ENCE 667Project Performance

Measurement

Patuxent Water Treatment Plant Upgrade schedule analysis

Presented by:

Luis Rubio

Isobo Tariah

Project Overview

• Location: Laurel, Maryland

• Total Cost: $45 million

• Capacity: 56 MGD

• Owner: Washington Suburban Sanitary Commission

• Contractor: Danis Environmental Industries

• Phases: Stage I & Stage II

Stage I

• Demolition of Filter Unit 1

• Construction of 3 treatment trains– Flocculation Basin– Sedimentation Basin– Chlorine contact chamber– Deep bed filters– Backwash tank– Chemical feed system

• Duration: 385 working days

Stage I Existing Filter Unit

Stage I Demolition of Filter Unit

Stage I Construction of new process structure

Stage II

• Demolition of Filter Unit 2, 3 & 4• Construction of 2 treatment trains

– Flocculation Basin– Sedimentation Basin– Chlorine contact chamber– Deep bed filters– Backwash tank– Chemical feed system

• Duration: 650 working days

Purpose of the Upgrade

• Save $24 Million using High-rate processes– Static Mixers for rapid mixing– Four-stage tapered-energy flocculation

shaft– Sedimentation plate settlers– Granular activated carbon– Sand filters with air backwash

• Capable to run at 72-80 MGD in emergency situation

Project Objectives

• To complete Stage I at the minimum time/cost tradeoff.– Develop a CPM schedule– Determine Critical Path– Crash activities in the critical path– Estimate cost associated with crashing

Project Performance Measurement Concepts Used

• CPM Schedule

• Gantt Chart

• Linear Programming – Minimize project cost – Obtain optimal crashing time

• Time/Cost trade-off curve

Project ActivitiesID Task Name Duration Predecessors3 Mobilization 10 -4 Process Testing 5 557 Soil Erosion Control 10 38 Install temp 16" Hs Line 8 711 Excavation for new treatment trains 15 2928 Shut down existing filter unit #1 4 829 Demolish existing filter unit #1 36 2831 Flocculation bsin bsae slab 27 1132 Sedimentation basin base slab 29 3133 Chlorine contct chamber base slab 28 3234 Filter / Filter gallery base slab 43 3338 Filter / Filter gallery lower slab 50 3445 Filtr control gallery slab 12 3847 Backwash tank slab 20 4848 Backwash tank walls 10 4555 Process tank water-lear test 5 8174 Install backwash drain valve 6 7979 Install backwash piping 30 4781 Install Control System / Electrical rough-in 90 74

Project Schedule

AOA Diagram Original

ST A B C D E

I J K L H

G F

M N O

P Q R END

103 7 8 28 29 11 31

33 34 38 45 48 47 79

32

74

81 55 4

10 8 4 36 15 27

29

28 43 50 12 10 20 30

6

5 590

0 0 10 10 2020 28 28 32 32 6868 83 83 110 110

139 139 167 167 210 210 260 260 272 272 282 282 302 302 332 332

338338 428 428 433 433 438 438

Project Crashing

• Estimated duration: 438 days

• Contractual required date: 385 days

• Difference: 53 days

• Penalty: $12,775 per day

• Bonus: $4,000 per day

Project Crashing

ActivityOriginal Duration

Max. Crash duration

Cost per crash unit

3 10 2 8,000.00$ 4 5 1 5,500.00$ 7 10 1 8,000.00$ 8 8 3 13,500.00$

11 15 3 16,800.00$ 28 4 0 12,000.00$ 29 36 5 14,500.00$ 31 27 5 7,500.00$ 32 29 5 14,000.00$ 33 28 2 5,000.00$ 34 43 8 13,500.00$ 38 50 9 15,850.00$ 45 12 1 10,000.00$ 47 20 3 5,500.00$ 48 10 1 4,000.00$ 55 5 1 9,500.00$ 74 6 1 11,500.00$ 79 30 4 7,500.00$ 81 90 10 10,000.00$

Penalty/Bonus

$(100,000)

$-

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

$700,000

373 378 383 388 393 398 403 408 413 418 423 428 433 438

Duration

Co

st

Penalty / Bonus

$268,275

406

Crashing Cost

$-

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

$700,000

$800,000

373 378 383 388 393 398 403 408 413 418 423 428 433 438

Duration

Co

st

Crashing Cost

$258,500

406

Project Crashing For optimal duration (406 days)

ActivityOriginal Duration

Max. Crash duration

Crash duration

Cost per crash unit Crashing Cost

3 10 2 2 8,000.00$ 16,000.00$ 4 5 1 1 5,500.00$ 5,500.00$ 7 10 1 1 8,000.00$ 8,000.00$ 8 8 3 13,500.00$ -$

11 15 3 16,800.00$ -$ 28 4 0 12,000.00$ -$ 29 36 5 14,500.00$ -$ 31 27 5 5 7,500.00$ 37,500.00$ 32 29 5 14,000.00$ -$ 33 28 2 2 5,000.00$ 10,000.00$ 34 43 8 13,500.00$ -$ 38 50 9 15,850.00$ -$ 45 12 1 1 10,000.00$ 10,000.00$ 47 20 3 3 5,500.00$ 16,500.00$ 48 10 1 1 4,000.00$ 4,000.00$ 55 5 1 1 9,500.00$ 9,500.00$ 74 6 1 1 11,500.00$ 11,500.00$ 79 30 4 4 7,500.00$ 30,000.00$ 81 90 10 10 10,000.00$ 100,000.00$

Total 438 65 32 258,500.00$

Sensitivity Analysis

$500,000

$550,000

$600,000

$650,000

$700,000

$750,000

373 378 383 388 393 398 403 408 413 418 423 428 433 438

Duration

To

tal

Co

st

Total Cost

$526,775

406

Total cost = Crashing Cost + Penalty/Bonus

Total cost = $258,500 + $268,275 = $526,775

AOA Diagram Original – Crashed

ST A B C D E

I J K L H

G F

M N O

P Q R END

83 7 8 28 29 11 31

33 34 38 45 48 47 79

32

74

81 55 4

9 8 4 36 15 22

29

26 43 50 11 9 17 26

5

4 480

0 0 8 8 1717 25 25 29 29 6565 80 80 102 102

131 131 157 157 200 200 250 250 261 261 270 270 287 287 313 313

318318 398 398 402 402 406 406

Schedule Alternative

• Some activities relations were changed in order to have parallel activities.

• Possible changes in the critical path.

• Estimated duration should decrease.

• Crashing: 53 days less than the estimated duration.

Project Schedule

AOA Diagram Alternative

ST A

B

C

D

E G

H

I

J

F

K M

103 7

8 28

29

11 31

33

34

38

45 48

47

79

32

7481 55 4

10

8 4

36

15 27

29 28

43

50

12 10

20

30

6 5 590

L

O END N

0 0 10 10 2222

18 18 37 37

64 64 93 93 121 121

164 164

176 176 264 264

214 214 234234 324324 330330 335335 340 340

Project Crashing For contractual date (287 days)

ActivityOriginal Duration

Max. Crash duration

Crash duration

Cost per crash unit Crashing Cost

3 10 2 2 8,000.00$ 16,000.00$ 4 5 1 1 5,500.00$ 5,500.00$ 7 10 1 1 8,000.00$ 8,000.00$ 8 8 3 3 13,500.00$ 40,500.00$

11 15 3 3 16,800.00$ 50,400.00$ 28 4 0 12,000.00$ -$ 29 36 5 2 14,500.00$ 29,000.00$ 31 27 5 5 7,500.00$ 37,500.00$ 32 29 5 5 14,000.00$ 70,000.00$ 33 28 2 2 5,000.00$ 10,000.00$ 34 43 8 8 13,500.00$ 108,000.00$ 38 50 9 9 15,850.00$ 142,650.00$ 45 12 1 10,000.00$ -$ 47 20 3 3 5,500.00$ 16,500.00$ 48 10 1 4,000.00$ -$ 55 5 1 1 9,500.00$ 9,500.00$ 74 6 1 1 11,500.00$ 11,500.00$ 79 30 4 7,500.00$ -$ 81 90 10 10 10,000.00$ 100,000.00$

Total 56 655,050.00$

Contractual date = Estimated duration - 53 days = 287 days

Penalty/Bonus

$-

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

$700,000

$800,000

287 292 297 302 307 312 317 322 327 332 337

Duration

Co

st

Penalty / Bonus

$357,700

315

Crashing Cost

$-

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

$700,000

287 292 297 302 307 312 317 322 327 332 337

Duration

Co

st

Crashing Cost

$206,500

315

Sensitivity Analysis

$550,000

$575,000

$600,000

$625,000

$650,000

$675,000

$700,000

287 292 297 302 307 312 317 322 327 332 337

Duration

Tota

l Cos

t

Total Cost

$564,200

Total cost = Crashing Cost + Penalty/Bonus

Total cost = $206,500 + $357,700 = $564,200

315

Project Crashing For optimal duration (315 days)

ActivityOriginal Duration

Max. Crash duration

Crash duration

Cost per crash unit Crashing Cost

3 10 2 2 8,000.00$ 16,000.00$ 4 5 1 1 5,500.00$ 5,500.00$ 7 10 1 8,000.00$ -$ 8 8 3 13,500.00$ -$

11 15 3 16,800.00$ -$ 28 4 0 12,000.00$ -$ 29 36 5 14,500.00$ -$ 31 27 5 5 7,500.00$ 37,500.00$ 32 29 5 14,000.00$ -$ 33 28 2 2 5,000.00$ 10,000.00$ 34 43 8 13,500.00$ -$ 38 50 9 15,850.00$ -$ 45 12 1 10,000.00$ -$ 47 20 3 3 5,500.00$ 16,500.00$ 48 10 1 4,000.00$ -$ 55 5 1 1 9,500.00$ 9,500.00$ 74 6 1 1 11,500.00$ 11,500.00$ 79 30 4 7,500.00$ -$ 81 90 10 10 10,000.00$ 100,000.00$

Total 25 206,500.00$

AOA Diagram Alternative – Crashed

ST A

B

C

D

E G

H

I

J

F

K M

83 7

8 28

29

11 31

33

34

38

45 48

47

79

32

7481 55 4

10

8 4

36

15 22

29 26

43

50

12 10

17

30

5 4 480

L

O END

N

0 0 8 8 2020

16 16 35 35

57 57 86 86 112 112

155 155

167 195 252 302

205 205 222222 302302 307307 311 311 316 316

Conclusions

• Optimal duration should be 406 days– Cost: $526,775

• When estimating the project bid, scheduling analysis should be perform to evaluate the necessity of crashing the project. If that is the case, the cost should be included in the bid.

Future Extensions

• PERT Analysis

• Limited resources allocation

Questions