WaterDistributionDesignAndModeling V8i SS3 SI QandA

8/12/2019 WaterDistributionDesignAndModeling V8i SS3 SI QandA

1/90

WaterCAD/GEMS, Water

Distribution Design and Modeling -Results Tables/Questions/Answers

Version: V8i (SELECTseries 3)Units: Metric

This document has been created so that you

can easily input your answers into the resultstables and questions.


2/90

Feb-12 2 Building a Network with Fire Flows - Q and A

Copyright 2012 Bentley Systems, Incorporated

Building a Network with Fire

Flows - Q and A

Results Table

Run 1 Run 2 Run 3

Pressure at J-1 (kPa)



HGL at J-5 (m)

Velocity in P-1 (m/s)

Velocity in P-6 (m/s)

Flow in P-3 (L/s)

Flow in P-7 (L/s)

Pipe with highest Headloss Gradient

Headloss Gradient in that pipe (m/m)


3/90

Feb-12 3 Building a Network with Fire Flows - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

Workshop Review

Now that you have completed this workshop, lets measure what you have

learned.

Questions

1 Why is the pressure so high at J-9 even though it is far from the source?

2 Why must you rely so heavily on pipes greater than 150 mm in this fairly

small subdivision?

3 What would really happen if you used the system from run 2 and had a

fire at J-6 that needed 63 L/s?

Enter your answer below:




4/90


Workshop Review

4 How does the split in flow between pipes 3 and 7 change as you change

pipe diameters? Why?

5 If another source of water were available along the highway at J-9, how

might that source affect the design?

6 What else could you do to help the pressures during normal demand

periods?





5/90


Workshop Review

Answers

* Some answers may vary between users due to the nature of this schematic

model

1 Why is the pressure so high at J-9 even though it is far from the source?

It is located at the lowest elevation in the system.

2 Why must you rely so heavily on pipes greater than 150 mm in this fairly

small subdivision?

Streets are not laid out with water distribution in mind. More loops would

result in smaller pipes/greater reliability.

3 What would really happen if you used the system from run 2 and had a

fire at J-6 that needed 63 L/s?

You would not be able to get 63 L/s. You would have lower flow with

higher pressures.

4 How does the split in flow between pipes P-3 and P-7 change as you

change pipe diameters? Why?

Initially they are the same but there is more flow through P-3 as it is

increased.

Run 1 Run 2 Run 3

Pressure at J-1 (kPa) 131 26 125

Pressure at J-6 (kPa) 247 -183 163

Pressure at J-9 (kPa) 515 210 462

HGL at J-5 (m) 202 171 197

Velocity in P-1 (m/s) 0.64 4.14 1.49

Velocity in P-6 (m/s) 0.07 3.57 2.01

Flow in P-3 (L/s) 4.3 35.7 48.0

Flow in P-7 (L/s) 4.5 34.9 22.5

Pipe with highest Headloss Gradient P-1 P-1 P-5

Headloss Gradient in that pipe (m/m) 0.003 0.081 0.016


6/90


Workshop Review

5 If another source of water were available along the highway at J-9, how

might that source affect the design?

You might need to make P-10 larger so it would not be a bottleneck for

the future source.

6 What else could you do to help the pressures during normal demand

periods?

If possible:

Put the tank at a higher elevation (higher static head)

Operate the tank with more water in the tank (higher static head).

Increase the system looping

Add a fire pump to maintain adequate flow/pressure


7/90

Feb-12 7Building a Network with Pumps, Tanks, and PRVs - Q and A


Building a Network with

Pumps, Tanks, and PRVs - Qand A

Workshop Review


learned.

Questions Run 1 AVG Daily

1 What is the hydraulic grade line elevation at junction J-6? At J-4?

2 Which PRVs will be the main feed to the lower zone? As the pressure

drops, which PRV will open last: PRV-1, PRV-2, or PRV-3? Why?




8/90

Feb-12 8Building a Network with Pumps, Tanks, and PRVs - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

3 Is tank T-1 filling or draining?

4 Are there any hydraulic problems in the system?

5 What can you say about the capacity of the system if this output is for

average flow conditions?

6 If the pump is a nominal 63 L/s pump, what can you generally say about its

efficiency?






9/90

Feb-12 9Building a Network with Pumps, Tanks, and PRVs - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

Questions Run 2 - Industry Demand of 95 L/s


2 Is the pressure adequate in the lower zone?








10/90

Feb-12 10Building a Network with Pumps, Tanks, and PRVs - Q andA


Workshop Review


average flow conditions?


efficiency?

7 How much more would the pump PMP-1 need to produce to keep the

tank T-1 from draining?





11/90



Workshop Review

Answers Run 1


J-6 has HGL at 320.5 m


2 Which PRVs will be the main feed to the lower zone? As the pressure

drops, which PRV will open last: PRV-1, PRV-2, or PRV-3? Why?

PRV-1 will open last because it has a lower HGL setting.


Filling


No

5 What can you say about the capacity of the system if this output is foraverage flow conditions?

The system is adequate to meet capacity for average daily conditions.


efficiency?

Good efficiency, because it is operating close (within 65.5 L/s) and 39.1 m

of head which is very close to the design point on the pump curve. A more

accurate efficiency % can be determined by consulting the efficiency

curves in the pump manufactures catalog.


12/90



Workshop Review

Answers Run 2




2 Is the pressure adequate in the lower zone?

Yes.


Draining


Yes. The pump cannot keep up with demands.


average flow conditions?The system is not adequate to meet capacity for average daily conditions

because the tank is draining.


efficiency?

The pump does not appear to be operating efficiently. It is operating at

approximately 8.4 L/s above its design operation point. A more accurate

efficiency % can be determined by consulting the efficiency curves in the

pump manufactures catalog.

7 How much more would the pump PMP-1 need to produce to keep thetank T-1 from draining?

Approximately 47.6 L/s


13/90

Feb-12 13Steady State Calibration of Field Measurements - Q and A


Steady State Calibration of

Field Measurements - Q and A

Results Tables

Static Condition

Node HGLObserved (m)

HGL Run 1 (m) HGL Q=2x (m) HGL C=80%(m)

HGL User 1(m)

HGL User 2(m)

J-1 56.7

J-2 47.5

J-4 48.5

J-8 48.5

J-12 47.9

J-13 47.9

J-23 48.2

J-32 47.9

Fire Flow at J-10


HGL Run 1(m)

HGL Q=2x (m) HGL C=80%(m)

HGL User 1(m)

HGL User 2(m)

J-1 53.6

J-10 39.3

J-13 41.1


14/90

Feb-12 14Steady State Calibration of Field Measurements - Q and ACopyright 2012 Bentley Systems, Incorporated

Results Tables

Fire Flow at J-31


HGL Run 1(m)

HGL Q=2x (m) HGL C=80%(m)

HGL User 1(m)

HGL User 2(m)

J-1 53.3

J-13 38.4

J-31 32.9


15/90


Workshop Review

Workshop Review


learned.

Questions

1 Did adjusting the nodal demands make a difference in the HGL? Why?

2 After which node did you notice a fairly abrupt drop in HGL in the

observed data?

3 Did changing the C-factors have a bigger effect on the static or fire flow

runs?





16/90


Workshop Review

4 What did you end up adjusting and why?

5 If you could get more data, what data would you get?




17/90


Workshop Review

Answers

Static Condition

Node HGL Observed (m) HGL Run 1 (m) HGL Q=2x (m) HGL C=80% (m)

J-1 56.7 50.6 49.2 51.3

J-2 47.5 49.2 47.5 49.4

J-4 48.5 48.8 48.3 48.8

J-8 48.5 48.9 48.6 48.9

J-12 47.9 49.7 48.4 50.1

J-13 47.9 49.4 48.2 49.6

J-23 48.2 49.0 48.3 49.1

J-32 47.9 49.4 48.1 49.6

Fire Flow at J-10


J-1 53.6 47.4 43.1 46.8

J-10 39.3 44.4 40.8 42.3

J-13 41.1 45.8 41.5 44.4

Fire Flow at J-31


J-1 53.3 45.9 41.7 44.8

J-13 38.4 42.9 38.1 40.2

J-31 32.9 37.9 32.2 32.6


18/90


Workshop Review

1 Did adjusting the nodal demands make a difference in the HGL? Why?

It had little effect on the static condition run.

It made a significant change on the fire flow runs.

The extra flow caused extra head loss but in the static condition scenario

the velocity was so low the HGL was flat.

2 After which node did you notice a fairly abrupt drop in HGL in the

observed data?

J-1

Closed valve suspected downstream of that valve.

3 Did changing the C-factors have a bigger effect on the static or fire flowruns?

It had a bigger effect on the fire flow runs.

The velocity was too low in static run.

4 What did you end up adjusting and why?

Closed pipe P-22.

Lowered C factors for cast iron to 60%

Changed demands as shown in the table on the next page


Another fire flow test with several residual gages downstream of P-22.


19/90


Adjusted Demands (L/s)

Adjusted Demands (L/s)

Node Initial Demand (L/s) Adjusted Demand (L/s)

1 6.3 7.6

2 5.0 6.3

3 3.5 3.5

4 6.3 7.6

8 0 0.6

9 0.9 1.5

10 0 0.6

11 0.6 0.9

12 0.5 2.0

13 0.9 3.2

14 0 1.2

15 0 1.7

16 0.6 0.8

17 1.6 2.2

18 0 1.3

19 0 0.9

20 0 0.8

21 0 1.3

22 0.6 1.6

23 0.3 0.924 0 1.9

25 0.9 1.3

26 0 1.9

27 1.3 1.9

28 0.9 1.3

29 0.9 1.3

30 2.2 2.6

31 0 1.3

32 0.6 1.3


20/90

Feb-12 20 System Design Improvements - Q and A


System Design Improvements -

Q and A

Results Tables

Diameters

Pipe # Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8

P-2

P-3

P-4

P-5

P-6

P-7

P-8

P-9

P-10

P-11

P-12P-13

P-14

P-15

P-16

P-17

P-18

P-19

P-20

P-21


21/90

Feb-12 21 System Design Improvements - Q and ACopyright 2012 Bentley Systems, Incorporated

Results Tables

Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8

Avg., Max, or Peak?

Fire at

Fire Q (L/s)

Pressure (min) (kPa)

@ node #

HGL @ node (m)

Velocity (max) pipe #

Velocity (max) (m/s)

Cost ($)

Check?


22/90


Workshop Review

Workshop Review


learned.

Questions

1 Explain why you selected the pipes you did.

2 Do you think the head loss in the 900 mm pipe is significant?

3 Why was node J-14 so troublesome? How did you resolve this problem?





23/90


Workshop Review

4 Why were 150 mm pipes not seriously considered in this system?

5 Why did node J-4 give you trouble at peak hour?




24/90


Workshop Review

Answers

Diameters

Pipe # Run 1 Run 2 Run 3 Run 4 Run 5 Run 6

P-2 300 400

P-3 300

P-4 300

P-5 300

P-6 300

P-7 300

P-8 200 300

P-9 200 300

P-10 200 300

P-11 200 300

P-12 200 300

P-13 200 300

P-14 200 300

P-15 200 400

P-16 200 300

P-17 200

P-18 200

P-19 200

P-20 200

P-21 200

Run 1 Run 2 Run 3 Run 4 Run 5 Run 6

Avg., Max, or Peak? Peak Peak Peak Avg Max Max

Fire at J-14 J-14

Fire Q (L/s) 230 230

Pressure (min) (kPa) 195 216 249 291 -662 162

@ node # J-4 J-4 J-4 J-4 J-14 J-14

HGL @ node (m) 285 287 291 295 191 276

Velocity (max) pipe # P-8 P-2 P-2 P-2 P-16 P-16

Velocity (max) (m/s) 1.95 1.66 1.30 0.53 7.32 3.25

Cost ($) 3.597 M 4.148 M 4.546 M 4.546 M 4.546 M 4.922 M

Check? OK OK OK


25/90


Workshop Review

1 Explain why you selected the pipes you did.

Used trial and error to meet requirements without excess capacity.

2 Do you think the head loss in the 900 mm pipe is significant?

It is not too bad in this problem.

3 Why was node J-14 so troublesome? How did you resolve this problem?

It is a dead end line at a high elevation.

4 Why were 150 mm pipes not seriously considered in this system?

Too much demand and high fire flows for that pipe size.

5 Why did node J-4 give you trouble at peak hour?

It has the highest elevation.


26/90

Feb-12 26 Automated Fire Flow Analysis - Q and A


Automated Fire Flow Analysis -

Q and A

Results Tables

Max Day Base Physical Scenario

Junction Node Pressure (kPa) HGL (m)

J-83

J-114

J-138

Fire Flow Analysis - Fire flow analysis run with the existingdistribution system

Node Fire Flow(Available) (L/s)

Pressure(Calculated Residual) (kPa)

Junction withMinimum Pressure(Zone)

Pressure(Calculated ZoneLower Limit) (kPa)

J-115

J-136

J-197

J-237


27/90

Feb-12 27 Automated Fire Flow Analysis - Q and ACopyright 2012 Bentley Systems, Incorporated

Results Tables

Auxiliary Results Pipe Data - List pipes with Velocity greater than3 m/s when fire flow node is J-115

Pipe Number Flow (L/s) Velocity (m/s)


28/90


Workshop Review

Workshop Review


learned.

Questions

1 In reviewing the pressures from the max day steady state run, what would

you conclude about the pressures in this system?

2 In the fire flow analysis for this system the node which limited the fire flow

was not near the fire, why was this the case?

3 Is the situation described in question #2 typical for most systems?





29/90


Workshop Review

4 What pipe(s) had the highest velocity and were most responsible for

limiting fire flows?

5 What was the source of the water during the Max Day run vs. the source

for the Fire Flow run?




30/90


Workshop Review

Answers

Max Day Base Physical Scenario

Junction Node Pressure (kPa) HGL (m)

J-83 284 558

J-114 643 557

J-138 960 557

Fire Flow Analysis - Fire flow analysis run with the existingdistribution system

Node Fire Flow

(Available) (L/s)

Pressure

(Calculated Residual) (kPa)

Junction with

Minimum Pressure(Zone)

Pressure

(Calculated ZoneLower Limit) (kPa)

J-115 68.01 136 J-114 130

J-136 107.17 387 J-83 130

J-197 72.89 131 J-144 148

J-237 107.17 178 J-83 130

Auxiliary Results Pipe Data - List pipes with Velocity greater than

3 m/s when fire flow node is J-115Pipe Number Flow (L/s) Velocity (m/s)

P-162 73.54 4.2

P-163 73.32 4.2

P-164 73.21 4.1


31/90


Workshop Review

1 In reviewing the pressures from the max day steady state run, what would

you conclude about the pressures in this system?

Pressures are generally quite high. More than half of the node pressures

are greater than 600 kPa.

2 In the fire flow analysis for this system the node which limited the fire

flow was not near the fire, why was this the case?

High points other than at the flowed hydrant can control available fire

flow.

3 Is the situation described in question #2 typical for most systems?

This is not typical of systems in flatter terrain.

4 What pipe(s) had the highest velocity and were most responsible for

limiting fire flows?

Non-looped pipes had the highest velocity (e.g. P-162, P-163, and P-164).

However for some cases, head loss back in the other part of the system

controlled fire flow.

5 What was the source of the water during the Max Day run vs. the source

for the Fire Flow run?

Max day flows came from the pump while fire flows came primarily from

the tank. Pumps are limited by their curve.


32/90

Feb-12 32 EPS Modeling and Energy Costing Analysis - Q and A


EPS Modeling and Energy

Costing Analysis - Q and A

Results Table

Please use graphs and data tables to complete the results table with approximate

values. Do not record zero hour values. Complete this first table after the

extended period simulation runs.

After you complete the energy costing runs, fill in the table below.

Attribute With Tank No Tank ConstandSpeed

No Tank VariableSpeed

Max Pressure J-1 (kPa)

Min Pressure J-1 (kPa)

Max Pressure J-3 (kPa)

Min Pressure J-3 (kPa)

Attribute With Tank No Tank ConstantSpeed


Max W-toW EfficiencyPMP-4 (%)

Min W-to-W EfficiencyPMP-4 (%)

Max Head PMP-4 (m)

Min Head PMP-4 (m)

Daily Energy Cost ($)


33/90

Feb-12 33 EPS Modeling and Energy Costing Analysis - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

Workshop Review


learned.

Questions

1 In the tank control run, why does the pressure vary more at J-1 than J-3?

2 In the variable speed pump run, why does pressure vary more at J-3 than

J-1?

3 What is the number of pump starts during the day for the scenario with

the tank? Is it excessive?





34/90


Workshop Review

4 Do you think the pumps have enough capacity for this application?

5 Which scenario had the lowest energy costs? Which do you think would

have the lowest life-cycle cost?

6 Why was the energy use for the no tank constant head scenario the

greatest? What did the other two scenarios do to lower costs?

7 What was the range of relative speeds for the variable speed pump? If the

target head were increase, how do you think the speed would change?






35/90


Workshop Review

Answers

Attribute With Tank No Tank Constant

Speed

No Tank Variable

Speed

Max Pressure J-1 (kPa) 579 702 537

Min Pressure J-1 (kPa) 406 630 537

Max Pressure J-3 (kPa) 481 692 527

Min Pressure J-3 (kPa) 438 589 495

Attribute With Tank No Tank ConstantSpeed


Max W-toW EfficiencyPMP-4 (%)

71.2 68.9 70.3

Min W-to-W EfficiencyPMP-4 (%)

70.5 43.9 48.8

Max Head PMP-4 (m) 54.9 65.9 50.0

Min Head PMP-4 (m) 51.6 59.6 49.1

Daily Energy Cost ($) 691 985 729


36/90


Workshop Review

1 In the tank control run, why does the pressure vary more at J-1 than J-3?

The tank tends to keep pressure constant. The cycling of pumps affects J-

1 the most because of location.

2 In the variable speed pump run, why does pressure vary more at J-3 than

J-1?

Pressure is controlled to be constant at J-1.

3 What is the number of pump starts during the day for the scenario with

the tank? Is it excessive?

5, not excessive.

4 Do you think the pumps have enough capacity for this application?

Yes, pumps turn off or run at less than full speed.

5 Which scenario had the lowest energy costs? Which do you think would

have the lowest life-cycle cost?

Tank had lowest energy cost, while variable speed will probably have

lowest life-cycle cost. Must compare VFD costs with tank costs and

benefits.

6 Why was the energy use for the no tank constant head scenario the

greatest? What did the other two scenarios do to lower costs?

Constant speed pump cannot turn off if there is no storage or slow down

if there is no variable speed drive.

7 What was the range of relative speeds for the variable speed pump? If

the target head were to increase, how do you think the speed would

change?

0.87 to 0.92, speed would increase if target head increased.


37/90

Feb-12 37 Analysis of Valving and Critical Segments - Q and A


Analysis of Valving and Critical

Segments - Q and A

Results Table

Result

Original Valves Max number of Isolation Elements

Outage Segments Length of the third longest outage segment (m)

Criticality System Demanded Flow (L/s)

Criticality System Supplied Flow for third largest segment (L/s)

Outage Segments Length of second longest outage segment (m) (Improved System)


38/90

Feb-12 38 Analysis of Valving and Critical Segments - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

Workshop Review


learned.

Questions

1 Why is it undesirable to have segments where a large number of valves are

needed to shut down the segment?

2 What do outage segments show?

3 Would you expect there to be a correlation between the length of

distribution segments and system shortfall.





39/90


Workshop Review

4 Would you expect the same results for a steady state and an EPS criticality

analysis?



40/90


Workshop Review

Answers

1 Why is it undesirable to have segments where a large number of valves

are needed to shut down the segment?

More difficult to shut down system making it more likely that some valves

will be inoperable, thus spreading the outage to additional customers.

2 What do outage segments show?

They show the impact of an outage. Sometimes, even in looped systems,

there may be significant number of downstream customers out of service.

3 Would you expect there to be a correlation between the length of

distribution segments and system shortfall.

In general, the shortfalls will be correlated with the length of the segment

because larger segments have more demand. However, a failure of a key

segment, no matter how small, can place a large number of customers out

of service. The size of the outage segment is more important in terms of

criticality than the size of the segment.

4 Would you expect the same results for a steady state and an EPS criticality

analysis?

For this system, yes, because no storage tanks were involved. If there

were storage tanks, the EPS and steady results would be very different

once the tanks drained.

Result

Original Valves Max number of Isolation Elements 9

Outage Segments Length of the third longest outage segment (m) 2,185

Criticality System Demanded Flow (L/s) 38.5

Criticality System Supplied Flow for third largest segment (L/s) 28.1

Outage Segments Length of second longest outage segment (m) (Improved System) 994


41/90

Feb-12 41 Automating Model Building using ModelBuilder - Q and A


Automating Model Building

using ModelBuilder - Q and A

Workshop Review


learned.

Questions

1 What was the pressure (kPa) at the following nodes?

2 There were some fields in the data file that were not mapped to an

attribute in WaterGEMS. Why was this the case?

Node Pressure (kPa) (Run Values)

A-26

A-162

J-8



42/90

Feb-12 42 Automating Model Building using ModelBuilder - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

3 The data could have been exported to a standard MS Access file and then

imported into WaterGEMS. Why was this not a good idea?

4 Instead of entering tank level information in WaterGEMS Modeler, how

else could you have brought that data into the model?

5 Explain the difference in the tolerance specified in ModelBuilders Specify

Spatial Options dialog and the tolerance specified in Network Navigator.

In general which should be lower?





43/90

Feb-12 43 Automating Model Building using ModelBuilder - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

Answers

1 What was the pressure (kPa) at the following nodes?

2 There were some fields in the data file that were not mapped to an

attribute in WaterGEMS. Why was this the case?

These fields were not needed in WaterGEMS and did not have a

corresponding attribute.

3 The data could have been exported to a standard MS Access file and then

imported into WaterGEMS. Why was this not a good idea?

Importing the feature classes directly into WaterGEMS enabled bends, (x,

y) coordinates, and topology to be automatically imported (preserved).

4 Instead of entering tank level information in WaterGEMS Modeler, how

else could you have brought that data into the model?

You could have created fields in your source file for tank elevations and

used ModelBuilder to bring in the data.

5 Explain the difference in the tolerance specified in ModelBuilders Specify

Spatial Options dialog and the tolerance specified in Network Navigator.

In general which should be lower?

In ModelBuilder, if the tolerance is met, the nodes are merged

automatically, while in Drawing Review, if the tolerance is met, the user is

given a chance to edit the nodes. As such, the ModelBuilder tolerances

should be set finer (Drawing Review larger). Drawing review will allow you

to double-check that other connections were not missed because of too

small a value in ModelBuilder.

Node Pressure (kPa) (Run Values)

A-26 262.7

A-162 495.5

J-8 497.8


44/90

Feb-12 44 Pump Selection - Q and A


Pump Selection - Q and A

Results Tables

Operating Points

Scenario Element Time Property Initial Design Alternate Design

Summer Big1 6:00 am Flow (L/s)

Summer Big1 6:00 am Head (m)

Peak Big1 3:00 pm Flow (L/s)

Peak Big1 3:00 pm Head (m)

Winter Small1 12:00 pm Flow (L/s) N/A

Winter Small1 12:00 pm Head (m) N/A

Pump Station Capacity

Topology Type Initial Design Alternate Design

Existing Rated 140 N/A

Existing Total 265 N/A

New Rated 461

New Total 580


45/90

Feb-12 45 Pump Selection - Q and ACopyright 2012 Bentley Systems, Incorporated

Results Tables

Energy Costs

Scenario Property Initial Design Alternate Design

PeakEPS221-61CS1 Daily cost

PeakEPS221-61CS1 Cost/ML

SummerEPS221-61CS1 Daily cost

SummerEPS221-61CS1 Cost/ML

WinterEPS126-61CW1 Daily cost N/A

WinterEPS126-61CW1 Cost/ML N/A


46/90


Module Review

Module Review

Now that you have completed this module, lets measure what you have learned.

Questions1 Why did the tank level fluctuate so much in the peak day but not on the

winter day?

2 Why could you conclude that the piping was adequately sized?

3 Could a small and large pump be run simultaneously with good efficiency?





47/90


Module Review

4 What would you like to change to make the system work better?



48/90


Module Review

Answers

Operating Points

Scenario Element Time Property Initial Design Alternate Design

Summer Big1 6:00 am Flow (L/s) 235 266

Summer Big1 6:00 am Head (m) 58 59

Peak Big1 3:00 pm Flow (L/s) 244 276

Peak Big1 3:00 pm Head (m) 56 56

Winter Small1 12:00 pm Flow (L/s) 145 N/A

Winter Small1 12:00 pm Head (m) 55 N/A

Pump Station Capacity

Topology Type Initial Design Alternate Design

Existing Rated 140 N/A

Existing Total 265 N/A

New Rated 460 470

New Total 580 630

Energy Costs


PeakEPS221-61CS1 Daily cost 600 629

PeakEPS221-61CS1 Cost/ML 22 23

PeakEPS221-69CS1 Daily cost N/A 629

PeakEPS221-69CS1 Cost/ML N/A 23

SummerEPS221-61CS1 Daily cost 499 527

SummerEPS221-61CS1 Cost/ML 23 24

SummerEPS221-69CS1 Daily cost N/A 526


49/90


Module Review

1 Why did the tank level fluctuate so much in the peak day but not on the

winter day?

Tank was sized right for the winter day but was small for the peak day

demand. System may need additional tank capacity.

2 Why could you conclude that the piping was adequately sized?

Velocities were reasonable, even on peak day. Plus, system head curvewas relatively flat.

3 Could a small and large pump be run simultaneously with good efficiency?

Yes, in this case they are compatible because their operating points are at

roughly 61 m of head and the best efficiency point of each pump is around

61 m.

4 What would you like to change to make the system work better?

SummerEPS221-69CS1 Cost/ML N/A 24

WinterEPS126-61CW1 Daily cost 243 N/A

WinterEPS126-61CW1 Cost/ML 22 N/A

Energy Costs



50/90

Feb-12 50Automating Demand Allocation using LoadBuilder - Q and

A

Automating Demand

Allocation using LoadBuilder -Q and A

Workshop Review


learned.

Results Table

Questions

1 How would you get metering data for a model run for demands in the year

2040?

Node Location Near Node Pressure(kPa)

Near Pipe Pressure(kPa)

Population & Land UsePressure (kPa)

C_028 North

D1_078 East

D1_091 Near Source



51/90

Feb-12 51Automating Demand Allocation using LoadBuilder - Q andA


Workshop Review

2 Why did small changes in demand make big differences in pressure in this

model?



52/90

Feb-12 52Automating Demand Allocation using LoadBuilder - Q andA


Workshop Review

Answers

1 How would you get metering data for a model run for demands in the year

2040?

You do not have a good source of meter data, so you need to use another

source such as population or land use to drive demands.

2 Why did small changes in demand make big differences in pressure in this

model?

This was a dead end system with a pump and no tank. Therefore any

change in demand affected not only head loss but the operating point on

the pump curve.

Node Location Near Node Pressure

(kPa)

Near Pipe Pressure

(kPa)

Population & Land Use

Pressure (kPa)

C_028 North 573 573 728

D1-078 East 366 366 520

D1-091 Near Source 589 589 741


53/90

Feb-12 53 Importing Elevations using TRex - Q and A


Importing Elevations using

TRex - Q and A

Workshop Review


learned.

Results Table

Questions

1 For a model this size, how long do you think it would take to read off all

the 2000+ elevations manually?

Node Elevation (m) Pressure (kPa)

Node-1

Node-1374

Node-1836



54/90

Feb-12 54 Importing Elevations using TRex - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

2 Look at the number of digits past the decimal place that elevation data are

reported. Is that precision justified?



55/90

Feb-12 55 Importing Elevations using TRex - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

Answers

1 For a model this size, how long do you think it would take to read off all

the 2000+ elevations manually?

At 2 minutes per node, about a week.

2 Look at the number of digits past the decimal place that elevation data are

reported. Is that precision justified?

No, most of those digits are meaningless.

Node Elevation (m) Pressure (kPa)

Node-1 2555.0 440

Node-1374 2566.2 325

Node-1836 2549.3 489


56/90

Feb-12 56 Skeletonizing a Large Model using Skelebrator - Q and A


Skeletonizing a Large Model

using Skelebrator - Q and A

Results Tables

Note: You may round your answers.

Smart Pipe Removal

Action Pipes Left Nodes Left Pressure A-100(kPa) Base

Pressure A-100(kPa) Fire

System HeadCurve PMP-1(m) Base

Start

Remove < 150 mm

Remove


57/90

Feb-12 57 Skeletonizing a Large Model using Skelebrator - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

Workshop Review


learned.

Questions

1 Why did the pressures during the Base scenario not change much as pipes

were removed?

2 Why did the pressures during the Fire at A-100 scenario seem more

sensitive?

3 Why were the effects less dramatic in the runs using the series, parallel,

and branch removal operations?





58/90


Workshop Review

4 Do you think you can generate system head curves with a fairly highly

skeletonized model?



59/90


Workshop Review

Answers

1 Why did the pressures during the Base scenario not change much as pipes

were removed?

The velocities (and hence head losses) in the system were so low that it

was difficult to see impact.

2 Why did the pressures during the Fire at A-100 scenario seem more

sensitive?

This scenario had much higher velocities so that the impact of removing a

pipe was more dramatic.

3 Why were the effects less dramatic in the runs using the series, parallel,

and branch removal operations?

These operations maintain hydraulic capacity.

4 Do you think you can generate system head curves with a fairly highly

skeletonized model?

Yes, the results show that you can skeletonize a model and still obtain anaccurate system head curve.

Smart Pipe Removal

Action Pipes

Left

Nodes

Left

Pressure A-100

(kPa) Base

Pressure A-100

(kPa) Fire

System Head Curve

PMP-1 (m) Base

Start 656 517 291.3 208.7 60.4

Remove < 150 mm 504 451 291.3 108.2 60.6

Remove


60/90

Feb-12 60 Pipe Renewal Planner - Q and A


Pipe Renewal Planner - Q and A

Results Tables

1 Report the number of isolation elements, length of segment, and system

demand shortfall (%) to isolate these segments.

2 In the fire flow report, what was the available fire flow at the following

nodes:

Segment Number of IsolationNodes (Base)

Segment Length (m)(Base)

System DemandShortfall (%) (Criticality)

1

2

16

Node Fire Flow Available (L/s)

J-47

J-85

J-91


61/90

Feb-12 61 Pipe Renewal Planner - Q and ACopyright 2012 Bentley Systems, Incorporated

Results Tables

3 In the pipe break results, find the 4 pipe elements with break rate scaled

greater than 0.6 breaks/yr/km. What are the rates?

4 Excluding pipes P-130 and P-131, what were the three pipes with the

highest score in the Pipe Renewal Planner, and which aspect was the

highest one for each (i.e. what was its major problem).

Pipe Break rate scaled(breaks/yr/km)

Initial Run

Pipe Score Worst Aspect

Including Material in Score



62/90


Workshop Review

Workshop Review


learned.

Questions

1 Do you think segment 2 is excessively large? What would you do to reduce

its size?

2 What would you do with the fire flow nodes that can not provide the

needed flow at 140 kPa?

3 What type of pipe were the pipes with the highest break rates?





63/90


Workshop Review

4 Why did we downplay the importance of pipes P-130 and P-131 in the

scoring?

5 Even though asbestos cement pipes had a high break rate, why did they

not show up especially high in the pipe score?




64/90


Workshop Review

Answers

1 Report the number of isolation elements, length of segment, and system

demand shortfall (%) to isolate these segments.

2 In the fire flow report, what was the available fire flow at the following

nodes:

3 In the pipe break results, find the 4 pipe elements with break rate scaled

greater than 0.6 breaks/yr/km. What are the rates?

4 Excluding pipes P-130 and P-131, what were the three pipes with the

highest score in the Pipe Renewal Planner, and which aspect was the

highest one for each (i.e. what was its major problem).

Segment Number of IsolationNodes (Base) Segment Length (m)(Base) System DemandShortfall (%) (Criticality)

1 9 411 3.3

2 9 835 4.9

16 6 415 24.6

Node Fire Flow Available (L/s)

J-47 62.1

J-85 67.6

J-91 34.3

Pipe Break rate scaled(breaks/yr/km)

P-68 1.24

P-59 0.74

P-40 0.70

P-60 0.69


65/90


Workshop Review

1 Do you think segment 2 is excessively large? What would you do to reduce

its size?

Very large with a lot of valves to close to isolate it. Need to insert some

additional valves to subdivide the segment into smaller ones.

2 What would you do with the fire flow nodes that can not provide the

needed flow at 140 kPa?

Use color coding to look at nodes that do not meet needed fire flow.

These turn out to be primarily on dead end parts of the system. For an

existing system, find the bottlenecks and try to improve hydraulic

capacity. In this case, some of the old cast iron lines could be cleaned or

replaced. For a new system, look for places to provide looping or upsize

pipes to 200 mm.

3 What type of pipe were the pipes with the highest break rates?

Asbestos cement

Initial Run


P-68 55 Pipe Break

P-34 54 Capacity

P-11 50 Criticality

Including Material in Score


P-11 63 Criticality and Material




66/90


Workshop Review

4 Why did we downplay the importance of pipes P-130 and P-131 in the

scoring?

These are the pump suction and discharge lines and there is a parallel

pump and pipes in case these should fail. However, that pump was off for

the analysis.

5 Even though asbestos cement pipes had a high break rate, why did they

not show up especially high in the pipe score?

That part of the system was well looped so the criticality was not great

and the looping helped the fire flow since no single pipe had a very high

velocity.


67/90

Feb-12 67Automating Calibration using Darwin Calibrator - Q and A


Automating Calibration using

Darwin Calibrator - Q and A

Results Tables

Average Day

Node HGLObserved(m)

Initial Run(m)

1/2 C-factor(m)

Adjust Conly (m)

Optimal(m)

DataError(m)

Optimizedw/Error

J-1 50.6 50.3

J-2 47.9 48.5

J-4 48.8 49.4

J-8 48.8 48.2

J-12 49.4 50.0

J-13 49.1 49.1

J-23 48.8 47.2

J-32 48.8 47.9

PUMP (L/s) 42.8 43.5

Fire Flow at J-10

Node HGLObserved(m)

Initial Run (m) 1/2 C-factor (m) Adjust C only(m)

Optimal (m)

J-1 45.7

J-10 42.1


68/90

Feb-12 68Automating Calibration using Darwin Calibrator - Q and ACopyright 2012 Bentley Systems, Incorporated

Results Tables

J-13 43.6

PUMP (L/s) 48.1

Fire Flow at J-31

Node HGLObserved(m)


Optimal (m)

J-1 43.9

J-13 40.2

J-31 33.8

PUMP (L/s) 49.8

Adjustment Factors

Initial 1/2 C-Factor Adjust C-only Optimized Optimized w/error

Cast Iron

Ductile Iron

Commercial

Residential

Fitness

Fire Flow at J-10

Node HGLObserved(m)


Optimal (m)


69/90


Workshop Review

Workshop Review


learned.

Questions

1 What would happen if you relied on a model that only adjusted C-factor?

2 Did changing the C-factors have a bigger effect on HGL in the static or fire

flow runs? Why?

3 What was the lesson learned when you tried to run optimal calibration at

low demand with some small errors in the data?





70/90


Workshop Review


5 In a real system would you expect all the commercial customers to have

the same demand adjustments?

6 What accuracy would you expect to get with real HGL measurements?





71/90


Workshop Review

Answers

Average Day

Node HGLObserved(m)

Initial Run(m)

1/2 C-factor(m)

Adjust Conly (m)

Optimal(m)

DataError(m)

Optimizedw/Error

J-1 50.6 50.7 53.9 50.8 50.3 50.3 50.3

J-2 47.9 49.3 49.5 49.3 48.2 48.5 48.3

J-4 48.8 48.8 48.7 48.8 48.7 49.4 48.6

J-8 48.8 48.9 49.0 48.9 48.8 48.2 48.8

J-12 49.4 49.8 51.2 49.7 49.3 50.0 49.1

J-13 49.1 49.4 50.2 49.4 48.9 49.1 48.8

J-23 48.8 49.0 49.2 49.0 48.8 47.2 48.7

J-32 48.8 49.4 50.2 49.4 48.9 47.9 48.8PUMP (L/s) 42.8 42.9 39.0 42.8 43.3 43.5 43.2

Fire Flow at J-10

Node HGLObserved(m)


Optimal (m)

J-1 45.7 47.3 45.1 46.6 45.5

J-10 42.1 44.1 32.8 43.0 42.1

J-13 43.6 45.6 38.6 44.7 43.5

PUMP (L/s) 48.1 46.6 48.7 47.3 48.4

Fire Flow at J-31

Node HGLObserved(m)


Optimal (m)

J-1 43.9 45.7 40.4 44.9 43.9

J-13 40.2 42.4 28.3 40.4 40.1

J-31 33.8 37.0 8.7 33.3 33.8

PUMP (L/s) 49.8 48.2 53.2 49.0 50.0

Adjustment Factors


Cast Iron 1.0 0.5 1.2 0.8 0.9

Ductile Iron 1.0 0.5 0.8 1.0 0.8

Commercial N/A N/A N/A 1.5 1.4


72/90


Workshop Review

1 What would happen if you relied on a model that only adjusted C-factor?

You would end up adjusting the wrong parameter to get calibration. HGL

would be right but C and demand are wrong. This is an example of

calibration by compensating error.

2 Did changing the C-factors have a bigger effect on HGL in the static or fire

flow runs? Why?

Much more dramatic effect on fire flow runs because of higher velocity.

3 What was the lesson learned when you tried to run optimal calibration at

low demand with some small errors in the data?

When head loss is on same order of magnitude as error in head loss, the

calibration does not know what to adjust.


Would run some actual C-factor tests on cast iron pipes.

5 In a real system would you expect all the commercial customers to have

the same demand adjustments?

No, they would be different.

6 What accuracy would you expect to get with real HGL measurements?

It depends on care taken and instruments used. With GPS elevations and

quality gages you can get +/- 0.6 m accuracy; with topo map and average

quality gage, +/- 3.0 m.

Residential N/A N/A N/A 1.3 1.5

Fitness 20.175 579.356 4.419 0.218 5.726

Adjustment Factors



73/90

Feb-12 73 Automating Design using Darwin Designer - Q and A


Automating Design using

Darwin Designer - Q and A

Workshop Review


learned.

Questions

1 For each of the first set of Design Runs, list the pipe sizes and cost (leave

blank if pipe not installed), Round cost to thousands of dollars.

2 For the multi-objective run, list the sizes, costs and benefits for 5 non-

inferior solutions.

Solution Internal West North South Total Cost($1000)

1

2

3

4

5


Benefit


74/90

Feb-12 74 Automating Design using Darwin Designer - Q and ACopyright 2012 Bentley Systems, Incorporated

Workshop Review

3 What solution would you recommend?

4 If you were adding another subdivision on the opposite side of town,

should you include sizing those pipes with the pipe sizing for this problem

or should you create a new design study?

5 Why did the South piping not get selected as the least cost alternative?

6 How would you force the South pipes not to be eliminated from the

solution?






75/90


Workshop Review

7 What do you think would have happened if you included a node that

could not reach 130 kPa for any combination of pipe sizes (e.g. a node on

the suction side of a pump) and what would you need to do to handle that

node?

8 How would you decide between non-inferior solutions in the tradeoff

analysis?

9 What would happen if you included a lot of nodes on the south side of the

system in calculating benefits?

10 Why would you not have used Average Day demands as an event in

Designer?






76/90


Workshop Review

Answers

1 For each of the first set of Design Runs, list the pipe sizes and cost (leave

blank if pipe not installed), Round cost to thousands of dollars.

2 For the multi-objective run, list the sizes, costs and benefits for 5 non-

inferior solutions.

3 What solution would you recommend?If your budget is limiting consider solution 4. Otherwise choose on budget

limit.

4 If you were adding another subdivision on the opposite side of town,

should you include sizing those pipes with the pipe sizing for this problem

or should you create a new design study?

It depends on whether there likely to be interactions between the piping

used to solve each problem.

5 Why did the South piping not get selected as the least cost alternative?

It contained the longest (and hence most costly) piping.

Solution Internal West North South Total Cost

($1000)1 200 200 175

2 150 200 182

3 200 200 187

4 250 200 196

5 250 200 208


Benefit

1 200 300 250 412 2.12

2 300 250 254 1.78

6 200 300 200 380 2.07

7 200 250 222 1.56

17 400 300 310 1.95


77/90


Workshop Review

6 How would you force the South pipes not to be eliminated from the

solution?

Not allowing them a zero diameter in the cost table.

7 What do you think would have happened if you included a node that

could not reach 130 kPa for any combination of pipe sizes (e.g. a node on

the suction side of a pump) and what would you need to do to handle that

node?

You would get a no feasible solution message and you would need to

set a very low pressure as the pressure constraint for that node (or only

enforce pressure constraints for a smaller selection set and not all nodes).

8 How would you decide between non-inferior solutions in the tradeoff

analysis?

You would need to consider available budget and amount of safety factor

you want to build in.

9 What would happen if you included a lot of nodes on the south side of the

system in calculating benefits?

Those solutions bigger pipes on the south side would tend to have higher

benefits and are more likely to show up as non-inferior.

10 Why would you not have used Average Day demands as an event in

Designer?

For most situations average day demands do not control pipe sizing.


78/90

Feb-12 78Multisource Mixing, Chlorine Residual, and Age Analysis -

Q and A

Multisource Mixing, Chlorine

Residual, and Age Analysis - Qand A

Results Table

Choose the minimum and maximum values by looking at the last 24 hours of each

simulation.

Node Condition Run 1 Run 2 Run 3

Constituent TDS-300 (mg/L) Chlorine Residualw/wall (mg/L)

Age (hours)

Initial values at T-1 300 0

Initial values at T-2 300 0

J-13 Min Value

J-13 Max Value

J-3 Min Value

J-3 Max Value

T-1 Min Value

T-1 Max Value

T-2 Min Value

T-2 Max Value


79/90

Feb-12 79Multisource Mixing, Chlorine Residual, and Age Analysis -Q and A


Workshop Review

Workshop Review


learned.

Questions

1 Why were initial conditions at the tanks maintained so long in comparison

with those at the nodes?

2 How long did it take to reach the equilibrium pattern of TDS at nodes:

3 What is the maximum water age at the two tanks (T1 and T2)? What type

of problems could result in tanks with water that is this old?


Node Hours

J-13

J-3

T-1

T-2



80/90



Workshop Review

4 If you were deciding where to live in town based on water supply, which

area would you choose and why?



81/90



Workshop Review

Answers

1 Why were initial conditions at the tanks maintained so long in comparison

with those at the nodes?

There is a much greater volume in the tanks than in pipes to flush out the

initial conditions.

2 How long did it take to reach the equilibrium pattern of TDS-300 at nodes:

3 What is the maximum water age at the two tanks (T1 and T2)? What type

of problems could result in tanks with water that is this old?

Maximum age in Tank T-1 is 3.5 days and the maximum age in Tank T-2 is

6 days. Especially in water as old as 5 days, you can lose your chlorine

residual and bacterial re-growth can occur.

4 If you were deciding where to live in town based on water supply, whicharea would you choose and why?

In the area served directly by Reservoir R-1 (near nodes J-1, J-14, J-12,

etc.) because it is always served by a single source, the water is very

young, the TDS is lower, and the pressure is reasonable (420 kPa).

Node Condition Run 1 Run 2 Run 3

Constituent TDS-300 (mg/L) Chlorine Residualw/wall (mg/L)

Age (hours)

Initial values at T-1 300 0 72

Initial values at T-2 300 0 144

J-13 Min Value 250 0.8 0.71

J-13 Max Value 440 0.9 1.32

J-3 Min Value 250 0.4 1.20

J-3 Max Value 398 0.8 65.87

T-1 Min Value 303 0.3 75.17

T-1 Max Value 305 0.4 83.32

T-2 Min Value 376 0.2 142.30

T-2 Max Value 378 0.2 150.81

Node Hours

J-13 10

J-3 10

T-1 250

T-2 300


82/90

Feb-12 82 Developing System Flushing Routines - Q and A


Developing System Flushing

Routines - Q and A

Results Tables

Pipe Velocity (Normal) (m/s) Maximum velocity (m/s)

(from Flushing Report)

P-675

P-665

P-455

P-294

Flushing TL-107 (Conventional)

Flushing TL-107 (UDF)

Normal Hydraulic Grade (Scenario Steady)

Zone Pump Discharge HGL (m)

Upper PMP-12

Lower PMP-1


83/90

Feb-12 83 Developing System Flushing Routines - Q and ACopyright 2011 Bentley Systems, Incorporated

Workshop Review

Workshop Review


learned.

Questions

1 What could have been done to improve flushing?

2 Why did the velocity at P-103 change so much between normal and

flushing demands?

3 What could you do to flush the short dead end pipes in the cul-de-sacs

without hydrants?





84/90


Workshop Review

4 Would you expect unidirectional flushing to be beneficial for TL-107?

Why?

5 In flushing P-294, the velocity was very high. What warning would you

give to operators that would be especially true for this pipe?




85/90


Workshop Review

Answers

1 What could have been done to improve flushing?

Turn on stand-by pumps at the sources.

2 Why did the velocity at P-103 change so much between normal and

flushing demands?

It was a dead end with virtually no demand on normal day.

3 What could you do to flush the short dead end pipes in the cul-de-sacswithout hydrants?

Install blow offs at end of line.

4 Would you expect unidirectional flushing to be beneficial for TL-107?

Why?

You would expect that but the impact was marginal because the pipes

being closed did not carry much flow to the flowed hydrant during

conventional flushing. The main being flushed is 300 mm which is going to

be difficult to flush in any case, especially when it is far from the source

and head loss between the source and flowed hydrant would be large.

5 In flushing P-294, the velocity was very high. What warning would you

give to operators that would be especially true for this pipe?

Be very cautious in closing and opening hydrants in these dead end pipes

to minimize water hammer.

Pipe Velocity (Normal) (m/s) Maximum velocity (m/s)(from Flushing Report)

P-675 0.0 0.0

P-665 0.0 0.0

P-455 0.02 1.66

P-294 0.01 4.24

Flushing TL-107 (Conventional) 0.01 0.72

Flushing TL-107 (UDF) 0.01 0.80

Normal Hydraulic Grade (Scenario Steady)

Zone Pump Discharge HGL (m)

Upper PMP-12 435.9

Lower PMP-1 382.1


86/90

Feb-12 86 Leakage Detection and Model Calibration - Q and A


Leakage Detection and Model

Calibration - Q and A

Module Review

Now that you have completed this module, lets measure what you have learned.

Questions

1 What time period of field data is good for leakage detection?

2 Which type of demand adjustment operation is used for leakage

detection?




87/90

Feb-12 87 Leakage Detection and Model Calibration - Q and ACopyright 2012 Bentley Systems, Incorporated

Module Review

3 What setting do you need to adjust when the detected number of leakage

nodes is the same as the prescribed maximum number of leakage nodes?

4 What is likely to be expected for the fitness values of optimized solutions

when increasing the maximum trials?

5 How are the final solutions affected when using a smaller value of Flow

per Fitness Point for flows and Head per Fitness Point?

6 What do you need to export for a leakage detection run? Whats not to

export for a leakage detection run?






88/90


Module Review

7 Which type of demand adjustment operation should be used for

optimizing the pattern at low demand hours?

8 Why should roughness and demand be optimized at the same time for a

high demand time step?

9 What should be exported to a scenario for the roughness and demand

optimization at high demand hour?

10 Which scenario should be used as representative for optimizing the

demand only at the high demand hours after roughness is calibrated?






89/90


Module Review

Answers

1 What time period of field data is good for leakage detection?

Minimum demand hours or minimum night flow hours, usually from 1:00

AM to 4:00 AM.

2 Which type of demand adjustment operation is used for leakage

detection?

Detect Leakage Node.

3 What setting do you need to adjust when the detected number of leakage

nodes is the same as the prescribed maximum number of leakage nodes?

Increase the maximum number of leakage nodes for each demand group.

4 What is likely to be expected for the fitness values of optimized solutions

when increasing the maximum trials?

Fitness value will be likely further minimized with more trials.

5 How are the final solutions affected when using a smaller value of Flow

per Fitness Point for flows and Head per Fitness Point?

Fitness val may be evaluated for a greater value, but the solution is likely

getting better because the possible solutions are better differentiatedwith scaled-up fitness.

6 What do you need to export for a leakage detection run? Whats not to

export for a leakage detection run?

You need to export emitter coefficients, but not demand.

7 Which type of demand adjustment operation should be used for

optimizing the pattern at low demand hours?

Multiply with Original Demand.


90/90

Module Review

8 Why should roughness and demand be optimized at the same time for a

high demand time step?

At the high demand hour, flow velocity is relatively high; head loss is

sensitive to the change of pipeline roughness values. To minimize the

compensation error, both demand and roughness should be calibrated

together.

9 What should be exported to a scenario for the roughness and demand

optimization at high demand hour?

Roughness value only, the optimized demand factor should be applied to

the demand pattern factor at the corresponding time step.

10 Which scenario should be used as representative for optimizing the

demand only at the high demand hours after roughness is calibrated?

The scenario that includes the calibrated roughness values.

Documents

WaterDistributionDesignAndModeling V8i SS3 SI QandA