WA0003-AG010410F'
COPPELL AGENDA REQUEST FORM
CITY COUNCIL MEETING: April 10, 2001 ITEM # l~[
ITEM CAPTION:
Presentation and update to the City of Coppeli's Water System Plan and discussion of the Water
Conservation Plan.
SUBMITTED BY: Kenneth M. GrLf~, P.E.
TITLE: Director of Engineering/Public Works
STAFF COMMENTS:
See attached memo.
BUDGET AMT $ AMT. EST. $ +\-BID
FINANCIAL COMMENTS:
DIR. INITIALS: ~ FIN. REVIEW'~ CITY MANAGER REVI
Agenda Request Form - Revised 5/00 Document Name: #eng2
MEMORANDUM
FROM THE
DEPARTMENT OF ENGINEERING
To: Mayor and City Council Members
From: Kenneth M. Griffin, P.E., Dir. of Engineering/Public Works ~-~
Date: April 10, 2001
RE: Presentation and update to the City of Coppell's Water System Plan and discussion of the
Water conservation Plan.
The City has been evaluating its Water Distribution System and Conservation Plan. We have been
working with the consulting firm of Shimek, Jacobs and Finklea to provide us information on our current
and projected water consumption. I have attached a copy of their preliminary evaluation report to this
agenda item. The report will be discussed in detail at the Council meeting.
Our current maximum day for purposes of this study is 20 million gallons per day (mgd). This was
arrived at by averaging the usage during the peak summer months of 2000. We had days in excess of 22
to 23 million gallons, however, on average we used approximately 17 mgd. Based on our build-out
population, this report projects that the projected maximum day demand will be approximately 25 mgd.
The maximum hour demands will be discussed in greater detail at the Council meeting.
The recommendations from the study are that the City of Coppell should plan for a pump station capacity
of approximately 40 mgd. Our current capacity at Village Parkway Pump Station is approximately 27
mgd. While we can pump in excess of 27 mgd, TNRCC regulations require that the capacity of our station
be evaluated with the largest pump out of service. The consultant is recommending that the City of
Coppell pursue the construction of a 2nd pump station that would allow us to meet the recommendation of
40 mgd. The pump station recommendation is in lieu of building additional elevated storage. Our current
elevated storage capacity exceeds the TNRCC requirement of 1.2 million gallons and the State Insurance
requirement of 2 million gallons. The preliminary evaluation report also recommends approximately 4
million gallons of additional ground storage be provided at the proposed new pump station.
One other item which we have asked the consultant to evaluate is our water consumption by area of the
City. Additional information will be provided on this at the Council meeting. However, generally the
community has been divided into four quadrants with the common point being the intersection of Denton
Tap Road with Sandy Lake Road. As noted in the preliminary report, the northwest quadrant accounts for
approximately 18% of the total water use, the northeast quadrant accounts for approximately 30% of the
total water use; the southwest quadrant accounts for approximately 24% of the total water use; and the
southeast quadrant accounts for approximately 28% of the total water usage. In essence, if you divide the
community at Sandy Lake Road, the north side of Sandy Lake Road accounts for approximately 48% of
the water usage and the south side accounts for approximately 52% of the water usage. There could be
some margin of error associated with these numbers because not all parcels could be coded into the
database.
"CITY OF COPPELL ENGINEERING - EXCELLENCE BY DESIGN"
In addition to system requirements, staff will be discussing our Conservation Plan. As Council is well
aware, each May 15th the City of Coppell implements a mandatory Conservation Plan. This plan runs
through September 15th of each year. Implementation of the Conservation Plan does create arbitrary high
water usage on Tuesdays and Thursdays, in particular, and to somewhat of a lesser degree on Saturdays
and Sundays. Discussion at the Council meeting concerning the Conservation Plan will include
suggestions for revising the plan with potentially a revised ordinance brought back to Council at the April
24, 2001 Council meeting. I am still reviewing data provided to me by the consultant and I will provide
recommendations at the Council meeting concerning the City's Conservation Plan.
Staff will be available to answer questions at the Council meeting.
"CITY OF COPPELL ENGINEERING - EXCELLENCE BY DESIGN"
SHIMEK, JACOBS & FINKI,EA, L.L.P.
CONSULTING ENGINEERS
8333 Douglas Avenue, #820 Dallas, Texas 75225-5816 Fax (214) 361-0204 Phone (214) 361-7900
RONALD V. CONWAY, P.E.
~o~n,~ w. ~nu~orr, P.E.
JOE R. CARTER, P.E.
GARY C. HENDKICKS, P.E.
PAUL A. CARL[NE, P.E. March 29, 2001
MATT HICKEY, P.E.
ROSS L. JACOBS, P.E.
L C. FINKLEA, P.E.
Mr. Kenneth M. Griffin, P.E.
Director of Engineering & Public Works
City of Coppell
P. O. Box 478
Coppell, Texas 75019
Re: Water System Master Plan
Preliminary Evaluation and Report - Water Supply
Dear Mr. Griffin:
As provided in our contract for preparation of the City of Coppell's Water Distribution System Master Plan,
we have completed our preliminary evaluated the long-term requirements for the City's water distribution
system as it relates to water supply and pump station capacity. From our discussions with you and your staff,
we know the City currently receives its water supply from Dallas Water Utilities at the Sandy Lake Road
Pump Station and the Village Parkway Pump Station. With this background, we understood our task to
include:
1. Project the Maximum Day Demand at Build-out
2. Evaluate the Existing and Ultimate Pump Station Requirements
3. Evaluate the Existing and Ultimate Ground Storage Reservoir Requirements
4. Evaluate Pump Station Locations
5. Develop a Conceptual Pump Station Site Plan and Determine Property Requirements
6. Develop an Opinion of Probable Cost for the Recommend First Phase Pump Station and Ground
Storage Facility
7. Evaluate water system use over last summer and make recommendations for modifications to the
City's water conservation plan.
Basic Assumptions and Existing Conditions
In order to develop projected maximum day system demand, the planning boundary and land use assumptions
must be determined. From our discussions with you and your staff, we understand the current City Limits is
to be the planning boundary for the water distribution system. The planning area contains approximately 14.7
square miles or 9,410 acres of land. The current residential population is estimated to be 35,000.
j 'c I tm cal'~copl~llX2001 - I 0~\1 ~'~'vl ~.o~*~k~,p~'~liminary d~ign re'po~ $igneddoc
Mr. Kenneth M. Griffin, P.E.
Director of Engineering & Public Works
City of Coppell
March 30, 2001
Page Number 2
Service Connections (Existing)
Using data provided by the City's Utility Billing department, we evaluated meter reading data from July,
August and September of 2000. The tabulation below shows the meter count by general account type:
Residential Meters: 10, 300 connections
City Meters: 92 connections
Other Non-Residential Meters: 801 connections
Total System Connections: 11,193 connections
Maximum Day Demand (Historic)
Over the last several summers the City has implemented a Water Conservation Plan that sets forth a citywide
irrigation schedule. The schedule allows irrigation on certain days of the week. From our evaluation of the
daily consumption records available from last summer, we found the maximum daily demand placed on the
system to be in the range of 23 million gallons per day (mgd). However, over the course of the highest use
weeks of the summer, we found the City consumed no more than 17 mgd supply on average from the City of
Dallas. Based on our review of the data, we believe the 23 mgd rate is artificially inflated due to the citywide
irrigation schedule. For the purpose of this preliminary evaluation and report, we recommend the City
consider the maximum day demand for the existing system to be in the range of 20 mgd. The conservative
maximum day rate is 3 mgd ~eater than the current supply contracted for from the City of Dallas.
Maximum Hourly Demand (Historic):
Records from the summer of 2000 indicate that on August 1, 2000, the Village Parkway Pump Station
pumped a maximum of 30 mgd while at the same time the City's elevated storage tanks dropped a total of 6-
feet for a combined volume of 0.53 million gallons in one hour. Converting the tank volume consumed
during this peak hour to a rate and combining it with the pump rate from the Village Parkway Pump Station
yields a maximum hour rate of 42.6 mgd.
Based on this data, the city's maximum hour to maximum day ration is 2.13. This is marginally higher than
we have observed in other Metroplex area cities and appears to be related to the City's water conservation
schedule.
Per Capita Demands (Historic)
Based on the data evaluated from last summer, the maximum day and maximum hour per residential per
capita demands are calculated as follows:
Maximum Day Demand
20 MGD = 571 gallons per capita per day (gpcd)
35,000
20 MGD = 1950 gpd/connection.
10,300 connections.
Maximum Hour Demand
42.6 MGD = 1,217 gpcd
35,000
42.6 MGD = 4,135 gpd/connection.
Mr. Kenneth M. Griffin, P.E.
Director of Engineering & Public Works
City of Coppell
March 30, 2001
Page Number 3
The maximum day residential per capita demands represent the daily amount of water supply required during
periods of peak demand. The maximum hour residential per capita demand represents the rate in which the
water must be delivered through the distribution system and forms the basis of the hydraulic computer model.
Water System Projections
The City's Comprehensive Plan projects a build out residential population of approximately 37,000. Using
this data and the historic water consumption data, we have projected the maximum day demand for the City of
Coppell will be approximately 25 million gallons per day (25 MGD). This represents the amount of water
that should be supplied to Coppell (purchased from Dallas Water Utilities) and the amount Coppell must be
able to pump into the water distribution system.
The build-out maximum hour demand is projected to be in the range of 53 million gallons per day (53mgd).
This represents the capacity that the water distribution system must be able to meet during the most severe
periods of use. This rate is met through a combination of pumping and elevated storage tanks and a properly
sized water distribution system. It does not represent the amount of water to be purchased from the City's
wholesale supplier.
Elevated Storage~ Pump Station and Ground Storage Reservoir Requirements
Elevated Storage:
Elevated Storage serves several functions in a water distribution system. It provides a source of emergency
supply for fire fighting; assist in providing a uniform pressure gradient across the distribution system, and
provides for emergency source of water and pressure in the distribution system in the event of power outages.
However, the elevated storage tank's most frequent and important function in the water distributions system is
to provide a source of water during periods of peak demand.
The City of Coppell currently has 3.5 million gallons of elevated storage (1.5 mg in the Southwestern
Elevated Storage Tank and 2.0 mg in the Wagon Wheel Ranch Elevated Storage Tank). This capacity
exceeds the Texas Natural Resource Conservation Commissions minimum standards for public water
systems, the State Board of Insurance minimum standards for fire protection and is adequate for future
growth. However, the existing capacity will not be adequate for meeting future peak hour demands. Using a
six-hour supply during the peak demand period, these two tanks combined contribute water to the distribution
system at a rate of 14 mgd. Assuming the pump stations pump the maximum day rate of 25 mgd, the total
water distribution system capacity to meet the peak hour demand is 39 mgd (14 mgd from elevated storage
plus 25 mgd from pumping). The estimated future peak hour demand is 53 mgd, or 14 mgd more than the
system can provide. This 14 mgd deficiency represents the need for an additional 3.5 million gallons of
elevated storage.
Although the calculations show additional elevated storage is required to meet the peak hour demand using a
baseline pumping approach, the existing elevated storage capacity does meet the minimum state regulated
requirements. Given the configuration for the existing water system and general lack of additional acreage
suitably located for elevated, we recommend the City consider building additional capacity into the pump
station facilities in order to meet future peak hour demands rather than building additional elevated storage.
Mr. Kenneth M. Griffin, P.E.
Director of Engineering & Public Works
City of Coppell
March 30, 2001
Page Number 4
Pump Station Recommendations
With the approach outlined above, we recommend the City of Coppell plan for a total pump station capacity
of approximately 40 million gallons per day. Thc current firm capacity of thc Village Park~vay Pump Station,
with the largest pump out of service, is estimated to be in thc range of 27 million gallons per day. Recall that
last summer, as much as 30 mgd was pump from this station. The TNRCC requires thc firm capacity of the
pump station be calculated with the largest pump out of service. The Village Parkway Pump Station has no
ability to bc readily expanded. Therefore, we recommend the City consider construction of a new pump
station located in the general vicinity of the Dallas Water Utility supply line. We recommend the station be
sized for a firm capacity of no less than 13 mgd. The attached exhibit shows a pump station site currently
under consideration by the City (Star Leaf Pump Station). This site is near the Dallas supply line and is
located favorably to meet the hydraulic conditions of the City's distribution system.
We recommend the first phase construction include a pump station building with slots for four pumps, with
two pumps being installed initially. The pumps are expected to be vertical turbine pumps installed inside the
pump building. Thc pump building will also house the pump control valves, isolation valves, discharge
header, motor control center and the SCADA panel. We envision thc pump station building to be constructed
of CMU block with a decorative brick veneer to match the surrounding development. The building will likely
be founded on a concrete foundation supported on drilled concrete piers. We have included an overhead
monorail crane with a push trolley and hand hoist for equipment manipulation inside the pump building.
Our vision for Coppell's future pump station is reflected in the enclosed pump station conceptual site plan and
pump station elevation view. Our conceptual layouts arc based on our recent conferences with your staff
where we discussed the project parameters.
Ground Storage Recommendations
In addition to pump capacity, the distribution system will also require ground storage reservoirs sized
adequately to meet the Texas Natural Resource Conservation Commission's (TNRCC) minimum
requirements and to insure a reliable supply of water during periods of peak demand. We recommend the
City consider no less than 4 million gallons of ground storage at the Star Leaf Pump build out. This amount
will provide for a 6-hour supply of water during the period of peak demand in the event of a disruption of
service from the City's water supplier. From our discussions with your staff, we recommend the ground
storage reservoir capacity be constructed in two phases: 2 million gallons initially followed by a 2 million
gallon reservoir in the future.
Opinion of Cost and Schedule
Based on our enclosed conceptual site plan, sketches and assumptions outlined above, our opinion of probable
construction cost for the first phase of the Coppell Pump Station, Supply Meter Station and 2.0 million gallon
Ground Storage Reservoir is in the range of $3,000,000. The budget includes an amount for engineering
design, construction administration and materials testing. It does not include an amount for acquisition of
land, land surveys nor preparation of plats. We are enclosing a copy of our itemized opinion of cost for your
review.
Geographic Water Consumption Evaluation:
Using the average of water billing records for the months of July, August and September, 2000, the total
monthly consumption was 375,000,867. Dividing this number by 30 days per months results in an average
daily use of 12.5 MGD. Again, this average use is based on billing data and does not include system losses.
Mr. Kenneth M. Griffin, P.E.
Director of Engineering & Public Works
City of Coppell
March 30, 2001
Page Number 5
We next divided the City into four quadrants and using the City's GIS database, we estimated the total
consumption per quadrant as follows:
City Quadrant Total Monthly Percent of City
Use (MG) Wide Total Use
Northwest: 67 18%
Northeast 111 30%
Southwest 92 24%
Southeast 105 28%
Total Use: 375 100%
If the City elects to proceed with a water conservation program that includes restrictions on outdoor ~vater
use, we recommend consideration be given to implementing a plan that program that balances the daily water
use. A plan that implements restrictions based on geographic regions of the City rather than the citywide
program currently in place would assist in that effort. We suggest splitting the City along Sandy Lake Road,
allowing outdoor use in the northern half and the southern half of the City on alternating days. Based on last
summers billing records, this would roughly split the system demand (48% in the north half, 52% in the south
half).
We are available to discuss our evaluation of your water system needs; the conceptual pump station design,
budget estimate and water conservation recommendations further at you convenience.
SHIMEK, JACOBS & FINKI EA, L.L.P.
CONSULTING ENGINEERS
8333 Douglas Avenue, #820 Dallas, Texas 75225-5816 Fax (214) 361-0204 Phone (214) 361-7900
To: Mr. Kenneth M. Griffin, P
From: Gary Hendricks, P.E. ~ ~¢ ~,
Date: March 1, 2001
Subject: City o£ Coppell - Water System Afialysis
PRELIMINARY DESIGN NOTES
I. PLANNING AREA
Current City Limits ............................................................................................... 9,410 Acres
14.7 Square Miles
II. POPULATION PROJECTIONS
Current Population Estimate ............................................................................... 35,000
Estimated Build-Out Population ......................................................................... 37,000
(Source: City of Coppell Comprehensive Plan)
III. SERVICE CONNECTIONS (2000)
Residential .......................................................................................................... 10,300
Commercial ................................................................................................................ 801
City ..................................................................... ~ .................................................. 92
Total: 11,193
IV. MAXIMUM DAY DEMAND (HISTORIC)
August 1, 2000 ........................................................................................................ * 23 MG
Average Maximum Daily Demand ............................................................................ 17 MG
* Coppell implements a Water Conservation Plan that requires a citywide irrigation schedule. The schedule
allows irrigation on certain days of the week. This inflates the maximum day demand to 23 MGD. On
average through these periods, of high demand, the City used no more than 17 MGD supply from City of
Dallas. Suggest for this analysis we use 20 MGD as the maximum day demand.
j:~clericalXcopp~lt~001-106\l~-rsXc, c~xkyr~lirn dg~,ign-rnow, o dec Page I of 5
V. MAXIMUM HOURLY DEMAND
August 1, 2001: { PumPElevated .................................................................................. Storage Tank 1: 6-Foot Drop ...................... 7' 0.23--'--~-30 MGDMG
Elevated Storage Tank 2: 6-Foot Drop ' 0.3 MG
'
i = 0.53 MG Per Hour
~__(= 12.6 MGD /
Total Maximum Hour Rate: ~42.6 MGD~
VI. MAXIMUM DAY TO MAXIMUM HOUR RATIO
20 MGD:42.6 MGD 2 ~, ~ - }.
Ratio, Max Day to Max Hour = 1:2.13 Seems High
Note: This is somewhat high ratio; may be artificially inflated due to irrigation schedule.
VII. PER CAPITA DEMANDS
A. Maximum Day Demand
35,000
2) 20 MGD = 1950 gpd/conn.
10,300 conn.
B. Peak Hour Demand
42.6 MGD = 1217
1)
35,000
2) 42.6 MGD = 4,135 gpd/conn.
10,300 conn.
VIII. SYSTEM PROJECTIONS
Maximum Day = 37,000 x 571 = . .................................................... 21.1 MGD
Maximum Hour = 37,000 x 1,217 = . ....................................................... 45 MGD T~
[Use: 53 MGD~
/
j ',clericalh:opp~llx2001 - 106xletters\corrm~Xprelim design-rrm'no doc Page 2 of 5
IX. ELEVATED STORAGE RECOMMENDATION
A. Base Line Pump Approach
1) Pump Maximum Day (100%)
2) Elevated Storage Provides Capacity for Maximum Hour
Maximum Hour ......................................................................................... 53 MGD
Maximum Day ........................................................................................... 25 MGD
............................................................................................................... 28 MGD Rate
3) Elevated Storage Capacity (6-Hour Supply) .............................................. 28 MGD x 24
= 7 MG
4) Current Elevated Storage Capacity ........................................................... 3.5 MG
Deficiency = 3.5 MG NG
B. TNRCC Maximum Requirement
100gallon/conn 100 x 12,000 ......................................................... 1.2 MG O.K.
C. State Insurance Minimum Requirement
130 gpcd x 37,000 x 10 Hr .................................................................... = 2.0 MG f
24 Hr.
X. PUMP STATION RECOMMENDATIONS
A. Hold Current Elevation Capacity (3.5 MG)
Maximum Hour Demand ................................................................................... 53 MGD
Contribution from Elevated Storage Tank 3.5 MG x 24 Hr .......................... t4 MGD
6 Hr. Supply
B. Pump Rate Required .......................................................................................... 39 MGD
Ce,/~ ~ CJ'c~ Use: 40 MGD
(9~0 ' (160% of Max. Day)
XI. CURRENT PUMP STATION CAPACITY
Village Parkway Pump Station
Firm Capacity: Pumps 1 + 2 + 3 ................................................................. 27 MGD f
Pumps Out of Service: 4, 5 and 6
.I "clencal\coppellTM I ~ 106\lette~;o~'~lim d~ign-memo doc Page 3 of 5
XII. STAR LEAF PUMP STATION REQUIREMENTS S ~v'~6-D
%"~..
A. Capacity: 40 MGD - 27 MGD ......... ~.~;~ ..... ~.7Z~....,~.~.£.0~-/c..~~ ......... 113 MGD Firm]
B. Pump Recommendation: Hp = lq x 1.55 x 215 x 62.4 .......................... 650 Hp '27r-]
90 x .85 x 550~
'~Recommend: 4 - 250 Hp Pumps (One on Standby)
XIII. GROUND STORAGE REQUIREMENTS
A. Total Storage ~ 50% Maximum Day Pump ..................................................... 20 MG
Current Capacities: Village Parkway Ground Storage ............................ 10 MG
Elevatit~ ................................................................. 3.5 MG
13.5 MG
Star Leaf Pump Station 6.5 MG
0_,,1 ~ ~ ial's' B. 6-Hour Supply ~ Maximum Pump Rate
~'~'0 MGD x 6 + 24 ~ l, ff MG Total
C. 6-Hour Supply ~ Star Leaf
,~,'JMGD x 6 + 24 ........................................................................................ 3c2'.25 MG
~' ~Jse: 4 Mq 2
Total System .................................................... 14 MG G.S.
3.5 MG E.S.
117.5 MG Storag~
~V. C.I.P. SCIIEDULES
A. Current Operating
Conditions
Current Maximum Day Demand ....................................................................... 20
Current Maximum Hour Demand ...................................................................... 43 MGD
Village Parkway Pump Station Pumps 1 - 4 Running ........................... 31 MGD
Elevated Storage Maximum Capacity .................................................... 14 MGD
Total 45 MGD
Under current operating conditions, only 2 MGD maximum hour capacity is available.
2 MGD + 1200 gpcd ........................................................................ 1,600 persons_
j:~clericalXcoppelg2001-106\l~ter~-xgre~orelim design-memo doc Page 4 of 5
B. If no Alternate Schedule on Conservation
Maximum Day ................................................................................................... 17 MGD '
Maximum Hour .................................................................................................. 36 MGD ~- ~
Village Parkway Pump Station Pumps 1 - 3 Running ........................... 27 MGD '
Elevated Storage Maximum Capacity .................................................... 14 MGD
Total: 41 MGD -: ---
Under the suggested revised condition, pump station and elevated has 5 MGD additional capacity
@ maximum hour or approximately 4,000 more rev/conn population.
XV. RECOMMENDATION
Depending on system operation, the Village Parkway Pump Station has capacity to support an additional
1,500 to 4,000 more residents or equivalent commercial growth. We recommend you move forward
with design of Star Leaf Pump Station now for an in-service date within next 2-years.
The pump station should be designed for a minimum of 14 MGD with at least 4 MG ground storage.
We recommend two 2-MG ground storage tanks for the site to provide operational flexibility and ease
of maintenance.
The recommended pump station capacity can be met with construction of four 250 HP pumps. A
schematic layout of the pump station and conceptual site plan is included.
XVI. GEOGRAPHIC WATER CONSUMPTION EVALUATION:
Using the average of water billing records for the months of July, August and September, 2000, the total
monthly consumption was 375,000,867. Dividing this number by 30 days per months results in an
average daily use of 12.5 MGD. Again, this average use is based on billing data and does not include
system losses.
We next divided the City into four quadrants and using the City's GIS database, we estimated the total
consumption per quadrant as follows:
City Quadrant Total Monthly Percent of City
Use (MG) Wide Total Use
Northwest: 67 18%
Northeast 111 30%
Southwest 92 24%
Southeast 105 28%
Total Use: 375 100%
If the City elects to proceed with a water conservation program that includes restrictions on outdoor
water use, we recommend consideration be given to implementing a plan that program that balances the
daily water use. A plan that implements restrictions based on geographic regions of the City rather than
the citywide program currently in place would assist in that effort. We suggest splitting the City along
Sandy Lake Road, allowing outdoor use in the northern half and the southern half of the City on
alternating days. Based on last summers billing records, this would roughly split the system demand
(48% in the north half, 52% in the south half).
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