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Chapter 3 — Concept Regional Drinking Water Distribution System <br /> Creating one overall water system from the four individual community systems will require a network of <br /> trunk watermain and booster stations to connect the systems and accommodate the different pressure <br /> zone elevations (hydraulic grade lines). Figure 1-2 in Section 1-5 shows the existing water <br /> infrastructure for the Northwest Metro communities. <br /> The basis for the regional water system assumes that a regional system utility will own and operate the <br /> following infrastructure: <br /> • Water supply and treatment plant <br /> • Trunk watermain constructed to connect the member communities <br /> • Booster stations <br /> It is assumed the individual communities will continue to own and operate their water towers and water <br /> distribution systems (watermain, hydrants, services, etc.). <br /> 3.1 Assessment Methods <br /> The following sections describe assessment methods for water modeling and cost estimating used in <br /> this report. <br /> 3.1.a Hydraulic Water Model <br /> To determine the layout and sizes of trunk watermain and booster stations, a hydraulic water model <br /> was constructed using WaterCADO. The existing water systems were imported into the water model <br /> and a future water supply, trunk watermain, and booster stations were added to create a functioning <br /> water system. Steady state scenarios were run to verify that system pressures and pipe velocities <br /> remained within acceptable limits. <br /> 3.1.b Basis for Concept Level Costs <br /> The concept level costs for the water treatment plants were developed using the book Cost Estimating <br /> Manual for Water Treatment Facilities, McGiveney and Kawamura, Wiley 2016. The concept level <br /> watermain costs were developed based on bid tabs and experience with similar types of projects. All <br /> costs are based on 2020 dollars and no escalation is included for date of construction. <br /> 3.2 Phased Watermain Approach <br /> Constructing the entire network of trunk watermain to meet ultimate demands for the Northwest Metro <br /> communities before it is needed would be very expensive and make a potential project not feasible. To <br /> spread the costs out so that the infrastructure is being constructed when it is needed, a phased <br /> approach was developed. <br /> Four different phases (Phases A-D)were identified as summarized in Figure 3-1 for two different water <br /> treatment plant (WTP) location sites. In Scenario 1, the WTP is located in Ramsey and is only a surface <br /> WTP. The WTP in Scenario 1 can only be a surface WTP because it is assumed that the TCW aquifer <br /> in Ramsey cannot support enough wells for a regional groundwater WTP. <br /> In Scenario 2, the WTP is located in Dayton and can either be a surface or a groundwater WTP. In <br /> Scenario 2 it is assumed that the TCW aquifer in Dayton could support a regional groundwater WTP <br /> through 2040. The phased plan developed for the regional trunk watermain is shown in Figure 3-2 for a <br /> WTP located in Ramsey and in Figure 3-3 for a WTP located in Dayton. <br /> Page—11 1 METROPOLITAN COUNCIL <br />