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IndianJournalof Engineering& MaterialsSciencesVol.5, August1998, pp. 223-235
Cost estimation models for drinking water treatment unit processes
Virendra Sethi'& RobertM Clarkb•
·OakRidgeInstitutefor ScienceandEducation,bWaterSupplyand WaterResourcesDivision
NationalRiskManagementResearchLaboratory,MS689, UnitedStatesEnvironmentalProtectionAgency,26, WestMartinLutherKingDrive,Cincinnati,OH45268, USA
Received12 August1997
Cost models for unit processes typicallyutilized in a conventionalwater treatment plant and in packagetreatment plant technology are compiled in this paper. The cost curves are represented as a function ofspecified design parameters and are categorized into four major categories : construction, maintenancematerials, energy and labour. The cost curves are developed so that cost indices may be used to update costestimates from the base year. These models can be used to assist in making decisions related to constructionof new water treatment facilities or modification of existing water treatment processes to meet drinkingwater standards or provide improved water quality. They can also be used as a part of sophisticatedeconomic evaluation such as the calculation of cost to benefit ratios.
Cost estimation plays an integral role in planning,implementation and administration of any watertreatment project. Over the last 20 years, U.S.Environmental Protection Agency (USEPA) hasdeveloped a substantial amount of cost data andrelated cost curves which can be used to estimatethe cost of various unit processes. These unitprocesses can in turn be aggregated into watertreatment systems. These cost curves have beenused extensively for determining the economicimpact of proposed federal drinking waterregulations. The initial cost curves were presentedin earlier works 1.2. Various efforts3•4 have beenmade to upgrade and modify these cost curves.This paper reports on a selected subset of a newand comprehensive effort to update and modifythese cost curves.
The objective of the present work is to presentsome of the cost models developed from thestudies referred to earlier. The choice of theprocesses and facilities was based on therequirements of a typical conventional watertreatment plant, and a complete package treatmentplant. A complete list of unit processes for whichcost curves have been developed are listed
5'elsewhere.
ApproachThe data modelled 10 the present work was
developed for maximum flexibility and use).Treatment systems were divided into two mainclasses. - large systems (1 to 200 mgd) and smallsystems (2500 gpd to 1 mgd). This separation wasmade because many processes applicable to onerange are not applicable to the other, and evenwhen a process is applicable, the conceptual designof the components varies significantly.
Costs were estimated under two main categories- construction costs and operation and maintenancecosts. Construction costs were presented in termsof eight components : excavation and site work,manufactured equipment, concrete, steel, labour,pipes and valves, electrical equipment andinstrumentation, and housing. Each componentcost can be updated using an appropriate costindex to reflect variations in escalation, or acomposite index such as the Engineering NewsRecord Construction Cost Index can be usedinstead. The cost curves developed in the presentwork are based on the use of the compositeconstruction cost index.
In addition to the construction costs, thefollowing special costs need to be added to obtainthe total capital cost: general contractors overheadand profit, engineering costs, land costs, legalfiscal and administrative costs, and interest duringconstruction. Since these costs vary significantly
224 INDIAN J. ENG. MATER. SCI., AUGUST 1998
from region to region, they were not included inthe current cost curves but can be added at theappropriate point in the calculations.
The operations and maintenance (O&M) costswere developed based on five main components :energy requirements (process related energy andbuilding related energy), natural gas, diesel fuel,maintenance materials and labour. Energyrequirements were separated for process andbuildings to account for the large geographicvariations in the building energy requirements.Local variations in energy and labour rates can beincorporated conveniently since the costs areobtained from the cost curves in terms of energyunits and labour hours. The maintenance materialsrequirements which are for all repair andmaintenance items, were calculated based onnational U.S. averages. Chemical costs are notincluded in these material costs due to largeregional variations in chemical costs. However,these costs need to be included in any final costcalculations.
Cost IndicesCost indices are widely used to adjust costs that
occur due to differences in geographic locationsand variations from year to year. It provides asingle numerical value to indicate trends with timeand the relative value of the index factors fromplace to place. All costs in this paper are reportedin U.S. dollars and all cost curves are based on theyear that the cost analysis was performed. The baseyear cost indices are listed in Table 1, and can beused to update the costs obtained from the curveusing the following expression:
Current Year Cost = Base Year CostCurrent Year Index
Base Year Index... (1)x
The most widely used indices in the construction
Table I-Construction cost indices and producer price indicesfor the costing analysis in the source documents
Base Year Construction Cost Producer PriceIndex (CCI) Index (PPI)
1979 265.4 99.71983 383.1 287.11990 445.0 345.01997 549.0 361.0
industry are the Engineering News Recordconstruction cost index (CCI) and the building costindex (BCI) which are published by EngineeringNews Record. Maintenance material costs can beupdated using Producers Price Index for FinishedGoods (PPI), and may be obtained from theMonthly Labor Review published by theDepartment of Labor.
Individual Unit Process CostingIn order to develop the unit process cost curves
a standardized flow pattern was assumed for thetreatment train and then each unit process was"costed out". This approach requires assumptionsabout such details as common wall constructionand amounts of interface piping required. After theflow pattern was established, the costs associatedwith specific unit processes were calculated. "Asbuilt" design and standard cost referencedocuments were used to calculate the costs ofequipment associated with a unit process. Adescription of cost curves for inorganic coagulant(alum) feed and rectangular clarifiers is presentedhere to illustrate the level of detail incorporated inthe costing analysis.
Inorganic coagulant feedDry alum is used as a coagulant in both small
and large treatment plants, although if the dry alumusage is greater than 300 Ib/day, liquid alumshould be used to minimize handling costs. Liquidalum is a clear amber liquid that contains 5.4pounds of commercial dry alum per gallon ofliquid. A typical liquid alum feed system includesIS or 30-day storage, two transfer pumps, a daytank and two metering pumps. One of each type ofpump is used as a standby pump. Fig. I shows atypical liquid alum feed system. Alum feed ratesrange from 40 to 85,000 pounds per day on drybasis. All systems, excluding the largest, provide30-day storage ranging from 240 to 300,000gallons. The largest system provides a 255,000gallon, IS-day storage capacity. All but thesmallest, system include day tanks that are filledusing transfer pumps, and have volumes rangingfrom 50 to 17,000 gallons. Costs are based onvertical, flat bottom, site constructed tanks, havingmaximum capacities of 60,000 gallons. Contain-ment walls are designed to hold the contents of thelargest tank. Wetted parts of the pump are plastic.
SETHI & CLARK: COST ESTIMATION MODELS FOR WATER TREATMENT PROCESSES 225
30-DayStorage Tan
Transfer Pump
ContainmentWalls
Metering Pump
Fig. I-Typical liquid alum feed system
1000000 ,------------------,
!!!Ulooco 100000.~
;:>iiicoo
• •
•
•
I
r I10000 L--,---,-,-,-,-u.L_'L......I..'..L' J...J''J.l"-"-"_L' -'-'-'-'-'-''LL"Lll"_-'----J.'--"-'-,.u.",ll"l
10 100 1000 10000 100000
Feed Rate. Ib/day alum
Fig. 2----{:onstruction costs for liquid .alum feed systems indollars versus feed rate in Ib/day alum
Piping and fittings are PVC, and valves are eitherPVC or PVDF plastic construction. Pipe sizes andlengths of piping vary from 3/4 to 6 in. and 200 to400 ft, respectively. The piping system assumes 8fittings per 100 ft of pipe. Construction costs areplotted in Fig. 2. Fig. 3 shows the operation andmaintenance costs. Labour requirements for
1~O'------------------'
~e::>o:I:o 1~,
.J:l.,-J
wCL
Process Energy (kWH/Vr)
Maintenance Malerial (S/Yr)
Feed Rate, Ib/day alum
Fig. J--Operation and maintenance costs for liquid alum feedsystems versus feed rate in Ib/day alum. Cost of processenergy, maintenance materials and labour on common y-axis inunits of kWH/year, $/year, and hours/year respectively
operation include the ordering and receiving ofalum, the maintenance and repair of pumps, therepair of feed lines and tanks, as well as thecleanup of any liquid spills. The system's electricalrequirements are for one metering pump and onetransfer pump. The metering pump is assumed to
226 INDIAN J. ENG. MATER. SCI., AUGUST 1998
run continuously. 24 h a day. and the transfer pumpruns IS ruin a day. Material costs include meteringand transfer pump replacement and any materialneeded to repair piping. tanks and valves.Additional material costs include protectiveclothing. gloves and goggles.
Rectangular clarifiersRectangular clarifiers may be used following
treatment by coagulation and flocculation or limesoftening. Cost estimates were made for clarifiersthat have 12-ft sidewall depth and that use chainand fl ight sludge collectors.
Construction cost includes the chain and flightcollector drive mechanism. weirs. the reinforcedconcrete structure complete with inlet and outlettroughs. a sludge sump. and sludge withdrawalpiping. Costs for the structure were developedassuming multiple units with common wallconstruction. Yard piping to and from the clarifieris not included in cost estimates. Construction costestimates are shown in Fig. 4.
Process energy requirements were calculatedbased on manufacturers' estimates of motor sizeand torque requirements. Maintenance materialcosts are for parts required for periodicmaintenance of the drive mechanism and weirs.Labour requirements are for periodic checking of
1000000
<II
<II
oU
.~ 100000"0::I-.;c:oU
1000
Area, ft>
10000
Fig. 4-Construction costs in dollars versus square feet ofsurface area for rectangular clarifiers
the clarifier drive mechanism, as well as periodicmaintenance of the mechanism and weirs.Operation and maintenance costs are shown inFig. S.
ModellingIn previous work, cost models have been
developed to facilitate the application of the datadeveloped by Gumerman et a/. 1.2 These models aredescribed extensively by Clark", Clark and Dorsey'and Adams and Clark". The purpose of this paperis to modify this earlier effort and aggregate all ofthe cost data collected by the USEPA's WaterSupply and Water Resources Division and make itaccessible in a standard and usable form. Thefollowing form of equation was adopted to fit allcost curves:
y = a + b XC ••• (2)where y is the costing unit ($-for constructioncosts, $/year for maintenance materials,kWH/year-for energy requirements, and hours/year- for labour); x is the design flow rate or designparameter for the specific unit process; a, band care parameters estimated using a curve fittingalgorithm. For some cases, where the designparameter (x) spanned two to three orders of
10000
Proce •• Energy (kWH/Vr)
>••••:;0J:(5.0CIS
...J
> 1000~~~
Maintenance M••• ,i.I, (S/YI)
~J:;:6 •wa.
Labor (Hours/Yr)
100100 1000 10000
Area, ft>
Fig. S-Operation and maintenance costs for rectangularclarifiers versus square feet of surface area. Cost of processenergy, maintenance materials and labor on common y-axis inunits of kWH/year, $/year, and hours/year respectively
Tabl
e:!-
Uni
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stor
age
syst
ems
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stru
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10-2
000
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edR
ate,
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ay24
516.
3313
372.
3289
0.93
090.
9575
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alco
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imie
/,p.
140
Proc
ess
Ener
gyPE
(10
-20
(0)
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Rat
e,Ib/day
4762
.612
43.
1177
1.47
860.
9087
619
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aint
enan
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MM
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500
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100
-10
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Rat
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/day
2000
01
I19
90-
Mai
nten
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eria
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Rat
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/day
2500
0I
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Rat
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1150
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118.
9127
0.78
240.
9976
419
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colm
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p.21
3Pr
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100
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ay76
230
II
1990
0 CIl
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346
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1990
tT1
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Rat
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/day
3416
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41.
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0.89
850.
9999
519
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Labo
urO
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lday
031
8.99
110.
241
0.95
487
1990
:> ~Li
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reed
syst
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stru
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ay67
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1033
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565:
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9762
419
90(5
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colm
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p.31
4PE
(40
-850
00)
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/day
ZPr
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1507
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829
3.04
2099
20.
8572
325
0.99
819
90s:
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nten
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5000
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63.0
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3.06
910.
6751
0.94
622
1990
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071
7.30
320.
0261
0.88
257
1990
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ay36
165.
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336.
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stem
s0.
7375
0.98
586
1990
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80.
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218.
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590.
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1990
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127
1990
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1990
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2699
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9.78
690.
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9880
219
90~ '"0
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548
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188.
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0.96
640.
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419
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278
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7832
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229.
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680.
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5.54
7250
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60.
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(10
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039
101.
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1990
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1990
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1990
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1990
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1990
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1990
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1990
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1990
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1990
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317.
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0.71
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9.36
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1990
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110.
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79
SETHI & CLARK: COST ESTIMATION MODELS FOR WATER TREATMENT PROCESSES 231
Coagulant f-----i Rapid Mix I---t Flocculation IlFeed
RectangularClarifier
1f-t
Gravity Filter GravityThickener Media Filtration
- 1
BasketCentrifuge Surface
Wash
magnitude, a 11x2 weighting function was used tobetter fit the cost data. For some data sets where asingle curve could not be found to fit the entiredata set, the set was broken into segments and thedata were represented by a combination ofpolynomial and straight line approximations.
Cost curves for 22 unit processes and facilitiesrequired for a conventional treatment plant, and 5processes and facilities for package treatment plantare listed in Tables 2 and 3 respectively. a, band care the parameters estimated for each curve as inEq. (2). "R2
" represents the goodness of fit of themodel to the cost data. The column labeled"parameter range" indicates the values of the inputparameters over which cost data were available todevelop the model. In some cases, the values ofparameter 'a' are negative. However, if the value
I RawWaler I
DewateredSludgeHauling
FinishedWater.
Pumping
of the input design variable is limited to the"parameter range", y results in a positive cost unit.The "unit" column describes the unit of flow or thedesign parameter used. For a different system ofunits of input of x, a and c would remainunchanged, but b would need to be replaced bybx(CF)C, where CF is the conversion factor. Forexample, for the construction cost model forchlorine cylinder feed and storage systems (Table2, # 1), if the inputs were given in kg/day instead oflb/day, the value of b (=372.3289) would bemodified to 775.6897[=bx(2.2)09309 where 2.2 isthe conversion factor from kg/day to lb/day and0.9303 is the value of parameter c]. "Base year"indicates that the cost estimates are based on thedollar index for that year. To update the date tocurrent cost estimates, the cost would have to be
Backwash Pumping
ChlorineInjectionSystem
Clear WellStorage
..-Fig. 6--Flow chart for a 40 mgd conventional treatment plant
232 INDIAN 1. ENG. MATER. SCI., AUGUST 1998
Package CompleteTreatment Plant 1--4
Raw WaterPumpingFacilities
SludgeDisposal
High ServicePumping I-------Station
Steel Backwash /Clearwell Tank
Fig. 7-Flow chart for a 350 gpm package treatment plant
multiplied by the ratio of the cost indices for thecurrent and base years (listed in Table I) usingEq. (I). The "process" column also refers to thesource document for the data.
Process Costing ExamplesTo illustrate the application of the cost curves,
two examples of treatment trains were selected': (i)a 40 mgd conventional treatment plant (Fig. 6), and(ii) a 350 gpm package complete treatment plant(Fig. 7). Costing analysis for these two examples ispresented in Tables 4 and 5 using the cost curveslisted in Tables 2 and 3 respectively. To estimatethe O&M costs in a treatment plant, the operatingcapacity (less than the design capacity) of the plantwas used. The costs have been updated to 1997using the CCI and PPI from Table I.
Costing of 40 mgd plantFig. 6 shows the flow chart for a typical
conventional treatment plant. Conventionaltreatment plants are primarily made fromreinforced concrete and cast in-place structures.They consist of chemical feed systems, rapid mix,flocculation, clarification, filtration, and sludgedisposal facilities.
Costing of package complete treatment plantPackage complete treatment plants include
coagulation, flocculation, sedimentation andfiltration, all included in factory preassembledunits or field assembled modules (Fig. 7). Therelatively low capital, and operational andmaintenance costs make these package plantssuitable for smaller water demand situations. Theexample includes complete and operable facilities,
including raw water pumping, clearwell storage,high service pumping, an enclosure for allfacilities, and chemical requirements. In thisexample, sludge lagoons were assumed fordisposal of sludge.
The annual costs for both the systems wereestimated using the rates listed in Table 6. Column2 in Tables 4 and 5 refers to the cost models usedfrom Tables 2 and 3. Total capital cost wasestimated by adding an additional 42% and 36 %of total construction costs for the 40 mgd and the350 gpm plants respectively. This was done toaccount for the cost for administration, laboratoryand maintenance buildings; sitework, interfacepiping and roads (~5%); contractors overhead andprofit( ~ 10%); engineering fee (~I 0%), and land,legal and administrative costs. These additionalcosts are based on the original estimates made byGumerman et al'; and should be evaluated foreach specific project. The cost of annual chemicalrequirements for the two systems are included inTables 4 and 5. The cost estimates from thisanalysis indicates a treatment cost of $0.55/kgal forthe 40 mgd plant, and $1.24/kgal for the 350 gpmplant.
ConclusionsCost appraisals are frequently used to eliminate
non-cost effective alternatives and to concentrateresearch and evaluation efforts onto pathwaysleading to the most promising end results. The costinformation presented here falls into a categorythat can be used for what might be termed "pre-design estimates". Pre-design estimates are usefulfor guiding research and for examining the most
Tabl
e4-
Cos
ting
for
a40
mgd
conv
entio
nal
wat
ertre
atm
ent
plan
t
#U
nit
Proc
ess/
Faci
lity
Cos
tD
esig
nC
C($
)O
pera
ting
MM
Ener
gyD
iese
lLa
bour
Ener
gyD
iese
lLa
bour
Tota
lO&
MC
apita
lTo
tal
curv
eca
paci
tyca
paci
ty($
/yea
r)(k
WH
/yea
r)(g
al/y
ear)
hour
s/ye
ar($
/yea
r)($
/yea
r)$/
year
($/y
ear)
($/y
ear)
($/y
ear)
(Tab
leV
JtT
I2)
-lI
Alu
mfe
edsy
stem
(43
1334
41b/
day
$281
,585
8400
lblh
$4,6
388,
539
090
8$6
83$0
$13,
620
$18,
941
$33,
086
$52,
027
:r:m
gIL)
$12,
067
~2
Sodi
umhy
drox
ide
feed
539
2ga
l/day
$30,
788
260
gal/d
ay$2
16B
E:17
40
548
$14
$8,2
20$2
41$3
,618
$241
()
syst
em(2
4m
g)PE
:301
1$2
41r ~
3Po
lym
erfe
edsy
stem
(0.2
467
lb/d
ay$5
3,79
945
lb/d
ay$7
9614
,569
078
4$1
,166
$0$1
1,76
0$1
3,72
2$6
,321
$20,
043
;>:I
mg/
I);><
::
4R
apid
mix
(45
s,G
=600
)6
2785
ft'$1
20,8
0327
85ft3
$90
283,
673
053
8$2
2,69
4$0
$8,0
70$3
0,85
4$1
4,19
4$4
5,04
8()
5Fl
occu
latio
n(3
5m
in,
2113
0,00
0fr
'$7
52,9
1713
0,00
0ft3
$8,9
3515
4,16
00
409
$12,
333
$0$6
,135
$27,
403
$88,
468
$115
,871
0 VJ
G=5
0)-l
6R
ecta
ngul
arcl
arifi
er22
40,0
00ft2
$4,6
47,4
7840
,000
W$1
8,16
770
,560
04,
344
$5,6
45$0
$65,
160
$88,
972
$546
,079
$635
,051
tTI
VJ
(100
0gp
d/fr
')::l
7G
ravi
tyfil
tratio
n(5
855
60W
$5,7
81,1
3155
60W
$14,
542
1,00
3,50
10
4,54
8$8
0,28
0$0
$68,
220
$163
,042
$679
,283
$842
,325
3:gp
m/fr
')~ -l
8Fi
lter
med
ia-m
ixed
med
ia9,
1040
mgd
$425
,453
$49,
991
$49,
991
(59
Surf
ace
was
hII
5560
W'
$351
,007
5560
W'
$725
78,4
880
330
$6,2
79$0
$4,9
50$1
1,95
4$4
1,24
3$5
3,19
7Z
10B
ackw
ash
pum
ping
(18
2010
010
gpm
$252
,792
5560
W'
$5,3
0613
2,87
40
296
$10,
630
$0$4
,440
$20,
376
$29,
703
$50,
079
3:gp
m/ft
')0 0
IIW
ash
wat
ersu
rge
basi
n12
2680
0ft3
$141
,881
$16,
671
$16,
671
tTI
12C
hlor
ine
feed
syst
em(2
I67
0lb/
day
$226
,422
450l
b/da
y$2
,093
30,8
770
1150
$2,4
70$0
$17,
250
$21,
813
$26,
605
$48,
418
r VJ
mg/
I,)."
13C
lear
wel
lst
orag
e(u
nder
-13
2500
kgal
$1,8
65,4
4525
00kg
al7,
783,
570
017
,550
$622
,686
$0$2
63,2
50$8
85,9
36$2
19,1
90$1
,105
,125
0 ;>:I
grou
nd)
~14
Fini
shed
wat
erpu
mpi
ng19
3819
4gp
m$8
32,0
2819
444
gpm
12,0
00,0
000
541
$960
,000
$0$8
,115
$968
,115
$97,
763
$1,0
65,8
78~
15G
ravi
tyth
icke
ner
1485
0ft2
$159
,587
850
ft2$4
544,
120
014
8$3
30$0
$2,2
20$3
,004
$18,
751
$21,
755
-l tTI
16B
aske
tce
ntrif
uge
1611
5,00
0gp
d$6
75,7
8070
,000
gpd
$7,7
0630
3,62
60
1,09
4$2
4,29
0$1
6,41
0$4
8,40
6$7
9,40
4$1
27,8
10;>:
I17
Dew
ater
edsl
udge
han-
1537
00gp
d$1
77,4
9722
00gp
d10
,890
5,94
682
8$8
71$7
,433
$12,
420
$20,
724
$20,
856
$41,
580
-l
dlin
gTo
tal
CC
=$1
6,77
6,39
6;>:
ItT
I
18A
dmin
istra
tive,
Engi
-42
%of
CC
$7,0
46,0
86$8
27,9
15~ -l
neer
ing,
Site
wor
ket
c.3:
Tota
lA
nnua
lO
&M
Cos
$2,3
31,9
51tT
I
Arn
oriti
zed
Ann
ual
Cap
ital
Cos
t:$2
,799
,142
Z -lC
hem
ical
Cos
tsU
nit
Cos
t'"C
Alu
m15
33to
ns/y
ear
$127
$194
,691
;>:I
0Po
lym
er16
425
Ib/y
ear
$4$5
9,13
0o
Sodi
umH
ydro
xide
602
tons
/yea
r$3
60$2
16,7
20tT
IV
J
Chl
orin
e82
tons
/yea
r$5
42$4
4,44
4V
JtT
ITo
tal
Ann
ual
Che
mic
alC
ost
$514
,985
C/l
Tota
lA
nnua
lC
ost
(Cap
ita1+
0&M
+Che
mic
al$5
,646
,077
Wat
erTr
eatm
ent
Cos
t($
/gal
):0.
0005
52
N w w
N V.) ~
Tabl
eo-c
-Cos
ting
for
a35
0gp
mpa
ckag
etre
atm
ent
plan
t
#U
nit
Proc
essl
Faci
lity
Cos
tD
esig
nC
C($
)O
pera
ting
MM
Ener
gyD
iese
lLa
bour
Ener
gyD
iese
lLa
bour
Tota
lO&
MC
apita
lTo
tal
curv
eca
paci
tyca
paci
ty(S
/yea
r)(k
WH
/yea
r)(g
al/y
ear)
hour
s/ye
ar($
/yea
r)(S
/yea
r)$/
year
(S/y
ear)
(S/y
ear)
(S/y
ear)
(Tab
le3)
ZI
Pack
age
raw
wat
er3
500
gpm
S49,
930
245
gpm
$181
28,4
620
72S2
,277
SO$1
,080
$3,5
38$5
,867
S9,4
040
pum
ping
faci
litie
s:;
2Pa
ckag
eco
mpl
ete
treat
-2
70ftl
$488
,287
245
gpm
$5,5
48B
E:15
,234
010
94$1
,219
$0$1
6,41
0$2
3,17
7$5
7,37
4S8
0,55
1Z
men
tpl
ant
(5gp
m/ft
',2
PE:3
,750
$300
•....$3
00$0
$0$3
00tr1
back
was
hes/
day
Z3
Stee
lba
ckw
ashl
clea
rwel
l4
100,
000
gal
$179
,403
$21,
080
$21,
080
Pta
nk~
4Pa
ckag
ehi
ghse
rvic
e5
500
gpm
$35,
137
245
gpm
$72
43,1
390
124
$3,4
51$0
$1,8
60$5
,384
$4,1
29$9
,512
;I>
pum
pst
atio
n..., tr1
5Sl
udge
dew
ater
ing
Ia-
I15
,000
ftl$1
1,94
312
,000
ftl$1
325
093
55$1
16$8
25$2
,266
$1,4
03$3
,669
?'go
onTo
tal
CC
=$7
64,7
00en o
6A
dmin
istra
tive,
Engi
-36
%of
CC
$275
,292
$32,
347
-ne
erin
g,Si
tew
ork
etc.
;I>
Tota
lA
nnua
lO
&M
Cos
t$3
4,66
4C 0
Am
oriti
zed
Ann
ual
Cap
ital
Cos
t:$1
22,1
99C
Che
mic
alC
osts
Uni
tC
ost
V1 ...,
Alu
mII
tons
/yea
rSI
27$1
,397
\0Po
lym
er26
4lb
/yea
r$4
$950
\0 00
Chl
orin
e2
tons
/yea
r$5
42$8
67To
tal
Ann
ual
Che
mic
alC
ost
$3,2
15To
tal
Ann
ual
Cos
t(C
apita
l+O
&M
+Che
mic
al$1
60,0
78W
ater
Trea
tmen
tC
ost
($/g
al):
0.00
124
SETHI & CLARK: COST ESTIMATION MODELS FOR WATER TREATMENT PROCESSES 235
Table 6--Assumptions for cost analysis in Tables 4 and 5
Item
Capital Cost AmortizationLabor costElectric Power costDieselOperating Capacity
Value
10% interest for 20 years$151h$0.08/kWH$1.25/gallon70% of Design Capacity
desirable of several process or design alternatives.Many water treatment processes originate in thelaboratory and are tested through field scale pilotplant studies. A cost estimate at this stage maydisclose the most costly features of the processesand reveal specific areas for further study. Thenext step is to conduct preliminary evaluations inwhich laboratory data and pilot plant data istranslated into equipment designs, piping, layout,buildings, etc.. At this point choices can be madeof unit processes that are most attractive from aneconomic viewpoint after all factors areconsidered. The final decision as to whether or notto build a treatment facility is complex andinvolves many factors that must be weighed byjudgement. Comparative costs may be used toevaluate these factors. The reliability of costestimates is a function of basic data, stage ofdevelopment, definition of scope, the timeexpended on the analysis, and experience of theanalyst.
This paper makes available models that can beused for making cost estimates for constructionand O&M costs for a selected number of unitprocesses that are frequently used in conventionaltreatment plants and package treatment plants.
AcknowledgmentThe authors would like to thank Drs Manohari
Sivaganesan and L K Jain for their assistance. Partof this work was completed during the firstauthor's appointment to the Postgraduate Research
participation Program administered by. the OakRidge Institute for Science and Education throughan interagency agreement between the U. S.Department of Energy and the U. S. EnvironmentalProtection Agency.
NomenclatureAl Alum feedBE Building EnergyCC Construction costsCl Chlorine FeedDF Diesel FuelFU Fuel Costsgpd U.S. gallon/daygpm U.S. gallons/minuteHC Heating coilsmgd million U.S. gallons/dayMM Maintenance materialsOL LabourPE Process energyPoly Polymer feedPU Pumping energy
ReferencesI Gumerman R C, Culp R L & Hansen S P, Estimating
Water Treatment Costs, Vol 1-4, EPA-600/2-79-l62a,USEPA, Cincinnati OH 45268, August, 1979.
2 Gumerman R C, Burris B E & Hansen S P, Estimation ofSmall System Water Treatment Costs, EPA-600/S2-84-184, RREL, USEPA, Cincinnati OH 45268, March 1984.
3 Malcolm and Pimie, USEPA In-house report(Unpublished), Contract 68-03-3492, 1989.
4 Eilers R G, Small System Water Treatment Costs forChemical Feed Processes, In-house report (unpublished),RREL, USEPA, Cincinnati OH 45268, June 1991.
5 Clark R M, Adams J, Abdesaken F, Sethi V &Sivaganesan M, Compilation of Cost Models for WaterTreatment Unit Processes, In-house report, Water Supplyand Water Resources Division, NRMRL, USEPA,Cincinnati, 1998.
6 Clark Robert M, J Environ Eng Div, ASCE, 108 (1982)819.
7 Clark Robert M, & Dorsey Paul, J Am Water WorksAssoc, 74 (1982) 618
8 Adams Jeffrey Q & Clark Robert M, J Am Water WorksAssoc, 81 (1989) 35.
