WA0003-CS 980219From the desk of...
Ken Griffin, P.E.
Director of Engineering &
Public Works
ATM
nGig 'era Aggies"
72)304-36 79 / (Metro d 71-2251)
SHIMEK, JACOBS & FINKLEA, L.L.P.
CONSULTING ENGINEERS
8333 Douglas Avenue, #820 Dallas, Texas 75225-5816 Fax (214) 361-0204 Phone (214) 361-7900
ROSS L. JACOBS, P.E.
RONALD V. CONWAY, P.E.
JOHN W. BIRKHOFF, P.E.
JOE R. CARTER, P.E.
GARY C. HENDRICKS, P.E.
I. C. FINFLEA, P.E.
February 19, 1998
Mr. Kenneth M. Griffin, P.E.
City of Coppell
Post Office Box 478
Coppell, Texas 75019
Re: Supplement to Water Distribution System ')
Hydraulic Model Update
Dear Mr. Griffin:
As you requested at our meeting on February 12, 1998, we have re-analyzed the City of Coppell's water
distribution system utilizing the Cybernet hydraulic modeling software. This letter serves as a supplement to
our 1997 Hydraulic Model Update report dated May 12, 1997. This supplement includes additional scenarios
for the proposed hotel development to be located at Northpoint Drive and S.H. 121. These scenarios are
outlined below.
Existing System
This scenario included running the same fire flow condition as outlined on page V-12 of The Water
Distribution System Master Plan prepared for the City of Coppell by Rady and Associates, Inc., in December,
1994, and comparing results. As you may recall, the 1994 report was prepared based on computer modeling
using the Kentucky Pipe (KY Pipe) software. We have recreated Table I0 of Rady's report below and added
a column showing the results using the Cyberuet file Exist_97.dwg.
TABLE 10
EXISTING FIRE FLOW DEFICIENCIES
Node No.
101
151
152
Location
Corporate Park Blvd. @ S.H. 121
Thweat Rd. at Royal Lane
Thweat Rd. at Royal Lane
Minimum Minimum
Residual Residual
Required Fire Pressure , Pressure
Flow (psi)* (psi)*
(gpm) Rady Report Cybernet
3,000 -168 -146
3,000 15 24
3,000 12 18
Mr. Kenneth M. Griffin, P.E,
City of Coppell
February 19, 1998
Page No. 2
Minimum Minimum
Residual Residual
Required Fire Pressure Pressure
Flow (psi)* (psi)*
Node No. Location (gpm) Rady Report Cybernet
153 Thweat Rd. at Royal Lane 3,000 17 24
201 Northpoint Dr. - West End 3,000 4 8
202 Northpoint Dr. @ Royal Lane 3,000 18 26
203 Gateview Blvd. - West End 3,000 13 16
205 Creekview Dr. 3,000 13 16
351 Coppell Rd. @ S.H. 121 3,000 -170 -149
352 Coppell Rd. near S.H. 121 3,000 -38 8
356 Coppell Rd. @ Corporate Park Blvd. 3,000 -26 33
401 Coppell Rd. @ Parkway Blvd. 3,000 -3 59
409 Coppell Rd. @ Minyard Dr. 3,000 0 57
413 Minyard Dr. @ Hampton Court 3,000 -2 57
420 Thweat Rd. @ Oakbend Dr. 3,000 8 38
421 Thweat Rd. @ Branchwood Trail 3,000 8 44
422 Thweat Rd. @ Coppell Rd. 3,000 9 48
559 Crestside Dr. near Lakeshore Dr. 3,000 18 14
1413 Fairway Dr. @ Belt Line Rd. 3,000 15 64
1414 Eastern End of Belt Line Rd. 3,000 -162 -128
* Fire flows simulated during maximum day demand (average hour) with elevated tank water level = 652.00
and 2 -450 horsepower pumps on at the Village Parkway Pump Station.
As you can see from the table, some pressures using the Cybernet software differ somewhat from those in the
Rady report. A possible explanation for these differences is that the geometry of the system in the KY Pipe
model was incorrectly input into the model. When we originally converted the KY Pipe model to the
Cybernet format, a number of pipes crossed the City from corner to corner, indicating mistakes in the original
input data for the KY Pipe model. This data was corrected in the Cybernet model. It is our opinion that the
results obtained for this supplemental report using Cybernet, closely resembles the pressures that the City
would encounter at these locations under these fire flow conditions.
Proposed System
As requested, we ran a couple of scenarios using the Cybernet file Prop_97.dwg, but deleted the Wagon
Wheel Ranch Elevated Storage Tank and the Sandy Lake Road water line improvements. The first scenario
included a maximum hour demand analysis of the proposed hotel development at Northpoint Drive and S.H.
121. We calculated a total maximum hour demand for the hotel of 1,000 gpm assuming the hotel used a 6-
inch meter for the hotel and a 3 -inch meter for irrigation purposes. This demand exceeds the minimum
requirements of the TNRCC of 1.5 gpm per connection during the maximum hour demand condition
assuming each of the 240 proposed hotel rooms is counted as a connection. We believe this is a conservative
approach to predicting the hotel demand. The results of this analysis indicate that 1,000 gpm can be supplied
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Mr. Kenneth M. Griffin, P.,.
City of Coppell
February 19, 1998
Page No. 3
to the hotel during the maximum hour demand at a pressure of approximately 32 psi. Pressures within the
system range between 32 psi and 93 psi during this demand condition with 2 -450 horsepower pumps in
operation at the Village Parkway Pump Station.
The second scenario included a fire flow analysis of the proposed hotel development during the maximum
hour demand condition. A fire flow demand of 3,500 gpm was distributed equally between junction nodes
153 and 201 as shown on the City's hydraulic map. The results of this analysis indicate a pressure of negative
58 psi ( -58 psi) at junction node 201 during this condition with 2 -450 horsepower and 2 -250 horsepower
pumps in operation at the Village Parkway Pump Station. This scenario clearly indicates that this fire flow
could not be supplied to the hotel under these conditions and the need for the Wagon Wheel Ranch Elevated
Storage Tank and Sandy Lake Road water line. Under this same scenario, a fire flow of approximately 1,057
gpm at 35 psi can be supplied to junction node 201 or 1,182 gpm at 35 psi can be supplied to junction node
153 while maintaining a minimum pressure of 35 psi within the remainder of the water distribution system.
We are available to discuss the hydraulic analysis of the City's water distribution system and this
supplementary report further at your convenience.
Sincerely , o
/
ary C. e drick , P. `
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