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Assessing the sustainability of small wastewater systems A context-oriented planning approach
Elsevier — EIR — p977775175 — 05-03-:0 12:40:55
Environmental Impact Assessment Review 20 (2000) 347–357 www.elsevier.com/locate/eiar
Assessing the sustainability of small wastewater systems A context-oriented planning approach Birgitte Hoffmanna,*, Susanne Balslev Nielsena, Morten Ellea, Søren Gabrielb, Anne Marie Eilersenb, Mogens Henzeb, Peter Steen Mikkelsenb a
Department of Planning, Technical University of Denmark, Building 115, DK-2800 Lyngby, Denmark b Department of Environmental Science and Engineering, Technical University of Denmark, Building 115, DK-2800 Lyngby, Denmark
Abstract The authors present a planning tool for comparing and assessing the sustainability of different wastewater systems. The core of the planning tool is an assessment method based on both technical and social elements. The point of departure is that no technique is inherently sustainable or ecological in itself, but that the sustainability of the total system of technologies for a particular settlement in a given location must be assessed in a holistic and transparent manner. A pilot case is used to demonstrate the structure and the results of the assessment method. The assessment method is still under development, and this paper discusses crucial points in the development of the method. 2000 Elsevier Science Inc. All rights reserved. Keywords: Small wastewater systems; Context-oriented planning approach
1. Introduction The lack of sewage treatment in nonsewered areas (approximately 350,000 houses) has become an environmental problem in Denmark. To fulfill the national “Aquatic Environment Plan” (Vandmiljøplan II), the municipalities have to make master plans for handling wastewater in areas currently without sewers. The planning of infrastructural solutions is often * Corresponding author. Tel.: 0045 45 93 64 11; fax: 0045 45 93 64 12. E-mail address: [email protected] (B. Hoffmann) 0195-9255/00/$ – see front matter 2000 Elsevier Science Inc. All rights reserved. PII: S0195-9255(00)00046-9
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carried out without prior dialog with the relevant stakeholders and without discussing alternatives to conventional solutions, in this case centralized sewage treatment. In principle, there are a number of different technical solutions to choose from. Only a few, however, are taken into consideration in practice, mainly because centralized treatment has been “the way” to handle sewage for many years. Large technological systems have an increasing momentum over time, and as a consequence of the large momentum of the centralized sewage treatment system there is a lack of general knowledge about alternative systems [6]. Nevertheless, the planning conditions in rural areas and in areas with summer cottages or allotments are obviously different to that in urban areas, and this is an opening for rethinking the concept of wastewater handling. Another problem is related to the assessment of sustainability. There are many different perceptions of this concept, but they are seldom formulated or assessed very explicitly [7]. This is certainly the case when it comes to assessing sustainable wastewater handling where there is no generally accepted concept of sustainability. There seems to be a general understanding that some techniques are sustainable while others are not, and that the task of researchers and technicians is to evaluate and compare different techniques. This approach overlooks the importance of the local context, which has to be taken into account in assessing the sustainability of a specific wastewater solution. It is the authors’ perception that the decision process within sewage planning has been rather unclear up until now in terms of the alternatives considered and the reasons for the choice of a given solution. The development project “Assessing the Sustainability of Wastewater Handling in Nonsewered Settlements” aims to produce a generally accessible and practicable planning tool for decision support that is context oriented, and that increases the number of types of solutions to be taken into consideration. The project is a crossdisciplinary collaboration between the Department of Environmental Science and Engineering and the Department of Planning, both at the Technical University of Denmark. This paper is based on the results from the first phase of the project where the method has been developed sufficiently for three pilot cases to be tested [3,4]. This paper is divided into five sections. The first section outlines the fundamental problems in the current planning of wastewater handling dealt with by the project. The second section gives an overview of the assessment method and the different tools involved. Section 3 illustrates the use of the assessment method in the planning of an eco-village. The fourth section discusses some of the difficulties and the challenges involved in the development of the assessment methodology used in the project, while the fifth section is a short conclusion. 2. The challenges of a context-oriented planning approach This section makes the case for some very important features of the project:
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No techniques or solutions are ecological or sustainable in themselves; the “best solution” is dependent on the local context; A sustainable solution demands a transparent decision process with a wide range of criteria, for example, environmental, technical, economic, hygienic, and socio-cultural criteria; The involvement of all the relevant stakeholders in the decision process will secure the viability of the handling system.
The aim of the project is to develop a methodology for using the local conditions, technical as well as social and environmental, in the evaluation of different wastewater systems. The context is crucial, as the need for sewage treatment and the potential of different technical solutions vary according to the local conditions. The performance of a specific system depends on its construction, use, and maintenance. Whether or not this performance is sustainable from an environmental perspective depends on the sensitivity of the natural environment. Thus, it is important to realize that the outcome of an assessment of the same system for wastewater treatment might be different under different conditions, i.e., a solution leading to environmental improvements in one project may be a bad solution in another context. Unfortunately, there are many examples of wastewater systems that do not relate to the local conditions; some of them are working despite their lack of suitability to the local environment, while other such systems fail. An example of the first can be the extension of central sewage systems into sparsely populated areas, using a lot of resources both for building and for running them, but nevertheless performing well with respect to treatment, hygienic conditions, etc. Examples of the latter are some of the so-called ecological plants that work well in a warmer climate, but without sufficient heat and sunlight they have no or very little effect, or they demand a lot of energy to work [2]. Other examples of the latter are the projects where the users are not properly informed about the vulnerability of a plant to the contents of the wastewater. If the users flush out some chemicals they may disrupt processes within the system. In conclusion, sustainability must be assessed in a local context. The choice of “the best solution” will have to be based on an integrated assessment of the local technical, environmental, as well as social aspects. Most projects today, of course, relate more or less to local conditions— for projects in the open countryside in Denmark, the condition of the water receiving the waste and the possibility of infiltration will be analyzed, parallel with an economic analysis of the project. Economy is traditionally the most important criterion for the decision, and only technical experts and politicians are involved in the decision process. Thus, the current practice does not, to a sufficient degree, include nontechnical aspects such as environment and local culture and politics. The large momentum of the traditional system also causes a general lack of knowledge concerning alternative systems and, as a consequence; the decision makers “play it safe” and choose the usual system with which they are familiar. To secure
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the sustainability of the solution it is necessary to include a wide range of criteria in the assessment, for example, environmental, technical, economic, hygienic, and socio-cultural criteria. People with highly differing preferences commonly occupy local settlements. A central aim for the development of wastewater handling in Denmark so far has been to develop robust systems, so that these would not be disrupted by any misuse. In this way a clear distinction between the experts and the users has been built up, leading to almost no interaction between them. Thus, the system is almost invisible to the users, and as an adverse effect it is very difficult to raise user awareness. Alternative smallscale wastewater handling systems are more sensitive to the amount and content of wastewater than large plants. Therefore, there is a need to make the users more responsible for their production of wastewater so as not to disrupt the function of the system, and to inform the municipalities about the users’ wishes so as to optimize their satisfaction with the wastewater handling system. Exchange of information is an important aspect in the process of decision making—especially between the experts and the users. The users must be involved in an appropriate way, and, consequently, new roles and relations between stakeholders need to be developed [7]. The involvement of all relevant stakeholders in the decision process is necessary to secure the viability of the handling system; thus, dialogue between stakeholders and information about user preferences are necessary features of the planning process. A participatory decision process will thereby increase the potential sustainability of the final system. Thus, there is a need for a clear method for drawing up relevant solutions to wastewater handling, and evaluating and choosing local systems. Such a method should be an operational tool, adapted to the general planning processes in the municipality. The planning tool should support decisions of sustainable sewage management. This does not mean that the method has to identify one best solution. By assessing a number of solutions relatively and in a transparent manner, the method makes it clear that the final choice of local infrastructural investments is always political.
3. Status of the planning method This section presents the principles of the method and the different tools within. Figure 1 shows the planning process. The first stage is an initial onsite analysis and a draft of possible alternative solutions, followed by a rough initial assessment and prescreening, where the most unsuitable solutions are rejected. The second round of on-site analysis, which forms the basis for a more detailed assessment based on local criteria and local preferences, follows this. If more detailed analyses and assessments are desired, the second stage can be repeated.
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Fig. 1. Process of the assessment method.
The method consists of a number of different elements relating to a planning process: •
•
•
An on-site-analysis. An analytic frame to uncover the local conditions at the site influencing the sustainability of different alternatives. The project seeks to develop an on-site analysis that is holistic and at the same time operational. The first on-site analysis is a structured checklist guided by opening questions. The second analysis will be closely connected to the technology information tool (see below). Dialogue-tools. This project aims to develop different tools for creating dialogue between the different actors in the planning process, and to draw up different sets of preferences. Two different dialogue tools, a dialogue workshop and a tool to define different profiles of preference, are under development. The dialogue tools establish a frame for the dialogue—both to ensure that the knowledge and perceptions of the different actors will be drawn into the process, and that the actors will be qualified to join the decision process. The dialogue workshop brings different stakeholders together and must be planned according to the local context [5,7]. The other dialogue tool aims to collate the different preferences of the local stakeholders and to structure them into profiles of preferences that will be part of the assessment. A technology information tool. A technology information tool will be prepared as a catalogue of ideas and a tool for decision makers. The tool will provide a general guide to the outcomes from different possible solutions. It will be structured on the principles of the relevant functions (production, transport/storage, treatment, and disposal) and not on systems. It should be used as a basis for drawing up different alternatives, and for comparing and evaluating the alternatives.
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A multicriteria evaluation. Prioritization of the alternatives leads to the final (political) decision. The result of the evaluation is an overview of the possible systems that fulfill both regulation and additional local demands, together with an indication of which solutions are the best in terms of the local preferences for economy, environment, operation, etc. This part of the method is inspired from work with traffic decision support systems [9].
An essential point of the method is that the users, whether they are the municipal or the future inhabitants of an eco-village, will not be left alone to make a choice from different technical solutions. Instead, the method will uncover the values that underlie their choice. These values will be used as input for the professional experts when they consider alternative solutions. On the other hand, it will be clear that the final choice of system is not only a given (technical or economic) choice, but based on a political priority.
4. A Pilot case: The eco-village Munkesøgaard A preliminary case study is presented in this section to illustrate the concepts of the assessment framework. Munkesøga˚rd is an ecological village, being built in 1999–2000. The village consists of five apartment complexes, housing 250 inhabitants in total. The ecological aspect of the village has been a driving force for the future inhabitants of Munkesøga˚rd. The houses will, therefore, be constructed so that a minimum of energy and water is required for daily use, and so that some of the waste products can be recirculated. There is no existing sewer system in the area. The on-site analysis showed that infiltration of wastewater was not acceptable due to the risk of ground water pollution. Therefore, the alternatives were to establish a sewer system leading to a centralized wastewater treatment plant, or to discharge the wastewater into a local stream after local treatment. Several different wastewater systems matching the local requirements could have been suggested, but at the stage DTU was introduced to the project, the discussion of the wastewater system was reduced to two handling systems for household wastewater and related streams of organic waste: (1) compost toilets involving urine collection, cocomposting of fecal and organic kitchen waste and treatment of gray wastewater in a biological sand filter; and (2) low-flush toilets involving urine collection and treatment of the solids in the black and gray wastewater at a centralized wastewater treatment plant, and treatment of the mainly soluble fraction in a biological sand filter. The urine is, together with composted organic kitchen waste, to be used as fertilizer on a farm close to the village. In the environmental assessment of the alternative systems a reference system was introduced, consisting of
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Table 1 Normalized scores Criteria
Compost
Low-flush
Conventional
Environment Operation Daily use Economy Flexibility Local development Health and security
2 ⫺4 ⫺4 ⫺4 2 4 ⫺3
4 ⫺3 ⫺2 ⫺2 3 4 2
0 0 0 0 0 0 0
a conventional system involving treatment of all wastewater at a centralized treatment plant [8]. The following stakeholders were identified as the most important: future inhabitants of Munkesøga˚rd, the cooperative housing society, the county, the municipality, the public health officer, and the authorities responsible for occupational health and safety. At a dialogue workshop the future inhabitants defined and prioritized about 50 criteria for assessing the different wastewater systems. The workshop created a dialogue within the group of future inhabitants, who had different views on the wastewater solution. A group of the future inhabitants saw the compost toilets as the only (ecological) solution, while others were sceptical of this solution and whether they were capable of carrying out the work connected with the operation and the daily use of this solution, i.e., handling the compost. A third group of future inhabitants did not feel they were competent to join in the discussion on this matter, which they felt concerned technicalities and economics. The workshop changed the discussion about wastewater treatment from a discussion about three concrete technical solutions to a discussion about demands on the future wastewater system. At this level there turned out to be a large degree of common agreement. The large number of criteria put forward at the workshop formed important input to the project for formulating assessment criteria for sustainable wastewater handling. The project operates with seven main categories of criteria that form a broad basis for the assessment: environment, operation, daily use, economy, flexibility, local development, and health and security. In the following assessment of the alternative solutions in the Munkesøga˚rd case the conventional solution is chosen as a benchmark. The assessment of the environmental parameters of the three alternative systems was made as a life-cycle assessment, whereas the other criteria were evaluated judgementally. To illustrate the principle of the assessment of wastewater systems, the evaluation of the three systems was tentatively transformed into a normalized score between ⫺5 and ⫹5 for the seven criteria (Table 1). Four different profiles of preferences were drawn up to exemplify four different priorities of the evaluation criteria (see Table 2).
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Table 2 Profiles of preference Criteria
Profile 1
Profile 2
Profile 3
Profile 4
Environment Operation Daily use Economy Flexibility Local development Health and security
0.1 0.2 0.2 0.3 0.0 0.0 0.2
0.4 0.1 0.1 0.0 0.1 0.1 0.2
0.1 0.3 0.2 0.1 0.1 0.0 0.2
0.3 0.0 0.1 0.0 0.2 0.3 0.1
By weighing the normalized parameters with the different priority of the evaluation parameters, a weighted, normalized score is generated (Fig. 2). This score illustrates to which degree the three different wastewater systems will satisfy the four different profiles of preferences. Much to the surprise of many of the future inhabitants of Munkesøga˚rd, the solution with compost toilets generally scored the lowest. This was primarily due to the proposed construction of concrete cellars under the compost toilets, a solution that is very expensive in money and energy. The low-flush solution generally scored the highest, and was more robust with regard to different stakeholders’ priorities among the evaluation parameters. At Munkesøga˚rd, the low-flush solution has been chosen. This is partly due to an assessment as the one illustrated above, and partly to very strict hygienic restrictions formulated by the authorities of occupational health and safety, which meant it was unacceptable for compost toilets to be placed in the cellars.
5. Crucial points in developing the assessment method The first edition of the method is being developed through the work with very different cases. Case studies are an important key to knowledge, and one project will be to collect and systematize the knowledge of existing practices. The second project is testing the pilot model for assessment, and to develop the different tools within the model. Some crucial points will be discussed, and choices will have to be made. Some of these are crucial
Fig. 2. Weighted and normalized scores.
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points not only in this specific method, but are relevant to most decision support systems for sustainable development. The choice of criteria is crucial. The criteria form the basis of the whole method of decision support and the internal connection between the onsite-analysis, the technology information tool, and the evaluation tool. The choice of criteria is, furthermore, subject to a number of different demands, not the least being the formulation of the criteria so as to be used by the different actors. The project works, as mentioned above, with seven criteria that together form the framework for assessing “sustainability.” To the more traditional criteria, such as economy and technical competence, are added a wide range of different criteria under the headings of environmental aspects, health and security, operation and, use, local development, and adaptability to future demands. This basic set of criteria will constitute an explicit core of criteria around which a locally dependent assessment can be made. It is, however, noted that criteria can be grouped in many other meaningful ways, depending on the local context. The relevant stakeholders can weight the locally dependent assessment criteria, and they may find it necessary to add extra criteria to ensure that all the significant issues are covered. The assignment of scores for each criterion is critical, as is the selection of an appropriate weight for it, relative to the weighting of the other criteria. Thus, there are problems with normalization of the different criteria, as this implies weighting. Because the criteria covers a wide range of impacts of concern, this will result in comparisons of dissimilar elements, and weighting of the more qualitatively criteria will be subjective. The scoring system must accept both hard and soft data in a similar format, and the weighting system will be constructed partly by default values, partly by user modifiable values. The performance of the different alternatives for wastewater handling will be compared to that of a reference condition, a benchmark performance. To assess the environmental impact, the method will be based on “life-cycle considerations,” a practical assessment approach derived from the concept of life-cycle assessment which, as such, it is not possible to carry out in practice. Creating dialogue is necessary but difficult. Two different dialogue tools are being developed to establish a frame for the dialogue between very different stakeholders—in particular, the users, the politicians, and the technical experts. The development of the dialogue workshops is based on previous experience of establishing dialogue and building up the participant’s competence using different technical problems as a basis [5]. Experience shows that the workshops bring together different actors by creating insight into, and understanding of, their different perceptions and roles. The challenge will be to develop “standard workshops” to be used in different local processes. The other dialogue tool aims at drawing up the different preference profiles to be part of the evaluation model. Here, the greatest challenge is the need to train the participants both to develop insight into wastewater treatment and to give different priorities to different
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criteria. The tool operates with different statements concerning different criteria formulated in everyday language. The participants will evaluate the different criteria by giving priority to questions presented in pairs. The tool will create a profile, which the participants can discuss. Used on a representative sample of the stakeholders, the methods will be able to produce different profiles of perceptions. Theoretical work is being carried out to formulate a framework for using the dialogue tools and some principles for “the quality of dialogue,” as both tools could be misused to legitimize a decision process as being democratic without it being so.
6. Conclusions This paper describes an assessment method for supporting the decisionmaking process when planning wastewater-handling systems in nonsewered settlements. The assessment method is developed to ensure “a good environmental solution,” and has reached the stage where four pilot cases have been tested. The method seeks, on the one hand, to increase the number of solutions taken into consideration, and, on the other hand, to avoid dogmatic and undocumented decisions. One major point is that technology is not inherently sustainable. The sustainability of the total system of technologies at an actual site must be evaluated in an transparent and holistic assessment including a wide range of criteria. The second major point at which this assessment method differs from other assessment methods is the participative approach, supporting dialogue between different stakeholders. Different dialogue tools will be developed to fulfill this approach. The case study demonstrates—together with the other cases—that the principles of the assessment method are practicable. It widens the spectrum of criteria included in the assessment: environmental, technical, and economic criteria, as well as criteria concerning everyday use and operation, health and security, local development, and adaptability to future changes. The case illustrates the use of the dialogue workshop, but also underlines the need to include all the relevant actors at an early stage. As the method offers a practical approach to the assessment of the sustainability of concrete solutions, the development of the method has to exceed some bounds of principles. In particular, concerning a workable definition of sustainability, the method includes weighting the very different criteria, and the use of dialogue tools. It has to be stated that even though the method does provide a better basis for the final decision—the final choice is a political decision.
Acknowledgment The project is being developed by a team of researchers in the Department of Planning and the Department of Environmental Science and Engi-
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neering. The Danish EPA finances the project through the “Action plan for ecological urban renewal and wastewater treatment.”
References [1] Colby ME. Environmental management in development: the evolution of paradigms. Ecol Econom 1991;2. [2] Dyck-Madsen S, Gabriel S, Hoffmann B. Alternative Wastewater Treatment—10 Illustrated Examples from Sweden (in Danish, Alternative Spildevandssystemer—10 Illustrerede Eksempler fra Sverige). Copenhagen: the Danish Ecocouncil, 1999. [3] Eilersen AM, Gabriel S, Hoffmann B, Nielsen SB, Elle E, Henze M, Mikkelsen PS. Assessing the Sustainability of Wastewater Handling in Non-Sewer Settlements. Report of Phase 1. (in Danish, Vurdering af Bæredygtig Spildevandsha˚ndtering i Kloak-løse Bebyggelser. Afrapportering af Fase 1). Lyngby: The Technical University of Denmark, Dept of Environmental Science and Engineering and Dept of Planning, 1999. [4] Eilersen AM, Nielsen SB, Gabriel S, Hoffmann B, Moshøj CR, Henze M, Elle M, Mikkelsen PS. Assessing the sustainability of wastewater handling in non-sewered settlements. Proc. Managing the Wastewater Resource—Ecological Engineering for Wastewater Treatment, June 7–11, Asa, Norway, 1999. [5] Hoffmann B, Kofoed J. From Spectator to Participant—Methods for Citizen’s Participation in Urban Ecology and Local Agenda 21 (in Danish Fra Tilskuer til Deltager, Metoder til Borgerdeltagelse i Byøkologi og Agenda 21). Copenhagen: The Danish Society for Conservation of Nature and The Danish Outdoor Council, 1999. [6] Hughes TP. The evolution of large technological systems. In: Bijker WE, Hughes TP, Pinch TJ, editors. The Social Construction of Technological Systems. Cambridge, MA: IMT Press, 1997. [7] Jensen JO, Nielsen SB. Wastewater Treatment of the Future, Report From a Workshop (in Danish Fremtidens spildevandsha˚ndtering, Report From a Workshop 14 May). Lyngby, Denmark: Technical University of Denmark, Dept of Planning, 1997. [8] Properzi S. An Evaluation and Comparison of Three Methods of Treatment for Organic Household Waste at the Eco-Village—Munkesøga˚rd. Lyngby, Denmark: Technical University of Denmark, Dept of Environmental Science and Engineering, 1998. [9] Rehfeld C, Leleur S. Modelling project feasibility robustness by use of scenarios. Proc. 38th Congress of the European Science Association, 28 Aug–1 Sept, Vienne, Austria, 1998.
Environmental Impact Assessment Review 20 (2000) 347–357 www.elsevier.com/locate/eiar
Assessing the sustainability of small wastewater systems A context-oriented planning approach Birgitte Hoffmanna,*, Susanne Balslev Nielsena, Morten Ellea, Søren Gabrielb, Anne Marie Eilersenb, Mogens Henzeb, Peter Steen Mikkelsenb a
Department of Planning, Technical University of Denmark, Building 115, DK-2800 Lyngby, Denmark b Department of Environmental Science and Engineering, Technical University of Denmark, Building 115, DK-2800 Lyngby, Denmark
Abstract The authors present a planning tool for comparing and assessing the sustainability of different wastewater systems. The core of the planning tool is an assessment method based on both technical and social elements. The point of departure is that no technique is inherently sustainable or ecological in itself, but that the sustainability of the total system of technologies for a particular settlement in a given location must be assessed in a holistic and transparent manner. A pilot case is used to demonstrate the structure and the results of the assessment method. The assessment method is still under development, and this paper discusses crucial points in the development of the method. 2000 Elsevier Science Inc. All rights reserved. Keywords: Small wastewater systems; Context-oriented planning approach
1. Introduction The lack of sewage treatment in nonsewered areas (approximately 350,000 houses) has become an environmental problem in Denmark. To fulfill the national “Aquatic Environment Plan” (Vandmiljøplan II), the municipalities have to make master plans for handling wastewater in areas currently without sewers. The planning of infrastructural solutions is often * Corresponding author. Tel.: 0045 45 93 64 11; fax: 0045 45 93 64 12. E-mail address: [email protected] (B. Hoffmann) 0195-9255/00/$ – see front matter 2000 Elsevier Science Inc. All rights reserved. PII: S0195-9255(00)00046-9
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carried out without prior dialog with the relevant stakeholders and without discussing alternatives to conventional solutions, in this case centralized sewage treatment. In principle, there are a number of different technical solutions to choose from. Only a few, however, are taken into consideration in practice, mainly because centralized treatment has been “the way” to handle sewage for many years. Large technological systems have an increasing momentum over time, and as a consequence of the large momentum of the centralized sewage treatment system there is a lack of general knowledge about alternative systems [6]. Nevertheless, the planning conditions in rural areas and in areas with summer cottages or allotments are obviously different to that in urban areas, and this is an opening for rethinking the concept of wastewater handling. Another problem is related to the assessment of sustainability. There are many different perceptions of this concept, but they are seldom formulated or assessed very explicitly [7]. This is certainly the case when it comes to assessing sustainable wastewater handling where there is no generally accepted concept of sustainability. There seems to be a general understanding that some techniques are sustainable while others are not, and that the task of researchers and technicians is to evaluate and compare different techniques. This approach overlooks the importance of the local context, which has to be taken into account in assessing the sustainability of a specific wastewater solution. It is the authors’ perception that the decision process within sewage planning has been rather unclear up until now in terms of the alternatives considered and the reasons for the choice of a given solution. The development project “Assessing the Sustainability of Wastewater Handling in Nonsewered Settlements” aims to produce a generally accessible and practicable planning tool for decision support that is context oriented, and that increases the number of types of solutions to be taken into consideration. The project is a crossdisciplinary collaboration between the Department of Environmental Science and Engineering and the Department of Planning, both at the Technical University of Denmark. This paper is based on the results from the first phase of the project where the method has been developed sufficiently for three pilot cases to be tested [3,4]. This paper is divided into five sections. The first section outlines the fundamental problems in the current planning of wastewater handling dealt with by the project. The second section gives an overview of the assessment method and the different tools involved. Section 3 illustrates the use of the assessment method in the planning of an eco-village. The fourth section discusses some of the difficulties and the challenges involved in the development of the assessment methodology used in the project, while the fifth section is a short conclusion. 2. The challenges of a context-oriented planning approach This section makes the case for some very important features of the project:
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•
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No techniques or solutions are ecological or sustainable in themselves; the “best solution” is dependent on the local context; A sustainable solution demands a transparent decision process with a wide range of criteria, for example, environmental, technical, economic, hygienic, and socio-cultural criteria; The involvement of all the relevant stakeholders in the decision process will secure the viability of the handling system.
The aim of the project is to develop a methodology for using the local conditions, technical as well as social and environmental, in the evaluation of different wastewater systems. The context is crucial, as the need for sewage treatment and the potential of different technical solutions vary according to the local conditions. The performance of a specific system depends on its construction, use, and maintenance. Whether or not this performance is sustainable from an environmental perspective depends on the sensitivity of the natural environment. Thus, it is important to realize that the outcome of an assessment of the same system for wastewater treatment might be different under different conditions, i.e., a solution leading to environmental improvements in one project may be a bad solution in another context. Unfortunately, there are many examples of wastewater systems that do not relate to the local conditions; some of them are working despite their lack of suitability to the local environment, while other such systems fail. An example of the first can be the extension of central sewage systems into sparsely populated areas, using a lot of resources both for building and for running them, but nevertheless performing well with respect to treatment, hygienic conditions, etc. Examples of the latter are some of the so-called ecological plants that work well in a warmer climate, but without sufficient heat and sunlight they have no or very little effect, or they demand a lot of energy to work [2]. Other examples of the latter are the projects where the users are not properly informed about the vulnerability of a plant to the contents of the wastewater. If the users flush out some chemicals they may disrupt processes within the system. In conclusion, sustainability must be assessed in a local context. The choice of “the best solution” will have to be based on an integrated assessment of the local technical, environmental, as well as social aspects. Most projects today, of course, relate more or less to local conditions— for projects in the open countryside in Denmark, the condition of the water receiving the waste and the possibility of infiltration will be analyzed, parallel with an economic analysis of the project. Economy is traditionally the most important criterion for the decision, and only technical experts and politicians are involved in the decision process. Thus, the current practice does not, to a sufficient degree, include nontechnical aspects such as environment and local culture and politics. The large momentum of the traditional system also causes a general lack of knowledge concerning alternative systems and, as a consequence; the decision makers “play it safe” and choose the usual system with which they are familiar. To secure
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the sustainability of the solution it is necessary to include a wide range of criteria in the assessment, for example, environmental, technical, economic, hygienic, and socio-cultural criteria. People with highly differing preferences commonly occupy local settlements. A central aim for the development of wastewater handling in Denmark so far has been to develop robust systems, so that these would not be disrupted by any misuse. In this way a clear distinction between the experts and the users has been built up, leading to almost no interaction between them. Thus, the system is almost invisible to the users, and as an adverse effect it is very difficult to raise user awareness. Alternative smallscale wastewater handling systems are more sensitive to the amount and content of wastewater than large plants. Therefore, there is a need to make the users more responsible for their production of wastewater so as not to disrupt the function of the system, and to inform the municipalities about the users’ wishes so as to optimize their satisfaction with the wastewater handling system. Exchange of information is an important aspect in the process of decision making—especially between the experts and the users. The users must be involved in an appropriate way, and, consequently, new roles and relations between stakeholders need to be developed [7]. The involvement of all relevant stakeholders in the decision process is necessary to secure the viability of the handling system; thus, dialogue between stakeholders and information about user preferences are necessary features of the planning process. A participatory decision process will thereby increase the potential sustainability of the final system. Thus, there is a need for a clear method for drawing up relevant solutions to wastewater handling, and evaluating and choosing local systems. Such a method should be an operational tool, adapted to the general planning processes in the municipality. The planning tool should support decisions of sustainable sewage management. This does not mean that the method has to identify one best solution. By assessing a number of solutions relatively and in a transparent manner, the method makes it clear that the final choice of local infrastructural investments is always political.
3. Status of the planning method This section presents the principles of the method and the different tools within. Figure 1 shows the planning process. The first stage is an initial onsite analysis and a draft of possible alternative solutions, followed by a rough initial assessment and prescreening, where the most unsuitable solutions are rejected. The second round of on-site analysis, which forms the basis for a more detailed assessment based on local criteria and local preferences, follows this. If more detailed analyses and assessments are desired, the second stage can be repeated.
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Fig. 1. Process of the assessment method.
The method consists of a number of different elements relating to a planning process: •
•
•
An on-site-analysis. An analytic frame to uncover the local conditions at the site influencing the sustainability of different alternatives. The project seeks to develop an on-site analysis that is holistic and at the same time operational. The first on-site analysis is a structured checklist guided by opening questions. The second analysis will be closely connected to the technology information tool (see below). Dialogue-tools. This project aims to develop different tools for creating dialogue between the different actors in the planning process, and to draw up different sets of preferences. Two different dialogue tools, a dialogue workshop and a tool to define different profiles of preference, are under development. The dialogue tools establish a frame for the dialogue—both to ensure that the knowledge and perceptions of the different actors will be drawn into the process, and that the actors will be qualified to join the decision process. The dialogue workshop brings different stakeholders together and must be planned according to the local context [5,7]. The other dialogue tool aims to collate the different preferences of the local stakeholders and to structure them into profiles of preferences that will be part of the assessment. A technology information tool. A technology information tool will be prepared as a catalogue of ideas and a tool for decision makers. The tool will provide a general guide to the outcomes from different possible solutions. It will be structured on the principles of the relevant functions (production, transport/storage, treatment, and disposal) and not on systems. It should be used as a basis for drawing up different alternatives, and for comparing and evaluating the alternatives.
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A multicriteria evaluation. Prioritization of the alternatives leads to the final (political) decision. The result of the evaluation is an overview of the possible systems that fulfill both regulation and additional local demands, together with an indication of which solutions are the best in terms of the local preferences for economy, environment, operation, etc. This part of the method is inspired from work with traffic decision support systems [9].
An essential point of the method is that the users, whether they are the municipal or the future inhabitants of an eco-village, will not be left alone to make a choice from different technical solutions. Instead, the method will uncover the values that underlie their choice. These values will be used as input for the professional experts when they consider alternative solutions. On the other hand, it will be clear that the final choice of system is not only a given (technical or economic) choice, but based on a political priority.
4. A Pilot case: The eco-village Munkesøgaard A preliminary case study is presented in this section to illustrate the concepts of the assessment framework. Munkesøga˚rd is an ecological village, being built in 1999–2000. The village consists of five apartment complexes, housing 250 inhabitants in total. The ecological aspect of the village has been a driving force for the future inhabitants of Munkesøga˚rd. The houses will, therefore, be constructed so that a minimum of energy and water is required for daily use, and so that some of the waste products can be recirculated. There is no existing sewer system in the area. The on-site analysis showed that infiltration of wastewater was not acceptable due to the risk of ground water pollution. Therefore, the alternatives were to establish a sewer system leading to a centralized wastewater treatment plant, or to discharge the wastewater into a local stream after local treatment. Several different wastewater systems matching the local requirements could have been suggested, but at the stage DTU was introduced to the project, the discussion of the wastewater system was reduced to two handling systems for household wastewater and related streams of organic waste: (1) compost toilets involving urine collection, cocomposting of fecal and organic kitchen waste and treatment of gray wastewater in a biological sand filter; and (2) low-flush toilets involving urine collection and treatment of the solids in the black and gray wastewater at a centralized wastewater treatment plant, and treatment of the mainly soluble fraction in a biological sand filter. The urine is, together with composted organic kitchen waste, to be used as fertilizer on a farm close to the village. In the environmental assessment of the alternative systems a reference system was introduced, consisting of
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Table 1 Normalized scores Criteria
Compost
Low-flush
Conventional
Environment Operation Daily use Economy Flexibility Local development Health and security
2 ⫺4 ⫺4 ⫺4 2 4 ⫺3
4 ⫺3 ⫺2 ⫺2 3 4 2
0 0 0 0 0 0 0
a conventional system involving treatment of all wastewater at a centralized treatment plant [8]. The following stakeholders were identified as the most important: future inhabitants of Munkesøga˚rd, the cooperative housing society, the county, the municipality, the public health officer, and the authorities responsible for occupational health and safety. At a dialogue workshop the future inhabitants defined and prioritized about 50 criteria for assessing the different wastewater systems. The workshop created a dialogue within the group of future inhabitants, who had different views on the wastewater solution. A group of the future inhabitants saw the compost toilets as the only (ecological) solution, while others were sceptical of this solution and whether they were capable of carrying out the work connected with the operation and the daily use of this solution, i.e., handling the compost. A third group of future inhabitants did not feel they were competent to join in the discussion on this matter, which they felt concerned technicalities and economics. The workshop changed the discussion about wastewater treatment from a discussion about three concrete technical solutions to a discussion about demands on the future wastewater system. At this level there turned out to be a large degree of common agreement. The large number of criteria put forward at the workshop formed important input to the project for formulating assessment criteria for sustainable wastewater handling. The project operates with seven main categories of criteria that form a broad basis for the assessment: environment, operation, daily use, economy, flexibility, local development, and health and security. In the following assessment of the alternative solutions in the Munkesøga˚rd case the conventional solution is chosen as a benchmark. The assessment of the environmental parameters of the three alternative systems was made as a life-cycle assessment, whereas the other criteria were evaluated judgementally. To illustrate the principle of the assessment of wastewater systems, the evaluation of the three systems was tentatively transformed into a normalized score between ⫺5 and ⫹5 for the seven criteria (Table 1). Four different profiles of preferences were drawn up to exemplify four different priorities of the evaluation criteria (see Table 2).
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Table 2 Profiles of preference Criteria
Profile 1
Profile 2
Profile 3
Profile 4
Environment Operation Daily use Economy Flexibility Local development Health and security
0.1 0.2 0.2 0.3 0.0 0.0 0.2
0.4 0.1 0.1 0.0 0.1 0.1 0.2
0.1 0.3 0.2 0.1 0.1 0.0 0.2
0.3 0.0 0.1 0.0 0.2 0.3 0.1
By weighing the normalized parameters with the different priority of the evaluation parameters, a weighted, normalized score is generated (Fig. 2). This score illustrates to which degree the three different wastewater systems will satisfy the four different profiles of preferences. Much to the surprise of many of the future inhabitants of Munkesøga˚rd, the solution with compost toilets generally scored the lowest. This was primarily due to the proposed construction of concrete cellars under the compost toilets, a solution that is very expensive in money and energy. The low-flush solution generally scored the highest, and was more robust with regard to different stakeholders’ priorities among the evaluation parameters. At Munkesøga˚rd, the low-flush solution has been chosen. This is partly due to an assessment as the one illustrated above, and partly to very strict hygienic restrictions formulated by the authorities of occupational health and safety, which meant it was unacceptable for compost toilets to be placed in the cellars.
5. Crucial points in developing the assessment method The first edition of the method is being developed through the work with very different cases. Case studies are an important key to knowledge, and one project will be to collect and systematize the knowledge of existing practices. The second project is testing the pilot model for assessment, and to develop the different tools within the model. Some crucial points will be discussed, and choices will have to be made. Some of these are crucial
Fig. 2. Weighted and normalized scores.
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points not only in this specific method, but are relevant to most decision support systems for sustainable development. The choice of criteria is crucial. The criteria form the basis of the whole method of decision support and the internal connection between the onsite-analysis, the technology information tool, and the evaluation tool. The choice of criteria is, furthermore, subject to a number of different demands, not the least being the formulation of the criteria so as to be used by the different actors. The project works, as mentioned above, with seven criteria that together form the framework for assessing “sustainability.” To the more traditional criteria, such as economy and technical competence, are added a wide range of different criteria under the headings of environmental aspects, health and security, operation and, use, local development, and adaptability to future demands. This basic set of criteria will constitute an explicit core of criteria around which a locally dependent assessment can be made. It is, however, noted that criteria can be grouped in many other meaningful ways, depending on the local context. The relevant stakeholders can weight the locally dependent assessment criteria, and they may find it necessary to add extra criteria to ensure that all the significant issues are covered. The assignment of scores for each criterion is critical, as is the selection of an appropriate weight for it, relative to the weighting of the other criteria. Thus, there are problems with normalization of the different criteria, as this implies weighting. Because the criteria covers a wide range of impacts of concern, this will result in comparisons of dissimilar elements, and weighting of the more qualitatively criteria will be subjective. The scoring system must accept both hard and soft data in a similar format, and the weighting system will be constructed partly by default values, partly by user modifiable values. The performance of the different alternatives for wastewater handling will be compared to that of a reference condition, a benchmark performance. To assess the environmental impact, the method will be based on “life-cycle considerations,” a practical assessment approach derived from the concept of life-cycle assessment which, as such, it is not possible to carry out in practice. Creating dialogue is necessary but difficult. Two different dialogue tools are being developed to establish a frame for the dialogue between very different stakeholders—in particular, the users, the politicians, and the technical experts. The development of the dialogue workshops is based on previous experience of establishing dialogue and building up the participant’s competence using different technical problems as a basis [5]. Experience shows that the workshops bring together different actors by creating insight into, and understanding of, their different perceptions and roles. The challenge will be to develop “standard workshops” to be used in different local processes. The other dialogue tool aims at drawing up the different preference profiles to be part of the evaluation model. Here, the greatest challenge is the need to train the participants both to develop insight into wastewater treatment and to give different priorities to different
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criteria. The tool operates with different statements concerning different criteria formulated in everyday language. The participants will evaluate the different criteria by giving priority to questions presented in pairs. The tool will create a profile, which the participants can discuss. Used on a representative sample of the stakeholders, the methods will be able to produce different profiles of perceptions. Theoretical work is being carried out to formulate a framework for using the dialogue tools and some principles for “the quality of dialogue,” as both tools could be misused to legitimize a decision process as being democratic without it being so.
6. Conclusions This paper describes an assessment method for supporting the decisionmaking process when planning wastewater-handling systems in nonsewered settlements. The assessment method is developed to ensure “a good environmental solution,” and has reached the stage where four pilot cases have been tested. The method seeks, on the one hand, to increase the number of solutions taken into consideration, and, on the other hand, to avoid dogmatic and undocumented decisions. One major point is that technology is not inherently sustainable. The sustainability of the total system of technologies at an actual site must be evaluated in an transparent and holistic assessment including a wide range of criteria. The second major point at which this assessment method differs from other assessment methods is the participative approach, supporting dialogue between different stakeholders. Different dialogue tools will be developed to fulfill this approach. The case study demonstrates—together with the other cases—that the principles of the assessment method are practicable. It widens the spectrum of criteria included in the assessment: environmental, technical, and economic criteria, as well as criteria concerning everyday use and operation, health and security, local development, and adaptability to future changes. The case illustrates the use of the dialogue workshop, but also underlines the need to include all the relevant actors at an early stage. As the method offers a practical approach to the assessment of the sustainability of concrete solutions, the development of the method has to exceed some bounds of principles. In particular, concerning a workable definition of sustainability, the method includes weighting the very different criteria, and the use of dialogue tools. It has to be stated that even though the method does provide a better basis for the final decision—the final choice is a political decision.
Acknowledgment The project is being developed by a team of researchers in the Department of Planning and the Department of Environmental Science and Engi-
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neering. The Danish EPA finances the project through the “Action plan for ecological urban renewal and wastewater treatment.”
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