Agenda - Council Work Session - 10/20/2020 - Special

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2.5 26 versus wells spaced throughout town, the worry is that the furthest points from the treatment plant may experience lower pressures due to headloss through the distribution system. An ADD of 1,72 IVIGD and a MDD of 4.7 MGD were assumed. Figures 9-10 in Appendix B show the operation of the treatment plant high service pumps and towers for both demand scenarios, and Figures 11-12 in Appendix 3 show the minimum pressures for both demands scenarios_ Pressures across the system were generally consistent throughout the 24-hour simulation for both demand scenarios, and at no point did the pressure drop below 50 psi during both demand scenarios, and at no point did velocities exceed 5 feet per second. Modeling of both demand scenarios show that the existing system performs very well with a treatment plant as the sole source of water. 2040 System 24-Hour Simulation By 2040, Ramsey's estimated average day demand is expected to increase to 3.5 IVIGD, and the maximum day demand is expected to increase to 10.3 MGD, With this increased demand, it is important to ensure that the distribution system and storage facilities are adequately sized to meet the future demand. The storage capacity of the current water system is 4 MG, which will still meet the Minnesota Department of Health's recommendation of having enough storage to meet or exceed the ADD, so additional storage will not be required through 2040. Although it is impossible to know where future watermain will be required, future watermain was added and sized according to previous reports, which can be seen in Figures 15-16 in Appendix B. Future demands were allocated based on locations future pipes and future development areas. Figures 13-14 in Appendix 3 show the operation of the treatment plant and towers for both demand scenarios, and Figures 15-16 in Appendix 3 show the minimum pressures for both demands scenarios of the 2040 24-hour simulation. Again, the pressures across the system were generally consistent throughout the 24-hour simulation for both demand scenarios, and at no point did the pressure drop below 50 psi during the ADD scenario. Pressures did drop to as low as 37 psi during the MDD scenario in some areas in the future north development between 173rd Ave NW and 181st Ave NW due to the higher elevations, although this can be alleviated by keeping the towers al a higher level. Velocities were kept below 5 feet per second, although a short segment of 16" pipe on Bunker Lake Blvd NW approached around 5,5 feet per second during the MDD scenario for a short period oftime, although this is not a concern_ Distribution Modeling Conclusions and Recommendations Modeling of Ramsey's water system shows that it performs well currently and with a treatment plant now and in the future. If the City choose to build a water treatment plant, raw watermain will be needed to bring the well water to the treatment plant. Currently there is raw watermain for bringing well water to the pumphouses, which can be utilized for the treatment plant, although additional and bigger sized raw watermain will be required. The raw watermain required is shown in Figure 1 in Appendix I, and was assumed in the modeling. Of note, the 16" watermain along Bunker Lake Blvd NW should be used as finished watermain, and was assumed to be in the modeling As the population grows, and thus the water demand, there are a few recommendations for improving the water system to be able to operate efficiently with 2040 demands, First, it is recommended that the 16" watermain along Bunker Lake Blvd NW be tied into the 12" watermain FEASIBILITY STUDY -DRAFT RAMSY 154354 Page 7