Potential for the Removal of Impervious Soil Coverage 2020
The consumption of land by construction leads to a loss of soil functions with permanently negative effects on the efficacy of the natural balance. Soils have a large variety of functions which need to be protected: they provide habitats for plants and animals, they store and filter the groundwater, they act as buffers against pollutants, they are the foundation for agriculture and for healthy living, and they are an archive of natural and cultural history. These fundamental functions of the soil must be secured by adequately taking the needs of soil protection into account when planning for the future.
Soil is increasingly gaining importance in societal and ecopolitical matters, especially in view of climate change and biodiversity. As a result, national measures and regulations have been implemented to reduce land consumption, and to provide sustainable land management in cities and municipalities.
In 2002, the Federal Government already formulated the goal of reducing new land consumption to 30 ha per day by 2020 (BMU 2016). Based on current reports, this goal will not be reached. The daily consumption currently (2014-2017) amounts to 58 ha per day (UBA 2019). With the German Sustainable Development Strategy 2016, the Federal Government has postponed the 2020 goal of 30 hectares to “below 30 hectares per day” by 2030 (indicator of the Sustainable Development Goal 11.1a, Statistisches Bundesamt 2018). Sustainable Development Goal 15 addresses the protection and the sustainable use of the resource soil and indicates degradation neutrality by 2050 as its top priority. Impervious soil coverage (“sealing”) is one of the 16 core indicators by which sustainable development in the State of Berlin is measured (Amt für Statistik Berlin-Brandenburg 2014). These actions have initiated a process in the State of Berlin with the goal of permanently taking the limited resource soil into account in the contentious area of construction and planning processes, on the basis of legally established regulation options.
The goal of the Senate Department for the Environment, Transport and Climate Protection (SenUVK) and the Senate Department for Urban Development and Housing (SenSW) is therefore to provide instruments for an active, practice-oriented land management system. This will particularly facilitate soil protection authorities in carrying out their duties as the representatives of the public interest, e.g. in the context of urban development planning, and of competently integrating aspects of soil-protection in the environmental impact assessment process.
One problem that appears regularly in planning practice is that it is hardly possible to materially compensate for the imperviousness of an area that necessarily results from construction activity. In principle, the best compensation would involve the removal of impervious coverage (de-sealing) of another area. However, due to the restrictions of availability of most land for such measures, it is difficult to find areas in Berlin where the impervious coverage may actually be removed. It is then not possible, using the Environmental Impact Assessment, to effect the realization of such measures, due to the lack of any adequate available land. Proposals for removing impervious coverage usually have a chance to be realized if areas available for having their impervious coverage removed are already known, have been checked for suitability, and are listed in a register.
An initial step was the compilation of Environmental Atlas Map Planning Advice for Soil Protection, an important planning instrument for soil protection assessment. The weighing of the various functions and sensitivities of the Berlin soils permitted a differentiated evaluation of urban development planning. For example, in the case of soils which, from a soil protection viewpoint, were classed as particularly valuable, the search for alternative sites for relevant development planning projects was recommended.
The project Potential for the Removal of Impervious Coverage in Berlin (only available in German) was initiated to improve the availability of areas for impervious coverage removal as a second step. The goal of the project is the ascertainment and evaluation of land which could potentially have its impervious coverage permanently removed in the foreseeable future. To the extent possible, the efficacy of the soil is to be restored, and habitats valuable from a conservationist point of view are to be developed for plants and animals. Moreover, the goal is to support a spatial linkage between the places of impact and the places of upgrade by means of a uniform system for the citywide recording and evaluation of areas. For this purpose, particularly the instrument of impact mitigation regulation (only available in German) is an obvious option – both with respect to construction law and with respect to conservation law.
In the context of the project phases since 2010, a survey was carried out in all Berlin boroughs, all four Berlin forestry agencies, and among private owners. The most recent update was carried out between July 2020 and December 2020. The data obtained during this survey process were compiled in a centrally administrated database, into which further information and suggestions for areas can in future continually be introduced by the various actors in the public administration.
Moreover, private landowners are to be able to not only obtain information on potential areas for the removal of impervious coverage, but also, if they wish, to propose their own areas which cannot be used for construction purposes and which, after examination for suitability, can be incorporated into the portfolio.
In order to continue to support the implementation of impervious coverage removal, a tool to derive simplified cost approaches for the expected dismantling costs has been prepared (an Excel input file simplifies the cost estimate for an impervious coverage removal measure). Based on the review of the literature, proposals for a guide to action regarding technical and qualitative standards for the regeneration of soil functions after the removal of impervious coverage have been developed (all documents only available in German).