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2.1 <br />Flow <br />Test <br />Pressur Pressure <br />Differential ifferentia Pressure <br />Field Model ifferential <br />Results Results (psi) <br />(psi) (psi) <br />11 Current dead-end on 149th Ave. NW I 1,234 5 <br />5 <br />0 <br />12 <br />West dead-end on 147th Ln. NW <br />1,123 <br />3 <br />8 <br />13 Dead-end on 137th Ave. NW <br />10 <br />-1 <br />14 <br />East dead-end on Rivlyn Ave. NW <br />1,031 <br />10 <br />10 <br />0 <br />During the calibration process of the Ramsey water system hydraulic model, pumping rates, <br />customer demands, and tower water levels were set to the conditions recorded during the field <br />testing. Individual pipe roughness coefficients (C-factors) were adjusted until the calibrated <br />system model closely simulated field test data as indicated in Table 2. As indicated from Tests 4 <br />and 12, the model was unable to be calibrated to match the field tests. For Test 4, it is believed <br />there was an error when measuring during the field test. The age and size of the pipe on 142nd <br />Ln. NW is the same as the pipe on 140th Ave. NW (Test 3), which the model calibrated closely <br />with. It is believed that the pipe roughness coefficient used for the pipe on 142nd Ln. NW is <br />accurate. For Test 12, it is believed that there is another pipe off of Bunker Lake Blvd. that <br />connects to the new development along 147th Ln. NW that is not yet geo-located, because when <br />adding an additional pipe, the model calibrates closely with the field data. The pipe along 147th <br />Ln. NW is a new 8" pipe, so it is believed that the pipe roughness coefficient used for the pipe is <br />accurate. Additionally, Test 10 was conducted on hydrants in a new development. Previously, <br />this area was at a lower elevation than it is currently. This caused the model to not correlate well <br />with the field-testing data. The elevations of the hydrants in the model were adjusted to more <br />closely correlate with the field data, and as the pipe in the development is new, it is believed that <br />the pipe roughness coefficient used for the pipe is accurate. <br />Once the computer water model was constructed and calibrated, the model was used to calculate <br />the operating conditions in the water distribution system. <br />existing System Static Pressures <br />Water system pressure is primarily a function of elevation with some degree of pressure loss as <br />water flows across the system. Static pressures throughout the distribution system as <br />determined by the water model are shown in Figures 1-3 in Appendix B for average day demand <br />(ADD), maximum day demand (MDD), and Peak Hour Demand. Low pressures generally occur <br />in areas where the elevations are relatively high compared to the overflow elevation or hydraulic <br />grade line (HGL) of the system. <br />As you can see in Figures 1-3 in Appendix B, the pressures across the system are generally <br />consistent, and are approximately the same between the three demand scenarios. All areas of <br />the system are within the range of 50 to 80 psi as you can see in Table 3. <br />FEASIBILITY STUDY RAMSY 154354 <br />Page 4 <br />