DDW-2025-008324

Page 0

WATER SYSTEM ANALYSIS

HIDDEN CANYON
E A S T Z I O N , U T A H

P R E PA R E D F O R :
K E V I N M C L AW S
H I D D E N C A N YO N , L L C

P R E PA R E D B Y:
K E L LY C H A P P E L L , P E

R E V I E W E D B Y:
K E L LY C H A P P E L L , P E

E N S I G N E N G I N E E R I N G
2 2 5 N O R T H 1 0 0 E A S T
R I C H F I E L D, U T 8 4 7 0 1
( 4 3 5 ) 8 9 6 - 2 9 8 3

J U N E 2 1 , 2 0 2 5

10675582-2202
KELLY L.
CHAPPELLLICENSED PROFESS IONAL ENGINEER
STATE OF UTAH

HIDDEN CANYON

Page 1
TABLE OF CONTENTS
TABLE OF CONTENTS .......................................................................................................... 1
LIST OF TABLES .................................................................................................................... 1
1. PROJECT OVERVIEW/LOCATION ............................................................................... 2
2. DESIGN OBJECTIVES AND METHODOLOGY .............................................................. 4
2.1. EXISTING PEAK DAY DEMAND REQUIREMENTS .................................................... 4
2.2. PROPOSED PEAK DAY DEMAND REQUIREMENTS.................................................. 4
4.0 PROPOSED TRANSMISSION/DISTRIBUTION.................................................................. 6
CONCLUSIONS .................................................................................................................... 7

LIST OF TABLES
Table 2.1-1 Existing zion mountain ranch peak day demmands ................................................................................... 4
Table 3-2.2-1 SOURCE REQUIREMENTS ............................................................................................................................ 5
Table 3-2.2-2 STORAGE REQUIREMENTS ......................................................................................................................... 5
Table 2.2-3 Source Demmand summary ............................................................................................................................ 5
Table 4-0-1 PRESSURE ZONE .............................................................................................................................................. 6
Table 4-0-2 PRESSURES ........................................................................................................................................................ 6
Table 4-0-3 FIRE FLOW RESULTS ........................................................................................................................................ 7
Table 4-0-4 MAXIMUM VELOCITIES ................................................................................................................................... 7

HIDDEN CANYON

Page 2

1. PROJECT OVERVIEW/LOCATION
This water system analysis was prepared to determine culinary water and fire flow demands and water
line sizes for the Hidden Canyon, located North Highway 9 between Mt. Carmel Junction and Zion
National Park, UT. The proposed development adds 61 nightly rental keys, a 70-seat restaurant and
small conference area. A proposed 500,000-gallon tank is proposed to be construct just North West of
the project site. The proposed water source for this project is Big Springs listed as WS002 in DEQ’s
database.

Although no future developments beyond the 61 keys are proposed now, a master plan for the area has
been performed showing possible future pressure zones, if development continues. Future planning
considers additional sources being pumped to the proposed 500,000-gallon tank. From this tank, a future
distribution line could be built to service other parcels in other zones. Currently, the proposed action is
the 500,000 gallon tank, approximately 1920’ of 12” water transmission line and approximately 7,900’ of
8” water distribution line along with four Pressure Reducing Valves (PRV’s). Figure 1 below shows the
vicinity map of the project, Figure 2 shows the overall master plan map, and Figure 3 shows the overall
utility plan of the project.

Page 3

This page is intentionally left blank
HIDDEN CANYON

Page 4

HIDDEN CANYON

Page 5

HIDDEN CANYON

Page 6

Page 4

2. DESIGN OBJECTIVES AND METHODOLOGY
2.1. EXISTING PEAK DAY DEMAND REQUIREMENTS

To determine the existing peak day demand requirements, R-309-510 was used to determine the existing
peak day demands. Existing connections consist of nightly rental units (59), a small restaurant (50
seats), and recreational homes (26).

The total peak day demand for Zion Mountain Ranch is 14.6 gpm. Calculations and figures are shown in
table 2.1-1 below.

TABLE 2.1-1 EXISTING ZION MOUNTAIN RANCH PEAK DAY DEMMANDS

2.2. PROPOSED PEAK DAY DEMAND REQUIREMENTS

Proposed Peak Day demands were based off of R-309-510. Proposed in the development include 61
nightly rentals, a 4 washer laundry facility a 72 seat restaurant, and a 150 person meeting hall. There is
no outdoor/irrigation demand required for the proposed resort. Total Demand Calculations shows the
type of connection, the number of units per connection, Peak Source Demand, and Storage Demand.
Based on the demand calculations, the peak day demand for the resort is 11 gpm as shown in table
3.2.2-1. Table 3-2.2-3 shows that Zion Mountain Resort, with the proposed improvements would still
have a surplus of 18 gpm.

Item Number Facility Qty Units
Unit
Demand
(gpd)
PDD
Demand
for All
Units (gpd)
Storage
Demmand
(gal)
Peak
Day
Demmand
Utah Code R-309-510
Code Reference
EXISTING
100 Zion Moutain Ranch
101 Restaurant 50 Seats 35 1,750 875 Restaurant, Ordinary
102 Keys 59 units 150 8,850 4,425 Hotel
10,600 5,300 7.4 gpm
200 Peaches
201 Lots 26 Lots 400 10,400 5,200 Recreational Home
10,400 5,200 7.2 gpm
TOTAL 14.6 gpm
HIDDEN CANYON

Page 5
TABLE 3-2.2-1 SOURCE REQUIREMENTS

Average demand for the resort (typical operating value) was assumed to be 50% of the peak day
demand. This value was also used to determine the size of storage required for the proposed resort. This
also include capacity to have enough for fire flow, which is 1,500 gpm for 2 hours, or 0.18 MG. The total
storage required is 186,220 gallons.

TABLE 3-2.2-2 STORAGE REQUIREMENTS
Proposed Peak Day Demand Storage
Requirement
187,745 gallons

TABLE 2.2-3 SOURCE DEMMAND SUMMARY
SOURCE REQUIREMENTS
Existing ZMR 15 gpm
Proposed Hidden Canyon 11 gpm
TOTAL 26 gpm
AVAILABLE 40 gpm
SURPLUS 14 gpm
ESTIMATED PEAK DAY DEMMAND CULINARY WATER SOURCE DEMMAND
Item Qty Code Item from R-309-510
Keys 61 room Hotels, Motels, and Resort 150 per unit 9150 gallons per day
Launderette 4 Washer Launderette 580 per washer 2320 gallons per day
Restaurant 72 Seats Food Service-Ordinary 35 per seat 2520 gallons per day
Meeting Hall 150 People * Estimate-No Item in R-309-510 relates 10 Per Person 1500 gallons per day
TOTAL 15,490 gallons per day
10.76 Gallons per minute
STORAGE SIZING
Fire Flow Storage
7,745 gallons per day 180,000 187,745 gallons Provide 500,000 gallons of storage
as sized to account for future
growth in the region
Unit Demand Total
Est. Peak Day Demmand Storage Required Storage Provided
Page 6

4.0 PROPOSED TRANSMISSION/DISTRIBUTION
The proposed project improvements were modeled and analyzed using the Bentley WaterCAD V8i
computer software. The junction elevations for the water model are based on the proposed ground
elevations at the junction points. The pipe sizes and lengths are based on the proposed civil design plans
and the necessary pipe sizes to meet requirements. The existing pressures, demands, and scenarios
described in the previous sections were implemented in the water model to verify the performance of the
proposed water system. The model was analyzed to include the demand for future phases within the
resort.

Demands for the model included the demand for the first phase of development as well as the demands
for the future phases. To be conservative in the hydraulic model and account for future development that
has not been fully planned out yet, a peak day demand of 120 gpm was used even though phase 1 only
requires 9 gpm. A factor of 2 was applied to the peak day demand to determine the peak instantaneous
demand.

The proposed system consists of 12” and 8” water line. The 12” water line is from the tank down to the
first main PRV, then looped 8” below that.

As required by State Code, the development shall meet the following minimum dynamic water pressure
requirements (R309-105-9(2)):
• 20 psi during conditions of the Fire Flow Demand (FFD) experienced during Peak Day Demand,
as well as a fire flow minimum of 1,500 gpm and velocity constraints of 10.0 ft/s. The velocity
constraint was used to help in design of the pipe size by forcing the velocity to be no more than
10.0 ft/s in any pipe.
• 30 psi during Peak Instantaneous Demand.
• 40 psi during Peak Day Demand.
Due to the size of the resort, the changes in elevation, the system was modeled with five different
pressure zones. The pressure zone elevations and pressure ranges are shown in the Table 4-1 Pressure
Zones.
TABLE 4-0-1 PRESSURE ZONE
Zone Elevation Range
(ft) Pressure Range (psi)
1 6975-6825 54-120
2 6825-6700 55-110
3 6700-6575 55-110
4 6575-6450 55-110

The table below lists the minimum pressures for each of the required flow scenarios:

TABLE 4-0-2 PRESSURES
Flow Demand
Scenario
Location of
Min.
Pressure
Minimum
Pressure
Required (psi)
Minimum
Pressure
Obtained
(psi)
Location
of Max
Pressure
Max
Pressure
Obtained
(psi)
Average
Pressure
(psi)
HIDDEN CANYON

Page 7
Peak Daily Demand
(PDD) J-20 40 54 J-17 125 82
Peak Inst. Demand
(PID) J-20 30 54 J-17 125 82

Table 4-3 gives a summary of the junction with the lowest fire flow available as well as the average fire
flow available for the entire development.
TABLE 4-0-3 FIRE FLOW RESULTS
Flow Demand
Scenario
Location of
Min. Fire
Flow
Minimum
Pressure
Required (psi)
Minimum
Pressure
Obtained
(psi)
Fire Flow
Required
(gpm)
Fire Flow
Obtained
(gpm)
Average
Fire Flow
(gpm)
Fire Flow with PDD J-15 20 20 1,500 1,579 1,981

Table 4-4 gives a summary of the pipe velocities for the system for each of the scenarios analyzed. For
fire flow it was analyzed with a 10.0 ft/s constraint.

TABLE 4-0-4 MAXIMUM VELOCITIES

CONCLUSIONS
The water model analysis demonstrates that the proposed waterline system will provide adequate
pressure for the required residential and fire flow demands. The pipes within the proposed network have
been sized to minimize head loss but comply with Utah State Code design requirements.

Ensign Engineering

Kelly Chappell, PE

Flow Demand Scenario Location of Max. Velocity Maximum Velocity Required (ft/s) Maximum Velocity Obtained (ft/s) Average Velocity (ft/s)
Peak Daily Demand (PDD) P-1 N/A 0.48 0.25
Peak Inst. Demand (PID) P-1 N/A 1.50 0.47
1,500 gpm FFD with PDD P-1 N/A 10.00