Whitesands Quarry is a 100ha site situated to the south-east of the town of Dunbar, East Lothian. Recognising the potential for the site to deliver for biodiversity and, in particular, wintering wildfowl and wader populations, Lafarge Tarmac and RSPB Scotland entered into an agreement to undertake an in-depth feasibility study, to explore different habitat creation options at the site.
To be determined
Potential best practice
In-depth feasibility study to determine the optimal restoration plan for the site/working with conservation NGO
A Memorandum of Understanding (MoU) was signed between RSPB Scotland and Lafarge Tarmac in 2013, which set out to devise and implement an overall strategy for the restoration of Whitesands quarry for the benefit of biodiversity and the public. Limestone was extracted from the site up until 2007, whereupon restoration works began to implement the agreed restoration scheme – originally to agriculture a multi-user ‘country park’ style designed landscape, incorporating a lake accessed by footpaths, cycle-ways and horse-trails. In 2010, post-land forming, the site was recorded as supporting a higher population of breeding ringed plovers than in the rest of East Lothian put together, leading to the RSPB and the Scottish Ornithologist’s Club approaching Lafarge Tarmac and East Lothian Council to investigate whether an amended restoration plan could be explored, focusing more on a nature conservation end use.
Opportunities identified by RESTORE
The proximity of the site to coastal, intertidal habitats supporting internationally-important wintering wildfowl and wader populations in the Firth of Forth Special Protection Area (SPA), suggests that suitable wetland habitats created at the site have the potential to attract important populations of these species in winter.
While the site had already had some restoration works undertaken, it still remained a relatively ‘blank canvas’ for an in-depth feasibility study to be undertaken, by RSPB Scotland for Lafarge Tarmac, to determine how viable the site would be for wildlife, should further restoration and habitat manipulation works be undertaken.
The project steering group was set up between RSPB Scotland and Lafarge Tarmac, which agreed the following project vision statement on 3 September 2013:
“The Whitesands Quarry Restoration Project will create a regionally important wetland ecosystem, with associated habitats, for the benefit of wildlife, people and the local economy. This work will transform Whitesands Quarry into an important site for breeding, wintering and migrant bird populations, as well as other important biodiversity.
It will provide a natural space for local people and visiting tourists to watch and enjoy wildlife and participate in nature-based tourism.
The project will demonstrate best practice in habitat creation / restoration and public engagement through an effective partnership between RSPB Scotland and Lafarge Tarmac and through regular liaison and consultation with the local community.”
Why Brackagh Quarry fitted RESTORE objectives:
The joint MOU between the RSPB and Lafarge Tarmac gave a unique opportunity to undertake an in-depth feasibility study at the site, exploring different habitat creation options. The site is of considerable size and, given its location, has the potential to deliver significant biodiversity gain if managed sympathetically. While the future of the site is still to be determined, the close working relationship between the two organisations forms a good foundation for the long-term viability of the site.
Feasibility Study report published.
The original restoration plan was for the site to be returned to its former agricultural use. However, post extraction, the stockpiled soil was found to be of a quality not suitable for agriculture. In an attempt to improve the soil characteristics, the Scottish Agricultural College was commissioned in 2007 to undertake a number of trials to examine the potential for quality compost to improve the poor-quality, replaced topsoil, sufficient for woodland, rough grazing and pasture restoration.
In addition to these trial areas, further habitats present on site include open water, native scrub, re-seeded species-rich grassland and un-seeded grassland establishment.
Our response and suggestions
Environmental data at the site was initially collated through desk studies and field surveys. This included information on the geology and soil types present on site; meteorological data (including average rainfall); hydrology for both the lake and the wider site; water chemistry, topography and bathymetry of the lake; and the habitats currently present on site. Each habitat type was then reviewed, with suggestions made as to how these could be enhanced:
Key restoration design principles
A set of key restoration design principles were initially identified for the project, which were then used to inform the land design and habitat-scoping process. These are:
- Create and maintain a complex habitat mosaic to maximise the areas of ecotonal (edge) habitat
- Allow natural colonisation to establish diverse semi-natural habitats
- Where there are opportunities to create / restore priority habitats, implement appropriate management regimes to create these
- Select and design habitats to maximise habitat connectivity and ecological coherence at a landscape scale
- Promote ecological processes (grazing, flooding, natural colonisation, immigration and emigration) to maximise biodiversity and reduce management costs
- Remove and control invasive non-native species, which cause a threat to native habitats and species
- Develop a system of spatial zoning to avoid/reduce disturbance to sensitive habitats and species
- Develop a programme of habitat and species monitoring (at appropriate spatial and temporal scales) to track the efficacy of restoration management and review restoration management accordingly.
Given the significance and the potential of the wetland features on site, further wetland-specific principles were also applied:
- Creation of bays, spits and bars and backfilling to create small islands varying in size, shape and profile in/or to maximise the interface between terrestrial and aquatic habitats
- Profile the lake margin to a shallow gradient (1:20 where possible) and backfill suitable areas around the lake margin to maximise the area of shallow water habitat
- Introduce a hydrological regime to allow seasonal flooding in winter and drawdown in spring/summer and autumn
- Increase the micro-topographical variation within the drawdown zone through the creation of shallow depressions – likely to lead to the development of emphermal lagoons for the benefit of aquatic invertebrates
- Create separate hydrological units to allow the introduction of a range of hydrological regimes and more diverse ecological conditions
- Maintain high water quality and minimise eutrophication from agriculture run-off by using bio-filtration/phytoremediation systems
- Allow arginal vegetation to develop by natural colonisation, but this should not lead to significant loss of moist muddy margins required by foraging waders.
To determine the suitability of the site for creating different wetland features within the safe minimum and maximum water level for the quarry lake (+2.6m AOD and +3.1 AOD respectively), a surface modelling software package ‘Surfer 11’ was used to assess a number of different restoration options. The most cost-effective option was determined to be a cut-and-fill construction method which minimises the importation of backfill to the site. The approach would profile shallow slopes around the lake to create 1:20 slope ratios and use the excavated material as backfill to create islands, see Figure 3 below.
How this best practice is transferable
There is a legacy of former extraction sites consisting of large, deep water bodies. This site has provided a case study of what is potentially achievable and how biodiversity features can be retrofitted at minimal cost through a carefully considered approach, aided by the use of surface modelling software.
This site is a key example of what can be achieved through partnership working. The Whitesands project has been unique, going far beyond just an advisory service, to a full rigorous analysis of what is achievable at the site that is cost efficient, and yet, will provide significant biodiversity gain, both at the local and national level. While such a close working relationship may not be practical at every mineral extraction site, it is definitely something to strive towards.
It also highlights the importance of setting up these partnerships right at the beginning of the proposed development, where appropriate. In the case of Whitesands, this would have limited the amount of retro-fitting required, saving both time and money, and potentially creating something even more innovative for nature conservation.
This report is based on the RSPB / Lafarge Tarmac Partnership report: Thornton, M. (2014) Whitesands Quarry Restoration Project – Feasibility Study. The feasibility was undertaken by Michael Thornton, with support from RSPB Scotland and Lafarge Tarmac. RESTORE would like to acknowledge the work undertaken and support given by the Whitesands project partnership.