Invertebrate Survey and Compensation at Brownfield Quarry Site in Derbyshire

Background

BSG Ecology undertook detailed invertebrate survey work and resolved statutory consultee concerns regarding the re-development of a large brownfield site in the Borough of Chesterfield, Derbyshire. Our ecological support informed a planning application to the county minerals authority for mineral extraction and subsequent restoration of the site.
The site comprises a 26 ha parcel of land made up of disused former foundry tips, industrial plant, and a partially restored former deep mine tip, overlain by up to 7 metres of made-up ground. The majority of works on-site ceased over 20 years ago, since which time the site has developed a mixture of grassland and open mosaic habitats, supporting a diverse mix of botanical and invertebrate communities.

The presence of a range of notable invertebrate species within the site was a key consideration in the re-development of this site. Robust invertebrate baseline information was therefore required to accompany the planning application, and to inform the mitigation/compensation approach for notable invertebrate species and assemblages at an early stage in the planning process.

BSG Ecology’s Role in the Project

dingy skipperThe site supports a complex mosaic of brownfield habitats[1]. The desk study revealed records of the presence of invertebrate Species of Principal Importance[2] within the locality, including dingy skipper from within the site boundary, associated with the former tips.

The invertebrate survey methodology was specifically designed and tailored to sample the key terrestrial habitats within the development site. Visual assessment of the habitats and sampling of the invertebrate community was completed initially in order to assess habitat quality. A range of survey techniques was used to subsequently target key invertebrate groups and habitats. Terrestrial invertebrate survey work was completed in May and June 2011, in order to coincide with the flight period for dingy skipper.

The survey identified 259 species, four of which were Species of Principal Importance, including dingy skipper, and 15 species which have Red Data Book (RDB) Nationally Scarce[3], Threatened or Near Threatened[4] conservation status. Many of the invertebrates recorded are known to be highly mobile species, some of which are early colonisers of pioneer habitats.

In total, approximately 8ha (30%) of the site was assessed as providing high quality invertebrate habitat, in particular open mosaic vegetation and grasslands occurring on the former tips. Without mitigation and compensation for the anticipated unavoidable losses, county-level impacts were anticipated on the invertebrate assemblage as a result of the development.

Design Solution for On and Off Site Mitigation and Compensation

Limited on-site avoidance and compensation was possible as part of the scheme design due to the uneven and unstable terrain of parts of the site supporting the key invertebrate assemblages, and the nature of the proposed works. Taken together, this meant that retention of the majority of the habitats associated with the former spoil heaps in-situ was not viable. The long-term storage of topsoil in order to replace habitats following the restoration of the site was also not an option, as the majority of the seeds for the plant species recorded at the site have a longevity of less than five years, and a high proportion less than one year[5]. As such, it was considered that the habitats at the site would not successfully re-establish following a period of storage and, as a result, the majority of notable invertebrates would be unlikely to persist, leading to a significant overall reduction in invertebrate species populations and diversity.

Off-site ecological compensation options were considered necessary in order to reduce the impact of the development on notable invertebrate species and the invertebrate assemblages. The client’s commitment to secure and deliver long-term management led to the identification of three receptor sites nearby within their landholding. Baseline survey work undertaken by BSG Ecology confirmed the sites’ suitability to provide compensation for invertebrates, which could be achieved through habitat translocation, creation and/or management. The principal benefit of off-site compensation areas was their immediate availability; the translocation and creation of habitats would provide the opportunity for early colonisation of flora and invertebrate fauna in the compensation areas whilst the existing habitats were still in-situ.

The final solution involved the delivery of mitigation, compensation and enhancement measures for the development across four sites: retained and / or enhanced areas of the development site and three off-site receptor sites, all set within 1.2km of the development site.

Detailed consultation was undertaken with the client team, Natural England (NE), Derbyshire Wildlife Trust (DWT) and Derbyshire County Council (DCC). Working closely with our entomologist and the landscape architects, the receptor site layouts were designed and Method Statements were prepared to describe the habitat translocation and/or creation works required to establish the habitats, as well as identify their on-going management requirements. The timing of the habitat translocation required careful planning so as to ensure that the appropriate stages of the invertebrate life cycles would be captured as part of the process.

It was agreed with consultees that the measures proposed would result in a net gain in good quality invertebrate habitat . As a result of the proposals, anticipated residual impacts on invertebrates were assessed as being neutral.

Outcome

DCC resolved to approve the minerals application with conditions and accompanied by a Section 106 obligation. Chesterfield Borough Council subsequently approved the application for the creation of development platforms for industrial uses. No objection was sustained from DWT or NE as a result of the range of measures proposed.

Whilst the proposals do not allow the retention of the mosaic of habitats in one single unit, the combination of on and off-site measures are considered to accord with the provisions of the NPPF to “minimise impacts on biodiversity and provide net gains in biodiversity where possible” with the aim to “establish coherent ecological networks that are more resilient to current and future pressures” through the long-term positive management of these sites (which will be secured by a Section 106 obligation).

The legacy of the development will be the creation of a number of high quality habitats at sites that will be positively managed for biodiversity that are well connected within the local habitat network.


[1] A number of habitats are Habitats of Principal Importance under the provisions of the Natural Environment and Rural Communities (NERC) Act 2006.

[2] Under the provisions of the NERC Act 2006.

[3] Shirt, D.B. (1987). British Red Data Books:2. Insects. Nature Conservancy Council, Peterborough. These status categories and criteria were introduced for British insects by Shirt (1987) and received some modifications by later authors (e.g. Hyman and Parsons (1992)).

[4] IUCN (2001) Red List Categories and Criteria: Version 3.1 These later status categories and criteria are based on IUCN Red List Categories and Criteria version 3.1 (IUCN, 2001) and have been applied to British butterflies, dragonflies and a few other invertebrate groups.

[5] Ecological Flora of the British Isles (2012) http://www.ecoflora.co.uk/

Invertebrate Survey and Compensation at Brownfield Quarry Site in Derbyshire – Project Profile

 

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