21-104292 -Water System Hydraulic -10-14-2021-V1Lakehaven
WATER & SEWER DISTRICT
Hydraulic Model Fire Flow Estimate
Request/Reporting Form
RECEIVED
Nov 19 2021
CITY OF FEDERAL WAY
COMMUNITY DEVELOPMENT
Requested By:
Federal Way Public Schools
Date:
11/24/2020
Location to be Modeled: Olympic View K-8 School / 1321039008 (Proposed Improvements)
Lakehaven %4 Section Grid:
E/9
intersection:
SW 327t' St & 26th Ave SW
Add. Description:
See attached map
Pressure zone: 538
Results By:
Date:
Model Run No.:
John Bowe
12/04/2020
Master Water System Model 2007.net
FF #417
Condition
Pressure (psi)
Flow (gpm)
Static
85
0
Fire Flow
20
4500
NOTES:
Lakehaven's adopted level of service goals for fire flow rates are 1000 gpm within single
family residential areas (including duplexes) and 2500 gpm for multi -family, commercial,
industrial areas.
Model results depict the theoretical performance of the water system under high demand
conditions and are not guaranteed to represent actual system performance. A design
professional should be consulted for site specific design purposes.
The calculated fire flow capacity in the above table is based on a currently available residual
system pressure of 20 psi at the location modeled. The model indicates that Lakehaven's
standard maximum allowable velocity of 10 ft/s is exceeded at a fire flow rate above 2300
gpm. Fire flow capacities greater than 2300 gpm may be accommodated through water
system improvements.
12042OFF 417 - Olyimpic View Elm (Form Update 1/6/17)
The above model run assumed an 8" diameter pipe loop across the property with no off -site
improvements. No hydrant locations were provided, so a test point was assumed near the
center of the property. A portion of the proposed on -site piping also reach the maximum
design velocity for new main of 8 ft/s. To achieve a fire flow greater than the requested
2750 gpm, on -site and off -site improvements would be needed.
Option 1:
On -site mains assumed at 12" diameter. Off -site improvements increased sections A and B
(�530 ft) to 8" diameter.
This run provided a maximum of 3100 gpm without exceeding system velocities (6000 gpm
at 20 psi).
Option 2:
On -site mains assumed at 12" diameter. Off -site improvements increased sections B, C and
D (�630 ft) to 8" diameter.
This run provided a maximum of 2800 gpm without exceeding system velocities (5900 gpm
at 20 psi).
Option 3:
On -site mains assumed at 12" diameter. Off -site improvements increased sections A, D, and
E (�860 ft) to 8" diameter.
This run provided a maximum of 3100 gpm without exceeding system velocities (6000 gpm
at 20 psi).
120420FF 417 - Olyimpic View Elm (Form Update 1/6/17)