Mining Stability

Green Cat Renewables (GCR) has extensive experience in the assessment of mining and mineral stability.

An increasing number of turbines are now being erected closer to urban centres. Many of the industrial towns in the north of the UK are located in areas with a long history of mining, dating back hundreds of years, sometimes to medieval or even Roman times. Since it was not until the late 19th Century that it became compulsory to survey mines on abandonment and lodge the plan with any government depository, many past workings are not recorded. For this reason a ‘Coal Authority appraisal’ is not sufficient even if it states that there are no recorded workings.

Whether the workings are recorded or unrecorded, it is essential to consider the stability of any workings under a turbine not just from the static point of view, familiar to those dealing with housing, industrial units, roads, etc., but also from the dynamic point of view, which requires a more in-depth knowledge and experience than is otherwise the case.

Some risks with respect to the mineral stability of a site are potential ‘showstoppers’. For example, if a mine shaft is located under or within influencing distance of the proposed turbine, then construction of the turbine at that position will normally not be practicable. Moving the turbine position at an early stage of planning is not usually a significant issue.

However, if this proves necessary late in the process, then problems leading to significant issues, costs and delays can occur if the planning application has to be amended to allow this.

Shallow workings may need to be grouted or the foundation loadings taken below the worked horizon. Either option will incur significant cost and may impact the financial viability of a scheme. It is therefore important that developers have a reasonable understanding of the risks before they approach potential funders.

GCR has significant experience in the assessment of mining issues:

• Desk studies to assess the risk to the development with respect to various types of mine workings to form a  preliminary opinion and to design any site investigation needed.
• The investigation of shallow recorded or unrecorded mine workings by drilling.
• The safe site investigation of mine shafts and adits (‘drift’ mines).
• The assessment of the static and dynamic stability with respect to turbine development in terms of: shallow past workings, current workings, steep seams, mine shafts, mine adits, mine gases and hydrogeological implications.

GCR can also design and supervise remedial works to cope with mineral stability issues to allow development to proceed. As always with regard to development, it is imperative that potential issues are identified and assessed realistically at an early stage in planning in order that the implications are fully understood, costs minimised and full advantage taken of any opportunities to make significant savings.