1. ENG421 (5c) – Water Treatment Plant Costs
Cost Estimating Example
- Direct Filtration Process

2. Estimating Cost of Direct Filtration Treatment Plant (1 of 19)
Initial Design
- entire Sunshine Coast
- approx 350,000 people
- good raw water quality (hence direct filtration acceptable)
110%
105%
100% 5%
10% 5%

3. Estimating Cost of Direct Filtration Treatment Plant (2 of 19)
Design capacity
- approx 350,000 people
- in : average water supplied 419 L/p/day (see Week 1 notes)
- assume 450 L/p/day as maximum daily demand
Capacity = 350,000 x 450
= 157,500,000 L/day
= 157,500,000 L / USgal
= 41,611,624 USgal/day
~ 40 million USgal/day
Hourly demand = 40 million/24 = million USgal/hour
Peak hourly demand = 2 x = 3.3 million USgal/hour

4. Estimating Cost of Direct Filtration Treatment Plant (3 of 19)
Treatment processes
- flash mixing
alum
cationic polymer
- flocculation
- polymer addition
- granular bed filtration
- Cl2 addition
- C x t tank
- clearwell
- pumping station
- clarifier
polymer
- holding tank
- thickener

5. Estimating Cost of Direct Filtration Treatment Plant (4 of 19)
Treatment processes
- flash mixing
3.3 million USgal/hour x = 3.63 million USgal/hour
assume 5 minute mixing time
flash mixer volume = 3.63 million x 5min/60hour
= 302,500 USgal
four 100,000 USgal each
four $700,000 each

6. Estimating Cost of Direct Filtration Treatment Plant (5 of 19)
Treatment processes
- flash mixing
alum
feed capacity lb/hour (40%)
$500,000
N.B. – 40% comes from 40 million USgal/day is
approx. 40% of maximum chart capacity
(100 million Usgal/day)

7. Estimating Cost of Direct Filtration Treatment Plant (6 of 19)
Treatment processes
- flash mixing
cationic polymer
feed capacity 100 lb/day (40%)
$1,400,000

8. Estimating Cost of Direct Filtration Treatment Plant (7 of 19)
Treatment processes
- flocculation
3.3 million USgal/hour x = 3.63 million USgal/hour
assume 10 minute mixing time, g force G=50
flocculation volume = 3.63 million x 10min/60hour
= 605,000 USgal
two 350,000 USgal each
two $500,000 each

9. Estimating Cost of Direct Filtration Treatment Plant (8 of 19)
Treatment processes
- polymer addition
feed capacity 100 lb/day (40%)
$1,400,000

10. Estimating Cost of Direct Filtration Treatment Plant (9 of 19)
Treatment processes
- granular bed filtration
3.3 million USgal/hour x = 3.63 million USgal/hour
assume filtration rate of 8 USgal/min/ft2, filter depth of 8 ft
filtration area required = 3.63 million/(8 x 60min/hour)
= 7562 ft2
media cost $330,000
four filter 2,000 ft2 each
four 16,000 ft3 each
= 16,000/7.48
= 2,200 USgal
four $400,000 each

11. Estimating Cost of Direct Filtration Treatment Plant (10 of 19)
Treatment processes
- Cl2 addition
require 1 mg/L
40 million USgal/day = 40 million x 3.785
= 151 million L/day
Cl2 required (at 20% retention)
= 151 million x 5
= 755 kg Cl2/day
= lb Cl2/day
$520,000

12. Estimating Cost of Direct Filtration Treatment Plant (11 of 19)
Treatment processes
- C x t tank
assume 30 minute contact
volume required = 0.5 x 3.3 million USgal
= 1.7 million USgal
two 1 million USgal each
two $1,000,000 each

13. Estimating Cost of Direct Filtration Treatment Plant (12 of 19)
Treatment processes
- clearwell
assume 6 hour storage
volume required = 6 x 3.3 million USgal
= 20 million USgal
five 4 million USgal each
five $2,700,000 each

14. Estimating Cost of Direct Filtration Treatment Plant (13 of 19)
Treatment processes
- pumping station
capacity required = 24 x 3.3 million USgal/hr
= 79 million USgal/day
$1,800,000

15. Estimating Cost of Direct Filtration Treatment Plant (14 of 19)
Treatment processes
- clarifier
circular
floor area 14,000 ft2 (40%)
$1,250,000
rectangular
floor area 70,000 ft2 (40%)
$490,000
(cheaper, but five times area)
- polymer
feed capacity 10 lb/day (10% of 40%)
$200,000
N.B. – 10% comes from 10% of flow as sludge to clarifier

16. Estimating Cost of Direct Filtration Treatment Plant (15 of 19)
Treatment processes
- holding tank
assume 10% flow, 6 hour storage
volume required = x 6 x 3.3 million USgal
= 2 million USgal
two 1 million USgal each
two $900,000 each

17. Estimating Cost of Direct Filtration Treatment Plant (16 of 19)
Treatment processes
- thickener
diameter 60 ft (40%)
$650,000

18. Estimating Cost of Direct Filtration Treatment Plant (17 of 19)
Treatment processes – cost summary
- flash mixing four $700,000 each $ 2,800,000
alum $ ,000
cationic polymer $ 1,400,000
- flocculation two $500,000 each $ 1,000,000
- polymer addition $ 1,400,000
- granular bed filtration four $400,000 each $ 1,600,000
filter media $ ,000
- Cl2 addition $ ,000
- C x t tank two $1,000,000 each $ 2,000,000
- clearwell five $2,700,000 each $13,500,000
- pumping station $ 1,800,000
- clarifier $ 1,250,000
polymer $ ,000
- holding tank two $900,000 each $ 1,800,000
- thickener $ ,000
Total Process Cost $32,550,000

19. Estimating Cost of Direct Filtration Treatment Plant (18 of 19)
Treatment processes – cost summary
- Total Process Cost $32,550,000
- Total Construction Cost
@ 135% of total process costs $43,940,000
- Total Project Cost or Total Capital Cost
@ 135% of total construction costs $59,320,000

20. Estimating Cost of Direct Filtration Treatment Plant (19 of 19)
Compare with overall plant capital cost estimation (40 million USgal/day)
- Total Construction Cost based on total process costs
$50,000, $43,940,000
- Total Capital Cost based on total process/construction costs
$68,000, $59,320,000
40 million USgal/day is 40% of 100 million USgal/day

21. Operation and Maintenance Costs (1 of 2)
Operating and Maintenance Costs
- fixed costs :
labour
supervision
administration
- variable costs :
chemicals
power
maintenance repairs
replacement of plant and equipment
services and supplies needed to operate treatment plant
- impacts on O&M Costs :
owner policies and approaches to operations and maintenance
e.g. proactive or reactive
climate and weather
e.g. impact on treatment site, impact of raw water quality
level of sophistication of plant instrumentation and controls

22. Operation and Maintenance Costs (2 of 2)

23. References
Kawamura, S., 2000, Integrated Design and Operation of Water Treatment Facilities, 2nd Ed., John Wiley and Sons, New York (TH4538K ), pages 62, 502 – 505
McGivney, W.T. and Kawamura, S., 2008, Cost Estimating Manual for Water Treatment Facilities, John Wiley and Sons, New York (TD434M ), entire book
Masters, G.M., 1998, Introduction to Environmental Engineering and Science, Prentice Hall, Upper Saddle River, pages