WA9403-CS 940707Rady & Associates, Inc.
Engineers · Architects · Planners
July 7, 1994
Mr. Ken Griffin, P.E.
City of Coppell
255 Parkway Blvd.
Coppell, TX 75019
RE: Sandy Lake Road Water Line Size
Coppell CIP/Impact Fee
R&A No. 94028
Coppell No. WA 94-03
Dear Ken:
Based upon the analysis of the City's ultimate water distribution system, Rady &
Associates, Inc. recommends the construction of a new 36" water line in Sandy Lake
Road from MacArthur Boulevard to Denton Tap Road. In order to determine the size
of rids water line, several alternatives were evaluated:
a) Install a new 24" water line parallel to the existing 16".
b) Install a new 30" water line and abandon the existing 16".
c) Install a new 30" water line parallel to the existing 16".
d) Install a new 36" water line and abandon the existing 16".
a) Installing a new 24" water line parallel to the existing 16" will not be
adequate for ultimate demands because headlosses will be too great to
overcome and still maintain minimum acceptable water levels in the elevated
tanks. Further increasing the pump head will result in pressures in the eastern
part of the system greater than recommended, causing increased energy
consumption and maintenance requirements within the distribution system.
b), c) , d) Installing a new 30" or 36" water line in Sandy Lake Road will provide more
efficient pumping and maintain reserves in the elevated tanks during the
maximum day demands. The 36" water line is recommended because it
provides the more efficient pumping characteristics and maintains minimum
elevated storage reserves of approximately 40%. Keeping the existing 16"
water line in service does not significantly enhance the resulting pressures or
pumping characteristics.
910 Collier Street · Fort Worth, Texas 76102-3542 · 817/335-6511 · Metro 817/654-4266 ° Fax 817/335-5070
Mr. Ken Griffin, P.E.
Page 2.
The results of the analysis are summarized below:
Max. Min. (% Reserves)
Pressure Pressure Min. Tank Levels
in System in System Existing Future
(psi) (psi) Tank Tank
a) 122 20 0.0% 25.4% (The model run
stopped when the
existing tank
emptied.)
b) 123 25 24.5 % 45.7 %
c) 123 20 21.0% 47.7%
d) 122 27 36.5 % 62.5 %
NOTES: The maximum pressure occurred at Village Parkway Pump Station. Modeling
the system with larger pumps to provide additional capacity against higher
total dynamic head, the maximum system pressure will rise to approximately
160 psi (proposed 24" water line in Sandy Lake Road).
The minimum pressure occurred at Bethel Road, west of Royal Lane.
Future tank is located on Thweat Road, west of Coppell Road.
If you have any questions regarding the enclosed information, please do not hesitate
to contact us.
Sincerely,
RADY & ASSOCIATES, INC.
~/bert J.~.
RJM/MRW/pb
P:\94028.00\94028LTR\WLSIZE. WP