase 2 Stormwater Report. In Appendix C the layout of the lake interconnection pipes for this model are shown and Figure 2-1 shows the same layout in the XPSWMM interface. 3.2.4 Contributory(ca) and Lake (la) drainage areas • ca: Approximated contributory drainage area used for phase 2 lake hydrograph as described in section 2.4.1. • la: Contributory drainage area scaled relative to the lake size compared to total lake area in phase 2 as described in section 2.4.2. 3.2.5 Phase 2 Pump Station (PS) • PS: Assumes there is a lake interconnection pipe (flat gravity pipe) between lake 12 in Phase 1 and the wet well at the Phase 2 pump station in watershed B/C10. $As described in Section 1.2, the actual Phase 2 Pump station will have 3 active pumps with twice the flow(25cfs)from described here (12.5cfs) as well as one standby pump. The 12.5cfs unit pumps are used for correlation with the other pump station (pump station A in Phase 1). 9 idem 10 Note that the 'Phase 2 Pump Station" (PS) configuration is different from the Phase 1 model configuration "Farm Pump" (FP) where a temporary pump is evacuating stormwater from lake 12. See River Islands Phase 1 Stormwater Mitigation report dated April 2020 for more information on the"Farm Pump"model configuration. River Islands Phase 2 Stormwater Mitigation Rev 2 18 Owmft_._.� PACE