Are you aware of the changes to guidance that have occurred over the last few years for sites affected by mining?
Coal mining affected sites earmarked for development require a Coal Mining Report and ‘Development High Risk Areas’ (http://mapapps2.bgs.ac.uk/coalauthority/home.html) also require a Coal Mining Risk Assessment (CMRA) to support the planning application. Development High Risk Areas include areas north and west of Manchester, from Nottingham to Bradford, south-eastern Bristol, Dudley and Wolverhampton, and County Durham to Newcastle, to name but a few.
The Coal Authority is a consultee in mining affected areas, so the risk assessment should comply with their publication ‘Risk Based Approach to Development Management – Guidance for Developers’. It should also be prepared by a ‘suitably qualified competent person’ who ‘holds membership of a relevant professional organisation’.
Our ground engineering team contains a number of such qualified geologists and engineers with a good understanding, and considerable experience, of mining related issues, so we can give a client an early heads up. The Coal Authority has made great strides in ensuring that their information is more easily available, for example:
- Over the last few years the Coal Authority’s website has been updated, providing access to very helpful GIS based data which our experts can appraise.
- The Coal Authority now offers a ‘Consultant’s Report’ which provides useful information beyond that provided in the conventional Coal Mining Report.
- Many of their historic mine abandonment plans are available electronically for when that extra bit of detail is needed.
Key to determining mining risks (especially ‘unrecorded’ mining) is a thorough understanding of a site’s geological setting, requiring large scale (1:10 000) geological maps to be consulted. Our London office is near the British Geological Survey where these can be inspected, and also the Geological Society which is another useful source of data.
Our engineers and geologists are familiar with the key industry document ‘Construction Over Abandoned Mine Workings’ (CIRIA Report SP32), which deals with the assessment and treatment of subsidence risks associated with mine workings and disused mine entries. This is currently being updated and our team has access to the revised draft. As well as changes to the assessment of risk, we need to be mindful of other changes to the industry. For example, as we move to greener energy and a reduction in coal fired power stations, the price of some bulk fill materials such as PFA, traditionally used to treat old mining workings, is subject to change.
Finally it should not be forgotten that not all mining is ‘up north’! CampbellReith has also facilitated developments over coal mining areas in Bristol and Kent. Not only that, but mining does not just relate to coal. We have helped clients deal with sites affected by mining in a variety of strata including chalk, salt, Weald Clay (ironstone), Northampton Ironstone and even coprolites (fossilised dinosaur dung!) to name but a few.
By Alex Dent, geotechnical associate at CampbellReith.