sustainability of wastewater transport systems · of storm water away from the urban environment....

Sustainability of wastewater transportsystems

Life Cycle Assessment on pipes transporting domestic wastewater in the WINNETregion

ETE – 81836 Master thesis, Urban Environmental Technology Management, Wageningen University

Supervisor: Jan Vreeburg

Loes Schoondermark 880314745050

Wageningen, 23th May 2016

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Abstract

This study aims to analyze the environmental impact of concrete and PVC pipes of differentdiameters within the urban water transport system. This research is based on a life cycle assessment(LCA) and the EcoInvent database, including the production, construction, maintenance and disposalof sewer pipes. The assembly stage comprises the production of the material and pipe, the transportto the facilities and the construction of the pipe. Additional processes are maintenance andexcavation of the pipe. Recycling (and reuse), landfill and incineration rates are modeled for thedifferent materials within the end-of-life scenarios. The results show that the assembly of sewerpipes has the largest environmental impact for both concrete, PVC and HDPE pipes. Consequently,the recycling and reuse of material can influence the amount of material produced and the totalenvironmental impact. This study highlights the importance of choosing the smallest diameterpossible, as smaller diameters have lower environmental impact.

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Table of ContentsACKNOWLEDGEMENTS ....................................................................................................................................4

INTRODUCTION................................................................................................................................................5

1. THEORETICAL FRAMEWORK .........................................................................................................................61.1 THE WASTEWATER SYSTEM.............................................................................................................................. 6

1.1.1 Complexity of the system...................................................................................................................... 61.1.2 Sustainability of the system.................................................................................................................. 7

1.2 SUSTAINABILITY WITHIN THE DECISION MAKING PROCESS....................................................................................... 71.2.1 Asset management............................................................................................................................... 81.2.2 Life Cycle Assessment (LCA) .................................................................................................................. 8

1.3 LOCAL CONTEXT ............................................................................................................................................ 9

2. METHODOLOGY ......................................................................................................................................... 112.1 PRINCIPLES, CRITERIA AND INDICATORS ................................................................................................................ 112.2 ENVIRONMENTAL IMPACT AND ECOPOINTS ........................................................................................................... 12

3. GOAL AND SCOPE ....................................................................................................................................... 153.1 GOAL ............................................................................................................................................................ 153.2 SCOPE ........................................................................................................................................................... 15

3.2.1 Temporal, geographical and technological coverage......................................................................... 163.2.2 System boundaries.............................................................................................................................. 16

3.3 EQUIVALENT ALTERNATIVE PRODUCT SYSTEMS....................................................................................................... 18

4. INVENTORY ANALYSIS ................................................................................................................................ 19

5. IMPACT ASSESSMENT................................................................................................................................. 215.1 LIFE CYCLES OF DIFFERENT MATERIALS IN 300-315 MM .......................................................................................... 22

5.1.1 Concrete 300 mm................................................................................................................................ 225.1.2. PVC 315 mm ...................................................................................................................................... 235.1.3. HDPE 315 mm .................................................................................................................................... 24

5.2 TOTAL ENVIRONMENTAL IMPACT ........................................................................................................................ 255.2.1 Concrete 300 mm................................................................................................................................ 255.2.2 PVC and HDPE 315 mm....................................................................................................................... 25

6. INTERPRETATION ....................................................................................................................................... 276.1 THE USE OF ECOPOINTS .................................................................................................................................... 276.2 TOTAL ENVIRONMENTAL IMPACT ........................................................................................................................ 276.3 SEPARATED AND COMBINED SYSTEMS .................................................................................................................. 30

6.3.1 Small diameters in separated systems................................................................................................ 306.5 LIFE CYCLE STAGES AND WASTE SCENARIOS........................................................................................................... 30

7. DISCUSSION................................................................................................................................................ 317.1 RESULTS ........................................................................................................................................................ 317.2 METHODOLOGY .............................................................................................................................................. 32

8. CONCLUSION .............................................................................................................................................. 34

BIBLIOGRAPHY ............................................................................................................................................... 35

APPENDICES ................................................................................................................................................... 37APPENDIX 1: READING GUIDE .................................................................................................................................. 37APPENDIX 2: GENERAL CONDITIONS DEFINING THE FUNCTIONAL UNIT .............................................................................. 39APPENDIX 3: TREE CONFIGURATION OF SINGLE PIPES IN 300 – 315 MM .......................................................................... 40APPENDIX 4: ABSOLUTE ENVIRONMENTAL IMPACTS OF SINGLE PIPES ............................................................................... 43APPENDIX 5: HDPE PIPE WITH PVC DISPOSAL SCENARIO .............................................................................................. 44

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Acknowledgements

I wish to sincerely thank my supervisor Jan Vreeburg (Wageningen University and Research Centreand KWR) for the opportunity of expressing the skills developed during my academic education thusfar but especially for creating the opportunity for gaining new skills and experience in sustainablesystems engineering during this project. He showed confidence in my ability to work independentlyand take responsibility for the research, and encouraged critical reflection on my own research anddecision-making.At times when the research and methodology seemed pointless, Tessa van den Brand took time tolisten and regain my enthusiasm for the research. I would like to thank her for keeping me motivatedto learn the method of Life Cycle Assessment, showing its advantages and disadvantages andreflecting critically on the choices that I had made.I want to thank Laurens van Miltenburg and his colleagues at WINNET that gave me access into theirdata and showed their willingness to answer questions and respect the process of this research.Lastly, I want to thank KWR, for their inspiring workplace, financial support, and keeping the researchgrounded within the context of the water sector.

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Introduction

In most modern cities, (waste) water services are delivered via networks of buried pipes that connectboth domestic and industrial customers to treatment facilities. The infrastructure related to thisrepresents a significant capital investment and is complex. Not only the current generations, butseveral future generations will inherent the outcomes of the investment decisions made today, aswell as that today’s generations cope with the investments decisions made in the past. This due tothe long technical lifespan of these infrastructures.The complexity of the system is, besides the long technical lifespan, related to the increasing push forwater recycling, nutrient removal, stricter regulatory on disposal of bio solids and the infrastructureitself. On top of this the whole water sector is being confronted with a greater number ofenvironmental management challenges, like increasing energy demands, greater awareness ofemissions and wastewater reuse streams. Sustainability of the wastewater system is therefore notdefined by the technical characteristics but also by environmental, economic and social factors.The explicit incorporation of sustainability in the decision support process requires assessment ofthese four factors. The selection and prioritization of interventions becomes particularly relevant,and there is a clear requirement for the development of methods that analyze and predictwastewater system performance within this holistic sustainability context.

This research is set in this context. A method for gaining insight in the sustainability of a system is aLife Cycle Assessment (LCA). LCA is used to analyze the total environmental impact of a product orservice during the whole lifecycle, meaning, the excavation of resources, production, transport, useand disposal; all stages of a products lifecycle. The aim of this research is to determine theenvironmental effects of the wastewater transport system, and the related materials and diametersused, within the context of the WINNET region, using the method of Life Cycle Assessment. Thesystems studied will be a separated system and a conventional combined system, studied in concrete(300 and 400 mm) and PVC (315 and 400 mm). These results will be compared to a combined systemin PVC 110 mm and HDPE 315 mm. The functional unit for this LCA study is the undergroundtransportation of domestic sewage and rainwater over a distance of 100 m by a gravity led pipesystem from the entrance of the house connection point to the transition point of the pressurizedsystem, over its complete service life cycle of 60 years, calculated per year.

The main research questions:What are the environmental impacts during the lifecycle of pipes of the wastewater transportsystems within the Winnet context identified using a LCA?

Sub questions are:What are the net life cycle impacts associated with the transport of domestic wastewater?What are the contributions of each life cycle stage to the net result for each impact category?What are the contributions of specific environmental releases to the net result for each system andimpact category?

Chapter 1 will set the research within precedent research. Chapter 2 discusses the methodologyused, and is connected to chapter 3 which is the first step of a LCA; the goal and scope definition.System boundaries are also discussed in this chapter. In chapter 4 the inventory table is shown anddiscussed. Chapter 5, the impact assessment, shows the results derived with the SimaPro software.Analysis of these results is done in chapter 6, concluding the report with a discussion and conclusionin chapter 7 and 8.

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1. Theoretical Framework

1.1 The wastewater system

The management of water has been recognized as a critical factor to achieve sustainability in theurban environment (Barbosa, Fernandes & David, 2012; Deltares, 2009; Ferreira et al., 2011). Thisdue to increasing pressures resulting from climate change, increasing industrialization, changingpopulations and demographics, heightened environmental awareness and more complex regulatoryand social circumstances. Within this context, recent studies and policy plans focus on the transportof storm water away from the urban environment. The transport of storm water makes theimportance of wastewater management noticeable. In most modern cities, (waste) water servicesare delivered via networks of buried pipes that connect the customers, both domestic as industrial asfrom the public domain, to treatment facilities. From the treatment facilities it is transported tosurface water mostly, which act both as sources of (drinking) water as sinks for wastewater.

The infrastructure related to this represents a significant capital investment. Besides, not only thecurrent generations, but several future generations will inherent the outcomes of the investmentdecisions made today, as well as that today’s generation copes with the investments decisions madein the past. The complexity of the system is, besides the long technical lifespan, related to theincreasing push for water recycling, nutrient removal, stricter regulatory on disposal of bio solids andthe infrastructure itself (Lane, de Haas, & Lant, 2015). On top of this the water sector is beingconfronted with a greater number of environmental management challenges, like increasing energydemands, greater awareness of emissions and concerns over contaminants in bio solids andwastewater reuse streams.

The construction of new infrastructures comes with the cost of capital, materials and energy input.The environmental impacts associated with these inputs are trade-offs for the benefit of improvedwater quality and ecosystem services and social and economic opportunities that result fromimproving wastewater management (Wang, Eckelman, & Zimmerman 2013). In theory at least,reducing the reliance on such networks has the potential to realize a significant reduction inexpenditures. Reducing water leakage, corrosion resistance and reduced maintenance are currentsolutions to improving the life-cycle performance of pipes. Analyzing the environmental effect of thepipe itself is there for important, and at the core of this research.

1.1.1 Complexity of the systemThe complexity of the underground utilities infrastructure refers to the total length of the networks,the variety of types of utilities, the different materials from which they are made, their differentsensitivities to disturbance, the different ages stretching back 100 years or more, and theinterconnectedness of the different utility networks (Rogers et al., 2012). The utility infrastructure is(almost completely) buried beneath the publicly owned land in urban areas: roads, cycle ways andpedestrian areas, making the assessment of the infrastructure difficult.Most sewage networks are compiled of ageing assets that are becoming increasingly moresusceptible to failure (Ward & Savic, 2012). Besides changes in the infrastructure, the context inwhich this system operates in is also changing. Wastewater production is increasing due to increasedwater consumption and due to changing climate; extremer cases of storm water run-off need to bedealt with. This puts more pressure on the capacity of the system and the connected surface waters.

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1.1.2 Sustainability of the systemWithin this context of increasing pressure the effectiveness of the system on the long term researchstresses the need for new sustainability developments within the wastewater system. For example,by improving the existing centralized systems or by (further) development of decentralized systems.Balkema et al. (2002) characterizes sustainability as multi-dimensional and identifies four dimensions(Balkema et al., 2002)- Economic sustainability implies paying for itself, with costs not exceeding benefits. Mainly focusingon increasing human well-being, through optimal allocation and distribution of scarce resources, tomeet and satisfy human needs. This approach should, in principle, include all resources: also thoseassociated with social and environmental values (e.g. in environmental economics). However, inpractice most analyses include only the financial costs and benefits.- Environmental sustainability implies the long-term viability of the natural environment. This shouldbe maintained to support long-term development by supplying resources and taking up emissions.- Socio-cultural sustainability has the objective to secure people’s social–cultural and spiritual needsin an equitable way, with stability in human morality, relationships, and institutions.- Technical sustainability considers the physical impacts and lifespan of the system.

All of these sustainability aspects are recognized by local government and implemented in policyplans (Gemeente Utrecht 2016). Policy plans specifically focus on the effective disposal of stormwater. For a few decades, urban water experts advocate to integrate a systems approach whenanalyzing the disposal of different types of wastewater (Daigger, 2012). Separated systems,conventional or upgraded, have become the common standard in the construction of wastewatertransport systems.

1.2 Sustainability within the decision making process

The explicit incorporation of sustainability in the decision support process requires assessment of thesocial, economic, technical and environmental consequences of potential options (Foxon et al.,2002). The Water Framework Directive and other European legislation and standards (e.g., EuropeanStandard EN752:2008) promote the protection of water resources and establish increasingly highperformance requirements for planning, design and operation of urban wastewater systems. Theincrease in regulatory requirements on protection of public health and environment has led toincreased attention on the performance of the systems. For wastewater systems, severalperformance domains have been identified (Cardoso et al., 2004; Ferreira et al., 2011; Ward andSavic, 2012), with different performance indicators:- hydraulics—water level, flow velocity, overflow volume, overflow peak and duration, ratio betweenmaximum wet-weather flow and maximum dry-weather flow;- environmental—concentration of pollutants, polluted overflow discharges, septicity;- structural—damage rate, leakage;- economic—maintenance costs, power costs;- social—disruption to public activities, complaints, odors

At the same time, stakeholders need to implement these regulations within a decreasing budget. Theselection and prioritization of interventions becomes particularly relevant, and there is a clearrequirement for the development of methods that analyze and predict sewer performance withinthis sustainability context.Given the long-term need for ecological sustainability, the goals for urban water systems need tomove beyond the protection of human health and receiving waters to include minimizing loss ofscarce resources, reducing the use of energy and water, reducing waste generation and enabling the

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recycling of plant nutrients (Lundin, Bengtsson, and Molander, 2000). It is a careful considerationbetween people, planet and profit. A different material or process could benefit people or planet butcould possibly need an investment that will not be returned. Insight in the environmental (but alsopsychical, social en economic) effects of different considerations could benefit such public debate.

1.2.1 Asset managementThe two stakeholders involved are increasingly setting up asset management plans and/or (waste)water policy plans including chapters on asset management, demonstrating their commitment toimproving their sewerage asset failure rate. The consequences of failure are however not limited toan engineering nature. Because of its strong relation to above ground activities, it is also related toeconomic activities. Improving failure rates is normally achieved by investments in sewerage assetmaintenance (Syachrani, Jeong, & Chung, 2013), as can be seen in the wastewater policy plans of themunicipalities.This failure and/or time driven management is only a part of the possible within the assetmanagement framework, where the goal is to ensure that investments return to the highest possiblebenefit. The ‘benefit’ is increasingly defined as something transcending the engineering andeconomical level but can also be defined within an environmental context. Asset managementsystems have not been considered from the whole related activities (El-Akruti, Dwight, & Zhang,2013). Analyzing the environmental impacts over the life cycle of the system is part of thisdevelopment. Life cycle assessment is such an analysis tool.

1.2.2 Life Cycle Assessment (LCA)A LCA is defined by Guinée as the “compilation and evaluation of the inputs, outputs and potentialenvironmental impacts of a product system throughout its lifecycle” (Guinée et al. 2001). LCA is usedto analyze the total environmental impact of a product or service during the whole lifecycle,meaning, the excavation of desired resources, production, transport, use and disposal; all stages of aproducts lifecycle. The total system of unit processes involved in the life cycle of a product is calledthe ‘product system’.

Analysis using a LCA within the wastewater system is not new. LCA has been used in the past andnear past for the analysis of conventional wastewater systems (Tillman, Svingby, & Lundstrom, 1998),storm water infrastructures (O'Sullivan et al., 2015), sludge recycling strategies and energy analysisof these systems (EPA, 2014; Remy and Jekel, 2012). Other LCA studies have been related, forexample on the effect of green infrastructure on (waste)water system (De Sousa, Montalto, & Spatari2012; Spatari, Yu, & Montalto 2011; Wang, Eckelman, & Zimmerman, 2013).

The last few years more LCA’s have been developed on the whole wastewater system and includedthe extensive transportation network. For example, used a LCA to analyze the relative contribution ofsewer systems within the urban wastewater system (Risch et al., 2015).

STOWA used a LCA to calculate and analyze the energy use of common practices and situationswithin the wastewater system (RIONED, 2012). This is done from the production/excavation of theraw materials to the construction of the wastewater system.A LCA has been done for the most common elements and practices of the wastewater system.However, only on the wastewater transport system by comparing different diameters and materialswithin different wastewater transport systems. The gaps of knowledge exist when looking at otherenvironmental impacts, besides the energy use but also related to toxicity, emissions to water, airand ground, the production of solid waste, and impacts on land use and ecosystems. Also notincluded in other studies is the potential difference in environmental impact between differentmaterials and different diameter. Commenting on the article of Risch (2015), Langeveld (2015)

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concluded that “additional research to quantify the influence of assumptions and case specificcharacteristics on the contribution of sewers and WWTPS on the overall environmental impact ofurban wastewater systems is required before more general statements on the relative contributioncan be made”(Langeveld, 2015, p. 376).Nevertheless, these complex approaches are seldom used for planning urban drainage systems(Ferreira et al., 2011). This is part due to the systems complexity, part to the lack of sufficient dataand part to the incompatibility between the time required to develop and validate such approachesand time used by policy makers. However, in order to achieve the goals set in the policy plans of themunicipalities, insight in the environmental impact of available materials and diameters of transportinfrastructure can be of added value. First, to facilitate debate on the effectiveness of differentmeasures and second, to prevent the use of measures that show an unacceptable environmentalimpact on the long term. Within this framework a LCA will be of added value.

1.3 Local context

This research focuses on the context of 14 municipalities within the Province of Utrecht and theWater board Stichtse Rijnlanden, which are organized together in the cooperation of Winnet. Intheir regional wastewater cycle policy it is mentioned that they want to achieve:

- A more uniform policy concerning the wastewater chain- A common ground in the most effective measure to take, when considering sustainability- To be able to take advised decisions on saving 15,2 million by 2020.

As been stated in the policy plan of the cooperation: “in order to be give an optimal service level andquality for our citizens and the living environment we consider the wastewater system as one. Bycooperation and common practices we are able to successfully (effectively and in a sustainablemanner) maintain and manage out wastewater system. This is our contribution to complete the cycleof water, energy and materials” (translated Winnet, 2015).

In the Netherlands two stakeholders can be identified that are in control of ensuring these servicequalities. Municipalities are responsible for the collection of wastewater and the transport of thewastewater to the point agreed with the water board. From this point onward the water board isresponsible for the transport to the wastewater treatment plant, for wastewater treatment anddisposal of the treated wastewater. These two public work departments are increasingly accountableto public expectations and new regulatory requirements for protection of public health andenvironment, efficient use of public funds and greater disclosure (Younis and Knight, 2014).

This research focuses on the environmental impact of wastewater infrastructure within the contextof the WINNET municipalities. The wastewater infrastructure of the municipalities consist of 11different materials, but mostly concrete and PVC. The diameters for the combined collection systemrange from 110 mm to 10000 mm, based on the management systems of the municipalities. Theseparated system shows a range from 50 mm to 900 mm for the dry weather flow pipe and 75 mmto 10000 mm for the rainwater flow pipes.

Table 1 shows the current characteristics of these infrastructures.

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Table 1: Materials used for wastewater pipes in Winnet region

Concrete and PVC are the most used materials. The high amount asbestos cement is mostlycontributed to the municipality of Utrecht.The data derived from the wastewater management systems shows a wide range of diameters andmaterials used. This shows the complexity of the system, as the current system consists of morematerials and diameters than would be used for construction (i.e. concrete pipes smaller than 250mm).

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2. Methodology

In the following chapters of the report the different sections of a Life Cycle Analysis are discussed.These are:

1. Goal and Scope definition2. Inventory Analyses3. Impact Assessment4. Normalization5. Interpretation

After the goal and scope of the LCA have been set up, it has been verified by coordinators of theWINNET region, during an expert meeting.The data used in the inventory analysis are based on data derived from previous LCA research,experts, local data from the municipalities and scientific literature.Also the database connected to SimaPro software (Analyst 8.0.3.14, May 2016) is used, specificallythe EcoInvent 3 database.This software program is also used for the calculation of the impact assessment.Quantitative data has been used when possible, qualitative data when necessary as will bementioned in the inventory analysis. In all cases, experts on sewer management have verified the useof these data.

The outcome of an LCA is dependent on the choices made in goal and scope, system boundaries anddata used. To make these choices as clear as possible these are elaborated upon within the chaptersor in the reading guide, included in Appendix 1: Reading guide.

2.1 Principles, criteria and indicators

This research can act as an input reference for policy decisions made within the WINNET region inthe future. These choices are based on principles, criteria and indicators. Principles are normativedefinitions or goals for sustainability. Criteria are the set of factors that may be used to make ajudgment about the relative sustainability of a set of options. Indicators measure the past andcurrent values of specific criteria, and may be used to set standards against which futureperformance can be assessed (Foxon et al., 2002).

In other studies the choice of indicators was guided by a number of principles: ability to demonstratea move towards or away from sustainability; applicability to a broad range of systems; ability toprovide early warning of potential problems; availability of good-quality data; comprehensiveness ofindicators; and cost-effectiveness (Foxon et al., 2002). The GRPs (Gemeentelijk Rioleringsplan) of themunicipalities provide such guidelines. However, the performance indicators related to theseguidelines are not always clear or well defined (internship report, 2015). The value of the LCA mighttherefor be subject to interpretation, and dependent on weighting, allocation and decisions made bythe researcher. Past studies have recognized this problem, e.g. Gouda et al. (2001) and Foxon et al.(2002) who describe sustainability as a function of various economic, environmental, ecological,social and physical goals and objectives. The interpretation part of the LCA is therefore the mostimportant part in order to make it applicable to the WINNET region.

As any other tool a LCA holds several possibilities and limitations. The purpose of a LCA is to compileand evaluate the environmental consequences of different options for fulfilling a certain function.This immediately shows the first possibility, evaluating different options on the same ground, and thefirst limitation. The LCA is restricted to environmental consequences, and does not include economic,social and/or technical characteristics.

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2.2 Environmental impact and Ecopoints

For the calculations in the impact assessment software of SimaPro is used (Analyst 8.0.3.14, May2016). Results will be shown according to the outline used by SimaPro; the ReCiPe endpoint methodis used for analysis. In the Netherlands two impact assessment methods have been developed, bothgrounded in the ‘environmental themes’ formulated by the Dutch Government in 1989 (VROM2000). Both have the same basic structure, with the indicator results obtained by multiplying theinventory results by the appropriate characterization factor. Together they form the environmentalprofile, which is then normalized.

Within the LCA framework the environmental profile resulting from this characterization step is animportant LCA result, with the grouping and weighting steps (which are more value based)constituting distinct, optional elements. Some existing methods deviate in this respect, however,weighting interventions directly. One example is the Ecopoints method, in which emissions andextractions are weighted using a distance-to-target method, i.e. based on policy targets (VROM2000), which is done in this research. Consequently, this method does not include a separatecharacterization step.

The environmental profile will be shown in three different lay-outs (tables, graphs and trees). Thefirst two show the values related to different environmental impacts. A cluster of category endpointsof recognizable value to society is referred to as an “area of protection”. In this method three aredistinguished: ‘human health’, ‘ecosystems’ and ‘resources’ (see Figure 1 and Table 2). These are alsoreferred to as ‘damage scores’. The human health damage model has been developed for respiratoryand carcinogenic effects, the effects of climate change, ozone layer depletion, and ionizing radiation.This contains for example the popular element for defining sustainability CO2. The ecosystemcategory consists of ecotoxicity, acidification, eutrophication, and land use and land transformation.The damages to resources are expressed as surplus energy for the future mining of resources.

The output of the LCA analysis, the total environmental impacts, will be expressed in Ecopoints (Pt).The Ecopoints method was developed in Switzerland in 1990 and is based on the use of nationalgovernment policy objectives. Environmental impacts are assessed directly and emissions areweighted in relation to environmental quality targets. That is, the evaluation principle used is thedifference between the total impact in a specific area and the target value (the distance-to targetmethod), which results are calculated in dimensionless Ecopoints. It should be stressed that variouspolitical, economic, and social considerations also play a role when formulating these objectives. Infact, the Ecopoints method is not so much an absolute environmental indicator as an indicator “inconformity with policy” and has been widely accepted as a useful instrument (Ekvall, Tillman, &Molander, 2005; Ligthart, Jongbloed, & Tamis, 2010; Risch et al., 2015). This ecoindicator istherefore a number that indicates the environmental impact of a material or process, based on datafrom a life cycle assessment. The higher the indicator, the greater the environmental impact.The value of 1 Pt is representative for one thousandth of a yearly environmental impact of oneaverage European inhabitant (VROM, 2000).

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Figure 1: Environmental impact and damage scores used in RecipeE/A method (VROM, 2000)

Impact categories inoutput Relating impact categories Description of impact Emissions Related to

Human health Climate change humanhealth Climate change (human) Concentration of greenhouse gasses

CO2,HCFC

High ozone depletion potential andhigh global warming potential

Ozone depletion Ozone layer depletionConcentration of ozone depletionsubstances HCFC

High ozone depletion potential andhigh global warming potential

Ionizing radiation Radiation effect (cancer) Concentration radionuclides Nuclides (Bq) Radioactive material

Particulate matterformation Respiratory effects Concentration fine dust Sox Health

Photochemical oxidantformation Respiratory effects

NH3,SPM,VOC's

Harmful VOCs typically are not acutely toxic,but have compounding long-term healtheffects.

Human toxicity Carcinogenic Concentration air, food, waterHeavy metals,PAH's Cancer related illness

Ecosystems Climate change Effect on target species Altered pH NOx Nutrient availability

Terrestrial acidification Acidification Sox Acidification

Freshwatereutrophication Eutrophication NH3 Eutrophication

Terrestrial ecotoxicity Ecotoxicity, toxic stress Concentration in soil, air and waterPesticides,Heavy metals Disruptive to ecosystems or species

Freshwater ecotoxicity Disruptive to ecosystems or species

Marine ecotoxicity Disruptive to ecosystems or species

Agricultural landoccupation Regional effect on species Land use Decrease of natural areas

Urban land occupation Decrease of natural areas

Natural landtransformation

Local effect on speciesnumber Land use conversion Decrease of natural areas

ResourcesMetal depletion

Surplus energy at futureextraction Concentration of ores Extraction of minerals

Fossil depletionSurplus energy at futureextraction Availability of fossil fuels Extraction of fossil fuels

Table 2: Impact categories and related emissions

3. Goal and Scope

In this chapter the set-up of the Life Cycle Assessment (LCA) for this research is introduced. Itdescribes the intended audience and determines the base of comparison. Furthermore, analyses anddecisions on the system boundaries and extensions are given and which factors are excluded fromthe LCA.

3.1 Goal

A LCA will be performed to compare the environmental impacts of different pipe materials anddiameters in different wastewater transport systems [1]. The systems studied will be:

- A combined sewer system- A separated sewer system

The initial diameters and materials under study are shown in Table 3. These are based on the mostcommon used diameters and materials within the WINNET region, as has been shown in Table 1.

Although the construction of combined sewer system is not common practice anymore it is includedto evaluate the base environmental outcomes to provide a baseline for comparison to the alternativewastewater infrastructure systems. The LCA will be built in a robust but flexible way, to establish aLCA that could be used to study other technologies and changes in the urban wastewaterinfrastructure.

Type of system Concrete (mm) PVC (mm)

Combined 300 315

400 400

Separated 300 315

400 400

Table 3: Materials and diameter studied

Based on the data derived from the municipalities and expert meeting, additional analysis will bedone on the following materials and diameters:

- PVC 110 and 250 mm- HDPE 110, 250 and 315 mm

3.2 Scope

The scope definition establishes the main characteristics of an intended LCA study, covering suchissues as temporal, geographical and technology coverage, the mode of analysis employed and theoverall level of detail of the study. The overall goal and scope report should justify all main choiceswith respect to function, functional unit, alternatives and reference flows and the phases ofInventory Analysis, Impact Assessment and Interpretation.

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3.2.1 Temporal, geographical and technological coverageThe base case model includes the wastewater transport systems over a lifetime of 60 years [2],within the WINNET region. Reference flows will also be collected from this region as much aspossible. It includes wastewater pipes, transporting domestic sewage and storm water, fromhouseholds to the pickup point by the water board. It, initially, included pipes of two differentmaterials and two different diameters per material. The reference base case is a combined sewertransport system, which will be compared to a separated system. Data will be used a recent aspossible, over a year period.

3.2.2 System boundariesThe initial system boundaries are shown in Figure 2. The phases included are the extraction of rawmaterials, production, construction, (operation), maintenance, dismantling and the end-of-life phasefor the design life of 60 years.The end-of-life phase is included in the initial system. Other research has often excluded this phasefrom the research (i.e. O’Sullivan, 2015 and Risch, 2015). They excluded the end-of-life phases,because of speculative future water regulations, end-of-life management and because the systemsoften are partly excavated and party disposed, but rarely are disposed as complete systems. Becausethis research only included pipes, and different materials have different disposal scenarios it isdecided to include these in the research, in order to compare the different materials in a morecomplete matter. The production of civil engineering equipment is excluded, as this will be a similaramong all different scenarios. The same goes for the works required to transport storm water runoffinto the systems (manholes, road channels etc.) and components that remove large debris from thesystem. The gravity-led system has no energy use or other inputs needed in order to operate. Theoperation phase was there for excluded.The range of materials used for production of pipes is based on the most common materials used inthe WINNET region (Table 1), and the materials that are increasingly used, like HDPE [3]. Theupstream boundary is defined as the raw domestic wastewater inflow from the house connection.The downstream boundary is set at the transition point to the pressurized system. This is usually atthe point where responsibility changes from that of the municipality to that of the water board.

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Figure 2: System boundaries

The scope of the study is defined in the functional unit. The functional unit is closely related to thefunctions fulfilled by the researched systems.

The function of the pipe sewerage system, both PVC and concrete, is to transport (gravity-led) acertain amount of sewage from the entrance of a public sewer system to the pressurized systemconnected to the wastewater treatment plant. In this research a section of this pipe system ischosen, from the house connection point to the entry point of the pressurized system. The basicassumption was that the definition of the functional unit should represent the function of the sewerpipe system over its entire life cycle: raw material extraction, material production, production of thepipes, the construction phase, the use phase and the processing of the waste at the end of life of thepipes. The elements that collect this wastewater (valves, manholes, house connection points areexcluded from this transport system.

The functional unit for this comparative LCA for sewer pipe systems has been defined as:

“The underground transportation of domestic sewage and rainwater over a distance of 100 m by agravity led pipe system from the entrance of the house connection point to the transition point of thepressurized system, over its complete service life cycle of 60 years, calculated per year”

General conditions that define the functional unit are described in Appendix 2: General conditionsdefining the functional unit.

3.3 Equivalent alternative product systems

The alternatives that are supposed to meet the requirements of the functional unit are:

A separated system with separate storm water and separate domestic sewer pipes.

After consultation with the WINNET municipalities it is decided to exclude an upgraded separatedsystem from further analysis. Upgraded separated sewers are placed mostly in industrial areas, not indomestic ones and differ from separated system in use of other elements, not in length of pipe.

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4. Inventory Analysis

Tables 4 to 9 show the data used for different aspects of the LCA. The life cycle of wastewater pipes,Table 4, includes five stages: production, construction/installation, maintenance,dismantling/excavation, and disposal. The production phase includes the extraction of raw materials,production of material and the transport between the different facilities.The construction stage is the installation of the pipes underground, in the domestic area and thetransport to this area.The use phase consists of maintenance (as operation was excluded from this research), and itincludes high-pressured cleaning of the system and the transport to the location.

The final phase comprehends dismantling and excavation and disposal. Dismantling is excluded butexcavation by a hydraulic digger is included in the research. For the three materials considered, threewaste disposal methods are considered: recycling, landfill and incineration (Table 9). Different wastestreams are allocated accordingly.All stages include transport of the pipes (or pipe material) to different locations. This includes thedistance travelled, vehicle types and fuel consumption. According to a LCA study done by Saegrov(Saegrov et al., 2003), the transportation is one of the substantial resource consuming stages ofwastewater infrastructure. However, their findings rely on specific conditions, i.e. transport length,which are larger than the lengths considered in this study (Table 8).

Phases used in SimaPro LCA Phase Included in analysis

Assembly Production andConstruction

- Raw material extraction- Production of pipe [3]- Transport between facilities- Construction of pipe by hydraulic digger

Other processes Maintenance andExcavation

- Use of water- Excavation by hydraulic digger

Disposal/Wastescenarios

Disposal - Recycling, Incineration and Landfill ofdifferent materials

Table 4: Life cycle phases

Some simplifications and assumptions were necessary in order to make the research questionmanageable. These will be further discussed in the discussion, chapter 7. In all cases, simplificationsand assumptions were discussed with either the WINNET representatives or experts. The tablesbelow include the included input data.

Production Length (m) Weight (kg/m) EcoInvent Other datasource

Concrete 300 mm 100 178,0 Concrete NIBE, 2016

Concrete 400 mm 100 248,1 Concrete NIBE, 2016

PVC and HDPE110 mm

100 4,3 [4] PVC pipe EHDPE pipe E

NIBE, 2016

PVC and HDPE250 mm

100 8,5 PVC pipe EHDPE pipe E

NIBE, 2016

PVC and HDPE315 mm

100 9,5 PVC pipe EHDPE pipe E

NIBE, 2016

PVC 400 mm 100 14,7 PVC pipe E NIBE, 2016Table 5: Pipe weight

20

Construction &Excavation forpipe in diameter:

Length (m) Trench (m3) EcoInvent Source

110 mm 100 215,6 Hydraulic Digger RIONED, 2008

300-315 mm 100 279,5 Hydraulic Digger RIONED, 2008

400 mm 100 315 Hydraulic Digger RIONED, 2008Table 6: Trench size

Maintenance Length (m) Water use (m3) EcoInvent Source

High pressure 100 9,2 Water NL(unspecifiedorigin)

Ooms andCuperus, 2013

Table 7: Maintenance

Transport Transport length (km) EcoInvent (unit) Data source

Within region 20 Lorry (tkm) Expert meeting

Outside region(production)

150 Lorry (tkm) NIBE, 2016

Table 8: Transport distance

Disposal/Wastescenarios

Landfill (%) Incineration (%) Recycling (%) Reuse (%) Source

Concrete 1,0 0,0 99,0 20% NIBE, 2016VPB, 2008

PVC 10,2 20,1 69,9 19% NIBE, 2016VPB, 2008

HDPE 10 85 5 20% NIBE, 2016VPB, 2008

Table 9: Disposal scenarios

21

5. Impact Assessment

The following chapter shows the results from the impact assessment done in SimaPro, based on theinventory analyses presented in chapter 4. Ecopoints and the impact categories are introduced abovein paragraph 2.2.

Table 10 shows the net life cycle impact per system for the different materials and diameters. It alsoincluded the total impact of separated systems in smaller diameters, where different materials arecombined. In these cases it should be noted that the waste scenario for PVC is used [5], noted with‘(Rec)’. The HDPE separated systems are modeled with both scenarios.The combined system has half the impact as a separated system, as the combined system is modeledas one pipe, and a separated system as two, with a lower maintenance (see Appendix 1 [4]). PVCpipes have a relative lower impact, but a smaller diameter concrete pipe of 300 mm has a lowerimpact than a PVC pipe of 400 mm. A single concrete pipe of 400 mm shows a higher impact than aseparated system of concrete 300 mm.

System Material and diameter Ecopoints (Pt)

Combined/Singlepipe PVC 110 mm 155

Combined HDPE 110 mm 176

Combined PVC 250 mm 282




Separated PVC 110 + 250 mm 417

SeparatedHDPE 110 + 250 mm(Rec) 419

Separated PVC 110 + 315 mm 445

SeparatedHDPE 110 + PVC 315(Rec) 448

SeparatedPVC 110 + HDPE 315(Rec) 449

SeparatedHDPE 110 + 315 mm(Rec) 452

Combined Concrete 300 mm 459


Separated HDPE 110 + 250 mm 497

Separated HDPE 110 + 315 mm 530

Combined Concrete 400 mm 621

Separated PVC 315 mm 625

Separated HDPE 315 mm 711

Separated Concrete 300 mm 917

Separated PVC 400 mm 924

Separated Concrete 400 mm 1240

Table 10: Net environmental impact

22

5.1 Life cycles of different materials in 300-315 mm

The next figures (Figure 3 - Figure 4) show the networks of a combined concrete system (300 mm)and a combined PVC and HDPE system (315 mm), the related attributes and their relative impact. Anetwork configuration is chosen, to model the connection between recycling and production of thematerial. Cutoff point is set at 1% (meaning that all contributions less than 1 % are excluded from thefigure). Additional tree configuration of the three models, with a cut-off percentage of 0%, areincluded in Appendix 3: Tree configuration of single pipes in 300 – 315 mm. Additional assistance forinterpretation of this figure is given is Appendix 1: Reading guide [6].

5.1.1 Concrete 300 mm

Figure 3: Life cycle of a single concrete pipe 300 mm

The network shows the high influence of the assembly of concrete, especially the production of theconcrete material itself (399 Pt). The waste scenario for concrete, which is 99 % recycling (see Table9) has a negative impact of 88,6 Pt. The negative impact is shown in green. The other phases,construction and maintenance, have a relative low impact. The total transport of the concrete pipes,between all different phases, contributes to almost 15 % of the total impact, due to the weight of thematerial. The digging of trenches during construction and excavation contribute to nearly 9 % of the

5,95 m3Concrete, normal{GLO}| market for

| Alloc Def, S

355 Pt

3,14E3 tkmTransport, freight,

lorry >32 metricton, EURO3

64,3 Pt

559 m3Excavation,

hydraulic digger{GLO}| market for

39,6 Pt

0,802 kgConcrete 300 mm

399 Pt

1 pAssembly Concrete

300 mm

525 Pt

2 kgDigging of trench

300-315 mm

39,6 Pt

1 kgMaintenance

3,27 Pt

0,99 kgRecycling Concrete

300 mm

-88,6 Pt

1 kgEnd of Life

Concrete 300 mm

-88,6 Pt

1 pLife Cycle Concrete

300 mm

459 Pt

23

total impact. The absolute impact of construction and excavation (including transport) is the samefor the PVC pipes (39,6 Pt), as seen in Figure 4.The green line between recycling of concrete and concrete 300 mm reflects the reuse rate of 20 % ofconcrete. It lowers the production of concrete with a fraction (1-0,802=)0,198, which is 20 % (reuserate) of 99 % (recycling rate).

5.1.2. PVC 315 mm

Figure 4: Life cycle of single PVC pipe 300 mm

As with the concrete pipe, the production of the pipe has the largest contribution to theenvironmental impact of a PVC pipe. The lower recycling rates of PVC are reflected in the network.The total negative impact of the disposal scenario of PVC is -41,2 Pt, to -88,6 Pt for a concrete pipe.Nonetheless the impact of recycling is still significant, and lowers the contribution of the pipeproduction with a fraction of 0,14. Impact of maintenance and construction and excavation are thesame and show no relative significance to the total environmental impact of the system. Thedifference in weight between a PVC pipe and a concrete pipe is reflected in the impact of transport,which is 6,4 Pt to 64,3 Pt for concrete.

824 kgPVC pipe E

267 Pt

313 tkmTransport, freight,lorry >32 metric

ton, EURO3 {RER}|

6,4 Pt

559 m3Excavation,

hydraulic digger{GLO}| market for |

39,6 Pt

0,867 kgPVC 315 mm

270 Pt

1 pAssembly PVC 315

mm

332 Pt


300-315 mm

39,6 Pt

1 kgMaintenance

3,27 Pt

1 kgEnd of Life PVC 315

mm

-41,2 Pt

0,699 kgRecycling PVC 315

mm

-41,3 Pt

1 pLife Cycle PVC 315

mm

313 Pt

24

5.1.3. HDPE 315 mm

Figure 5: Life cycle of a single pipe HDPE 315 mm

As shown in the inventory analysis, the two plastic pipes are modeled with the same weight.However, the production of HDPE (pipes) has a larger impact than the production of PVC. Thisdifference is reflected in the difference in total impact between HDPE and PVC pipes. 5 % of theHDPE pipes is recycled and therefor little material is reused, resulting in a small negative impact ofrecycling (-3,17 Pt) which is lowered by the impact of transport. The negative impact of the wastescenario is -2,52 Pt.

938 kgHDPE pipes E

310 Pt


ton, EURO3 {RER}|

6,83 Pt

559 m3Excavation,


39,6 Pt

0,99 kgHDPE 315 mm

312 Pt


300-315 mm

39,6 Pt

1 pAssembly HDPE

315 mm

336 Pt

1 kgMaintenance

3,27 Pt

0,05 kgRecycling of HDPE

315 mm

-3,17 Pt

1 kgEnd of Life HDPE

315 mm

-2,52 Pt

1 pLife Cycle HDPE

315 mm

356 Pt

25

5.2 Total environmental impact

The next figures show the total environmental impact within the different impact categories, asdefined in the RecipeE/A method. The analysis is done of single pipes in concrete, PVC and HDPE in300 mm and 315 mm respectively. The use of environmental impact categories is introduced inparagraph 2.2.

5.2.1 Concrete 300 mm

Figure 6: Impact categories concrete 300 mm

Figure 6: Impact categories concrete 300 mm shows the characterization of the different impactcategories (See 2.2 Environmental impact and Ecopoints).As 99 % of the concrete is recycled and 20 % of that concrete is reused within the cycle, the end-of-life phase of its lifecycle shows a negative impact to all impact categories that also have a positiveimpact. The environmental impact of a concrete pipe is largely contributed by the assembly stage,and somewhat ‘compensated’ or deducted by the reuse of concrete within the system, as discussedin the previous paragraphs. Five impact categories are identified with a positive score higher than 75Pt (see the total characterization and related Ecopoints in Appendix 4: Absolute environmentalimpacts of single pipes). The lifecycle (or mainly the assembly) of a concrete pipe produce emissionsand others outputs that have influence on these 5 categories: climate change (both human andecosystems), human toxicity, natural land transformation and fossil depletion. Climate change(human) and human toxicity are related to the ‘human’ impact category, climate change (ecosystem)and natural land transformation to ‘ecosystems’ and fossil depletion to ‘resources’.

5.2.2 PVC and HDPE 315 mm

Figure 7 shows the characterization of the environmental impact of a single PVC pipe and HDPE pipeof 315 mm. The highest score is shown in fossil depletion, with a single positive score of 191,8 Pt forthe HDPE pipe (see Appendix 4: Absolute environmental impacts of single pipes). Other positivescores above 80 Pt are seen in climate change categories, both human and ecosystem. These impactcategories contribute to all three of the damage assessment categories; fossil fuel depletion toresources, climate change to human health and climate change to ecosystems.

26

Figure 7: Impact categories single PVC 315 mm

The tree highest positive impact scores also show the tree highest negative impact scores for the endof life scenario. This does not apply to for the human toxicity score; the total positive impact is 10,1Pt but the negative impact is -0,578 Pt. The waste scenario for PVC does not deduct the impact onhuman toxicity as much as it does for the other impact categories.

Figure 8: Impact categories single HDPE 315 mm

The same goes for the waste scenario of HDPE. With an incineration rate of 85 % and landfill rate of 5%, the impact of the disposal of HDPE is not deducted. Appendix 4: Absolute environmental impactsof single pipes shows the impact into more detail.Compared to PVC, the emissions related to the life cycle of a HDPE pipe are related to the samecategories.

-50

0

50

100

150

200

Climat

ech

ange

Human

Health

Ozone

depleon

Human

toxic

ity

Photoch

emica

l oxid

ant fo

rma

on

Parcu

late

ma

er form

aon

Ionisi

ng radia

on

Climat

ech

ange

Ecosy

stem

s

Terrestr

ial acid

ifica

on

Fresh

water eutro

phicaon

Terre

stria

l eco

toxic

ity

Fresh

wate

r ecoto

xicity

Mar

ine

ecoto

xicity

Agricu

ltura

l land

occupa

on

Urban

land

occupa

on

Natura

l land

transfo

rma

on

Meta

l deple

on

Foss

il deple

on

Pt

Environmental Impact PVC 315 mm

End of Life

Maintenance

Digging of trench

Assembly

27

6. Interpretation

6.1 The use of EcopointsAs has been mentioned in the Methodology, chapter 2. 100 Ecopoints is the environmental impact ofone average European citizen. Other examples are:

- 15 Pt: a return flight, crossing Australia from east to west.- 0,004 Pt: a newspaper- 0,03: a can of alkyd paint.

Note that the lifetime of a pipe is set at 60 years by the SimaPro database. The total environmentalimpact of the pipes mentioned, refers to the environmental impact of pipes over the lifetime of 60years. The environmental impact of a small diameter PVC pipe equals the impact of about 10 returnflights of 6600 km, that of concrete 300 mm 30 flights.

6.2 Total environmental impact

System Material and diameterEcopoints(Pt) Pt/year Pt/p/year

Combined/Singlepipe PVC 110 mm 155 2,6 0,1

Combined HDPE 110 (Rec) 158 2,6 0,1

Combined HDPE 110 mm 176 2,9 0,1

Combined PVC 250 mm 282 4,7 0,2

Combined HDPE 250 mm (Rec) 287 4,8 0,2


Combined HDPE 315 mm (Rec) 318 5,3 0,2



Separated PVC 110 + 250 mm 417 7,0 0,3

SeparatedHDPE 110 + 250 mm(Rec) 419 7,0 0,3

Separated PVC 110 + 315 mm 445 7,4 0,3

SeparatedHDPE 110 + PVC 315(Rec) 448 7,5 0,3

SeparatedPVC 110 + HDPE 315(Rec) 449 7,5 0,3

SeparatedHDPE 110 + 315 mm(Rec) 452 7,5 0,3

Combined Concrete 300 mm 459 7,7 0,3


Separated HDPE 110 + 250 mm 497 8,3 0,3

Separated HDPE 110 + 315 mm 530 8,8 0,4

Combined Concrete 400 mm 621 10,4 0,4

Separated PVC 315 mm 625 10,4 0,4

Separated HDPE 315 mm 711 11,9 0,5

Separated Concrete 300 mm 917 15,3 0,6

Separated PVC 400 mm 924 15,4 0,6

Separated Concrete 400 mm 1240 20,7 0,8

Table 11: Ecopoint per year per connected person

28

The absolute life cycle impacts per product system are given in Table 11, ranked from lowest tohighest. The data is further split into Ecopoints per year (total lifetime is 60 years), and per inhabitantconnected to the pipe (set at 25 inhabitants connected to 100 m pipe). The system with the highestscore (a separated concrete system in 400 mm) has an impact of 0,8 Pt per person per year. This isless than 0,1 percent of the total environmental impact of all activities of this person over one year,which is a 1000 Pt. The lowest score for a separated system (0,2 Pt for a single PVC pipe in 110 mm),is nearly 0,01 percent of this impact.

Note that again a difference is made between HDPE pipes in the original waste scenario and with thesame scenario as the PVC pipe. All separated systems combining the two plastic pipes are alsomodeled with this scenario for PVC [8].

6.2.1 Difference in materialsTable 12 shows the relative contribution (%) of the scores for the different impact categories, for allsingle pipes. The three materials in 300-315 mm are shown in Figure 9. All materials have scoreshigher than 1 % in the same impact categories: climate change (human and ecosystems); humantoxicity; particulate matter formation; and fossil depletion. These impact categories were describedin further detail in paragraph 2.2. The concrete pipes have scores in higher than 1 % in one additionalcategory: natural land transformation. Also the concrete pipe scores relatively high on emissionsrelated to human toxicity, compared to the plastic pipes.

Figure 9: Impact of different materials in 300-315 mm

Table 12: Environmental impact per category for all single pipe scenarios

Impact category Unit PVC110

mm

HDPE11

0m

m

HDPE110

mm

(Rec)

PVC250

mm

HDPE25

0m

m

HDPE25

0m

m(R

ec)

PVC315

mm

HDPE31

5m

m

HDPE31

5m

m(R

ec)

Concret

e300

mm

PVC400

mm

Concret

e400

mm

Total Pt 155,3089 176,3722 157,6821 282,4602 323,9548 287,1844 313,4251 356,3943 317,6774 459,3528 463,2194 621,0229

Climate change Human Health % 27,9 22,7 21,9 28,1 22,4 21,6 28,2 22,4 21,6 24,1 28,3 24,1

Ozone depletion % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Human toxicity % 4,2 3,0 3,0 3,3 2,0 2,0 3,2 1,9 1,9 20,8 2,8 20,9

Photochemical oxidant formation % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Particulate matter formation % 4,4 3,3 3,2 4,1 3,0 2,9 4,1 2,9 2,8 3,3 4,0 3,2

Ionising radiation % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Climate change Ecosystems % 22,3 18,1 17,5 22,5 17,9 17,2 22,5 17,9 17,2 19,2 22,6 19,2

Terrestrial acidification % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Freshwater eutrophication % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Terrestrial ecotoxicity % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Freshwater ecotoxicity % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Marine ecotoxicity % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Agricultural land occupation % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Urban land occupation % <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Natural land transformation % <1 <1 <1 <1 <1 <1 <1 <1 <1 15,7 <1 16,0

Metal depletion % <1 <1 <1 <1 <1 <1 <1 <1 <1 1,1 <1 1,1

Fossil depletion % 39,5 51,6 52,8 40,7 53,7 55,2 40,8 53,8 55,3 14,4 41,3 14,1

6.3 Separated and combined systems

As mentioned above the difference between a combined system and a separated system in thisstudy is in the amount of pipes used and the maintenance frequency. A separated system in PVC 400mm (924 Pt) for example has two single pipes of PVC 400 mm (463 Pt), also a ‘combined system’ inthis research and 1,5 times the frequency of that single pipe.

The impact of maintenance is low; therefore a separated system is nearly double the impact of acombined system in the same diameter and material. The separated systems in 315 mm or higher inthe same material have the highest scores (see Table 11: Ecopoint per year per connected person).Also separated systems in HDPE, with the current waste scenario score have higher scores, albeittheir score is in the midrange, as the difference with the next higher score (a single concrete pipe of400mm) is 90 Pt.

6.3.1 Small diameters in separated systemsSeparated systems in small diameters are a combination of a small diameter, 110 mm in this research(as a sewer pipe) combined with a mid-range diameter (250 or 315 mm, as a rainwater pipe). Thiscombination has lower environmental impact than separated systems in conventional diameters, asless material is used. The separated system with the lowest score is a PVC system in 110 + 250 mm.This system has a slightly lower impact than the same system in HDPE, when modeled in the samewaste scenario as PVC. This is due to the difference in contribution of the production of HDPE versusPVC, as discussed in paragraph 5.1.3. This small difference is also seen when looking at the separatedsystems in the 110 mm and 250 mm configuration. When considering the same waste scenario thedifference between the systems is small. If the same HDPE systems are modeled in the current wastescenario they have the highest scores of the separated systems (with a small diameter).

6.5 Life Cycle Stages and waste scenarios

The assembly of the pipes has the highest impact on the total environmental impact of all pipes (seeparagraph 5.1). For all materials this is due to the production of the material. As the total impact ofplastic pipes is lower, the construction and excavation of a 300-315 mm trench has a relative higherimpact on the total impact of PVC and HDPE (about 13 %) than to that of concrete (about 7%). Thelarger weight of the concrete pipes leads to a higher impact of transport (expressed in ton perkilometer, tkm), as the distances are set the same for concrete and PVC in this research. Itcontributes to 14 % of the total impact for concrete, and about 2 % of the total impact of plasticpipes.

The end of life scenario of all materials has a negative impact, and deducts the total impact of thepipes. The recycling rate of concrete is higher, but the reuse rates used are nearly the same as theplastic pipes (20 % concrete, 19 % PVC). In the case of concrete, this recycling and reuse rate lowersthe total impact of concrete with 16 %. In the case of PVC, the reuse lowers the impact with 12 %.Due to the small recycling rate, the reuse rate of HDPE is low and deducts the total impact with lessthan 1 %. However, as discussed, higher recycling rates influence the total environmental impact ofHDPE significantly (see Appendix 5).

31

7. Discussion

7.1 ResultsIn this research, 19-20 % of the recycled material is reused. In practice, new pipes might consist oflower levels of recycled materials and this recycled material may only be used a few times. Or thematerial might not be reused in the pipe itself but as a material for construction of other elements. Itshould be noted that this research only contributed the reuse of material in the actual pipe, but thereuse rate is an assumption made based on reports of the concrete and PVC sector. The reuse ofmaterial within the whole wastewater system lowers the environmental impact of concrete and PVCpipes significantly and could result in the same for the waste water transport system in general. Thesmall(er) recycling rates of the plastic pipes, and especially for the HDPE pipes, could have severalorigins. The low recycling rates of HDPE might be explained by the low feasibility of recycling due tothe low weight of the material. Another explanation could be the long related life expectancy and therelative ‘newness’ of the material; simply not much HDPE pipes have been disposed yet. Therefor

Other uncertainties exist when considering the data used for transport distances, maintenance andtrench size. For maintenance different options exist, and used technologies develop over time. Only(surface) water use is considered in this study, as the database did not contain options that could berelated to the material or equipment used for maintenance of sewers. However, it was consideredthat the maintenance techniques used would be the same for all pipes and therefore could beexcluded from the comparison. New techniques, (i.e. as a Recycler which reintroduces thewastewater in the system for high pressure cleaning (Ooms & Cuperus, 2013), where less vehicles areneeded, and there no abstracting or discharge from or to water bodies, could turn out to bebeneficial compared to the conventional technique.

The results show the lowest environmental impact for small diameters. Balkema mentioned that thedevelopment of decentralized systems should improve the sustainability of the wastewater system(Balkema et al. 2002). When this implies the use of separated systems, which is one of thecharacteristics of decentralized systems, the environmental impact can be significantly lowercompared when applying small diameters to the use of conventional diameters. A separated systemin PVC 110 and 250 mm has a higher environmental impact as a combined PVC pipe 315 mm. This is,when looking at the impact of pipes alone, as done in this research. When combining this researchwith the analysis of Balkema, a smaller diameter separated system would be expected to show thelowest impact on the environment.It should be noted that, as only pipes are included in this research, the environmental benefits ofseparated systems are not confirmed by this research. From the technical perspective, a separatedsystems means more pipes, more material and therefor a higher environmental impact. Theenvironmental impact of separated systems is not well defined by looking at the transport pipesalone and could do better embedded in a more complex analysis of the whole wastewater system.

This interconnectedness with the wastewater system gives options for improvement for furtherresearch. The research encompasses only a small part of the total wastewater system, as differentmaintenance techniques are not included. The data included in the EcoInvent database is highlydetailed and complex. Input data for new materials or products should match this level of detail tosome extent. Early on in the research it was decided that other elements than pipes that are part ofthe transport system (valves, pumps, but also rubber rings connecting different pipes) were excludedfrom the research. Earlier research had shown that the impact of these elements was low and had nosignificant influence (Risch, 2015), and as with maintenance, are considered the same for allscenario’s.

32

Within the Winnet region, the current infrastructure of the combined systems consists of less than 2percent of the small diameter pipes (160 mm or lower). For the separated system it adds up to about5 percent (5,8 % for dryweatherflow and 4,5 % for rainwaterflow). Altering policy and practice andconstructing pipes in small diameters therefor could improve the environmental impact of thewastewater transport system in the WINNET region.

7.2 Methodology

The use of LCA as a tool to analyze environmental impact has been debated in the past in differentresearches. Some of these arguments can be applied to the use of LCA within this research as well.Most life cycle data is produced from site-specific or individual sites or activities. In order to makethis work for the LCA and make the data more reliable and simplify the LCA process is to increase thedata (Curran 2014). The Recipe method and EcoInvent database are common standard with LCAstudies done in the Netherlands, and local data is added as much as possible. It is expected that thelack of site specific data to the region of WINNET has not influences the relative total environmentalimpacts of the studied systems. Same can be expressed for the exclusion of other elements thanpipes. The applicability of a LCA lies in modeling the relative differences between systems and act asa starting point for discussion for weighting the different impact categories. It is expected that theexclusion of other elements than pipes has had no relevant influence to the relative outcome of themodels.

It is debated to which extent LCA can address localized impacts (Guinée et al., 2001) It is possible toscale down some of the results and to identify the regions in which certain emissions take place,after which differences in the sensitivity of these regions can be taken into account in the context ofLCA. But LCA does not provide the framework for a local life cycle or risk assessment study,identifying which impacts can be expected locally.LCA results are also typically unaccompanied by information about the temporal course of theemission (some environmental impacts may occur in the future) or the resulting concentrations inthe receiving environment (Curran, 2014). With the inherent uncertainty in modeling environmentalimpacts, an impact indicator is the outcome of a simplified model of a very complex reality. A moreholistic approach would therefore be advisable. LCA is typically a steady state, rather than a dynamicapproach. However, future technological developments are increasingly taken into account in moredetailed LCA studies, as mentioned by Guinee et al (2002) and the increase of LCA research on thewastewater transport system. Also, an additional step of weighting the results and analyzing someimpact categories into more detail could increase the quality and usability of the research.

Although the researcher has made effort to make the LCA as science-based as possible, it involves anumber of technical assumptions and value choices. Ideally, as mentioned by several LCA guidelines,the process of selection and set up of the LCA is done in collaboration with other researchers ormultiple experts. As this research was mostly done by one researcher, important aim was to makethese assumptions and choices as transparent as possible. By adding an appendix clarifying thechoices made, the researcher has tried to increase the transparency.

The availability of data and choice of data sources have limited the outcome of the research,especially for the concrete pipes. SimaPro database only provides the production of concrete, notthe production of a concrete pipe (which is the case for a PVC pipe or HDPE pipe). The environmentalimpact of the assembly is mostly based on the production of concrete, construction processes andtransport. For a PVC pipe, the assembly phase is both the production of PVC as well as making a PVCpipe from this material. The researcher has tested whether the production of a material has the mostsignificant impact within the production of a pipe. It was concluded from this analysis that theproduction of material has the highest impact and therefore could be used in further analysis.

33

The availability of data also showed limiting when trying to construct a sensitivity analysis, i.e. MonteCarlo analysis. Such an analysis would improve the quality of the results. Uncertainty of the datacould only be done on the data that was produced by the researcher. A large majority of the datawas provided by the EcoInvent database and did not contain any indicated level of uncertainty. Only0,0009 % of the data contained an indicated level of uncertainty and the quality of the sensitivityanalysis showed to be insufficient. The fact that the vast majority of the data was drawn from theEcoInvent database could indicate a sufficient level of quality of the data.

The method used in this research was Recipe E/A, with Ecopoints unit. Further research couldcompare the results from this method to another method, for example focused on CO2 emissions orenergy use specifically, and analyze whether based on these methods, the same scenarios show thelowest environmental impact. This research can act as an input reference for criteria or indicators inpolicy decisions made within the WINNET region in the future.

34

8. Conclusion

When comparing a combined system to a separated system in different materials and diameters itcan be concluded that smaller diameters have a smaller impact. The choice for a smaller diameterwill have greater environmental benefit than the choice for a different material. When the samediameters are compared, plastic pipes show a lower impact than concrete. The total impact of aHDPE pipe (315 mm) is higher than PVC with similar diameters, but this is mainly related to the lowrecycling and high incineration rates used for HDPE in this study. Based on the data and assumptionsused in this study, the lowest environmental impact is shown in separated systems constructed inPVC 110 and 250mm.

The damage assessment and impact scores for all three materials show that the production of thematerials has the highest impact on the total environmental impact of the different pipes.Maintenance and construction techniques were considered alike and had no significant influence.The end-of life scenario (recycling, incineration and landfill rates) has the second largest influence onthe total impact, and can lower the total impact with 16 %.

The research shows the specific environmental impact scores related to ‘resources’, ‘ecosystems’and ‘human health’. The largest contributions are shown for climate change related emissions andfossil depletion, which affect all three categories used in the Recipe E/A method.

It is recommended that further research is done on the analysis of more materials and elements ofthe wastewater transport system. Expanding the system boundaries to other elements and forexample the reuse of concrete pipes within these elements could lead to more extensive insight inthe total environmental impact of the wastewater transport system.

35

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37

Appendices

Appendix 1: Reading guide

[1] Chosen systems

Initially an upgraded separated system (“verbeterd gescheiden system”) would be included in theresearch, where the first flush of storm water is transported to the sewer and connected wastewatertreatment plant. During the expert meeting it was concluded to exclude this system from theanalysis; these systems typically are constructed in industrial areas and differences between anupgraded separated system and conventional separated systems are found in use of elements andnot pipe length. Both the industrial area and elements are not included in the functional unit orresearch.

[2] Technical life time of 60 years

The life expectancy and technical service life of waste water transport systems is subject to a wideset of variables. During the expert meeting life time’s ranging from 15 to 100 years were discussed asbeing ‘normal’. The EcoInvent database has data on plastic pipes, based on a technical life span of 60years. This was taken as the average life span for all pipes in the study.

[3] Materials used and excluding virtuous clay

The materials used are the ones most relevant for current construction of new sewers, as discussedin the expert meeting. Virtuous clay was considered as a fourth material. The EcoInvent databasehowever did not contain any data on this material, or related material. The researcher has tried tocollect data on virtuous clay both by researching the material as by contacting other researchers whoincluded the material in their (LCA) research. The quality of the data turned out to be too low to becompared to the other material, as no data on emissions could be found.

[4] Assumptions made in input data

- Based on data source www.nibe.info the weight of both plastic pipes was considered equal- Small diameters (110 and 250 mm) were calculated accordingly, as different data sources

show a variety of weights for different materials and diameters.- Maintenance and the amount of water used is based on the frequency of once every seven

years for the combined system, an average length of pipe that is cleaned of 650 m per dayand water use of 66 m3 per day. The separated system has 1,5 times that amount, as therainwater pipe will be expected to be cleaned every 14 years.

[5] Disposal scenarios

The HDPE pipes are modeled with two different waste scenarios. The current scenario, which has arecycling rate of 5 %, and a future scenario, which has a recycling rate of nearly 70 %, similar to PVC(see Table 9). This future scenario is labeled with ‘(Rec)’. The current practice of disposal of HDPEheavily influences the total environmental impact (see Appendix 5). Besides, it is expected, that inthe near future the recycling of HDPE has become more common, as more material has beencollected. Therefor it was decided to also model the HDPE pipes with another waste scenario, so thetwo plastic pipes could be compared.

38

Additionally, SimaPro has the limitation of only modeling one waste scenario for the whole product.Two different waste scenario’s for two different materials in a separate system (like PVC 110 mmand HDPE 315 mm) could not be included using this method.

[6] Interpretation of networks in SimaPro lay out

Two lines can be distinguished. The red line indicates a ‘positive’ impact and the green one a‘negative’ environmental impact. Note that the cut off for the network configuration is set at 1 %, allimpacts lower than 1 % are excluded in these figures. The number at the lower left corner representsthe impact in Ecopoints of all lines connecting as an input. For the Life of concrete 300 mm thismeans that the total impact of 459 Pt consist of 525 (Assembly) + 3,27 (Maintenance) + 19,8 (Diggingof 1 trench) – 88,6 (End of life scenario).The numbers on top represent input data or the fraction it represents. For example, the productionof a concrete pipe (listed as ‘Concrete 300 mm) is 0,802 kg. As 99 % is recycled and 20 % is reused, afraction of 0,198 is reused. This represents the green line and together it adds up to 1 kg. The unit kgis chosen by SimaPro but should be seen as unit less.

[7] Transport dataAll distances are set the same for the materials (see Table 8). The unit however is tkm, ton perkilometer. For every stage the different weights were calculated and converted into tkm. For theexcavation and construction of the pipes only a hydraulic digger was considered and not theadditional transport of material. This additional transport was included in the phases connected.

5,95 m3Concrete, normal{GLO}| market for

| Alloc Def, S

355 Pt

3,14E3 tkmTransport, freight,


64,3 Pt

559 m3Excavation,

hydraulic digger{GLO}| market for

39,6 Pt

0,802 kgConcrete 300 mm

399 Pt

1 pAssembly Concrete

300 mm

525 Pt


300-315 mm

39,6 Pt

1 kgMaintenance

3,27 Pt


300 mm

-88,6 Pt

1 kgEnd of Life

Concrete 300 mm

-88,6 Pt

1 pLife Cycle Concrete

300 mm

459 Pt

39

Appendix 2: General conditions defining the functional unit

Some general conditions to define the functional unit are ((RIONED 2015)(Nibe, 2016) residentialarea:

- 920 inhabitants- connected inhabitants per 100 m: 25- max discharge of domestic wastewater: 9m3/h- total discharge capacity combined system: 12,5 m3/h- reference length: 100 m

Basic conditions for the concrete pipes:- internal diameter 300 mm or 400 mm- Reference length 100m; - Filling rate 100% -> number of households connected: 12,5 per pipe

Basic conditions for PVC pipes:- Internal diameter: 110 mm, 250 mm, 315 mm and 400 mm- wall thickness: 7,7 mm and 9,8 mm for the 315 and 400 mm.- strength: SN4- reference length 100m; - filling rate 100% -> number of households connected: 12,5 per pipe

Basic conditions for HDPE pipes- Internal diameter: 110, 200 and 315 mm- wall thickness: not given- strength: SN8- reference length 100m; - filling rate 100% -> number of households connected: 12,5 per pipe

Appendix 3: Tree configuration of single pipes in 300 – 315 mm

1 p

Life Cycle Concrete300 mm

459 Pt

1 p

Assembly Concrete

300 mm

525 Pt

1 kgConcrete 300 mm

498 Pt

7,42 m3

Concrete, normal

{GLO}| market for |Alloc Def, S

443 Pt

2,67E3 tkm

Transport, freight,

lorry >32 metric ton,

EURO3 {RER}|

54,6 Pt

4,05 MJ

Electricity mix, AC,

consumption mix, at

consumer, 1kV -

0,0719 Pt

3,19E-7 kg

Dummy CaF2 (low

radioactice)

0 Pt

9,51E-7 kg

Dummy Highly

radioactive waste

0 Pt

1,13E-6 kg

Dummy Medium and

low radioactive

wastes

0 Pt

1,13 kg

Dummy Overburden

(deposited)

0 Pt

1,89E-9 kg

Dummy Plutonium as

residual product

0 Pt

0,000558 kg

Dummy Radioactive

tailings

0 Pt

2,11E-6 kg

Dummy Slag

(Uranium conversion)

0 Pt

1,89E-6 kg

Dummy Waste

radioactive

0 Pt

2,18E-6 kg

Dummy Uranium

depleted

0 Pt


300-315 mm

19,8 Pt

0,02 tkm

Transport, freight,


EURO3 {RER}|

0,000409 Pt

280 m3

Excavation, hydraulic

digger {GLO}| marketfor | Alloc Def, S

19,8 Pt

356 tkmTransport, freight,


EURO3 {RER}|

7,28 Pt

1 kg

Digging of trench

300-315 mm

19,8 Pt

0,02 tkmTransport, freight,


EURO3 {RER}|

0,000409 Pt

280 m3


digger {GLO}| market

for | Alloc Def, S

19,8 Pt

1 kg

Maintenance

3,27 Pt



EURO3 {RER}|

3,27 Pt

1 kg

End of Life Concrete

300 mm

-88,6 Pt


300 mm

-88,6 Pt

486 tkm

Transport, freight,


EURO3 {RER}|

9,95 Pt

-0,198 kg

Concrete 300 mm

-98,6 Pt

-1,47 m3

Concrete, normal{GLO}| market for |

Alloc Def, S

-87,7 Pt

-529 tkm

Transport, freight,


EURO3 {RER}|

-10,8 Pt

-0,801 MJ

Electricity mix, AC,

consumption mix, at

consumer, 1kV -

-0,0142 Pt

-6,31E-8 kg

Dummy CaF2 (lowradioactice)

0 Pt

-1,88E-7 kg

Dummy Highlyradioactive waste

0 Pt

-2,23E-7 kg

Dummy Medium andlow radioactive

wastes

0 Pt

-0,223 kg

Dummy Overburden(deposited)

0 Pt

-3,75E-10 kg

Dummy Plutonium asresidual product

0 Pt

-0,000111 kg

Dummy Radioactivetailings

0 Pt

-4,18E-7 kg

Dummy Slag(Uranium conversion)

0 Pt

-3,75E-7 kg

Dummy Wasteradioactive

0 Pt

-4,32E-7 kg

Dummy Uraniumdepleted

0 Pt

0,99 kg

Waste concrete, not

reinforced (waste

treatment) {CH}|

0,000697 Pt

0,01 kgLandfill Concrete 300

mm

0,000746 Pt

0,0356 tkm

Transport, freight,


EURO3 {RER}|

0,000728 Pt

0,01 kg

Waste concrete

(waste treatment){GLO}| market for |

Alloc Def, S

1,84E-5 Pt

41

1 p

Life Cycle PVC 315mm

313 Pt

1 p

Assembly PVC 315

mm

332 Pt

1 kg

PVC 315 mm

311 Pt

950 kgPVC pipe E

308 Pt



EURO3 {RER}|

2,91 Pt

19 tkm

Transport, freight,

lorry >32 metric ton,EURO3 {RER}|

0,389 Pt

1 kg

Digging of trench

300-315 mm

19,8 Pt



EURO3 {RER}|

0,000409 Pt

280 m3Excavation, hydraulic

digger {GLO}| market

for | Alloc Def, S

19,8 Pt

1 kg

Digging of trench

300-315 mm

19,8 Pt

0,02 tkm

Transport, freight,

lorry >32 metric ton,EURO3 {RER}|

0,000409 Pt

280 m3


digger {GLO}| marketfor | Alloc Def, S

19,8 Pt

1 kg

Maintenance

3,27 Pt

160 tkm

Transport, freight,

lorry >32 metricton, EURO3 {RER}|

3,27 Pt

1 kg

End of Life PVC 315

mm

-41,2 Pt

0,699 kg

Recycling PVC 315

mm

-41,3 Pt


lorry >32 metric

ton, EURO3 {RER}|

0,19 Pt

-0,133 kgPVC 315 mm

-41,4 Pt

-126 kg

PVC pipe E

-41 Pt

-18,9 tkm

Transport, freight,

lorry >32 metric

ton, EURO3 {RER}|

-0,387 Pt

0,699 kgPVC (waste

treatment) {GLO}|

recycling of PVC |

-0,12 Pt

0,102 kg

Landfill of PVC 315

mm

0,0184 Pt



EURO3 {RER}|

0,00404 Pt

0,102 kgWaste

polyvinylchloride

(waste treatment)

0,0143 Pt

0,199 kg

Incineration of PVC

315 mm

0,0335 Pt



EURO3 {RER}|

0,0155 Pt

0,199 kgWaste incineration of

plastics (rigid PVC),

EU-27 S

0,018 Pt

-4,9E-8 kg

Dummy CaF2 (low

radioactice)

0 Pt

-1,53E-7 kg

Dummy Highly

radioactive waste

0 Pt

-1,81E-7 kg

Dummy Medium and

low radioactive

wastes

0 Pt

-0,0307 kg

Dummy Overburden

(deposited)

0 Pt

-2,92E-10 kg

Dummy Plutonium as

residual product

0 Pt

-8,55E-5 kg

Dummy Radioactive

tailings

0 Pt

-6E-7 kg

Dummy Slag

(Uranium

conversion)

0 Pt

-3,04E-7 kg

Dummy Waste

radioactive

0 Pt

-3,34E-7 kg

Dummy Uranium

depleted

0 Pt

42

1 pLife Cycle HDPE

315 mm

356 Pt

1 pAssembly HDPE

315 mm

336 Pt

1 kgHDPE 315 mm

316 Pt

947 kgHDPE pipes E

313 Pt


ton, EURO3 {RER}|

2,91 Pt


300-315 mm

19,8 Pt



0,000409 Pt

280 m3Excavation,


19,8 Pt



0,389 Pt


300-315 mm

19,8 Pt



0,000409 Pt

280 m3Excavation,


19,8 Pt

1 kgMaintenance

3,27 Pt



3,27 Pt

1 kgEnd of Life HDPE

315 mm

-2,52 Pt

0,1 kgLandfill of HDPE

315 mm

0,0269 Pt



0,00389 Pt

0,1 kgWaste

polyethylene(waste treatment)

0,023 Pt

0,05 kgRecycling of HDPE

315 mm

-3,17 Pt



0,000971 Pt

-0,01 kgHDPE 315 mm

-3,16 Pt

-9,47 kgHDPE pipes E

-3,13 Pt

-1,43 tkmTransport, freight,


-0,0291 Pt

0,05 kgPE (waste

treatment) {GLO}|recycling of PE |

-0,00998 Pt

0,85 kgIncinertation ofHDPE 315 mm

0,623 Pt

13,7 tkmTransport, freight,lorry >32 metric

ton, EURO3 {RER}|

0,28 Pt

0,85 kgWaste

polyethylene(waste treatment)

0,343 Pt

43

Appendix 4: Absolute environmental impacts of single pipes

Impact category Unit PVC110

mm

HDPE11

0m

m

HDPE110

mm

(Rec)

PVC250

mm

HDPE25

0m

m

HDPE25

0m

m(R

ec)

PVC315

mm

HDPE31

5m

m

HDPE31

5m

m(R

ec)

Concret

e300

mm

PVC400

mm

Concret

e400

mm

Total Pt 155,3 176,4 157,7 282,5 324,0 287,2 313,4 356,4 317,7 459,4 463,2 621,0

Climate change Human Health Pt 43,3 40,0 34,5 79,5 72,7 62,0 88,3 79,9 68,7 110,6 131,0 149,6

Ozone depletion Pt <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1

Human toxicity Pt 6,6 5,2 4,7 9,4 6,5 5,7 10,1 6,9 6,1 95,4 13,1 129,9

Photochemical oxidant formation Pt <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1

Particulate matter formation Pt 6,8 5,8 5,1 11,7 9,6 8,2 12,9 10,5 9,0 15,2 18,5 20,1

Ionising radiation Pt <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1

Climate change Ecosystems Pt 34,6 31,9 27,6 63,4 58,0 49,5 70,4 63,8 54,8 88,3 104,5 119,4

Terrestrial acidification Pt 0,2 0,1 0,1 0,3 0,2 0,2 0,3 0,2 0,2 0,3 0,4 0,5

Freshwater eutrophication Pt <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1

Terrestrial ecotoxicity Pt 0,1 0,0 0,0 0,1 0,0 0,0 0,1 0,0 0,0 0,3 0,2 0,4

Freshwater ecotoxicity Pt <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1

Marine ecotoxicity Pt 0,2 0,2 0,2 0,3 0,2 0,2 0,3 0,3 0,2 2,9 0,3 4,0

Agricultural land occupation Pt <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 <0,1 0,6 <0,1 0,7

Urban land occupation Pt 0,1 0,1 0,1 0,1 0,1 0,1 0,1 0,1 0,1 2,0 0,1 2,6

Natural land transformation Pt 1,2 1,3 1,2 1,6 1,6 1,6 1,6 1,7 1,6 72,3 2,0 99,4

Metal depletion Pt 0,9 0,8 0,8 1,2 1,1 1,0 1,3 1,1 1,1 5,2 1,5 6,8

Fossil depletion Pt 61,4 91,0 83,3 114,9 173,8 158,6 127,9 191,8 175,7 66,3 191,5 87,5

Appendix 5: HDPE pipe with PVC disposal scenario

Impact category Unit Life

Cycle

HDPE 315m

m

Life

Cycle

HDPE 315m

m(R

ec)

Total Pt 356,394 317,677

Climate change Human Health Pt 79,935 68,670

Ozone depletion Pt 0,001 0,001

Human toxicity Pt 6,890 6,070

Photochemical oxidant formation Pt 0,004 0,003

Particulate matter formation Pt 10,459 9,042

Ionising radiation Pt 0,004 0,004

Climate change Ecosystems Pt 63,785 54,797

Terrestrial acidification Pt 0,246 0,211

Freshwater eutrophication Pt 0,001 0,001

Terrestrial ecotoxicity Pt 0,032 0,014

Freshwater ecotoxicity Pt 0,001 0,001

Marine ecotoxicity Pt 0,260 0,235

Agricultural land occupation Pt 0,026 0,025

Urban land occupation Pt 0,120 0,114

Natural land transformation Pt 1,698 1,647

Metal depletion Pt 1,135 1,095

Fossil depletion Pt 191,797 175,748

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