The Small Sites Metric (SSM) is a biodiversity assessment tool tailored specifically for smaller developments. Introduced as part of efforts to maintain ecological balance in development projects, the SSM allows for straightforward biodiversity calculations on small sites. However, there are several important restrictions governing its use. This article explores the criteria for when and how the SSM can be applied, and the circumstances under which an alternative tool may be required.
What Qualifies as a “Small Site”?
The SSM is designed for use on “small sites,” as defined by the Town and Country Planning (Development Management Procedure) (England) Order 2015. This definition excludes developments classified as “major.” So, how do you know if your site qualifies as a small site? It must meet the following conditions:
Residential Development:
The development consists of 1 to 9 dwellings, and the total site area is 1 hectare or less.
If the number of dwellings is unknown, the site area must be less than 0.5 hectares.
Commercial Development:
The total floor space created is less than 1,000 square metres, or the site area is less than 1 hectare.
Other Development:
The development does not involve the extraction of minerals (e.g., mining) or land designated for mineral working. The project is not related to waste management activities.
If your development meets the criteria of a “major” project, you cannot use the SSM. Instead, the Statutory Biodiversity Metric Calculation Tool (SBMCT) must be employed.
Additional Criteria for Using the SSM
Even if your project is classified as a small site, additional conditions need to be met for the SSM to be applicable:
Habitat Restrictions:
The SSM can only be used if the site contains habitats that are included in the SSM. If the site contains other habitats, such as riparian zones, the SBMCT must be used.
Priority Habitats:
If your site contains priority habitats, the SSM cannot be used. However, some medium distinctiveness habitats, like certain hedgerows and arable field margins, are included in the SSM.
Protected Sites and Species:
The site must not include statutory protected sites or habitats. European protected species must not be present on the site.
Flexibility and Professional Advice
Even if all the above criteria are met, using the SSM is not mandatory. Developers always have the option of using the SBMCT instead. In some cases, the proximity of protected areas can also influence whether the SSM is appropriate. If your site is within 500 metres of any statutory protected sites or priority habitats, you should consult with an ecologist.
In such cases, even if you proceed with the SSM, a warning flag will appear to highlight the potential risks, and a section of the SSM report must be completed accordingly.
Important Guidelines for Using the SSM
Developers should note that only one biodiversity metric tool—either the SSM or SBMCT—should be used for the on-site biodiversity calculation. It’s not permissible to combine both tools for different parts of the site.
If any part of the development requires assessment using the SBMCT (due to the presence of specific habitats or species), then the entire site must be assessed using the SBMCT.
Conclusion
The Small Sites Metric (SSM) provides a simplified approach to biodiversity calculations for small-scale developments. However, strict guidelines must be followed regarding its use. The SSM is suitable for smaller residential and commercial projects but is not appropriate for sites containing certain habitats or species.
Developers should carefully assess whether their site meets the criteria for using the SSM and, when in doubt, consider consulting an ecologist or opting for the more comprehensive SBMCT. By adhering to these restrictions, developers can ensure that their projects comply with biodiversity regulations while supporting the protection of local ecosystems.