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With over 25 years in the business Geoinvestigate has acquired considerable experience and expertise in providing Coal mining risk assessments or CMRAs for commercial, industrial and residential developments. Our clients include architects, developers, structural engineers, local authorities and home owners.
Stepping ahead, Geoinvestigate has recently developed its own “state of the art” highly specialised Microdrilling equipment enabling the company to carry out quick turnaround, safe, cost effective drilling and probing investigations of shallow coal mine workings, shafts, adits and infilled ground.
With the addition of Microdrill Geoinvestigate can now offer the whole Coal mining risk assessment package to clients from the CMRA Desk study to the hard borehole proof on what actually exists below a site. This makes sense because more often these days drilling is required in HIGH development risk areas.
Depending on the geological conditions at the site borehole depths of 15m, 20m, 25m or 30m may be appropriate.
Without a professionally competent CMRA a development will not get the go-ahead from the Local Planning Authority – essentially because planning approval will be blocked by the Coal Authority until one is provided.
Typically the CMRA is a Desk study based exercise leading to a report. The information reviewed includes the initial Coal Authority (CA) report and available geological plans, historical maps, satellite imagery, borehole records and other data.
The outcome of the CMRA is a risk assessment report which identifies the potential hazards to a development from shallow coal mining, mine entries, mine shafts (vertical entries), mine adits (sub-horizontal tunnels) and surface extraction/quarrying or open casting.
With abandoned coal workings there is also an attendant hazardous gas risk to surface development resulting from the upward seepage of toxic and explosive gases including Methane, Carbon Dioxide and Carbon Monoxide.
As coal mining can date back as far back as the 12th Century in some parts of the country there is often considerable uncertainty about whether a site is, or isn’t, underlain by very old workings which pre-date older and more modern records.
The following statement taken from a CA report highlights the uncertainty when dealing with old coal mine workings
Even where, as in this case, there was no clear evidence that a coal mining problem existed such a statement immediately casts doubt and uncertainty about the stability of the site and its safety.
Geoinvestigate’s CMRA report also provides advice on whether further intrusive investigation is required using Boreholes, trench excavations or geophysical methods to establish the depth of the workings beneath the surface or the positions of shafts or infilled ground within or adjacent to the site.
Where there remains uncertainty, as there often is, drilling is being resorted to more and more frequently to provide a conclusive outcome. This is because drilling still remains the only dependable way of proving that a site is, or is not, underlain by cavities, holes or mine workings.
Following on from this a major advantage of appointing Geoinvestigate right from the start to provide the CMRA is that we can offer a discounted price for the full Desk study and drilling package because we have developed our own in-house Microdrilling system. This enables us to safely, cheaply and quickly probe and drill mine workings to depths up to 30m and deeper.
Geoinvestigate Microdrill meets the highest safety standards set by the UK Coal Authority for the investigation of coal bearing ground and coal mine workings. This is because its small volume water injection system poses a negligible risk of igniting coal which the drill may encounter, nor is the method likely to generate hazardous gas or cause toxic or explosive mine gas to seep into adjacent buildings.
Microdrill is compact, tidy, very safe and fast and can enter most small properties and spaces.
The drill water turns black indicating an unworked coal seam lies at 12m and the site is stable
Let Geoinvestigate quote for your next Coal mining risk assessment or drilling investigation.
Please do not hesitate to contact Geoinvestigate for a quote.