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

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%

Estimating Cost of Direct Filtration Treatment Plant (2 of 19) Design capacity - approx 350,000 people - in 2005-2006 : 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 / 3.785 USgal = 41,611,624 USgal/day ~ 40 million USgal/day Hourly demand = 40 million/24 = 1.67 million USgal/hour Peak hourly demand = 2 x 1.67 = 3.3 million USgal/hour

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

Estimating Cost of Direct Filtration Treatment Plant (4 of 19) Treatment processes - flash mixing 3.3 million USgal/hour x 1.10 = 3.63 million USgal/hour assume 5 minute mixing time flash mixer volume = 3.63 million x 5min/60hour = 302,500 USgal four tanks @ 100,000 USgal each four tanks @ $700,000 each

Estimating Cost of Direct Filtration Treatment Plant (5 of 19) Treatment processes - flash mixing alum feed capacity 2000 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)

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

Estimating Cost of Direct Filtration Treatment Plant (7 of 19) Treatment processes - flocculation 3.3 million USgal/hour x 1.10 = 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 tanks @ 350,000 USgal each two tanks @ $500,000 each

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

Estimating Cost of Direct Filtration Treatment Plant (9 of 19) Treatment processes - granular bed filtration 3.3 million USgal/hour x 1.10 = 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 units @ 2,000 ft2 each four tanks @ 16,000 ft3 each = 16,000/7.48 = 2,200 USgal four tanks @ $400,000 each

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 = 3430 lb Cl2/day $520,000

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 tanks @ 1 million USgal each two tanks @ $1,000,000 each

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 tanks @ 4 million USgal each five tanks @ $2,700,000 each

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

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

Estimating Cost of Direct Filtration Treatment Plant (15 of 19) Treatment processes - holding tank assume 10% flow, 6 hour storage volume required = 0.10 x 6 x 3.3 million USgal = 2 million USgal two tanks @ 1 million USgal each two tanks @ $900,000 each

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

Estimating Cost of Direct Filtration Treatment Plant (17 of 19) Treatment processes – cost summary - flash mixing four tanks @ $700,000 each $ 2,800,000 alum $ 500,000 cationic polymer $ 1,400,000 - flocculation two tanks @ $500,000 each $ 1,000,000 - polymer addition $ 1,400,000 - granular bed filtration four tanks @ $400,000 each $ 1,600,000 filter media $ 330,000 - Cl2 addition $ 520,000 - C x t tank two tanks @ $1,000,000 each $ 2,000,000 - clearwell five tanks @ $2,700,000 each $13,500,000 - pumping station $ 1,800,000 - clarifier $ 1,250,000 polymer $ 200,000 - holding tank two tanks @ $900,000 each $ 1,800,000 - thickener $ 650,000 Total Process Cost $32,550,000

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

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 $50,000,000 $43,940,000 - Total Capital Cost based on total process/construction costs $68,000,000 $59,320,000 40 million USgal/day is 40% of 100 million USgal/day

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

Operation and Maintenance Costs (2 of 2)

References Kawamura, S., 2000, Integrated Design and Operation of Water Treatment Facilities, 2nd Ed., John Wiley and Sons, New York (TH4538K38 2000), pages 62, 502 – 505 McGivney, W.T. and Kawamura, S., 2008, Cost Estimating Manual for Water Treatment Facilities, John Wiley and Sons, New York (TD434M38 2008), entire book Masters, G.M., 1998, Introduction to Environmental Engineering and Science, Prentice Hall, Upper Saddle River, pages 274 - 278