The hydraulic computer model was used to simulate system conditions for existing demands. The model was set up as an extended period peak day model to capture both peak day and peak hour demand periods. Peak day demands with fire flow were also modeled. Model results for these scenarios are included in the following figures:
1. Figure 7-1 shows minimum pressures for the existing water system with peak day demands.
a. Zone 1 has minimum pressures greater than 120 psi along the eastern edge near the Jordan River. This area typically ranges between 120 psi and 150 psi. While the City prefers pressures to remain under 120 psi, it is not a requirement. All service lines in the area should be equipped with a functioning service line PRV.
b. Along the western edge of Zone 1, west of 2700 W, minimum pressures drop below 50 psi. While pressures are lower than the desired range, they are not in violation of State requirements.
c. The southwest corner of Zone 1 also has pressures that drop below 50 psi. This area can range between 43 psi and 55 psi, primarily due to its elevation along the western boundary of the zone.
d. In Zone 4, pressures are above 120 psi north of 7800 S, along the eastern pressure zone boundary. This area ranges between 120 psi and 140 psi. While the City prefers pressures to remain under 120 psi, it is not a requirement. All service lines in the area should be equipped with a functioning service line PRV.
e. The northern half of Zone 5 along the western pressure zone boundary have pressures that drop below 50 psi. This area can drop to 45 psi during the peak of the day.
2. Figure 7-2 shows maximum pipe velocities for the existing water system with peak day demands.
a. A large majority of the pipes in the City's water system have velocities under 5 ft/second.
3. Figure 7-3 shows available fire flows during the peak day of demand with a residual pressure of 20 psi.
a. There are a few areas of the distribution system that do not meet fire flow requirements. In general, most fire flow deficiencies are caused by the following concerns:
i. High Elevation - Junctions near the upper end of pressure zones will have difficulty meeting fire flow requirements without large supply pipes and looping.
ii. Dead-Ends - Dead end connections often have fire flow deficiencies because high velocities through a single pipe cause higher pressure losses. Dead-end connections frequently require oversized pipes to meet fire flow requirements unless the connection can be looped another way.
iii. 6-inch and Smaller Pipes - The City has a few areas that cannot meet fire flow demands due to small pipes. Many cul-de-sacs are fed by a 6-inch, dead end pipe. If the small pipe is in a long street, or a neighborhood completely fed by small pipes, fire flows at the furthest junction may not be able to meet the 1,000 gpm requirement.
b. One non-residential location, West Jordan Elementary School, is not able to meet the specified 3,250 gpm fire flow requirement. The model shows the current available fire flow at just over 1,600 gpm.
c. Residential areas that are not able to meet the fire flow requirement include:
i. 9240 S at Edenbrooke Way
ii. Executive Drive, from 7000 S to 7265 S
iii. Mcgregor Lane at Dunlop Drive
iv. Wood Cove Drive at 2940 West
v. Beverly Glen Avenue at 2470 West
vi. 2980 West at 7140 South
