(1) General
Requirements.
The distribution system shall be designed to ensure adequate
flow and that minimum water pressures as required in
R309-105-9 exist at all points within the distribution system.
(2) Peak Instantaneous Demand for Indoor
Water Use.
(a) Large or complex water systems
may determine peak instantaneous demand using hydraulic modeling. The hydraulic
model must either apply an instantaneous peaking factor to account for peak
instantaneous demand or use actual peak instantaneous water flow data.
(b) Alternatively, the peak
instantaneous demand for a single pipeline shall be calculated for indoor use
using the following equation:
Q = 10.8 x N
0.64
where N equals the total number of ERC's, and Q equals the
total flow (gpm) delivered to the total connections served by that pipeline.
(c) For Recreational
Vehicle Parks, the peak instantaneous flow for indoor use shall be based on the
following:
TABLE 510-6
Peak Instantaneous Demand
for Indoor Water Use for
Recreational Vehicle Parks
Number of Connections Formula
0 to 59 Q = 4N
60 to 239 Q = 80 + 20N0.5
240 or greater Q = 1.6N
NOTES FOR TABLE 510-6:
Q is total peak instantaneous demand (gpm). N is the
maximum number of connections. However, if the only water use
is via service buildings, the peak instantaneous demand shall
be calculated for the number of
plumbing fixture units as
presented in the state-adopted plumbing code.
(d) For small
non-community water systems, the peak instantaneous demand for indoor water use
shall be calculated on a per-building basis for the number of plumbing fixture
units as presented in the state-adopted plumbing code.
(3) Peak Instantaneous Demand for Irrigation
Use.
Peak instantaneous demand for irrigation use is given in
Table 510-7. The procedure for determining the map zone and irrigated acreage
for using Table 510-7 is outlined in
R309-510-7(3).
TABLE 510-7
Peak Instantaneous Demand for Irrigation Use
Map Zone Peak Instantaneous Demand
(gpm/irrigated acre)
1 4.52
2 5.60
3 6.78
4 7.92
5 9.04
6 9.80
(4) Fire Flow.
(a) Distribution systems shall be designed to
deliver needed fire flow if fire flow is required by the local fire code
official or if fire hydrants intended for fire flow are provided. The
distribution system shall be sized to provide minimum pressures as required by
R309-105-9 to all points in the distribution system when needed fire flows are imposed
during peak day demand in the distribution system.
(b) The water system shall consult with the
local fire code official regarding needed fire flow in the area under
consideration. The fire flow information shall be provided to the Division
during the plan review process.
(c) If direction from the local fire code
official is not available, the water system shall use Appendix B of the
International Fire Code, 2015 edition, for guidance. Unless otherwise approved
by the local fire code official, the fire flow and fire flow duration shall not
be less than 1,000 gallons per minute for 60 minutes.
Notes
Utah Admin. Code R309-510-9
Amended by
Utah
State Bulletin Number 2015-15, effective
7/15/2015
