The quarry has been worked since just after the 1st World War, but Tarmac Ltd acquired the site in 1980 and in 1990 installed a new plant to produce crushed aggregate. The quarry was then acquired by J Suttle Transport in January 2011. To date c 20 million tonnes of stone have been produced, with 95% sold to within a 35 mile radius of the site.
Case study date
2014
Size
48.60ha
Location
Worth Matravers, Dorset
Operator
J Suttle Transport
Mineral Planning Authority
n/a
Mineral Type
Crushed Limestone
Habitat(s) Created
Calcareous Grassland
Restoration / Priority Habitats
Calcareous Grassland
Partnership Working
J Suttle Transport (previously owned by Tarmac)
Key Issues
Revision of permissions to enhance priority delivery
Adjacent SSSI habitat
Experimental approach to developing suitable natural seed mixes
Ongoing monitoring to ensure success
Public Benefits
Local community access to nature
Biodiversity
Background
The quarry has been worked since just after the 1st World War, but Tarmac Ltd acquired the site in 1980 and in 1990 installed a new plant to produce crushed aggregate. The quarry was then acquired by J Suttle Transport in January 2011. To date c 20 million tonnes of stone have been produced, with 95% sold to within a 35 mile radius of the site.
The western edge of the quarry is contiguous with the South Dorset Coast SSSI, which holds the majority of Dorset’s unimproved limestone grassland, with a nationally important population of wild cabbage Brassica oleracea and geological interests. The site is also only 400m to the north of Worth
Matravers village, and a local liaison and Restoration committee meeting annually.
Planning
Only in 1994 was a planning requirement made for restoration plans. The original restoration scheme included a series of different habitats, although calcareous grassland was the main habitat, other parts were to be restored to woodland and to agriculture. Swanworth submitted a variation to the permission to extend extraction to June 2017, instead of 2010 and in 2011 submitted an improved restoration plan.
The new plans will:
- Restore a higher proportion to priority limestone grassland habitat
- No longer restore back to agriculture
- Reduce the extent of woodland creation
Habitat creation details
The restoration of limestone grassland began in 1997. A project to determine the best means of creating high quality limestone grassland evaluated several different aspects: seed mixes, sowing rates, substrate preparation, seed sourcing and natural regeneration.
The research informed the restoration scheme by identifying that it was not necessary (and could be counter-productive) to import top soil, instead;
- Incorporating waste crushed limestone from the quarry is a good base for the habitat
- Ameliorated top soil fertility is critical to success (high fertility encourages coarse grasses that would replace the desired vegetation).
The work also assessed the use of local seed versus imported seed, with some evidence that being locally adapted local plants survived better. (Smith, Diaz, Winder and Daniels 2005 The effect of provenance on the establishment and performance of Lotus corniculatus L. in a re-creation environment Biological Conservation 125-1 pp37-46)
The limestone grassland restoration on the site is being undertaken in a four phases over the life of the quarry. The phases were designed to fit into the extraction of the stone, so as extraction moved to the next area or phase, the previous area was started to be restored. Phase one was completed in the first two years of the permission and the 2nd phase is now 90% complete.
Phase two was sown in 2004 with seed brush-harvested (a technique usually using specialist small-scale machinery which collects seed without damaging the donor habitat) from limestone grassland managed by the National Trust. Seed was collected in late summer and early autumn after flowering, but before seeds are shed from the plants.
Originally woodland creation was included in the submitted restoration plans. Although some trees have been planted, the new restoration plans have switched some of the areas originally designated for tree planting to limestone grassland, which will make a large contiguous area of a priority grassland habitat, with an ample seed source to continue the natural regeneration.
Stepwise approach to creating limestone grasslands at Swanworth Quarry
Management
The restored grassland is being grazed by sheep on a low intensity regime which began in 2005, to allow the species richness to develop and be maintained. It is proposed to put cattle on in the winter of 2010/11 to help to disturb the grass sward and litter, to provide gaps for new plants to colonise, and to graze down the grasses and herbs to prevent a thatch developing. As calcareous grassland dependent biodiversity is best served by a relatively short sparse grass sward, it is important that grazing is sufficiently intensive to generate this structure. However with the relatively small area and the need to fence cattle out of the active quarry, it is difficult to attract graziers (Smith, pers. comm.)
Contractors have been used on the site to control the growth of scrub and especially buddleia on the restored site.
In the long term, management will be one of different grazing regimes and scrub management. Once the after-care period finishes it is proposed that the site will be taken on by a nature conservation organisation.
Monitoring
Vegetation has been monitored since the start of the original experimental restoration on the site. In total 157 species of plant have been recorded, and the sown species richness on the experimental plots has been maintained since 2000.
Invertebrate diversity on the restored areas of Swanworth is high, with in a 2007 5 nationally notable species being recorded, including Lulworth skipper Thymelius action and six-belted clearwing Bembecia ichneumoniformis.
Issues
Geodiversity is important in the restoration because the whole Portland Stone and Purbeck succession is visible. The operating company aims to leave some faces exposed to so that the geodiversity can be studied, where safety permits.
Meanwhile, the local community of Worth Matravers wish to see some quarry infrastructure retained in place for some low scale industrial use, as an economic benefit to the community. However as it is not part of the approved restoration and aftercare plans it is being consulted on.
Public benefits
It is intended that when fully restored there will be public access through the site, with 2km of new footpaths to link and complement the current ones. Meanwhile, Swanworth used to hold open days for the public on the site every year, until interest waned from the locals. Now opendays are held as and when a new milestone is reached or when the local liaison group make a request. Swanworth was receiving around twenty and thirty schools visits per year, but following the foot and mouth outbreak and schools being more reluctant due to health and safety concerns, this number dropped significantly. School tours can still be arranged by contacting the site office.
Acknowledgements
With thanks to Barbara Smith, researcher and Derek Haddon, quarry manager for their cooperation and information supplied.
The information set out within this advisory sheet in no way constitutes legal or regulatory advice and is based on circumstances and facts as they existed at the time Nature After Minerals compiled this document. Should there be a change in circumstances or facts, then this may adversely affect any recommendations, opinions or findings contained within this document