Agenda - Council Work Session - 09/13/2022

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2.4 distribution system was done for junctions (watermain intersections and at dead -ends) instead of hydrants, so the fire protection in some areas may be better than shown as a hydrant may be nearby on a larger sized watermain. In general, low fire flows occur where normal pressures are already low, and in areas with small diameter watermains, or in areas with older watermains. Dead -ends typically have noticeably weaker fire flows than looped watermain as well. To determine if the water system is deficient in available fire flow, a basis for fire protection must be established. For planning purposes, the minimum fire protection requirement can be based on land use according to Table 4. Table 4 — Minimum Fire Flows Land Use lila(gpm) Park 500 Single -Family 1,000 R-1 Low -Density Single Family 1,000 Two -Family 1,000 Multi -Family 1,500 High -Density Multi -Family 1,500 Service Office 1,500 Community Commercial 2,500 General Commercial 2,500 Industrial 3,500 Mixed Use -Neighborhood 2,000 Mixed Use -Community 2,000 Mixed Use -Regional 2,000 In general, the City is well protected with over 98% of the distribution system having fire flows of 1,500 gpm or higher. When comparing available fire flows with the City's existing land use map there are a few areas where the available fire flow may be deficient. Specifically, a small industrial land use area north of Highway 10 and south of the southern dead-end of Jaspar Street NW, as well as the dead-end of 142nd Lane NW in the southeastern part of the City. existing System 24-Hour Simulation — Treatment Plant Similar to the existing system 24-Hour simulation, a 24-hour extended period simulation was run for ADD and MDD demands to model how the existing system performs in terms of pressure, velocity, and tank levels with a treatment plant as the sole source of water. With a single source 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 MGD 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 B 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 FEASIBILITY STUDY RAMSY 154354 Page 7