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CVEN 3323: HYDRAULIC ENGINEERING
WATER DISTRIBUTION SYSTEM DESIGN PROJECT
This project involves the design of a water distribution system for Wolf Ranch
subdivision in Colorado Springs. The community consists of the following: (i) residential area –
consisting of a variety of housing (single family houses to apartment complexes of various sizes)
shown as Residential type A through F; (ii) commercial area; (iii) Elementary school; (iv)
Middle school; (v) Golf course; (vi) Club house and (vii) Parks & Open space. A site plan for the
community is given is Figure 1 and a skeleton of the pipe network model for the community is
given in Figure 2. The site plan and the EPANET file of the network can be obtained from
http://civil.colorado.edu/~balajir/CVEN3323/spring04-design-project or the class web page, as
wolfranch.bmp (and rm_water_fims.dwg an autocad file), wolfranch.net, respectively. In
addition
Water is piped to the subdivision from three surface reservoirs (as can be seen in the site
plan) through a set of pumps. The length of the pipes, co-ordinates and elevation of the nodes
within the network are included in the EPANET file. The various steps you need to follow in the
design are:
1.Estimation of the demands
2.Sizing of pipes and pumps
3.Checking your design for various operational scenarios, including potential fires.
1.Estimation of demands
Land use and per unit summer and winter consumption are given below in the table.
Land Use
Acres
Du/Ac
Units
Indoor Use
gpcd
Winter Use Average Use
gpd/Unit
gpd/Unit
Residential A
118.1
1.99
235
Residential B
392.6
3.49
1370
Residential C
444.9
4.99
2220
Residential D
150.5
7.99
1202
Residential E
10.9
11.99
131
Residential F
46.8
24.99
1170
Commercial
16.4
16.4
2259.0
603.7
1200.0
Elementary School
30.6
3.06
35296.4
9433.3
18750.0
Middle School
20.7
2.07
35296.4
9433.3
18750.0
197.9
197.9
6.7
6.7
214.9
214.9
Golf Course
Club House
Parks & Open
Space
gpcd = Gallons per capita per day
gpd
= Gallons per day
Du / Ac = Dwelling Units per Acre
Residential Demand
Indoor use is 62.18 gpcd and Outdoor use is 217.85 gpcd.
Outdoor use is computed as 217.85*(4.99 / (Du / Ac))(1/3)
Summer use consists of Indoor use + Outdoor use
Winter use consists of Indoor use + 6% of Outdoor use
Average use consists of Indoor use + 40% of Outdoor use
The number of residents per unit is 2.5
Open Space Demand
The Golf course and Club house have a Summer Use of 2000 gpd/unit; parks and open spaces
have a Summer Use of 200 gpd/unit. Winter Use for the Golf course and open spaces is 0
gpd/unit. The club house has a Winter use of 200 gpd/unit.
Fire Demand
Fire demand (gpm) is estimated from an empirical formula and yields the following demands:
8000 gpm for 4 hours for each fire
The probability of more than one fire at any time is very low.
(a)The maximum daily demand and maximum hourly demand are determined as some multiples
of the average daily demand. The demand factors also depend on the size of the community,
and are significantly larger than the values given in the above table for small communities.
Use demand factor values of 4 to obtain Maximum hourly Demand and 2.5 for Maximum
Daily Demand from Average Daily Demand.
[You have to compute the Summer, Winter and Average demand in gpd. Then compute the
Maximum Daily and Hourly Demands using the demand factors].
(b) Estimate the total daily storage that the community needs in the reservoirs (or access to) to
meet the requirements.
[The total daily storage is the sum of Maximum Daily Demand, fire demand (assuming one fire)
and some emergency storage (typically, 33% of the Maximum Daily Demand) ]
2. Design Criteria
The water distribution system should satisfy the following criteria:
1.Simulated nodal pressures should be larger than 60 psi for maximum daily demand
2.Simulated nodal pressures should be larger than 30 psi for maximum daily demand
combined with a fire demand at any one of the demand nodes (the fire demand can occur at any
demand node, and the design should be checked for all possibilities.
3.Try to keep costs as low as possible (schedule of costs will be placed on the class webpage).
3. Materials
Assume ductile iron pipes are available in diameters at 2" intervals beginning from 6". The
American Turbine catalog (accessible on the web – linked from the class webpage) can be used
to select pumps with the desired characteristic curves.
4. Suggested Approach for the Design
1. Compute the average daily demand and using the demand factors the maximum hourly
demand for the entire sub-division. [You would have already done this in 1.]
2. You can split the demand equally to all the nodes or split them only at major nodes or split
them based on the per unit demand. Try at least two different methods.
3. Input the pump curves for the five pumps that have to be designed.
4. With this information of the demands and the pumps, size the pipes to ensure that all
pressures are acceptable at maximum hourly demand. [Typically, larger pipes are used for
the main pipeline and smaller as you go down to the block level].
5. The next step is to check the above network design under conditions of maximum daily
demand + a fire demand at any of the nodes. The demands at the nodes are modified to
represent this condition, moving the fire demand around to different nodes to determine the
critical conditions. (Fire demands at nodes farthest from the supply are likely to be critical).
You can also check to see if the network satisfies the maximum hourly demand as well.
You can adjust pipe diameters in EPANET at any stage, to revise your design.
6. Try to get a design with the least cost (i.e. smaller pipes and pumps).
7. Once you have the “final design” estimate the cost of the network.
5. Report
Your report should include:
(1)Table showing the demands (total annual, average daily summer, maximum daily and
maximum hourly demand) – as mentioned in 1. above.
(2) Network map showing final pipe diameters and pumps.
(3) Map of flows and pressures during max. daily demand
(4) Map of flows and pressures during critical fire demand
(5) Cost estimate for the network.
(6) Your observations of the results.
(You will get bonus points for trying to get a “least cost” design)