HomeMy WebLinkAboutMisc B Bleyl & Associates 1722 Broadmoor
Suite 210
Planning • Engineering • Management Bryan, Texas 77802
A Tex.Reg. No. F-678
cx 11
May 22,2015
Erika Bridges
City of College Station
P.O.Box 9960
College Station,TX 77842
RE: Letter of Acknowledgement
Ms.Bridges,
This letter is to acknowledge that all infrastructure improvements have been designed to the City of College
Station and BCS Unified design guidelines and ordinances. The water, sewer, street, and drainage
infrastructure have been designed and analyzed to verify that they meet all appropriate rules and regulations.
All calculations,analysis,and construction documents were prepared under my direct supervision.
Should you or any member of the review staff have any questions, please do not hesitate to contact me at
979-268-1125.
Thank you again for your assistance.
Sincerely,
\AAA,/
. .10, ..\
Sam J.V rnon,P.E.
Project Manager
Bleyl&Associates
F-678
Bryan Austin Conroe
(979) 268-1125 (512) 328-7878 (936) 441-7833
(979) 260-3849 Fax (512) 328-7884 Fax (936) 760-3833 Fax
B Bleyl & Associates 1722 Broadmoor
Suite 210
Planning • Engineering • Management Bryan, Texas 77802
A Tex.Reg. No. F-678
ct
May 21,2015
Erika Bridges
City of College Station
P.O.Box 9960
College Station,TX 77842
RE: Revised Sterling Heights Fire Flow Analysis
Dear Erika,
As requested the fire flow capacity from the existing City of College Station 6" AC waterline on the north
side of Sterling Street to the proposed Sterling Heights development has been analyzed. The subject tract is
located on 218 Sterling Street in College Station approximately two blocks south of Holleman on the east side
of Texas Avenue.
A fire flow test was completed by the City of College Station on a fire hydrant located adjacent the property
at 211 Sterling Street. This fire hydrant is known as FH (E-151) under the City of College Station
nomenclature. Fire Hydrant (E-012) was also analyzed during this flow test for static and residual pressures
while FH (E-151) was flowed. The fire hydrant flow test is summarized in Table 1 below as well as attached
for your reference.
Table 1: Fire Hydrant Flow Test
FH(E-151) FH(E-012)
Flow(gpm) 1,455 NA
Pilot reading(psi) 70 NA
Static pressure (psi) NA 100
Residual pressure(psi) NA 94
The existing City of College Station waterline was modeled in Bentley NVaterCad V8i to determine the
available amount of fire flow to the proposed development. A schematic layout of the model and the
WaterCAD input and output data is attached for your reference.The first step in the modeling process was to
calibrate the model to accurately represent the flows and pressures determined during the fire flow test. First
the model was set up to have a static pressure in the system of 100 psi as determined in the fire flow test.The
approximate elevation of the existing line at this location is 300'. A pressure head of 531'was assigned to the
reservoir,"R-1", serving our model.This difference in pressure head is 231'or exactly 100psi.A reservoir was
used to recreate the static pressure found in FH (E-112) simplifying the model to avoid recreating the system
upstream of our area of concern. R-1 represents pressures served by the City of College Station water system.
The second calibration was done was to ensure that FH-(E-151) was left with a pressure of 70psi when
flowing at 1,455gpm. This was completed by assigning a calculated length to P-1, the pipe connecting "R-1"
and FH-(E-151).This calculated length created the head loss required to decrease the pressure in FH-(E-151)
to 70 psi when flowing at 1,455gpm. This length, although arbitrary in itself, represents the headloss
Bryan Austin Conroe
(979) 268-1125 (512) 328-7878 (936) 441-7833
(979) 260-3849 Fax (512) 328-7884 Fax (936) 760-3833 Fax
determined in the City of College Station fire flow test through the existing piping, bends, etc. thus
simplifying the model.
Once the model was calibrated a single fire flow analysis was completed of the subject development with a
single fire wall.The results the scenarios are summarized in Table 2 below.
Table 2: Fire Flow Analysis
Scenario Construction Building IBC Fire Fire Flow Fire Sprinkler Peak Residential
Type Area(SF) Area(SF) (gpm) Demand(gpm) Demand(gpm)
<15,600
Single Fire Wall V-B 28,861 1,750 180 108
>18,000
P-1 flow/avg velocity(') P-2 flow/avg velocity
Scenario (gpm)/(ft/sec) (gpm)/(ft/sec) Pressure in Pressure @ Sterling
FH(E-151) Heights (psi)
Existing 6"AC line Prop 4"Service
Static Test 0/0 0/0 100 100
Fire Flow Test 1,455/8.26 0/0 70 70
Single Fire Wall 2,038/11.56 288/7.35 45 44
Notes:
(1) The average velocities were determined by taking the velocity in P-1 and dividing it by two.Currently the Bleyl
& Associates model only feeds FH(E-151) from one direction. This assumption was made knowing that the
actual distribution system feeds FH(E-151) from both directions creating a looping system. The flow was
assumed to be fed evenly from both side of the distribution system in fire flow conditions thus decreasing the
velocity in each supply pipe by half. The BCS Unified Guidelines limit velocities in a main to 12ft/sec under
fire flow conditions.The maximum velocity may be increased on a case by case basis.
The single fire wall scenario analyzed the proposed development as a "double" unit with one fire wall. As
previously stated the proposed apartments are a 28,861 SF Type V-B construction development. Under the
International Building Code (IBC) a Type V-B construction area between 15,601SF-18,000SF requires
3,500gpm of fire protection. Since this development will include fire protection sprinklers the required fire
flow can be reduced by 50% to 1,750gpm. Under a fire flow analysis of 1,750 gpm,including residential and
fire sprinkler demand, a minimum pressure of 44 psi was maintained at FH(E-151) and the proposed Sterling
Heights development.
To summarize, the analysis proves that if the building is constructed as proposed with 28,861SF, Type V-B
construction, 108 gpm maximum residential demand, and 180gpm fire sprinkler demand that one fire wall
will be required to meet fire flow regulations. Under these conditions 1,750 gpm of fire flow will be required
which would leave a pressure of 44psi in the distribution system. Under this flow scenario the velocity in the
existing 6"main would be 11.569ft/sec which under the 12ft/sec limit.
Sincerely
.gt.....
•
David L.Besly,P.E. 0*i
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Project Manager •
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Bleyl&Associates j DAVID L. BESLY
F-678 �Ij'09.• 81873 `Q1
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Scenario: Fire Flow Calibration
FH-(E-151) R-1
P-1
r.
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Sterling Heights
Bentley Systems,Inc. Haestad Methods Solution Bentley WaterCAD V8i(SELECTseries 5)
Sterling Heights Fire Flow.wtg Center (08.11.05.61)
2/25/2015 27 Siemon Company Drive Suite 200 W Page 1 of 1
Watertown,CT 06795 USA +1-203-755-1666
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CCeCollege Station Utilities
Reliable, Affordable, Community Owned
Date test completed Thursday, February 19, 2015
Time completed 2.00
Test completed by JUSIN
Witness HOWARD
FLOW HYDRANT
Location 221 STERLING
Nozzle size 2.5
Hydrant number E-151
Pitot reading in PSI 70
Flow in G.P.M. 1455
STATIC HYDRANT
Location 311 STERLING
Hydrant number E-012
Static PSI 100
Residual PSI 94
Comments REQUESTED