WA0003-CS 960621SHIMEK, JACOBS & FINKLEA
CONSULTING ENGINEERS
8333 Douglas Avenue,//820
D~las, Texas 75225
(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.
C. L. SHIMEK, P.E.
1. C. FINKLEA, P.E.
JAMES E. LAUGHLIN, P.E.
June 21, 1996
Mr. Kenneth M. Griffin, P.E.
Assistant City Manager/City Engineer
City of Coppell
Post Office Box 478
Coppell, Texas 75019
Re: Water Distribution System Master Plan Update
Dear Mr. Griffin:
As requested, we have completed our hydraulic analysis of the City' s existing and buildout water distribution
systems to determine what, if any, system improvements are required to construct the proposed 2 million
gallon elevated storage tank near the intersection of Northpoint Drive and Royal Lane
The basis of our analysis was the December 1994 Water Distribution System Master Plan Report prepared by
Rady and Associates and the KY Pipe data sets associated with their report. As you are aware, we had
previously converted these KY Pipe data sets to the Cybernet hydraulic model format for the City as we were
in the design phase of the additions to the Village Parkway Pump Station. The Cybernet hydraulic model was
used to aid our analysis and was updated as required to reflect the addition of new waterlines and demand
changes that have occurred since the model was prepared in 1994. System demands were increased by 10%
from the 1994 existing system hydraulic model to project probable system demands for the City in 1996. In
addition, the estimated demands for the proposed hotel development along the S.H. 121 corridor were also
added to the model based on water records for similar developments in the metroplex. The existing system
demands used in the hydraulic model are summarized below:
CITY OF COPPELL
Existing Water Distribution System
Hydraulic Model Demands
Year Average Day Maximum Day Maximum Hour Minimum Hour
Demand (mgd) Demand (mgd) Demand (mgd) Demand (mgd)
1994 4.25 14.03 28.13 3.36
1996 4.75 15.66 31.39 3.75
.Mr. Kenneth M. Griffin, P.E/~
City of Coppell
June 21, 1996
Page No. 2
Our analysis of the system began by constructing the tank in the model at the City's proposed location and
connecting the tank to the existing distribution system without including any other system improvements. This
analysis resulted in an unsatisfactory fill rate for the proposed tank.
A number of waterline locations and sizes were considered to connect the proposed elevated tank to the
existing system which were narrowed down to two options. The first includes the construction of a 24 inch
waterline in Sandy Lake Road west of Denton Tap Road. This distribution line connects the existing 16-inch
water lines in Sandy Lake Road and Denton Tap Road and would run west in Sandy Lake Road, northwest on
Coppell Road, west on Thweat Road, south on State Road, then west on Northpoint Drive to the proposed
elevated tank site. The second option requires the installation of a 24-inch waterline in State Road. This line
would connect to the existing 16-inch waterlines at the intersection of Bethel Road and Freeport Parkway and
run noah to Noahpoint Drive and west to the proposed elevated tank.
Computer analysis revealed that the proposed Sandy Lake Road water line allows the proposed and existing
elevated tanks to draw down and re-fill at satisfactory rates, and pressures within the system are within an
acceptable range. Although the State Road water line option does enhance the operation of the proposed tank,
it falls short of meeting the target refill rates. Various combinations of the two options did not provide for any
significant enhancement to the overall operation of the system. The tabulation below summarizes the results of
our hydraulic analysis of the City' s existing water distribution system:
Proposed 2.0 MG Elevated Storage Tank
Hydraulic Analysis Results
Analysis Condition
Existing System, No Improvements
Sandy Lake Rd 24-inch Water Line
State Rd 24-inch Water Lines
Draw-down Rate- MGD
(max. hr. demand)
Re~H Rate - MGD
(rain. hour demand)
Exist. 1.5 MG Prop. 2.0 MG Exist. 1.5 MG Prop. 2.0 MG
Tank Tank Tank Tank
9.3 3.5 4.3 0.63
5.6 7.2 6.4 3.8
7.2 5.6 3.8 1.2
We recommend the City consider including the construction of the Sandy Lake Road water line in with the
proposed elevated storage tank project. Including this line will provide for the best operation of the elevated
tank as well as being in conformante with the current master plan. Figure No. 1 shows the recommended
system improvements along Sandy Lake Road. Our opinion of probable construction cost of the distribution
system improvements recommended to properly operate the proposed elevated storage tank is in the range of
$1,200,000.
As with any distribution system utilizing more than one elevated tank, we also recommended that an
electronically controlled valve be installed at the existing 1.5 MG elevated tank and the proposed 2 MG
elevated tank so that in the event that one tank fills before the other, the filled elevated tank can be valved off
so the other tank can continue to fill. ~
Mr. Ker[neth M. Griffin, P.E~'~
City of Coppell
June 21, 1996
Page No. 3
As requested, a buildout computer analysis was also performed in order to verify the necessity of the proposed
36-inch waterline in Sandy Lake Road from MacArthur Blvd. to Denton Tap Road. For the buildout model,
we generally concur with the recommendations outlined in Rady and Associates 1994 Water Distribution
Master Plan Report. However, it should be noted that Rady's buildout hydraulic model does not include the
existing 16-inch waterline in Sandy Lake Road. Including this existing water line in the model allows the
recommended 36-inch water line to be reduced to a 33-inch diameter with roughly the same results. Figure
No. 2 shows our recommended buildout waterline improvements along the Sandy Lake Road corridor.
The 33-inch waterline is proposed to act as a transmission line dedicated to serve the western portion of the
City; therefore, this line could be located along another thoroughfare such as Parkway Boulevard (shown as
alternate route 2) or Bethel School Road (shown as alternate route 3). However, both of these alternative
routes are longer and would likely require the removal and replacement of existing concrete pavement,
significantly increasing the cost of the improvements. We recommend the Sandy Lake Road water line project
remain in the City' s long term master plan, but that consideration be given to decreasing the line size to 33-
inches in diameter.
We are available to discuss these proposed water distribution system recommendations further at your
convenience.
cc: Mr. Matt Cast
Enclosures
.~ndric ~
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Dallas, Texas
FIGURE NO. 2 JUNE, 1996
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SANDY LAKE ROAD CORRIDOR
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TRANSMISSION LINE MAP
EXISTING 24' WATER LINE Nii■ C _ BUILDOUT CONDITION
PROPOSED 33" WATER LINE \
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4 /0 , • _ CONSULTING ENGINEERS
Dallas, Texas
FIGURE NO. 2 JUNE, 1996