Remediating the Broekpolder (Netherlands); Scenario planning on soil remediation and development of the Broekpolder

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Remediating the Broekpolder (Netherlands);

Scenario planning on soil remediation and development of the Broekpolder

Cas Verbeek 11042133 Jorg de Visser 10736859

Interdisciplinary Project – University of Amsterdam 22-12-2017

Supervised by Donya Danesh (University of Amsterdam)

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ABSTRACT

The persistent soil pollution on the Broekpolder is in need of remediation, since it hinders

development and poses a threat to the health of the ecosystem. However, stakeholders and

local government might have opposing views on the remediation method and subsequent

development of the area. Therefore, this paper presents an interdisciplinary scenario

analysis to clarify the discussion by providing extrapolated possible futures, in addition to a

stakeholder analysis. Furthermore, a previously overlooked remediation method is proposed

to provide novel solutions in the stakeholder dialogues; phytoremediation. To provide the

scenarios two disciplines were integrated; biology and human geography. This

interdisciplinary approach is warranted by the complex interactions between nature and

society, and the pollution at the interface between them. The provided scenarios give insight

into the underlying assumptions in the discussion and the long-term consequences of

continuation of trends in both directions. The selected trends are stakeholder influence and

a shift in remediation methods. Phytoremediation has been shown to be potentially

applicable on the Broekpolder, although further site-specific research is needed.

Furthermore, phytoremediation is shown to be more cost effective relative to conventional

remediation.

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INTRODUCTION

The Broekpolder is an area in the province of South Holland, near Vlaardingen and Rotterdam. The Broekpolder originated from dredging waste out of the Rotterdam harbour, raising the area by 4 - 7 m, during the period of 1958 to 1975. The dumping of dredging waste introduced numerous pollutants into the area, amongst which were drin pesticides (aldrin & dieldrin) and heavy metals (Cu, Cd, Ni and Zn) (Osté, 2016).

Since the Broekpolder is an extensive area (350 ha), direct soil remediation has not been

undertaken. Instead, measures to ensure the pollution is contained within the Broekpolder are in place. These measures take the form of carbon filters, which prevent the pollutants from leaving the Broekpolder through the effluent of the area (Osté, 2016). However, according to a Deltares study by Osté (2016), these filters have a limited capacity and have proven to be especially lacking during periods with high rainfall. Hence, one of the main conclusions and recommendations of Osté (2016) was that filtering and water storage capacity needed to be improved to accommodate peak flows of the effluent, especially for the most polluted sections of the Broekpolder.

The Osté (2016) study was conducted on behalf of the Delfland water board (Hoogheemraadschap - Dutch administrative subdivision responsible for regional water management). Thus, the aim of the recommendations was to support the water board in its obligation to maintain water quality in the area under their jurisdiction. By conducting the research in this way, Osté (2016) does not evaluate methods to improve soil pollution, nor does it consider the different uses of the Broekpolder by the various stakeholders. Therefore, this study will attempt to supplement and tailor these recommendations to the needs of the stakeholders of the

Broekpolder, answering the primary research question; how can soil remediation types influence the stakeholders of the Broekpolder?

To answer this question, an interdisciplinary approach is needed to understand and approach the problem from the perspective of the different stakeholders, and is further warranted by the nature of soil pollution. Soil pollution has many interactions with biological and physical components of a system, influences the possible extent of economic exploitation, alters the

perception of nature (and humanity's presence in it) and can affect human health and safety. These aspects, in turn, may influence stakeholder positions and discussion making, making this a complex problem. To incorporate these complex facets into this research, two disciplines will be integrated to achieve a holistic view of the problem; biology (C. Verbeek) and human geography (J. de Visser).

The biological discipline is needed because the ultimate concern of the pollution on the Broekpolder is damage to the ecosystem, should the pollutants be introduced in the food chain. The biological perspective allows for the understanding of interactions of the ecosystem with the pollutants, and the possible opportunities that that may provide (e.g. phytoremediation). On the other hand, the human geography discipline is needed, because the Broekpolder is a manmade environment and the present pollution forms a barrier to development and exploitation.

Additionally, a human geographical perspective can provide insight into the perceived (emotional and functional) value of those involved in the Broekpolder. In this paper, the motivations of stakeholders and dialogues about the development of the area are taken into account.

The stakeholders of the Broekpolder can be broadly categorized as commercial,

governmental, recreational and ecological (i.e. the value of the ecosystem to the species living in the ecosystem). To give a more detailed structure of the stakeholders, a stakeholder analysis is made in cooperation with Balance. Our results will be directed towards informing all stakeholder

participating in the debate, and primarily towards the province of South Holland, who oversees the municipality and the hoogheemraadschap, is familiar with the stakeholders and can pass legislation

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2 to improve soil quality. The consultancy firm Balance is involved in the stakeholder discussion, and has helped to guide and focus this research on the most relevant aspects of the discussion, as well as inform the stakeholder analysis.

Our primary findings will be presented by means of a scenario planning approach (as described by Nekkers (2012)). In this way the intricate aspects of the Broekpolder remediation can be clearly presented to legislators/ stakeholder without the necessity for them to have extensive prior knowledge about any one field of research. Therefore, to be able to communicate these complex problems clearly, the biology and human geography disciplines have to be integrated into a unified theoretical framework.

THEORETICAL FRAMEWORK

Interdisciplinary integration method

To integrate the biological and human geography discipline, a framework for integration was used adapted from Hirsch Hadorn, Pohl & Bammer (2017). Herein, they describe six questions that are useful in guiding a framework for integration (provided in the appendix). Their method leaves room for adjustments to fit the unique problem it is applied to.

From an integration perspective, the selection of the inherently interdisciplinary research method of scenario planning has allowed us to involve social and natural science in our research, leading to a novel approach and meaningful insights into the particular problems on the

Broekpolder. The integration of both disciplines is further reinforced by expansion of concepts into both fields, which has yielded a relevant integrated theoretical framework. A monodisciplinary, reductionist approach would certainly under appreciate some aspects of the pollution problem on the Broekpolder, be it in the social or natural science. Therefore, the integrated framework described below attempts to apply an appropriate interdisciplinary integration to be able to holistically analyse the complex Broekpolder pollution problem.

Integrated theoretical framework

In order for the aims of the research to be accomplished, knowledge from the two disciplines has to be united into a single integrated theoretical framework. To do so, common ground must be found, and points of conflict between the disciplines have to be resolved or explicitly stated. Starting with the common ground; connections between biology and human geography can be found at the interface of nature and human societies.

From the biological perspective an assessment can be made of the physical and natural conditions, limitations, and opportunities for the pollution problem in the Broekpolder. Human geography on the other hand is the study of societies in relation to place and space. From this perspective, the historical relationship of humans and nature can be defined as place dependent, where the attachment to nature is primarily functional (i.e. provisioning). In modern urban areas, the relation of society and (scarce) nature has shifted to place identity, where attachment is emotional and symbolic (Moore & Scott, 2003). The modern attachment is exemplified by the relation of local residents and stakeholders to the Broekpolder (see federatiebroekpolder.nl). In turn this place identity connection can, in the case of the Broekpolder, be seen as a cultural ecosystem service, connecting it to the biological discipline. Ecosystem services is a concept that was developed in order to enable valuation of ecosystems and therefore emphasize the dependence of humanity on nature (Costanza et al. 1997).

The Millennium Ecosystem Assessment (2005) defines ecosystem services as: “the benefits people obtain from ecosystems.” In this respect, both use-value and non-use value (i.e. intrinsic

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3 value) will make up the total value of an ecosystem. The concept of ecosystem services thus

provides a bridge between the human geography and the biology disciplines (figure 1). Furthermore, the Broekpolder can provide more than cultural ecosystem services alone. The regulatory ecosystem service, phytoremediation, provides an opportunity to clear or reduce the presence of the pollutants on the Broekpolder. Until recently, this remediation method has been absent from stakeholder dialogues concerning the Broekpolder. The prospects of phytoremediation will be further elaborated in the phytoremediation section below.

Conflicts may nonetheless arise between the two disciplines. Since human geography is inherently anthropocentric, the intrinsic value of nature may be understated, while frequently receiving much consideration in the biological community (e.g. in conservation efforts). This bridge can be partially gapped by expanding the definition of place identity to include intrinsic value in the symbolic attachment. This does not fully overcome the gap between the disciplines, because even then place identity still only encompasses human appreciation of intrinsic value. However, this dichotomy does not need to be further resolved for the scope of this paper, because intrinsic value is rarely considered by policy makers and often severely misinterpreted (G. Oostermeijer, personal communication, 27 November 2017). Thus, a more extensive consideration of intrinsic value may be counterproductive for the discussion.

Additionally, the concept of ecosystem services in itself is not enough for a satisfactory integration of the disciplines, because monetary valuation of itself does not dictate a course of action (although money is a powerful incentive). Thus, the concept of ecosystem services has to be integrated into a methodological framework appreciative of the interdisciplinary nature of the subject. Such a theoretical framework can be provided by scenario assessment. A scenario analysis takes trends from the physical, as well as from the societal/political environment, to paint a picture of what a possible future might look like (and how this future can be achieved or avoided). As such, a scenario assessment takes into consideration the complex nature of the problem and sheds light on the influence that different trends have on the system – and what futures they can produce. The scenario method described by Nekkers (2012) will be used as a template for our analysis. Since remediation methods might be a valuable aspect of the scenario assessment phytoremediation is elaborated firstly.

Figure 1. Integration diagram. Ecosystems (represented by the biological discipline) and societal needs

(represented by the human geography discipline) overlap where society makes use of ecosystem services. The ecosystem services of the Broekpolder may include cultural, as well as regulatory services.

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Phytoremediation

The consultancy firm Balance has indicated that phytoremediation as a possible means to remove pollution from the Broekpolder has been unexplored in the stakeholder discussion. Therefore, it is valuable for this paper to briefly give an overview of phytoremediation and its potential application on the Broekpolder.

Chemical pollution such as pesticides are often retained in soils long after their intended uses. Eventually these chemicals can end up in the food chain and accumulate in the adipose tissue of animals with detrimental health effects (Eevers, White, Vangronsveld & Weyens, 2017). The same accumulating properties have been found for heavy metals (Gavrilescu, 2004). Conventional soil remediation of these contaminants is comprised of incineration, disposing polluted soil on landfills, composting and use of chemical amendments (Eevers, et al., 2017). Since these methods often require extensive excavation and transportation, conventional remediation is highly cost- and labour intensive (see table 1). Moreover, these methods are highly disruptive to local (soil) ecosystems (Eevers, et al., 2017).

A method that might reduce the costs and invasiveness of soil remediation is

phytoremediation. Phytoremediation is made possible by the same properties that make pesticides and heavy metals dangerous; bioaccumulation. If the pollution accumulates in plants, the biomass containing the pollution can be more easily removed compared to excavation (via a process called phytoextraction). Furthermore, in some cases, the plants may also metabolize the pollutants, rendering them harmless, less harmful or less mobile (Eevers, et al., 2017).

Specific plant species are known that can accumulate and metabolize the pesticides present in the Broekpolder (Mahar, et al., 2016; Eevers, et al., 2017). A preliminary assessment has indicated that the following plants may be used to remediate the pesticide and heavy metal pollution on the Broekpolder: Deschampsia cespitosa, Eleocharis acicularis, Ricinus communis and Thlaspi

caerulescens (Verbeek, 2017 - unpublished).

Using phytoremediation techniques, the present use of the Broekpolder as a

natural/recreational area can be maintained with less disruption than conventional remediating techniques. However, these techniques cannot be applied haphazardly. Glick (2003) recommends that a bio- and phytoremediation should be tailored and optimized for every individual site where these techniques are applied. Introducing non-indigenous species into an ecosystem inherently brings the risk of introducing invasive species. Careful planning and management is needed to prevent this.

Furthermore, phytoremediation is limited by the regional and local climate (Mahar, 2016). If the environmental conditions in the Broekpolder are not optimal for the remediating plants, the process may be limited, further supporting Glick’s (2003) recommendation. Lastly, phytoremediation takes an extended period of time to completely remediate soils (10-150 years, depending on the nature and extent of the pollution) (Mahar, 2016), thus excluding application on areas with short term development plans. Hence, phytoremediation is a plausible method of remediating the

Broekpolder, if no further development of the area is planned. To further substantiate the possibility of applying phytoremediation (and with the request from Balance) a cost analysis of

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METHODS

Data was collected from published scientific literature to assess remediation strategies and to make a cost analysis. Relevant literature was acquired through the use of the search engines Web of Science and Google Scholar. Literature reviews were the primary focus, because these studies emphasize the current understanding in the field, and, in the case of remediation types, summarize general limitations. Additionally, the use of review studies limits the influence of possible oversights caused by a relative lack of expert knowledge of the writers of this paper.

For the scenario assessment, information on the interest of the stakeholders was sought from the consultancy firm Balance. Balance is involved in the stakeholder dialog and has knowledge on the opinions of the stakeholders. From the literature review and dialog with Balance, a

stakeholder analysis is constructed and drivers of change in the Broekpolder are selected to be incorporated in the scenario analysis.

Stakeholder analysis

Through a stakeholder analysis, various actors with interests are identified, categorized and lastly, the relationships between the stakeholders are resolved. This process of analysing the stakeholders is done according to the methodological framework of Reed, et al. (2009). The analysis is based upon vision statements, policy documents, websites and a semi-structured interview with Jorian Bakker of Balance. Balance is an independent actor which is currently working as a mediator in the

Broekpolder dialogue.

Scenario planning method

To compose the scenario’s, the method of Nekkers (2012) was used. In this method drivers of change are selected and ranked according to impact and uncertainty. Selecting these drivers requires a broad understanding of the problem, thus a multidisciplinary team is advised. Furthermore, by using a broad multidisciplinary team, the influence of personal biases can be minimized (Nekkers, 2012). From the drivers, trends of change can be extrapolated, which will inform the scenarios. Four scenarios will be created by selecting the two most important trends (highest uncertainty and impact) and extending these trends into the extreme, showing the exaggerated, possible futures these trends may create. By extrapolating the drivers, the trends can be put on two axes, creating a diagram with four quadrants, representing the four different scenarios (Nekkers, 2012) (figure 3).

Drivers

The three primary drivers of the Broekpolder development discussion are; (i) the need for remediation, (ii) the need for housing development, and (iii) the need for a recreational area. The possibility of housing development on the Broekpolder urged local stakeholders at the time to form the Federatie Broekpolder (see www.federatiebroekpolder.nl). Although no current housing development is planned, the need for housing development is included, because it has been the catalyst for the Broekpolder discussion since its inception. In that sense, the “need for housing development”-driver can be substituted for any possible profitable future development on the Broekpolder. Any current development however, is hindered by the need for soil remediation.

The need for remediation can be seen as an underlying core driver. Whichever direction the Broekpolder is developed in, the need for remediation remains and is mandated by law. However, different types of remediation may be preferable for different development futures of the

Broekpolder. Therefore, the initial uncertainty of this driver is low, but uncertainty remains as the method of remediation is not fixed. The impact of different types of remediation, on the other hand,

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6 is high. Conventional remediation methods are (relatively) quick, costly and labour intensive and is primarily desirable when short term development (e.g. housing projects) are the preferred direction of development. Alternative remediation methods, such as phytoremediation, may favour the recreational future of the Broekpolder, since remediation takes an extended period of time (but is cheaper – see remediation cost analysis). Thus, the remediation method chosen may determine the development of the Broekpolder.

As for the last drivers, the need for housing development or a recreational area both have a low uncertainty. Yet, uncertainty in the development remains as stakeholder discussions continue. Thus, the need for housing development and the need for a recreational area can be represented by a single driver; stakeholder influence. Pollard, et al. (2004) identified (demand for) engagement of stakeholders in land contamination policy as increasing trend. In this sense of the word ‘stakeholder’ primarily refers to the non-governmental stakeholders of the Broekpolder (i.e. Federatie

Broekpolder), however the broader sense of the term ‘stakeholder’ is recognized and listed in table 1. Stakeholder influence, has both high uncertainty, as it depends on willingness of the local

government for cooperation, and high impact, as the goals of the stakeholders are perpendicular to those of the municipality (i.e. the Broekpolder as a recreational area vs. housing development). The uncertainty of this driver also indirectly imparts uncertainty in the choice of remediation.

Trends

The drivers with the highest uncertainty and highest impact are selected, and extrapolated into trends. The selected drivers are remediation type (conventional remediation vs. phytoremediation) and stakeholder influence (high- vs. low influence). Hence, the trends most relevant to the

Broekpolder development are; a shift in the discussion of remediation type (phytoremediation has been absent from the discussion until recently), and increasing stakeholder involvement (see Pollard, et al., 2004). These trends are visualized in the scenario diagram (figure 2) in the results section.

The shift in remediation types is informed by currently available methods. In the future new techniques may arise or old ones may be improved, thus the scenario outcomes may need to be revised if drastic progress is achieved in any of the remediation methods. Furthermore, it should be noted that stakeholder influence is primarily dependant on two factors; (i) stakeholder involvement, and (ii) governmental cooperation. Hence, in the scenario assessment, shifts in stakeholder influence can be caused by changes in either of these factors.

The broad trends and holistic scenarios resulting from the scenario assessment, indicate a successful interdisciplinary integration and subsequent research.

RESULTS

Stakeholder analysis

In figure 2 the relevant actors and stakeholders are shown in a structured overview. The

interrelations between different actors are representing governing structures sorted by scale level (top: province level, bottom: local level). The dotted lines between the Municipality Council, the College of Mayors and Deputies and the Federatie Broekpolder represents the triangular relationship of the so-called “Public-Private Social Co-operation” between these actors. This

relationship is unique in the Netherland (Federatie Gebruikers Broekpolder, 2017) and is in line with the trend of increasing public participation in policy making.

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Figure 2. Overview of different stakeholders in the Broekpolder. Sorted on spatial scale (top: province level,

bottom: local level). Data from Bakker (Semi-Structured interview, December 15, 2017).

In the following section, the parties will be elaborated upon briefly. First, the Province of South-Holland is involved since the pollution dates back before 1987 and therefore the Province holds responsibility to address the problem (Bakker, Semi-Structured interview, December 15, 2017).

The municipality of Vlaardingen is involved, because they own most of the land of the Broekpolder and have interests in having a safe, recreational and natural area for their inhabitants (Bakker, Semi-Structured interview, December 15, 2017). The division between the two branches of the municipality shown in figure 2 is not relevant in this regard. Next, DCMR is the “Central

Environmental Management Service Rijnmond” (own translation). This is an environmental law enforcement service, working on behalf of municipality and the province. Due to the soil pollution in the Broekpolder, this is a closely involved actor. Additionally, the Hoogheemraadschap Delfland is the involved water board. In the Broekpolder, this organisation is involved with water quality issues and a water treatment plant.

Staatsbosbeheer (national forest management) owns and manages a part of Broekpolder and is therefore also involved. Next, the Golfclub Broekpolder is involved, because they are leasing the land, but also have to contribute financially for a treatment plant for drainage water (Bakker, Semi-Structured interview, December 15, 2017). Finally, the Federatie Broekpolder has become an important stakeholder in the Broekpolder. This federation has been established in 2006 through concerned citizens, who strived for the Broekpolder remaining a natural- and recreational site (Federatie Broekpolder, n.d.). The municipality has embraced their input, and they have become involved in the policy-making process of the development of the Broekpolder. Now they represent citizens (users of the Broekpolder), entrepreneurs in the Broekpolder and social organizations. Their objective is to maintain and improve the nature- and recreational functions of the area.

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8 While conducting the interview, it became clear that there are several processes of change at stake in the area. Actor involvement strongly depends on which process is being discussed. The processes and which actors are involved is listed in the table 1.

No. Process Involved actors

1 The founding of a coöperative association

Staatsbosbeheer, Hoogheemraadschap, Federatie Broekpolder, Municipality of Vlaardingen

2 Forrest vision Staatsbosbeheer, Province of South-Holland

3 Area development All stakeholders. Municipality of Vlaardingen and Federatie

Broekpolder are most active

4 Soil remediation All stakeholders

5 Reviewing the water drainage process

Golfclub Broekpolder, Hoogheemraadschap, Staatsbosbeheer, Municipality of Vlaardingen

6 The founding of the archaeological area

Federatie Broekpolder, Municipality of Vlaardingen, Hoogheemraadschap, Bureau Stroming

7 Water purification process Hoogheemraadschap, the golfclub, Staatsbosbeheer, DCMR and

the province

Table 1. Overview of different processes of development in the Broekpolder. And involved actors per

process. Data from Bakker (Semi-Structured interview, December 15, 2017).

For the purpose of this report, the soil remediation is the most important of the processes listed above. The stakeholders mutually agree that action has to be taken (which is also required by law). Here, the challenge is to achieve an agreement on how the soil should be remediated, who will be affected and to what extent, and more importantly, who is financially accountable. The Province of South Holland is accountable, but the pollution being present in either soil or water is important for whether DCMR or the Hoogheemraadschap Delfland is accountable.

A shared interest of most actors and stakeholders is that the soil remediation should not be too destructive and disruptive for the area. Several conventional soil remediation methods have these implications. Innovative soil remediation methods, such as phytoremediation are potentially suitable in the Broekpolder and its stakeholders, by preserving the values of the area, while the soil is being remediated.

Remediation cost analysis

Assessment of the costs of phytoremediation have been largely absent from scientific literature (Wan, Lei & Chen, 2016), perhaps explaining why phytoremediation has not been more widely applied. Recently, a case study from China (Huanjiang county) has done just that and concluded that phytoremediation was cheaper than conventional remediation. In this section an extrapolation of the cost analysis of Wan, Lei & Chen (2016) will be applied to the Broekpolder.

The study area of Wan, Lei & Chen (2016) comprised 700 ha of farmland contaminated with Pb, Cd and As, and the remediating plants used (over two years) were; Pteris vittata (a fern), Sedum

alfredii (perennial herb), Saccharum officinarum (sugar cane) and Morus cathayana (mulberry tree).

The costs for phytoremediation that were found are shown in table one, compared to conventional remediation methods (converted from US$ to euro, with a 1.19 conversion rate at the time of

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9 writing). The total costs per cubic meter are converted into the hypothetical total costs of

remediating the upper 20 cm of soil across the entire Broekpolder (350 ha). A reference depth of 20 cm was used, because root depth of 20 cm is typical for remediating plants (Wan, Lei & Chen, 2016).

Remediation method Cost/m3 (€) Total costs (€)

Off-site disposal 571 – 967 1.92 * 1011 – 5.51 * 1011

Incineration 96 – 300 5.47 * 109 – 5.29 * 1010

Biopile (on-site) 154 – 309 1.41 * 1010 – 5.63 * 1010

Phytoremediation 45 1.18 * 109

Table 1. Costs for remediation. Table showing the cost per cubic meter and total costs in euros for different

remediation methods. Data from Wan, Lei & Chen (2016).

These hypothetical costs are used in the scenario assessment as high costs for the conventional remediation scenarios (scenario II & IV) compared to the phytoremediation scenarios (scenario I & III – figure 2).

Scenario assessment

Division of the two primary trends into quadrants has yielded four distinct scenarios.

I. “Natural” reserve

The municipality of Vlaardingen has decided of its own volition to apply phytoremediation on the Broekpolder as a cost saving alternative to conventional remediation. After an experimental pilot proved successful, phytoremediation is applied on as large a surface area as possible to optimize remediation speed. Intensive fertilization and mild pesticides are used to further optimize plant growth for increased remediation. When planting the remediating plants, previous use of areas in the Broekpolder are disregarded; dog walking is prohibited as they might trample/damage plants, playgrounds are closed in favour of more remediation, etc. Staatsbosbeheer decides to cooperate and also incorporate remediating plants in areas under their management.

This leads to exclusion of the local residents from the park, turning it into a natural exclosure for phytoremediation, or “natural” reserve, accessed primarily by researchers and the parks

department. The Golfclub Broekpolder remains as sole recreational area. Under pressure of the Hoogheemraadschap Delfland, Golfclub Broekpolder has invested in additional water processing filters, thus ensuring their long-term lease of the area. Eventually, once remediation has been sufficiently completed, the “natural” reserve opens up to development. To compensate for the investment costs and the long-time period where no profits have been made on the Broekpolder area, a profitable housing district is developed by the municipality of Vlaardingen. Unless the Federatie Broekpolder is able to persuade the municipality at a later time, this will cause the former Broekpolder to shift into the concrete jungle scenario.

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Figure 2. Scenario diagram. Diagram showing the different scenarios caused by extrapolation of the following

trends; stakeholder influence (x-axis) and remediation method (y-axis), resulting in four scenarios; (I) “natural” reserve, (II) concrete jungle, (III) “natural” park and (IV) green city.

II. Concrete jungle

In this scenario stakeholder influence is low (primarily the Federatie Broekpolder), due to either lack of cooperation from the government or reduced stakeholder involvement over time due to attrition. Because of the reduced influence, the municipality of Vlaardingen has opted to apply conventional remediation to remove the pollution at a high cost (see table 1). To compensate for this high cost, highly profitable, luxurious housing development is planned, with long term financial gain in mind.

The value as a natural-recreational area the Broekpolder once had, is disregarded in this new development pathway. To optimize profits every square meter is used for houses and apartments, leave no room for nature or recreation.

III. “Natural” park

The Federatie Broekpolder has successfully convinced the municipality that the Broekpolder should remain as a natural-recreational area. However, the problems of heavy metal and pesticide pollution remain. In order to not disrupt the ecosystem on the Broekpolder, the municipality and

Staatsbosbeheer start looking into alternatives for remediation. After successful pilot experiments the application of phytoremediation appears promising. In a dialog between the Federatie

Broekpolder and the government it is decided which areas are most suitable for phytoremediation and where it can be incorporated without disrupting the recreational use of the Broekpolder. Over time this cooperation leads to a significant pollution reduction while the recreational use is

maintained and stakeholder satisfaction is high (although the new plants are not to everyone's liking).

IV. Green city

Even though the Federatie Broekpolder has been trying to convince the local government that the Broekpolder should remain as a recreational area, the municipality simply cannot forgo a potential housing neighbourhood, both for economic reasons and to cope with population growth. However,

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11 the pleas of the federation have certainly been heard, and small-scale parks, green streets and gardens have been incorporated into the development plan, thus meeting the Federatie Broekpolder halfway (the so-called Dutch “poldermodel”). New residents from outside the area are especially happy with this green neighbourhood. Older “natives” from the area are slightly less satisfied. Unfortunately for them, the Broekpolder could not remain as a natural/ recreational area, but they are ultimately mildly content with the compromise they had to make.

CONCLUSION & DISCUSSION

The remediation cost analysis shows that phytoremediation can be a cheaper alternative to conventional remediation. A 53% cost reduction compared to the cheapest conventional

remediation method is shown. These cost analyses are very site specific however. For instance, Wan, Lei & Chen (2016) included infrastructure construction in the price for all off-site disposal, something which is already (presumably) sufficient near the Rotterdam harbour. Furthermore, costs for

construction/purchase of irrigation systems (likely not necessary in the Broekpolder) and plant nursery equipment were also included in the price per cubic meter. Thus, the provided cost per cubic meter and the total costs are likely overestimations since considerably less infrastructure and

irrigation investment is needed for remediation in the Netherlands. Nevertheless, this may be (partially) compensated by higher labour costs compared to China. Furthermore, the case study from China only investigates heavy metal remediation, not pesticides (Wan, Lei & Chen, 2016). However, since heavy metal and pesticide accumulation/remediation is very similar in practice, costs for pesticide remediation are estimated to be within the same order of magnitude as those found for heavy metals. The primary difference being that pesticides and heavy metals differ in their allowed concentrations, which indicates that different time frames may be needed for phytoremediation of heavy metals and pesticides.

Thus, the contribution of the cost analysis is providing an estimate of the proportional difference in costs between the remediation methods. This difference in cost subsequently contributes to the scenario assessment. Of these scenarios, the “natural” reserve scenario (I) is particularly interesting. In the long run, this scenario might be the most financially profitable by combining low remediation costs with high development profits. The long-term shift in scenario I towards the concrete jungle scenario (II) emphasizes that continued stakeholder involvement is needed, even after a seemingly stakeholder-friendly development approach is chosen.

The most preferred scenario from the Federation Broekpolder perspective is the “natural” park scenario (III). In this scenario, it is important to note that not everyone will be happy with this direction for the Broekpolder. Even here concessions have to be made with regard to the current use of the Broekpolder. Furthermore, income from housing development could be used for the

development of social security, schools or libraries. Indeed, this money might even be used to expand, improve or conserve other natural areas in the region (e.g. Rietputten and Vlietland are <4 km away from the Broekpolder). Lastly, the green city scenario (IV) provides the middle road between a natural and developed area. This might seem like a preferable solution; nevertheless, it disregards notions of place identity and intrinsic value, which cannot be replaced or compensated for by placeholder parks and gardens. However, that does not mean any form of compromise should be excluded; no decision can please all involved parties equally.

The analysis of the physical aspects of the pollution on the Broekpolder could have benefitted from the addition of the earth science discipline and/or chemistry disciplines. Similarly, the laws involved and governmental structures may have been improved by the addition of the

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12 political science discipline. Unfortunately, due to limited available contributors, these disciplines could not be incorporated.

In conclusion, the overall value of this research is to provide a theoretical overview of the stakeholder discussion that might provide valuable insights into the viewpoint of opposing parties, or lay bare implicit viewpoints of one's own faction. Furthermore, this research introduces a novel practical method of addressing the pollution on the Broekpolder; phytoremediation. For this method to be put into practice, research and pilot experiments are recommended, and have to be gradually scaled up to gather knowledge and expertise specific to the Broekpolder. Laboratory experiments can indicate the potential of phytoremediation using Broekpolder-soils in laboratory greenhouses. Additionally, such an experiment can be used to provide an initial timeframe for remediation. If the results are sufficient, the experiment can be scaled up to pilot areas inside the Broekpolder. DCMR has indicated that several areas on the Broekpolder without zoning plan could be made available for such experiments, providing the most relevant data possible for the assessment of

phytoremediation of the Broekpolder.

DISCLAIMER

As a closing statement the writers would like to disclose their shared personal bias towards nature conservation, perhaps explained by their shared Future Planet Studies background (the internal- and external supervisors of this research might also share such bias, having backgrounds in biology and Future Planet Studies, respectively). Influence from this bias can be eliminated by cooperating with researchers and consultants from more varied backgrounds. However, we are confident that this bias is of minimal influence on the presented paper.

Furthermore, the writers of this paper have no conflict of interest regarding the Broekpolder, financial or otherwise, and are not associated with the consultancy firm Balance (Balance Ervaring op Projectbasis B.V.). Thus, we do not benefit from any possible conclusions, interpretations or implications of this study. Additionally, aside from education, no benefits or interest of the University of Amsterdam for collaborating with Balance are known to the writers.

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Remediating the Broekpolder (Netherlands); Scenario planning on soil remediation and development of the Broekpolder