TGN Browfields

Francesca Giudetti, Gianluca Bernardi

This work offers a reflection on various paradigms of contemporary urbanism from both a practical and theoretical point of view. The designing potential of urban ecology, urban metabolism, resilience and long-lasting projects are examined in order to understand key elements of the topic we chose and their capacity for generating new urban shapes.

Our topic is “Brownfield regeneration” and it concerns the cleanup, the design, and the reuse of derelict land, such as the ones that surround Tarragona’s port. Firstly, we tried to understand the meaning of brownfield and what its regeneration involves. We collected some data about the levels of micropollutants in the petrochemical area of Tarragona. One of the most important industrial complexes in Southern Europe is located in Tarragona County (Catalonia, Spain). The zone is characterized by numerous potentially pollutant industrial sources, such as a big oil refinery, a chloralkali plant, several plastic- manufacture chemical companies, a hazardous waste Incinerator (HWI), and a municipal solid waste incinerator (MSWI). In addition, the concurrent traffic density is really relevant, with an important highway and several motorways in this area. The industrial sector is located near to various inhabited suburbs and close to Tarragona City downtown. The presence of this chemical/petrochemical complex, together with the knowledge of increasing pollution in metropolitan areas, has been for many years a reason of concern for the local population. We made an analysis of the territory, including both the vacant lands and the built ones (residencial, commercial, etc.). According to our opinion a 21st century approach to social responsibility is the issue of remediation. This work questions how this issue can be engaged with to better understand sites of degeneration and misinterpretation, and reappropriate these places in Tarragona in a meaningful way that regenerates the site and enables the public to use these spaces.

 Levels of contamination:        Present state of the frame in Tarragona (Spanish cadastre +Personal Hypothesis)

This brownfield roadmap illustrates the general steps involved in the investigation and cleanup of the site. Actual steps may vary depending on site conditions and applicable state and federal regulations.The table just above shows the types of micropollutants both in the petrochemical and in the unpolluted area. The values we reported have been taken from the environmental monitoring programme that started in 2002. Our personal classification tries to build a sort of remediation programme, according to the different levels of micropollutants present in the soil. That’s why there are three levels: low, medium and high, categorized starting from the average value of each micropollutant.

                                                                                                                                                                         Brownfield Roadmap

We found a very interesting study* concerning the different levels of micropollutants in Tarragona. The present study was aimed at determining the levels of organic (PCDD/Fs, PCBs, PCNs and PAHs) and inorganic (heavy metals) pollutants in soil and herbage sampled in various zones of Tarragona County as part of the third year of the environmental surveillance program. The temporal trends for each pollutant were assessed. Moreover, the airborne content of the contaminants was also analyzed to detect more easily the influence of industrial/urban pollution sources.

The sampling zone was divided into 4 areas according to potentially pollutant sources:

  1. petrochemical (Northern industrial complex), where a big oil refinery has been working for more than 30 years;
  2. chemical (Southern industrial complex), with several important chemical companies;
  3. urban/residential, in the downtown/centre of various towns and suburbs;
  4. unpolluted, in a blank zone outside the potential influence of the industries here evaluated.
                                       

* Nadal M., Montse M., Schuhmacher M.,b, Domingo J. L., Multi-compartmental environmental surveillance of a petrochemical area: Levels of micropollutants, article in “Environment international”, August 2008.

LAYER 1: CONTAMINATION          LAYER 2: TERRITORY’S GRID        LAYER 1+2:  “new” vacant lands

PROPOSAL: REMEMBRANCE, REMEDIATION, REACTIVATION

Our work engages with the thematic concepts of remembrance, remediation and reactivation and analyses these through a series of precedent international case studies to bring together a set of imperatives to frame this design research. Remediation is discussed with regard to the rehabilitation, recuperation and reclamation of site qualities, social functionality and the remediation of ecologies.

                                      
 STRATEGY

The starting point in the process of vacant land’s reactivation is the investigation of contaminated areas in order to screening the different kind of pollutant and the range of contamination, because all type of intervention is strictly connected to the different level of pollution. Due to this kind of approach we create a degree scale, zero to 100%, of pollution, divided into 3 range categories: LOW, MEDIUM & HIGH to link each one of this category to three different kind of actions. Following the timeline, the second step is the selection of clean-up options, that depend on the level or in this case the percentage of pollution in each piece of land; soil remediation strategy changes every single time and we choose to mix clean-up options because we think that it’s totally uncorrect treat all the areas in the same way. Consistently a new function for a piece of land goes accordingly to the percentage of contamination, and so the third step is link the range of pollution and new function, for example low polluted area can be reused such as green spaces of wetlands because the level of contamination is lower enough to accept vegetation, clearly the same thing can’t be proposed for an higher polluted soil.

Soil remediation strategy is divided in three clean-up techniques based on the percentage of soil pollution, we can organize the strategy in:

– low contaminated areas, with a range of contamination around 30%, where we can apply a kind of biological approach, using a biological remediation like phytoremediation or microbial remediation. It’s a long time period of remediation but not obstrusive; of contamination around 30%, where we can apply a kind of biological approach, using a biological remediation like phytoremediation or microbial remediation. It’s a long time period of remediation but not obstrusive;

 – medium contaminated areas, with a range of contamination around 50%, where we can apply a chemical approach, a little bit more invasive, but necessary to clean-up in a good way the soil. The techniques that we can use in this case are immobilization, land farming  or bio-ventilation;  contaminated areas, with a range of contamination around 50%, where we can apply a chemical approach, a little bit more invasive, but necessary to clean-up in a good way the soil. The techniques that we can use in this case are immobilization, land farming  or bio-ventilation;

 – high range of contamination, around 90%, using a removal approach, where we must remove the soil from the areas and replace with a new soil. This kind of approach is recomended for a very compromised areas.

If the ground has been cleaned-up in a right way it is ready to welcome new functions and so for different kind of contamination range we can link a different function. We divided functions in three categories of public spaces: green spaces, sport & leisure, energetic production.   

LANSCAPE IN TRANSITION

The territory of Tarragona is very heterogeneous at the urban level: it is composed mainly of a residential centres whose boundaries are unclear at some peripherical locations. In fact, there are areas bordering on disused land, used for infrastructure or old industrial batches with discontinued activity and therefore again in disuse. In our frame, especially, there is a strong concentration of all these pieces of land without an idiosyncratus, such as pieces of puzzle reversed on disorganized land, of which the vast majority need to be restored and rehabilitated since contaminated or adjacent area. Industrial or, as has already been said, by old industries which are now in disuse. Another problem beyond the abandonment of these lands is their disconnection, considering also that some are cut off by the railroad which becomes a barrier in the north – south connection.  Our intent is, therefore, to give an identity to each of these “vacant land” and link them together to redistribute the puzzle, which is supposed to become a larger public space.

In our project we would like to offer a challenging perspective, which is that we begin viewing vacant lots as opportunities for land use transformations that can contribute to community development. Vacant land in cities could provide important social and ecological benefits, including habitat for biodiversity, provisioning of ecosystem services, and new green space for residents in underserved neighborhoods of the city.

So, why are we so captivated with these overlooked, unmanaged, vacant spaces in Tarragona, especially considering that they are not the most pleasant places in which to conduct research? For one simple reason: vacant, underutilized land has the potential to provide towns with opportunity to create and develop new ecosystems that support biodiversity and increase the provisioning of vital ecosystem services for urban residents. Vacant land is ripe for transformation into more sustainable, resilient urban forms. Urban ecologists have long recognized that the ecology in the city is not relegated to parks and protected natural areas, but exists everywhere: on rooftops, in sidewalk cracks, in backyards, in soils, rivers, and streams, in narrow green islands between streets, and also in vacant land areas.

TIMELINE                                                                                                 NEW FUNCTIONS IN THE VACANT LANDS

SCENARIOS              Image on the left: Natural borders of the park + temporary spaces for events in Tarragona (Personal Project’s View) Images on the right from the top to the bottom: Now: piece of vacant land in the frame of Tarragona, After: how territories will appear at the end of the brownfield regeneration’s process


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