Planning Advice for Soil Protection 2020

Methodology

Differentiated Assessment of Soil Functions

To address the dual objectives of developing a nuanced assessment of soil functions, and translating this evaluation into Planning Advice, Map 01.13 implements the following considerations and steps:

Initially, soil functions, as represented in (Maps 01.12.1 through 01.12.5) are assigned varying weights. The weighting is based on their significance within Berlin’s specific conditions, as detailed in the documentation of the Berlin State Soil Database (available only in German):

• It is extremely important to protect soils that serve as archives and those capable of supporting near-natural or rare plant communities due to their irreplaceable nature.
• It is generally important to protect soils that are highly capable of regulating the water balance and providing buffering and filtering functions. This importance increases in locations where both functions receive a ‘high’ rating.
• Soils with a ‘high’ yield function for cultivated plants should be preserved in agricultural areas.

This sets a priority based on the importance and vulnerability of soil functions.

Moreover, soils with considerable potential for material contamination, such as those found in sewage farms, are excluded from the evaluation. This is because they may be compromised in their natural functions, including regulating, filtering, buffering, and their capacity to support cultivated plants. These soils pose a potential contamination risk to groundwater and the food chain.

To gauge the soil’s level of protection needed, five protection categories have been established, ranging from the highest to the lowest level. These categories help provide guidance and recommendations on how to actively address soil interventions resulting from planning and construction projects.

The level of protection for soils is represented by the following categories:

• highest protection level,
• very high protection level,
• high protection level,
• medium protection level and
• low protection level (soils without additional requirements).

All information and assessments presented here relate to soils without impervious cover, consistent with the other soil topics of the Environmental Atlas (except for that of impervious soil coverage). The extent of impervious coverage is of great importance, however. Its degree is therefore not only presented as part of the factual data but also reflected in the colour. There are three different colour shades; as impervious coverage decreases, the colour intensity of the protection category also decreases.

Impervious coverage thresholds of 5 % and 30 % were adopted. Areas falling into the category of 5 % or less are considered to be effectively without impervious cover, interrupted only by scattered buildings, pathways etc. This category includes forests, farmland as well as meadows and pastures. Areas with impervious coverage between more than 5 % and less than 30 % fall into the ‘moderate’ category, comprising allotment gardens, single-family homes, park facilities and other open spaces, which may still feature near-natural soils. Impervious coverage exceeding 30 % is primarily found in residential and commercial areas as well as in traffic areas, where natural soil associations are largely absent.

Highest protection level

This category is assigned when either the ‘habitat function for near-natural and rare plant communities’ and/or the ‘archival function for natural history’ receives a ‘high’ rating.

This highest protection level covers only approx. 5 % of the evaluated area. Careful consideration should be given in potential planning processes to explore alternative sites and avoid interventions. This is because restoring the habitat function for near-natural and rare plant species is challenging, and the archival function for natural history cannot be restored (Smettan and Litz, 2006). Therefore, projects or initiatives involving interventions in soils with the highest protection level, which cannot be avoided, should only be approved in consultation with the soil protection authority (Leitbild und Maßnahmekatalog (Catalogue of models and measures), 2021, only in German).

Fig. 1: Categorisation process for the ‘highest protection level’

Very high protection level

The ‘very high protection level’ is assigned based on the following criteria:

1. Both the ‘habitat function for near-natural and rare plant communities’ and the ‘archival function for natural history’ receive ‘moderate’ ratings, or
2. the ‘yield function for cultivated plants’ is rated as ‘high’ on areas with agricultural use (farmland, meadows and pastures or tree nursery/ horticulture), or
3. both the ‘water regulation function’ and the ‘buffering and filtering function’ receive ‘high’ ratings.

Most areas in this protection category are classified as such due to their habitat and archival function, while a smaller portion is designated for their regulation or buffering and filtering function. Very few areas are classified based on the yield function for cultivated plants.

For areas with a ‘very high protection level’, interventions should be avoided from a soil protection standpoint, or suitable alternative sites should be sought in accordance with other requirements. Moreover, a net loss of soil without impervious cover and soil functions are not permissible.

Fig. 2: Categorisation process for the ‘very high protection level’

High protection level

The ‘high protection level’ is assigned when either the ‘water regulation function’ or the ‘buffering and filtering function’ receives a high rating.

The protection level is lower here compared to the ‘very high protection level’, as fewer soil functions are affected in this category. Only one criterion (either the water regulation function or the buffering and filtering function) is rated as ‘high’. Despite the lower protection level, efforts should still be made to avoid or compensate for any net loss of land and soil functions, in consultation with the soil protection authority (Leitbild und Maßnahmekatalog (Vision and Catalogue of Measures), 2021, available only in German).

Fig. 3: Categorisation process for the ‘high protection level’

Medium protection level

The ‘medium protection level’ is assigned when both the ‘water regulation function’ and the ‘buffering and filtering function’ receive ‘moderate’ ratings.

The moderate capacity of these functions may be improved through technical measures, such as retaining rainwater or choosing a soil cover that allows for water and air permeability. The goal is to work with the soil protection authority to avoid a net loss of these functions and to minimise any net loss of land (Leitbild und Maßnahmekatalog (Vision and Catalogue of Measures), 2021, available only in German).

Fig. 4: Categorisation process for the ‘medium protection level’

Low protection level (soils without additional requirements)

The remaining soils are classified as having a ‘low protection level’.

Only the general legal requirements for soil protection apply here without any additional specific requirements. These general requirements are outlined in the Federal Soil Protection Law of 1998 (BBodschG), the Federal Soil Protection and Residual Waste Ordinance of 1999 (BBodSchV), the Berlin Soil Protection Law of 2004 (Bln BodSchG), the Building Code of 2017 (BauGB), and the Vision and Catalogue of Measures of 2021 Leitbild und Maßnahmekatalog (Catalogue of models and measures), 2021, available only in German) apply.

Fig. 5: Categorisation process for the ‘low protection level’

Fig. 6: Area [ha and %] by soil protection category and degree of impervious coverage (excl. streets and bodies of water)

Fig. 7: Total area [ha] and actual area [%] without impervious cover by soil protection category

Fig. 8: Area [%] by land use, categorised by soil protection level

Tab. 1: Area balance of the soil protection categories (excl. streets and bodies of water)

Advice for Implementation in Planning Practice

The planning advice for soil protection outlines the essential requirements and guidelines relevant to each soil protection category. While primarily geared towards development planning, their principles can also be adapted for other spatial projects and planning endeavours. For methodological reasons, the map legend presents a simplified version of the advice. More detailed information for each specific area is available in tabular format through the factual data display of the FIS Broker. Terms used here, such as ‘avoidance’ and ‘compensation’ are not legal terms but rather directives pertaining to soil protection. It is important to note here that the evaluated soil functions only consider those parts of the blocks that are without impervious cover.

The factual data display includes the soil protection category, the soil association and land use underlying the assessment, the ratings for each of the five soil functions (from Maps 01.12.01 through 01.12.05) as well as the degree of impervious coverage. The planning requirements table, however, which is available for each individual area, is particularly useful.

Structure and contents of the planning requirements table:

• Row 1 states the soil protection category.
• Row 2 describes the overall soil protection goal.
• Row 3 summarises the classification criteria (cf. Methodology, first section). The information in the rows that follow are based on these key soil functions.
• Row 4 details avoidance and reduction measures that should generally be pursued. It does not differentiate between avoidance and reduction since their distinction might vary depending on the context and the perspective of the parties involved. The main focus is on preventing interventions in soils that need to be protected rather than getting caught up in semantic differences.
• Row 5 offers suggestions for compensatory measures, ideally tailored to specific functions. Initially, it mentions requirements that can be conditionally imposed based on Building Code (BauGB) regulations.
• Row 6 may include additional measures, from a soil protection perspective, to address significant impacts on soil functions.
• Row 7 contains other relevant notes or explanations.

Tab. 2: Example of a planning requirements table in the Geoportal Berlin