WA9402-CS 911121 GINN & CASE, INC. CONSULTING ENGINEERS
November 21, 1991
Mr, Steve GoRAM
Director of Public Works
City of Coppell
P.O. Box 47g
Coppe!l, Texas 75019
Re: Proposed Hackberry Rd. Supply Maln & Rate of Flow Controller
Dear Mr. Goram:
Per your request, we have evaluated the possibility of moving the proposed
Hackberry R.O.F.C, to the northern portion of the City to allow cost sharing
with Lewisville and Flower Mound, In our opinion, this would not be in the
best interest of the City of Coppeil and would most likely result in higher
capital and operating costs for the City,
The current Master Plan calls for a new 24' main along Sandy Lake Road from
the Village Parkway Pump Station to the proposed elevated tank at Sandy Lake
(Thweat) and Freeport, The plan also calls for a second rate oF flow
controller in the vicinity of South Belt Line Road and Hackberry Road. There
are several fundamental hydraulic factors which led to these projects and
their proposed locations;
1) The Village Parkway site is at elevation' of 450' msl. This is one of the
lowest points within the city. Operating pressure limitations and system
hydraulics will restrict the VPPS a maximum input of 17-20 MGD to the
'water system. Since ultimate projections indicate a potential demand of
27 MGD, a second supply with ground storage and high service pumps will
be required. In order not to interfere with the VPPS, the proposed
station should be as far away as possible with an elevation more
consistent wi~h the industrial areas of town.
2) When designing an efficient water system, it is desirable to have the
load center (demand) between the elevated storage and pumping station.
This allows the system to minimize pumping head and maximize the benefits
of elevated storage, A graphic depiction of thls principal is attached
(see figure 6-22 & 6-23 from Water and Wastewater Technology by Mark J.
Hammer, John Wiley & Sons).
The Hackberry site places the bulk of Coppell's light industrial areas
between the proposed pump station and the existing elevated tank. It
also has a ground elevation of :~537' msl or ~87' higher than VPPS. This
would result in a ~:175 HP reduction from the VPPS motor size for a 10 MGD
pu rap. ~ ~~.~~,~,~////,
17103 Pr~ion Road * Suitel00 ® Dallas, Texas75248 · Phone 214/248-4900
P.O. Box796577 · Dallas, Texas75379-6577 , FAX 214/931-145l
The 24" main in Sandy Lake Road is proposed for a dual purpose. This
wlll allow the YPPS to pump to the proposed elevated tank with minimal
friction head losses and when the pumps are not running, the main will
equalize pressures and provide flow from the proposed elevated tank to
the areas primarily north of Sandy Lake Road. The existing 16" in Sandy
Lake is undersized for allowing the VPPS to efflclently~ pump to the new
elevated tank. The old elevated tank, existing 24" Cro'js-town main and
existing 16'in Sandy Lake Road will serve the areas south of Sandy Lake.
4) Construction In and along the Sandy Lake Road corridor will be difficult
and expensive due to the existing 8" and I6~ Coppell waterlines, 30" DWU
water!ino, gas, phone, electrical, and storm sewers from the proposed
widening. It is our opinion that Lewisrifle and Flower Mound will find
it more economical to route the proposed line north along MacArthur
through less congealed areas. Putting the station in the northern most
portion of the city would be of little benefit to the southwestern
portion of the City. This would also necessitate an increase in main
size of many proposed l[nes in the western half of the city.
Construction along Hackberry will be through less conSeated areas and
subsequently less expensive.
5) The existing DWU main to DFW airport currently runs along Hack berry Road.
The Hackberry site may allow for an emergency interconnect with the
existing DWU line. This could possibly allow for the station to have a
supply from two DWU systems.
In summary, the second R.O.F.C. and pump station are projected to serve growth
and demand in the southwestern industrial areas of the City. The Hackberry
site will satisfy this purpose with lower operational costs and higher
efficiency than other sites in the .northern portion of the City. An order of
magnitude estimate for the Hackberry site is attached for your use.
Current projections indicate the hackberry Rd. extension will not be required
until ~2010, We do recommend that the City participate at this time with
Irving in the oversizing of the new main from the Elm Fork Plant to Hackberry
Rd. This will minimize future capital costs, Should you have any questions
or need additional information, please feet free to contact our office,
San~~ CasY/"/~//~e, p.E'~/~.
attachments
cc: Howard Parford
File 90445 '.
.~ ' ESTIMATE OF PROBABLE PROJECT COST''
HACKBERRY ROAD EXTENSION
FROM IRVING'S DELIVERY POINT TO BELT LINE
36" R.C.P. ±9,000 LF @ $125/LF $1,125,000
54" Jack & Bore ±200 LF ~ $550/L[ 110,000
36w Valves 7 @ $7,500/ea. 52,500
Air Release Valve As~emblies 5 @ $3,000/ea. 15,000
Bonds/Insurance/Mobilization/Miso. 78,500
Subtotal $1,381,000
10% Contengencies 13S,000
Total Estimated Construction $1,519,000
Engineering/Administration/Inspection/ 39S,000
Testing
Total Estimate of Probable Project Cost $1,914,000
Ginn & Case, Inc.
11/21/91
170
140
2G,000 ft el 24~in,, C ,, 100 pipe
PumpTn, station '* Load center
Figure 6-22 Hydraulic gradients wjlh nO storage rot ]~x~mple 6-4.
Maximum deify plus partial tire flow (8.4 mid)
Max iml.~m daily (6,0 rm. ld)
210 - Peak h~lrlV (6.0 mcJd)
Average deity (4.0 rood) Averag0 ~dfy ~d maxim~m daily
176 _ ~~M
~' 171 ' Peak hourly (3.0
~ 146 aximum d~i~y plu~ fir~
.
~ -
~' ' ' ~ C= 100
Pu,~p;,~J Lo;d
~t~lion Cen~er tank
:}~ ~l' FIgure 6-23 }iydrRuliC gradients with elevatcd sloragc ~yond load ~ntcr ~or Examplc 6-4.