The directors yesterday agreed upon a contract with the British Geological Survey, to conduct quarry site assessments on Westray. Once completed the Trust will share the information with it’s members and broader community.
The contract is commercial sensitive, so therefore the Trust is unable to publicly disclose the full details however the following is a summary of the intended work.
(i) Conduct an assessment of 3-4 sites identified as potential resources of natural stone on the Isle of Westray. Those site(s) identified as the most prospective will be studied in greater detail. The assessment will be based on examination of rock exposed at the sites, as well as borehole cores and records, if available(note 1). The following will be assessed:
- stone character and stone variability
- fracture distribution and the effect of fractures on the size and shape of extractable blocks
- estimates of the volume of recoverable stone and overburden at the sites
- geological features that have the potential to limit quarry expansion or increase the waste ratio
A number of representative samples will be collected from potential resources for analysis and characterisation.
(ii) Conduct a comparison and assessment of the quality of the sampled natural stone for a range of purposes, including dimension stone, walling stone and as crushed stone for farm tracks.
This will include petrographic analysis as well as geotechnical testing of representative samples. The programme of geotechnical testing will be conducted by a third party (a well-reputed testing house) who specialise in lab-based test methods(note 2). Test results will be interpreted by BGS. Results will be compared to those from materials currently imported to the island for building purposes to allow a cost-benefit analysis to be conducted by the client.
(iii) Prepare a report describing the outcomes of (i) and (ii).
Advice will be given on potential uses of the stone, its durability, and on appropriate methods for extracting and storing stone.
The price quoted below includes the cost of a member of staff spending five days on Westray to examine the quarries and conduct representative sampling for material characterisation.
The price also assumes that assistance will be offered by Westray Development Trust for the following:
1) Transportation of BGS staff and equipment between sites on the island during the visit
2) Shipping and/or provision of suitable tools for quarry sampling
3) Shipping of samples to BGS and test labs (up to 100kg. of material may be required)
4) Co-ordinating landowner permission for access and sampling of the sites
If you have any questions relating to the quarry assessment, then please do not hesitate to contact Andy on 01857 677858