A streamlined sustainability assessment tool for improved decision making in the urban water industry

A Streamlined Sustainability Assessment Tool for ImprovedDecision Making in the Urban Water IndustryMatthias Schulz,y Michael D Short,*y and Gregory M Petersy,zyUNSWWater Research Centre, School of Civil and Environmental Engineering, The University of New SouthWales, Sydney, NSW 2052,AustraliazDepartment of Chemical and Biological Engineering, Chalmers University of Technology, Goteborg, Sweden

(Submitted 16 January 2011; Returned for Revision 28 February 2011; Accepted 5 July 2011)

ABSTRACTWater supply is a key consideration in sustainable urbanplanning. Ideally, detailedquantitative sustainability assessments are

undertaken during the planning stage to inform the decision-making process. In reality, however, the significant time and cost

associated with undertaking such detailed environmental and economic assessments is often cited as a barrier to wider

implementation of these key decision support tools, particularly for decisionsmade at the local or regional government level. In

anattempt toovercome this barrier of complexity, 4water serviceproviders inMelbourne, Australia, funded thedevelopmentof

a publicly available streamlined Environmental Sustainability Assessment Tool, which is aimed at a wide range of decision

makers to assist them in broadening the type and number of water servicing options that can be considered for greenfield or

backlog developments. The Environmental Sustainability Assessment Tool consists of a simple user interface and draws on life

cycle inventory data to allow for rapid estimation of the environmental and economic performance of different water servicing

scenarios. Scenario options can then be further prioritized by means of an interactive multicriteria analysis. The intent of this

article is to identify the key issues to be considered in a streamlined sustainability assessment tool for the urban water industry,

and to demonstrate the feasibility of generating accurate life cycle assessments and life cycle costings, using such a tool.Weuse

a real-life case study example consisting of 3 separate scenarios for a planned urban development to show that this kind of tool

can emulate life cycle assessments and life cycle costings outcomes obtained through more detailed studies. This simplified

approach is aimed at supporting ‘‘sustainability thinking’’ early in the decision-making process, thereby encouraging more

sustainable water and sewerage infrastructure solutions. Integr Environ Assess Manag 2012;8:183–193. � 2011 SETAC

Keywords: Sustainable water management Life cycle assessment Life cycle costing Streamlined sustainability assessmenttool Multicriteria analysis

INTRODUCTIONThere is an increasing recognition of the need to improve

the sustainability of our cities. In particular, there is ongoinginterest from both industry and government bodies inmeeting specific water service provision objectives at minimalenvironmental and economic cost. Water is often at theforefront of urban sustainability considerations, because itfrequently constitutes a large fraction of all material flowsthrough urban systems (Decker et al. 2000). Urban waterservice provision is most commonly achieved by centralizedmechanisms, involving large-scale water and wastewatertreatment facilities and distribution networks. Populationpressure continues to increase the production of wastes andthe demand for water, whereas climate change has thepotential to further reduce water availability from conven-tional sources (Cohen 2006). As a result, innovative anddiverse approaches to urban water supply, such as blackwaterrecycling, graywater reuse, rainwater tanks, stormwaterharvesting, dual pipe systems, and desalination, have receivedincreased attention.

Sustainability assessment tools such as life cycle assessment(LCA), life cycle costing (LCC), and multicriteria analysis

(MCA) allow for more holistic assessments of infrastructurealternatives, allowing decision makers to consider both theeconomic and environmental consequences associated with agiven water service delivery strategy. Because of their holisticand comprehensive scope, these techniques are also recog-nized as being both time- and resource-intensive and require ahigh degree of expert knowledge. Unfortunately, these factorsare often cited as a barrier for the more widespreadapplication of approaches such as LCA in the industry andpolicy-making sectors (Bala et al. 2010). Consequently, therehas been significant recent interest across a number ofindustrial sectors in the development of so-called ‘‘stream-lined’’ approaches and tools to reduce the burden of thesemore detailed assessment processes.

The water sector has been at the forefront of the develop-ment and application of LCA, with some of the first reportedLCA studies in this area conducted prior to the publication ofthe original ISO 14040 Standard in 1997 (e.g., Emmersonet al. 1995; Roeleveld et al. 1997). Australia has played asignificant role in these developments (Peters 2009) and anextensive body of literature is now available on LCA studiesin the area of water cycle management, both in Australia andinternationally (Friedrich et al. 2007). The most comprehen-sive of this work was performed by Lundie et al. (2004) andcovered the total operations of Australia’s largest water utility(Sydney Water), including bulk water supplies, water filtra-tion plants, reticulation, and wastewater treatment. Anotherdetailed study by Friedrich et al. (2009) included both water

Integrated Environmental Assessment and Management — Volume 8, Number 1—pp. 183–193� 2011 SETAC 183

* To whom correspondence may be addressed: [email protected]

Published online 12 July 2011 in Wiley Online Library

(wileyonlinelibrary.com).

DOI: 10.1002/ieam.247

Case

Stu

dy

supply and wastewater treatment services for a South Africanmunicipality. Other studies have addressed specific aspects ofeither wastewater systems (Emmerson et al. 1995; Tillmanet al. 1998; Lundin et al. 2000; Beavis and Lundie 2002; Limand Park 2009; Pasqualin et al. 2009), different biosolidsmanagement options (Dennison et al. 1998; Peters andLundie 2001; Peters and Rowley 2009), or potable watersupply systems (Crettaz et al. 1999; Friedrich 2002;Tangsubkul et al. 2005; Landu and Brent 2006). Additionalstudies investigating both environmental and economicimpacts of different aspects of the urban water cycle alsoexist (Nogueira et al. 2007; Høibye et al. 2008; Lim et al.2008; Sharma et al. 2009). All of the aforementioned researchhas been carried out using the traditional and more detailedmethodologies, and published reports detailing the applica-tion of ‘‘streamlined’’ sustainability assessment tools in thewater industry are rare (Friedrich et al. 2007).

Simplified or ‘‘streamlined’’ sustainability assessment toolshave the capacity to provide similar results to more detailedassessment approaches but at lower cost and with reducedrequirements for operator time and expertise (Hochschornerand Finnveden 2003; Bala et al. 2010). This is particularlyrelevant in the context of industry and policy-making sectors,where decisions with potentially large environmental andeconomic consequences are often made with limited time andfinancial resources, and where the decision-making processoften cannot wait for the results of full LCAs (Bala et al.2010). In the context of the urban water sector, thedevelopment and application of a streamlined EnvironmentalSustainability Assessment Tool (ESAT) would enable assess-ment of the relative sustainability of alternative water andsewage servicing (infrastructure) options and, therefore,would better position industry decision makers to ultimatelyselect the most environmentally and economically sustainableapproach.

This article demonstrates the feasibility of creating such atool. ESAT was developed by researchers at the University ofNew South Wales, Australia, in partnership with the SmartWater Fund and can be downloaded from the Smart Waterhomepage (Schulz and Peters 2008b). ESAT enables quanti-tative LCA and LCC to be carried out in a user-friendlyMicrosoft Excel1 environment. Locally, water service pro-viders have indicated a desire to be able to quantify financialand environmental performance indicators and then contrastand prioritize decision options by means of an MCA. ESATfacilitates this by allowing the user to measure 1 economicand 5 environmental performance indicators, with a built-inMCA utility that provides a mechanism for weighting andcombining the results from the individual performanceindicators. Our model is intended to support and encourage‘‘sustainability’’ or ‘‘life cycle thinking,’’ as described byElshof (2009), by identifying and measuring key variables toinform and promote sustainable decision making in the areaof water and sewerage infrastructure provision and assetmanagement. In this article, some of the capabilities of ESATare demonstrated through a case study assessment of theenvironmental and economic sustainability of 3 differentwater servicing options for Kalkallo, a greenfield developmentarea northwest of Melbourne, Australia. The robustness ofresults generated by the simplified ESAT tool was thenassessed by comparing these results with those of a detailedLCA and LCC study undertaken by an independent group ofresearchers during 2005 and 2006.

METHODSHere, we describe the general principles for the construc-

tion of a simplified tool for sustainability assessment of watersystems in any city, with Melbourne used as an example. Thekey to accelerating the application of ‘‘life cycle thinking’’ inwater service provision is to simplify the creation of complexlife cycle inventories (LCIs) for alternative servicing options.Achieving this requires a balance to be struck between thefuture extent of software tool application (i.e., tool universal-ity) and the need for a simple user interface. The dialogue inwhich we engaged water industry representatives taught usthat a simplified tool should make a range of informationavailable that is broader in scope than what water engineersare likely to encounter during a ‘‘normal’’ week, withoutattempting to match the level of comprehensiveness (datainput types, modeling methods, or environmental perform-ance indicators) offered by commercial LCA and LCCsoftware packages such as GaBi (PE International 2011) orSimaPro (PRe Consultants 2008). In the following sections,the main types of information and adjustable design featuresneeded in such a simplified tool are described. For more detailon the features, input variables required, relevant LCI data,and modeling principles of ESAT, please refer to the onlinemanual (Schulz and Peters 2008a).

End-use water balance

An end-use water balance is an essential first step in theplanning of any water infrastructure. To accurately estimatethe levels of water demand and wastewater generation for aparticular development, the user should be able to specify thenumber of households and/or buildings in the development,the number of people per household and/or building, anadditional water demand for nonhousehold use (i.e., munic-ipal irrigation or industrial and/or commercial use) and theexpected level of efficiency of various household appliances(e.g., washing machines, shower heads, and so forth). ESATassumes an initial individual water demand of 207 L/person/d(L/p/d), which represents the consolidated average dailyresidential water consumption for Melbourne (Wilkenfeldand Associates 2003; WSAA 2006; WELS 2008). At present,the user can select the location of the proposed urbandevelopment from 5 subregions of Greater Melbourne. Thisfunction draws on a 30-y daily time-step historical rainfallrecord for each subregion to enable spatially relevantestimations of rainwater and stormwater runoff to be made.Prior research has shown that rainfall records of this lengthand interval are appropriate for facilitating accurate simu-lations of future rainfall (Mitchell et al. 2008). For furtherdetails on the assumptions incorporated into ESAT regardingthe end-use water balance, rainwater, and stormwatermodeling calculations, the reader is again referred to theonline ESAT manual (Schulz and Peters 2008a).

Reticulation options

Three different sewage reticulation systems may be ofinterest in a simplified tool: conventional gravity systems, lowpressure sewage systems, and vacuum systems. Naturally, thetopography and scale of urban developments directly influ-ences their associated environmental impacts and cost. As aconsequence, the inclusion of additional input fields allowsthe user to perform detailed modeling of different parts of thereticulation system, including the selection of different piping

184 Integr Environ Assess Manag 8, 2012—M Schulz et al.

materials, diameters, and lengths; the number of installedpumping stations combined with rising mains and gravitymains; and the incorporation of maintenance holes. Withinthe reticulation modeling component of ESAT, particularattention was given to the pumping energy calculations,because earlier work had shown that the environmentalimpacts associated with pumping energy requirements aresignificant in situations where there is a heavy reliance oncoal-fired electricity generation, such as in Australia (Lundieet al. 2005). ESAT calculates the energy requirements forpumping wastewater through the rising mains, based onthe approach of Coulson and Richardson (1985). It is alsopossible to model the connection to an existing sewernetwork and to enter the respective energy consumptioninvolved. Again, further details on reticulation assumptionand pumping energy calculations can be found in the onlineESAT manual (Schulz and Peters 2008a).

Wastewater treatment options

Many different treatment technologies might be consideredin a simplified sustainability assessment tool, some of whichare more relevant at particular geographic scales. We thinkthe analyst also needs the option of including industrial orcommercial wastewater inputs into the normal domesticwastewater stream. This option may be appropriate if theplanned development includes some commercial facilitiesthat produce wastewater, or if nearby existing businesseswant to connect to the wastewater treatment system of theproposed development. ESAT allows the user some degree offlexibility in terms of how wastewater is treated. A house-hold-scale graywater treatment system and 8 different house-hold- and neighborhood-scale blackwater treatment systemswith different treatment technology configurations may beselected. The respective LCI data was obtained directly frommanufacturers or from the relevant literature; for details, seeSchulz and Peters (2008a). The environmental and economicperformance of these systems can be compared to that of aconventional centralized sewage treatment plant (STP) ifdesired. ESAT also is capable of modeling the reuse of treatedwastewater in the event there is a demand for recycled waterwithin the development. If treatment at a conventional STP isrequired, the location of the development determineswhether the sewerage goes to Melbourne’s Eastern orWestern treatment plants (Melbourne Water 2006a,2006b), both of which have different operating conditions.

Water supply options

Six common water supply options are noteworthy amongthe urban water LCA studies mentioned earlier in this article:surface water, groundwater, seawater desalination, rainwatertanks, stormwater, and recycled water supplies. In addition tothese water supply choices, questions of scale may play a roleand necessitate the software user’s detailed definition, forexample, the choice of rainwater tank volume. Depending onthis, and given the connected roof area, the chosen rainwaterend uses, and the modeled rainfall for the selected region,ESAT calculates the relative contribution to the householdwater balance made by rainwater yield. Further details on LCIdata and rainwater modeling assumptions can be found inSchulz and Peters (2008a).

In ESAT, stormwater may be treated by 2 differenttreatment options: a rain garden or a surface wetland. The

main focus is on the nutrient removal capabilities of bothsystems. The Model for Urban Stormwater ImprovementConceptualisation (MUSIC) software (eWater 2005) wasused to estimate treatment performance in terms of thekey water quality parameters of interest (total suspendedsolids, total N, and total P) and the capital and operatingexpenditures for different sizes of both stormwater treatmentsystems. In addition, a stormwater reuse option is availablebased on the collection of stormwater runoff from impervioussurfaces around the house. Recycled water for nonpotablepurposes can be made available to households by connectingto a water recycling plant via a centralized ‘‘3rd pipe’’ option(also called ‘‘dual reticulation scheme’’) or from local suppliessourced from some of the decentralised wastewater treatmentoptions. A range of end-uses for the recycled water orstormwater can then be selected. Further details on theassumptions underlying water recycling in ESAT are availableelsewhere (Schulz and Peters 2008a).

Cost analysis

The industrial partners of the Smart Water Fund wantedany simplified tool to include an evaluation of cost in amanner that reflects widespread industry practice. ESATtakes into consideration capital expenditure, energy cost–related operating expenditure, and other operating expendi-ture (e.g., maintenance, chemicals, and so forth) for all waterservicing infrastructure items and calculates a LCC expressedas the net present value (NPV) as described in Equation 1:

NPV ¼ C0 þXN

t¼1

Ct

ð1þ rÞt ð1Þ

where C0¼ initial investment, N¼ total time of the project(assumed as 50 y), t¼ time of the cash flow,Ct¼ net cash flow,and r¼ adjusted discount rate (Huppes et al. 2004).

Life cycle impact indicators

The selection of indicators will necessarily reflect the needsof the urban water industry and the preferences of environ-mental managers in water companies that wish to benefitfrom using such simplified tools. Following dialogue withindustry, we selected a suite of regional and global perform-ance indicators for incorporation into ESAT (Table 1).These impact indicators are common among many detailedLCA studies, both within and outside the water field. InESAT, the results of these indicator calculations are displayedalongside the environmental impacts resulting from thehousehold water balance as well as the detailed impactsassociated with the LCI data such as electricity and materialsassociated with the scenarios chosen. For the calculation ofimpact indicator results, the most appropriate availablecradle-to-gate LCI data sets were used (e.g., greenhouse gas[GHG] emissions for 1 kWh of electricity produced inVictoria). For further details on the presentation of results inESAT, please refer to the online ESAT manual (Schulz andPeters 2008a).

ESAT VALIDATION: A CASE STUDY OF 3 SCENARIOSKalkallo is a planned greenfield development area for

86 000 people located north of Craigieburn, approximately30 km northwest of the city center of Melbourne, Australia.The development will convert a total area of 3062ha of

Sustainability Assessment Tool for the Urban Water Industry— Integr Environ Assess Manag 8, 2012 185

predominantly agricultural land into residential, industrial,commercial, and community areas. A detailed LCA and LCCcomparing different water and sewerage servicing options forthe area has already been undertaken by another researchgroup during 2005 and 2006 (Grant and Opray 2005; Sharmaet al. 2005; Sharma et al. 2006).

In order to critically assess the accuracy of our streamlinedtool, 3 of the scenarios described in the detailed LCA andLCC study are analyzed and compared with the resultsobtained from ESAT. In the first 2 scenarios, labeled ‘‘1AUDM’’ and ‘‘1A WPDM’’ in the original detailed studies,potable water and sewerage services are provided by conven-tional means. The only difference between these 2 scenarios isthe water demand management assumptions. The usualdemand management (UDM) scenario refers to water end-use figures corresponding to a lower standard of water-savingappliances than the so-called ‘‘white paper’’ demand manage-ment (WPDM) scenario (DSE 2004), both of which havebeen calculated using Yarra Valley Water data and theAustralian/New Zealand Standard for Water Efficient Prod-ucts (AS/NZS 2003). Hence, WPDM assumes a reduction inthe usual residential water demand from approximately 223L/p/d (in the UDM scenario) to approximately 188 L/p/d, ora 15.6% reduction (Sharma et al. 2005). In the 3rd scenario,

‘‘1B.1 WPDM,’’ the wastewater from residential, commer-cial, industrial, and community sectors is treated at a localSTP and returned to the development via a 3rd pipe systemfor reuse in toilets and outdoor areas across all sectors. Forease of interpretation, these 3 original scenarios ‘‘1A UDM,’’‘‘1A WPDM,’’ and ‘‘1B.1 WPDM’’ are hereafter relabeledscenarios A, B, and C, respectively, in our analysis. Anoverview of these 3 scenarios is given in Table 2.

Comparative LCA goal and scope

The goal of this comparative LCA is to evaluate differentwater and sewerage servicing options for the Kalkallodevelopment using ESAT and to verify the accuracy of theseresults by comparison with parallel results from a detailedLCA and LCC of the same options. The functional unit wasdefined as the supply of potable water and water sewerageservices to the Kalkallo development for 1 y. The systemboundary encompassed all processes from the source ofpotable water to the treatment of wastewater and wastewaterreuse. For these processes, environmental burdens associatedwith different materials and energy use were included in boththe detailed LCA and in ESAT. The environmental andeconomic LCI data was taken from the respective detailed

Table 2. Description of the investigated water servicing scenario options for the proposed Kalkallo developmenta

Scenariosb Water supply Water use Sewerage system

Scenario A (1A UDM) Reticulated, centralized bulkwater supply system

Usual demand management (UDM) Reticulated, centralized treatmentat Werribee STP

Scenario B (1A WPDM) Reticulated, centralized bulkwater supply system

Reduced water demand by using WhitePaper demand management (WPDM)

Reticulated, centralized treatmentat Werribee STP

Scenario C (1B.1 WPDM) Reticulated, centralized bulkwater supply system

Treated wastewatervia 3rd pipe

Reduced water demand by using WhitePaper demand management (WPDM)

Recycled water for toilets andoutdoor areas

Decentralized treatment plantat Kalkallo

aScenario configurations adopted from detailed LCA study of Grant and Opray (2005) and Sharma et al. (2005).bScenario labels provided alongside original scenario names from the detailed LCA and LCC study (given in parentheses).

Table 1. Description of the environmental life cycle impact indicators used during this study

Impact categories Units Description

Primary energy use MJ Gross calorific value of all fossil energy use associatedwith the production ofmaterials, generationof electricity, and consumption of transport fuels.

GHG emissions t CO2-eq Accounts for all GHG emissions linked to themanufacture of water infrastructure, the provision ofoperating materials, including electricity generation and emissions from transport. The IPCC(2007) equivalence factors were applied.

Water use ML H2O Reflects both the water used during material production or electricity generation as well as theremaining potablewater demand. For the first component of thewater use, the characterizationmethod EDIP 97 has been used (Wenzel et al. 1997).

Eutrophication potential kg PO4-eq The impact indicator called ‘‘Nutrients’’ in ESAT refers to eutrophication potential and describesthe nutrient discharge in connection with the full life cycle of the water servicing optionsincluded in ESAT. This impact indicator is based on CML (2001) methodology.

Physical footprint Ha Describes the land area physically occupied by infrastructure necessary for the chosen waterservice scenario. It follows a simple land use approach as described by Heijungs et al. (1997) andis not to be confused with the ‘‘ecological footprint.’’

ESAT¼ Environmental Sustainability Assessment Tool; GHG¼greenhouse gas; IPCC¼ Intergovernmental Panel on Climate Change.


LCA report (Grant and Opray 2005; Sharma et al. 2005) andLCC report (Sharma et al. 2006). The GHG emissions, wateruse, eutrophication potential, and LCC are common indica-tors to both the detailed LCA/LCC and ESAT, and weretherefore considered to be an appropriate basis for comparingthe 2 approaches.

Life cycle inventory data

Household and/or building water balance. The residential areaconsists of 28 695 lots with 3 people living in each lot; both ofthese input variables can be set in ESAT. ESAT assumes adefault city-wide average water demand of 207 L/p/d, basedon Greater Melbourne average data (WSAA 2006). In orderto match the assumed 223 L/p/d for the Kalkallo develop-ment scenario A and the 196 L/p/d for scenarios B and C, plusan assumed leakage rate of 4% (Sharma et al. 2005),appropriate water-saving appliances were selected in ESAT.The potable water demand and wastewater generation rates ofthe commercial, industrial, and community areas were takenfrom the detailed LCA report and were entered into ESAT asan additional ‘‘nonhousehold water demand’’ (scenario A:7133 ML/y; scenarios B and C: 5756 ML/y). In the same way,the amount of wastewater produced in these 3 sectors iscaptured in ESAT as an ‘‘industrial/commercial wastewaterinput’’ (scenario A: 6206 ML/y; scenarios B and C: 4893 ML/y). The average annual rainfall in the proposed Kalkallodevelopment area is 601mm. This value is close to the defaultvalue of the ‘‘central development region’’ as defined inESAT, which is based on the Melbourne Regional Officerainfall station records of a median yearly average of 610mm.

Potable water supply. In all scenarios, it is assumed that thepotable water supply comes from a reservoir and undergoeswater filtration. The electricity demand for potable watertreatment and potable reticulation was estimated to be 0.28kWh/kL and 415 kWh/ML, respectively, based on the workof Grant and Opray (2005). These values were used as defaultvalues in ESAT.

Decentralized wastewater treatment. Scenario C would requirethe construction of a local STP at the Kalkallo developmentsite. Because the development was in the early planning phaseand no detailed infrastructure plans were available at the timeof study, the detailed LCA based its assumptions regarding alocal wastewater treatment facility on the existing WhittleseaSTP and up-scaled the infrastructure to suit the servicerequirements for the planned Kalkallo development. TheKalkallo STP would be approximately 20 times larger thanthe Whittlesea STP. The modeling approach taken in ESATwas based on connecting Kalkallo to a centralized STP(scenario A and B) but also to provide recycled water via awater recycling plant (scenario C). Considering the largevolume of wastewater produced in Kalkallo and the com-paratively small volumetric capacity (300 kL/d) of the mostsuitable neighborhood-scale decentralized wastewater treat-ment system incorporated in ESAT, this approach wasconsidered to be most realistic. The wastewater and recycledwater treatment processes are modeled from generic tech-nology descriptions and process performance data; for furtherdetails, please refer to Grant and Opray (2005) and Schulzand Peters (2008a). Regarding the electricity consumption forwastewater and reclaimed wastewater treatment, values of

0.73 and 0.95 kWh/kL, respectively, were entered into ESAT,based on the assumptions of the previous detailed LCA report(Grant and Opray 2005).

Reticulation. The detailed LCA and LCC reports list LCI datafor more than 20 different pipe diameters and their respectivelengths, materials, and total construction cost per meter for allreticulation requirements for all scenarios (Sharma et al.2005; Sharma et al. 2006). Because ESAT is designed for useat a reduced level of data complexity, several simplifyingassumptions had to be made to allow the more detailed datato be compressed for inclusion in the ESAT platform. Toestimate the total pipe material requirements, a length-weighted average cross-sectional area of the detailed retic-ulation data was calculated to determine an equivalentaverage pipe diameter and then multiplied by the total lengthof the reticulation network. Because ESAT only caters for 2different pipe materials—unplasticized polyvinyl chloride(uPVC) and ductile iron cement-lined (DICL) pipes—thepipe materials listed in the detailed LCA report had to beassociated with these 2 pipe material categories. To achievethis, all polyethylene, uPVC, and glass-reinforced plasticpipes were treated as uPVC pipes, and all DICL, mild steelcement-lined, and vitrified clay pipes were treated as DICLpipes. Although the physical properties and attributes ofsome pipe materials are not readily interchangeable with thedefault uPVC and DICL materials (e.g., glass-reinforcedplastic and vitrified clay pipes), the lengths of these materialswere relatively insignificant in terms of the total reticulationnetwork, and the overall consequences of this assumedsubstitution on the results were considered negligible.

The detailed LCA report assumes an identical electricitydemand for supplying 1 ML of potable water to Kalkallo in allmodeled scenarios. According to Yarra Valley Water energymaps, the electricity demand for potable water reticulation is415 kWh/ML (Grant and Opray 2005). The electricitydemand for the reticulated sewer network of 451 kWh/MLwas based on the values of Grant and Opray (2005) and wasused in ESAT. Because the physical location of a proposed‘‘local and/or decentralized’’ Kalkallo STP (scenarioC) wouldnot be expected to be significantly different to that of a‘‘centralized’’ STP (scenarios A and B), it was consideredappropriate to adopt the same value for sewerage reticulationelectricity demand. In addition to sewerage energy consid-erations, the electricity demand for supplying recycled waterin scenario C also needed to be considered. Because nospecific data was available, it was assumed that the source ofrecycled water supply was similar in both distance andelevation to the potable water supply. The relevant energyrequirements for pumping wastewater and recycled water arecalculated in ESAT by means of an incorporated formula(Coulson and Richardson 1985; Schulz and Peters 2008a).

To estimate the total construction cost of different pipeconnections, the cost data for the various pipe materials anddiameters was drawn from the detailed LCC report and usedto calculate a total construction cost function in ESAT. Incontrast to the pipe material calculations, a length-weightedaverage diameter was calculated for both uPVC-type andDICL-type pipes and combined with the calculated costfunction in ESAT.

Additional modeling parameters. For most water treatmentfacilities, energy consumption dominates overall environ-


mental performance, particularly when GHG emissions areconsidered. Therefore, it is necessary to enter specific energyconsumption data for all water servicing options whenapplying ESAT to real-life scenarios. In order to increase theflexibility of ESAT to be able to handle as many differentcircumstances as possible, the user has the option of enteringdefined energy consumption values for their particular treat-ment processes. In the detailed LCA study, the water balancemodel ‘‘Aquacycle’’ (Mitchell 2005) was used to calculate thewater balance outcomes for the different scenarios. Oneassumption in Aquacycle is that there is no stormwater inflowor infiltration into the wastewater reticulation system;consequently, the relevant input variable in ESAT is set to adefault 0%. It should be noted, however, that adjustment ofinflow and infiltration parameters is a feature of ESAT suchthat users can easily choose to set inflow and infiltrationvariables according to site-specific preferences.

The detailed LCA did not include any estimates of materialreprocessing or recycling. ESAT, however, has the capacity totake into account that some materials (i.e., steel andpolyethylene) are recycled and reprocessed to produce newmaterials. From an environmental perspective, reprocessing ofthese materials represents a material and/or energy saving oran environmental credit. For the purposes of this case study,the recycling rates were set to 0% to reflect the input variablesof the comparative detailed LCA. If available, life spans usedfor different infrastructure items in the detailed LCA werematched accordingly in ESAT. ESAT also accounts forenvironmental burdens in relation to transport distances forvarious materials, i.e., truck and ship transport for materialsand preinstalled systems. In the detailed LCA, only transportburdens associated with pipe installation were considered.

Biosolids, a byproduct of wastewater treatment, can beapplied during agriculture as a substitute for conventionalnitrogenous and phosphorous fertilizers. Results from arecent study of various biosolids management systems suggestthat for each dry kilogram of biosolids applied to fields,0.011 kg of N-fertilizer and 0.037 kg of P-fertilizer can beavoided (Peters and Rowley 2009). Once again, ESAT has the

capacity to incorporate this environmental credit based onbiosolids production for each scenario, whereas the detailedLCA did not include any information on biosolids manage-ment. To ensure consistency for the purposes of thisvalidation study, biosolids management aspects were alsoomitted from the comparative assessment in ESAT.

In both the detailed LCC and ESAT, relevant cost dataincluded capital expenditure for water supply reservoirs andall reticulation infrastructure, as well as wastewater treatmentand recycling facilities, operating expenditure separated byannual maintenance costs for different infrastructure items,and electricity costs for water and wastewater treatment andpumping. For further information on detailed cost data,references, and further assumptions, please refer to the ESATmanual and the detailed LCC report (Sharma et al. 2006;Schulz and Peters 2008a). Because reticulation is often a largeproportion of the LCC of a water supply network and becausepipe cost data may vary significantly, the LCC component ofESAT allows the user to enter specific construction costfunctions for uPVC and DICL pipes. For the LCC modeling,ESAT assumes an adjusted annual discount rate of 6.5% andan electricity cost of A$0.16/kWh, based on the priorassumptions of the detailed LCC study (Sharma et al.2006). An analysis period of 50 y was chosen for LCCmodeling in ESAT, and it was assumed that both theremaining useful life of all components and the salvage valueof any infrastructure after the analysis period were zero.These assumptions reflected those made for the LCCcomponent of Sharma et al. (2006).

RESULTS AND DISCUSSIONOverall, results from the comparative assessment of ESAT

outputs versus those from more detailed prior LCA and LCCresearch for the same development site (Grant and Opray2005; Sharma et al. 2005; Sharma et al. 2006) showed astriking similarity for many indicator categories across theLCA and LCC components. The water balance results for theKalkallo development are shown in Tables 3 and 4, with anoverall summary of the absolute results provided in Table 5.

Table 3. Scenario A water balance for the Kalkallo development area comparing values from the detailed LCA study (Grant and Opray 2005;Sharma et al. 2005) with ESAT-derived values

Units

Sector

TotalResidential Commercial Industrial Community

Number of lots 28695 45 447 5

Potable demand (detailed LCA) L/lot/d 670 85890 32425 84658

ML/y 7306 1468 5504 161 14439

Potable demand (ESAT) ML/y 7297 1468 5504 161 14430

Discrepancy potable demand % 0.1 0 0 0 0.1a

Wastewater produced (detailed LCA) ML/y 5214 1322 4740 144 11420

Wastewater produced (ESAT) ML/y 5697 1322 4740 144 11903

Discrepancy wastewater % �9.3 0 0 0 �4.2b

aSlight discrepancy in total water demand due to an inexact match of residential water demand values stemming from small differences in assumed efficiency

ratings for water-saving appliances.bDiscrepancy relates to differing assumptions surrounding residential wastewater generation, i.e., proportion of residential water demand used for irrigation

assumed in ESAT (24.6%) was different to that assumed in the detailed LCA study (30.9%).

ESAT¼ Environmental Sustainability Assessment Tool; LCA¼ life cycle assessment.


A breakdown of these results for each investigated scenarioand across each of the chosen life cycle impact indicators ispresented in Figures 1 to 4, with scenario results shownrelative to the ‘‘base case’’ scenario A.

With both the streamlined and the detailed approaches toLCA and across all life cycle impact indicators, the reducedwater demand of scenario B was responsible for a superiorenvironmental performance compared to the base casescenario A (Figure 2). Scenario C scored better again thanscenario B with regard to water use (Figure 2) andeutrophication potential (Figure 3); however, slightly higherGHG emissions (Figure 1) resulted from the higher electricityrequirement for treating wastewater to a level suitable forreuse (0.95 kWh/kL) relative to electricity required toproduce potable water from a dam (0.28 kWh/kL).

Results from the LCC assessment are presented as bothabsolute (Table 5) and relative cost (Figure 4). From a purelyeconomic standpoint, scenario B was the most preferable

option followed by scenario A. Scenario C was shown to havethe highest LCC mainly due to the additional reticulationinfrastructure requirements of the 3rd pipe reuse system.Notably, the capital expenditure required for installation ofthe reticulation network made the biggest single contributionto the total LCC in all scenarios, and this trend was reflectedin both the outputs of ESAT and also the detailed LCC study.

After comparison of the relative environmental andeconomic performance for each life cycle impact indicatoracross all investigated scenarios, Figures 1 to 4 demonstratethat the 2 modeling approaches are able to produce consistentoutputs for the purposes of strategic environmental analysis,in that the relative environmental and economic performancemetrics differed by less than 10%, with the greatest differencebeing 7.2% for scenario C GHG emissions.

Although relative differences between measured perform-ance indicators for ESAT and the detailed LCA and LCCstudy were small, there were some more notable differences

Table 4. Scenarios B and Cwater balance for the Kalkallo development area comparing values from the detailed LCA study (Grant and Opray2005, Sharma et al. 2005) with ESAT-derived values

Units

Sector

TotalResidential Commercial Industrial Community

Number of lots 28695 45 447 5

Potable demand (detailed LCA) ML/y 3499 1001 3680 110 8290

Reclaimed water use (detailed LCA) ML/y 2432 161 713 18 3324

Total water demand (potable plus reclaimed)(detailed LCA)

L/lot/d 565 68886 26281 67898

ML/y 5931 1162 4393 128 11614

Total water demand (ESAT) ML/y 6144 1162 4393 128 11827

Discrepancy: total water demand % �3.6 0 0 0 �1.8a

Wastewater (detailed LCA) ML/y 4113 1042 3737 114 9006

Wastewater (ESAT) ML/y 4544 1042 3737 114 9437

Discrepancy: wastewater % �10.5 0 0 0 �4.8b

aSlight discrepancy in total water demand due to an inexact match of residential water demand values stemming from small differences in assumed efficiency

ratings for water-saving appliancesbDiscrepancy relates to differing assumptions surrounding residential wastewater generation, i.e., proportion of residential water demand used for irrigation

assumed in ESAT (24.6%) was different to that assumed in the detailed LCA study (30.9%).

ESAT¼ Environmental Sustainability Assessment Tool; LCA¼ life cycle assessment.

Table 5. Summary of absolute ESAT results versus those of the detailed LCA study (Grant and Opray 2005; Sharma et al. 2005; Sharma et al.2006) for the proposed Kalkallo development water servicing scenariosa

Indicator Unit

Scenario A Scenario B Scenario C

ESAT detailed LCA ESAT detailed LCA ESAT Detailed LCA

GHG t CO2-eq 25086 26290 20293 21520 22376 21560

Water use ML 14539 14000 11916 11580 8601 8084

Eutrophication potential kg PO4-eq 403508 96570 323714 81050 277173 60790

LCC NPV ($M) 518 526 485 509 604 601

aESAT¼ Environmental Sustainability Assessment Tool; GHG¼greenhouse gas; LCA¼ life cycle assessment; LCC¼ life cycle costing.


in terms of the absolute magnitude of these indicators. In thecase of eutrophication potential, for example, the absolutevalues calculated by ESAT were, on average, approximately 4times higher than those from the detailed LCA report(Table 5). The basis for such a large discrepancy in thisinstance was attributed to the different primary referencesources having been used for water quality metrics (i.e.,biochemical oxygen demand, total N, and total P [TP]) indifferent kinds of water. The main source of the apparentdifference was found to be the much lower TP concentrationassumed for treated wastewater and recycled water in thedetailed LCA study. Whereas the detailed LCA assumed a TPconcentration of 0.5mg/L for both types of water, ESATassumed TP levels that were orders of magnitude higher, at8.8mg/L and 4mg/L for treated wastewater and recycledwater, respectively. Because the reference sources used in thedetailed LCA were considered to be either outdated or poorlydefined, values for ESAT were drawn from more recent

(2005–2006) Melbourne Water Data (Melbourne Water2006b), because these were considered to provide a moreaccurate reflection of the true eutrophication potential.

With regard to the outcomes of the comparative economicassessment, ESAT was shown to calculate slightly lowerabsolute LCCs for scenarios A and B and a slightly higherLCC for scenario C, although the relative magnitude differ-ence between outputs from ESAT and the detailed LCCstudy was less than 5% across all scenarios. Reasons for thesediscrepancies were thought to be related to a combination ofthe relatively simple total pipe construction cost calculationin ESAT, different data assumptions having been made forannual maintenance costs of water servicing options, and theuse of different data sources for the capital expenditurecomponent of the water supply and treatment infrastructure.

The capital expenditure associated with reticulation infra-structure dominates the LCC for each of the chosen waterservicing scenarios for the Kalkallo development, yet the vast

Figure 3. Comparative eutrophication potential for the 3 Kalkallo

development water servicing scenarios shown as a percentage of scenario

A values. Data calculated by ESAT (dark gray bars) provided alongside data of

the detailed LCA study (light gray bars) (Grant and Opray 2005; Sharma et al.

2005).

Figure 4. Comparative life cycle cost of the 3 Kalkallo development water

servicing scenarios shown as a percentage of scenario A values. Data

calculated by ESAT (dark gray bars) provided alongside data of the detailed

LCA study (light gray bars) (Grant and Opray 2005; Sharma et al. 2005).

Figure 2. Comparative water use for the 3 Kalkallo development water

servicing scenarios shown as a percentage of scenario A values. Data

calculated by ESAT (dark gray bars) provided alongside data of the detailed

LCA study (light gray bars) (Grant and Opray 2005; Sharma et al. 2005).

Figure 1. Comparative greenhouse gas (GHG) emissions for the 3 Kalkallo

development water servicing scenarios shown as a percentage of scenario A

values. Data calculated by ESAT (dark gray bars) provided alongside original

data of the detailed LCA study (light gray bars) (Grant and Opray 2005; Sharma

et al. 2005).


majority of the environmental burdens come from theoperation and maintenance phase. For example, ESAT resultsfor scenario A show that this phase accounts for 97.4% of thetotal environmental burden in GHG emissions and 96.8%and 96.7% in scenarios B and C, respectively. Within theoperation and maintenance phase itself, the GHG emissionsrelating to electricity production and consumption (e.g., frompumping and/or treating water) account for 92% of the totalemissions in the scenarios without water recycling and 93% inscenario C. This shows that pumping and treatment energyrequirements predominate in terms of the environmentalimpact of urban water service provision, and this observationreflects the findings of prior research (e.g., Lundie et al.2005).

Calculated GHG emissions relating to the production ofwater servicing infrastructure were slightly higher (�4%–6%)in the results of the detailed LCA compared with thoseobtained using ESAT. The reasons for this small difference inresults between the 2 approaches were thought to be relatedto the simple pipe materials estimation process, the way inwhich treatment plant infrastructure is accounted for, and/orthe omission of other minor infrastructure works in the ESATmodel. Unfortunately, lack of access to the raw LCI data ofthe detailed study means that no further insights as to thesources of this variation can be provided. ESAT also providesthe user with an analysis of the GHG emissions resulting fromtransport activities; however, the contribution of transport toall 3 investigated scenarios was negligible (<0.2%). The GHGcredits that can be realized from avoided fertilizer use due tobiosolids application were equally minor, at approximately0.2% of the total figure. Figure 5 shows the contribution ofeach of the different life cycle phases to the total GHGemissions for each of the 3 Kalkallo development scenarios.

It should be noted that because the main goal of this articlewas to compare the accuracy of results obtained throughESAT with those from detailed LCA and LCC studies, nosensitivity analysis was performed. If the main goal had been

to compare the environmental and economic impacts ofdifferent water servicing scenarios for the Kalkallo develop-ment by using ESAT, then a sensitivity analysis that testeddifferent assumptions about infrastructure items, theiroperation, or climatic conditions would obviously have beenan essential element. Compared with the utility of detailedLCA and LCC investigations, we believe that ESAT offersenhanced opportunities for scenario testing, because alter-native scenarios, including their respective LCI data, arealready inbuilt and hence would be readily available for suchinvestigations.

CONCLUSIONSIn this article, we outlined the key adjustable input

parameters and performance indicator results we believe arenecessary for a simplified sustainability assessment toolsuitable for use in the urban water industry. With regard tothe 3 scenarios assessed in the case study, it has beendemonstrated that analyses performed with a streamlinedsustainability tool such as ESAT can produce resultsconsistent with those from more detailed LCA and LCCstudies. Relative differences between the results of ESAT andthe full LCA and LCC study were considered small enoughthat they would be unlikely to change the outcomes of arobust MCA, such that both approaches would ultimately beexpected to yield a similar decision outcome. Considering thesignificant time and resource investments necessary to under-take detailed LCA and LCC studies, ESAT can effectivelyserve as a rapid and easy alternative for informing sustainabledecision-making processes. Admittedly, only 3 scenariosserved as the test case for comparing ESAT outputs againstthose of more detailed LCA and LCC studies; however,because of the striking similarity of results shown in thepresent example across all indicators and modeled scenarios,it can be expected that ESAT would also deliver a robust basisfor decision making in other similar case studies.

Figure 5. Relative process contributions to total greenhouse gas emissions for the 3 Kalkallo development water servicing scenarios (solid bar area shows

‘‘transport’’ contribution; transparent bar area shows ‘‘manufacturing and infrastructure’’ contribution; light gray bar area depicts contribution from ‘‘operation

and maintenance’’). Data calculated by ESAT provided alongside original data of the detailed LCA study (det. LCA) (Grant and Opray 2005; Sharma et al. 2005).


Validation of the ESAT tool by use of data from a real-lifeurban development revealed possible areas for futureimprovement of such simplified tools. For example, it maybe beneficial to further disaggregate the results from theimpact indicators, such that GHG emissions from differenttypes of electricity use could be presented separately to allowfor more specific life cycle impact interpretation. The LCCcomponent could also be split to show NPV from capitalexpenditure versus operational expenditure relating to bulkenergy use or energy use from maintenance work. Thediscrepancy in the results of the eutrophication potentialindicator between the 2 LCA approaches also suggests thatfurther data entry requirements may be required; inparticular, nutrient removal performance data for specificwater and wastewater treatment processes would improve theutility of such tools.

Despite these suggested improvements, one of the specificgoals during the development of ESAT was to strike a balancebetween specificity and generality and also between complex-ity and simplicity. Modifications such as additional data inputrequirements and extra analytical capacity, although they mayenhance the accuracy of ESAT outputs, could also compro-mise the tool’s user-friendliness and ease in which results canbe obtained and interpreted by decision makers. Theapplication of ESAT to a real-life scenario here has alsoshown that creative ways of using ESAT can be applied by theuser to best represent specific scenarios (e.g., 2 separatescenarios were used to model scenario C in ESAT). BecauseESAT was designed primarily for residential developments,the reuse options for recycled water are limited when itcomes to commercial or industrial recycled water reuse. Inorder to account for the proposed recycled water demand, theresidential reuse for toilet flushing was modeled first in 1scenario and then the remaining recycled water demand foroutdoor use and toilet use in the other 3 sectors wasaccounted for in a separate scenario. Following this, theresults from both disaggregated scenarios were combined toyield the total scenario C output. This capacity for a ‘‘tiered’’modeling approach in ESAT may be considered advantageousin certain situations.

Another potential limitation of ESAT at present is therestriction of its geographical scope. Although ESAT’s scopeis currently limited to the Greater Melbourne area, weemphasize that the tool could easily be expanded to considerother geographical regions in Australia or, indeed, the world.The 2 main adaptations necessary to achieve this wouldinvolve obtaining and importing the respective local rainfallrecords and remodeling the stormwater treatment scenarioson the basis of the new rainfall data. The updating oftransport distances and cost data (if appropriate) would beexpected to require only minor additional effort. Also, thedefault option of using 1 of the 2 major Melbourne STPscould easily be expanded to consider other locations andtreatment plants. Furthermore, the market for decentralizedwater and wastewater treatment systems is developingrapidly, which may lead to the requirement of updating LCIdata for this component of ESAT as well. The fact that ESAThas been developed using the commonly available MicrosoftExcel1 software platform should make the implementationof these updates comparatively straightforward.

Simplified sustainability assessment tools such as ESATwill be most useful in early phases of infrastructure planning,when detailed information is not yet available and rough

guidance about the environmental and economic consequen-ces of certain water servicing options is required. This initialscreening assessment can probably be achieved by a tool suchas ESAT for a cost that is an order of magnitude or lowerrelative to that of a full LCA and LCC. In addition to thelikely cost benefits, an added benefit is avoidance ofpotentially lengthy time delays in acquiring detailed resultsfrom specialist LCA and LCC analysts. Future developmentand enhancement of ESAT could involve adding additionalclimate data to allow for application of the tool to other citiesand towns while allowing for the incorporation of changes tolocal rainfall forecasts based on regional climate changeimpacts. In addition, and as a detailed process modelingtool, it may be worthwhile combining ESAT with one of theinput/output–based modeling tools to populate the lowerproduction orders and generate hybrid process and input/output LCA results for a more thorough environmentalassessment.

Acknowledgment—We acknowledge the Smart Water Fundfor providing financial support as well as for supplying relevantdata and reports.

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