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MEMORANDUM Rice Creek Commons Water Distribution System Modeling Results Update January, 2025 Page 12 H:\KIMLEYHO_PR\0T4133552000\2_Preliminary\C_Reports\Preliminary Design Report Update\Report Update\Water Preliminary Engineering Analysis\Memo-Rice Creek Commons Water Distrib Sys Modeling Results Update Final Draft 01.24.2025.docx To estimate these needs it was assumed that water service to Outlot A would be constructed initially followed by the addition of the Spine Road transmission pipeline. Areas east of the Spine Road service area were not included in these analyses, making the assumption that the initial development growth will occur in the areas serviced by Spine Road and Outlot A. Demands were sequentially increased in these areas and the results were analyzed to approximate when the tank and pump station would be needed by determining the system’s ability to provide the target fire flow for a 3 hour period. Incremental demands were added to the system during maximum day demand scenarios. The incremental demands were added to the system were 0.6 MGD, 0.75 MGD, 1.0 MGD, 1.5 MGD and 2.25 MGD (full build out). The amount of fire flow the system could provide for the 3 hour duration was determined for each of the demand scenarios. An initial analysis determined the fire flow availability without the addition of the tank or pump station. The results of this analysis estimate that the system can provide approximately 3,340 gpm fire flow when the maximum day demand for TCAAP is 0.6 MGD (approximately 27% of the anticipated total future demand). For a 0.75 MGD demand, the available fire flow is approximately 3,200 gpm. At 1.0 MGD, fire flow is approximately 2,940 gpm; and 2,280 at 1.5 MGD. Adding a 1.5 MG tank indicated that the system could provide in excess of 5,000 gpm fire flows for the growth scenarios up through the 1.5 MGD demand, but was not sufficient to provide the needed fire flows for full development. The addition of the pump station would also be required to provide adequate service beyond this demand. Finally, a scenario was analyzed where the addition of the pump station occurred without the addition of the tank. The results of this scenario indicate that fires flows when the system demand is 0.6 MGD are approximately 4,350 gpm. At a TCAAP demand of 0.75 MGD, 4,210 gpm fire flow can be supplied; 4,100 gpm at 1.0 MGD; and 3,840 gpm at 1.5 MGD. Adding the 1.5 MG tank and the proposed pump station indicate that the system could adequately supply the future full-development demands and provide a 5,000 gpm fire flow for three hours. As noted above, the allowance for future growth and the fire flow criteria / simulation parameters will be evaluated with City of Arden Hills staff during final design in order to finalize the required volume of water storage. Allowing for potential reductions in these parameters, the required volume of storage is anticipated to be 1.0 to 1.5 MG. Recommended Improvements Based on the analyses above, the following recommendations are made: x Construct a new west booster station along Old Highway 10 (Old Snelling Ave N). The booster station may be constructed on the north or south side of I-694. This booster station may have pumps with the same design point as the existing east booster station’s pumps. Construction of the booster station is recommended to occur concurrently with the Spine Road project. The booster station will provide redundancy to the north pressure zone, as the entire north pressure zone is fed solely from the existing booster station. Additional SCADA controls and security features will be included in the final design. x Construct a 0.75 MG water tower having the same high-water elevation as the existing north tower. Construction of the tower should be complete by the time Phase 1 of the proposed RCC development plan is fully occupied. This tower size will be adequate for the