Let Geoinvestigate quote for your next coal mining risk assessment (CMRA), coal mining investigation, mining report, mineshaft investigation, desk study, ground investigation, borehole investigation, site investigation, geotechnical, geo-environmental or contaminated land investigation on the South Wales Coalfield which extends across parts of Pembrokeshire, Carmarthenshire, Swansea, Neath, Port Talbot, Bridgend, Rhondda, Cynon Taf, Merthyr Tydfil, Caerphilly, Blaenau Gwent and Torfaen.
Geoinvestigate’s desk top CMRA studies unravel South Wales Coal Mining Legacy
With over 18 years in the business, several regional offices offering a nationwide service, highly qualified and experienced technical professional staff, and its own drilling equipment, Geoinvestigate is best placed to give the most competitive and professional coal mining investigation service in South Wales .
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The following article gives a brief background to mining activity in the South Wales Coafield and the services Geoinvestigate provide to enable house buyers, home owners, developers, architects, surveyors and engineers both to buy to build safely in respect of the regions coal mining legacy.
The South Wales Coalfield
The South Wales Coalfield extends across parts of Pembrokeshire, Carmarthenshire, Swansea, Neath Port Talbot, Bridgend, Rhondda Cynon Taf, Merthyr Tydfil, Caerphilly, Blaenau Gwent and Torfaen.
It comprises a fully exposed synclinorium with a varying thickness of “coal measures” (Upper Carboniferous / Pennsylvanian) deposits with thick, workable seams in the lower parts and generally thinner and sparser seams in the upper parts, together with a development of sandstones (Pennant Sandstone). See also the Geology of South Wales. These sandstones have been much used in building construction (including the characteristic terraces of former miners’ houses) and give rise to bleak uplands rising 300–600 metres above sea level between the steep-sided valleys in which most deep mines were developed.
The coal generally increases in grade or “rank” from east to west, with bituminous coals in the east, and anthracite in the west. The Rhondda Valley was particularly known for steam coals which fueled steamships of the 19th and early 20th centuries.
Exploitation of the Coalfield
Communications along the valley floors provided the main routeways for exporting coal south to ports and docks such as Newport Docks, Cardiff Docks and Barry Docks. Early activity was mainly by levels or adits driven into coal seams from outcrops in the valley sides. Development of the coalfield proceeded very actively from about 1850, when deep mining become significant in the previously entirely rural Rhondda Valley. Tramway-fed canals such as the Swansea Canal and Glamorganshire Canal were supplemented, and then superseded, by the development of numerous competing railway branches which fed docks principally at Swansea, Cardiff, Newport, Llanelli and Barry. These towns grew dramatically as a result. Later colliery shafts were sunk as deep as 800 Yards (732 Metres) in order to reach the thicker, better quality seams.
The coal industry suffered many serious mining accidents, which included Britain’s worst at Senghenydd, claiming 439 lives, and others at Abercarn, Risca, in the Rhondda Valleys, in the Cynon Valley, Tondu and Aberbeeg, culminating in the Aberfan disaster. Some collieries, e.g., Morfa Colliery, near Port Talbot, Glamorgan, and Black Vein Colliery, Risca, Monmouthshire, each suffered at least three disasters before their closure on safety grounds.  The main problem was firedamp explosions, often followed by ignition of airborne coal dust.
Crowd gathering at the pit head of the Senghenydd Colliery in October 1913
Iron ore was also extracted from the coal measures, principally from the north crop area (including Merthyr Tydfil and Blaenavon). The availability of coal and nearby limestone (as a flux) gave rise to a substantial local iron and steel industry which was perpetuated in the 20th century by the location of modern steelworks at Ebbw Vale, Newport and Cardiff and Port Talbot. These used imported iron ore.
New collieries, particularly in the western part of the coalfield where anthracite is found, were developed into the 1960s by the National Coal Board (for instance, Cynheidre Colliery No 1 shaft, at 798 yards (730 m) deep was sunk in 1954/6). Following the general collapse of the UK coal industry, most pits closed during the 1980s and the last deep mine, at Tower Colliery on the north crop, ceased mining in January 2008. However, a few small licensed mines continue to work seams, mostly from outcrop, on the hillsides. Although some areas of the coalfield are effectively worked out, considerable reserves remain. However, geological difficulties make the cost of significant further extraction high. The coalfield experienced a late-stage development when opencast mining was commenced on a large scale, mostly on the gently-dipping north crop. Most of the old sites have been filled and landscaped, but new operations continue.
Borehole Investigation of Shallow Coal Mining
Over the past 6 months Geoinvestigate’s new compact microdrill system has proven its worth and that it’s just the answer for investigating Nottinghamshires coal mining legacy. Microdrill offers restricted access, small diameter rotary open-hole drilling which is first and foremost SAFE, fast, clean, quiet, cost effective and environmentally friendly. New Microdrill has been designed for probing for shallow workings in limestone, sandstone and coal as well as locating mine shafts and sinkholes.
New Microdrill reaches the places other rigs cannot get to
Recently Microdrill was in action in Newcastle on the Northumberland Coalfield. Having previously obtained a coal drilling permit from the Coal Authority to drill with small volume water injection flush Microdrill was delivered to site on the back of a standard flatbed trailer.
Shallow mine working investigation of a housing estate in Newcastle
Access to the drilling positions in several gardens was tricky but achievable with Microdrill.
In accordance with Coal Authority Guidance on Managing the Risk of Hazardous Gases when Drilling or Piling Near Coal (essentially a Code of practice for safe drilling and piling through coal) Microdrill new small volume water injection system was in this instance considered to be the safest flushing medium.
Potential gas emission hazards arising when drilling into abandoned coal mine workings
This is because there was assessed to be an unknown or undetermined gas risk as is so often the case in exploratory drilling works on the UK coalfields.
New Microdrills small volume water flush injection system is by far the safest way of drilling mine workings
The Coal Authority normally stipulates small volume water injection flush for their internally managed exploratory drilling works because it ensures minimal risk to the public from hazardous gases including carbon dioxide, methane and carbon monoxide. In fact it is rare under the Coal Authorities strict safety policy for drilling through coal for them to permit anything else but water.
Probing for shallow mine workings and coal in Newcastle Microdrill on it’s 50th job in Newcastle
The Coal Authorities strict policy with regard to water flush is something to be considered by site investigation companies when compiling a Coal Mining Risk Assessment (CMRA) or drawing-up a source-pathway-receptor based risk assessment for drilling permit application.
High pressure small volume water injection makes Geoinvestigates New Microdrill system safest
It should also be borne in mind by drilling contractors and consultants that the CA polices drill sites checking some 10% of drill sites per year to ensure compliance with the permit. A change in drill flush from that originally agreed with the CA would be a breach of terms and conditions and could result in prosecution.
Geoinvestigate’s New Microdrill working through the night on a coal mining investigation
New Microdrill has been demoed to the CA who gave it their nod of approval suggesting that in their opinion it was easily capable of reaching 50m and much deeper though up till now it has only been tested to 30m which is typically the limit of interest for shallow mining investigation.
Coal at 11m depth turns drill water black indicating the seam is intact and the ground is stable
Geoinvestigate carrying out a contaminated land site investigation and gas survey in Hartlepool
If you require a coal mining investigation, Phase 1 desk study, coal mining risk assessment (CMRA), Phase 2 intrusive site investigation, geotechnical investigation, ground investigation or you need a contaminated land survey or landfill gas survey, trial pitting or borehole drilling please do not hesitate to contact one of our regional offices. Our team are only too happy to assist with your enquiry and will ensure that you get our most competitive quote.