Mineworkings & Mineshaft Treatment

The company has been involved in the stabilisation of old shallow mine workings from surface for over 30 years. Forkers is considered a specialist in this field and is in the unique position of being able to resource large mine workings treatment schemes from its in-house labour and plant resources.

Our capability and experience includes:

• Treatment of shallow coal, ironstone, chalk, sandstone and fireclay workings generally up to 60m deep
  
• Infilling of limestone workings up to 150m deep
  
• Major shallow coal workings treatment contracts with over 10,000 drill holes, up to 250,000 tonnes of grout,26 treatment grids and working over distances up to 26 km
  
• Bulk Infilling of open workings with pfa/cement paste, sand, gravel and crushed stone
  
• Grouting of collapsed workings with pfa/cement grout, sand/cement grout, clay (bentonite) based grouts and use of thixotropic or polymeric additives
  
• Infill quantities of up to 700,000 tonnes
  
• Pumping mixed infill materials up to 3000m to injection points
  
• Infilling both dry and flooded mine workings including dealing with artesian water conditions
  
• Creation of infill barriers in mines and roadways up to 15m in height by installation of materials from surface through large diameter cased boreholes including gravel, crushed stone, sand, concrete
  
• Creation of barriers to treatment grids in collapsed working
  
• Location and treatment of mine shafts up to 1000m deep and sites with over 100 shafts including, probing, filling open shafts with granular material, proving shafts, stage grouting, use of drilling platforms, grout caps and reinforced concrete caps

The company operates 30 rotary and rotary percussive drilling rigs and has resourced up to 20 drilling rigs on individual sites. Specialist ‘dual head’ rigs allow simultaneous drilling/casing methods to drill unstable ground or to provide accurate, one pass fully cased holes up to 375mm dia and 350m deep for any function. Additionally all our rigs are now equipped with interlocked drill string guards as required by the HSE.

We can offer a wide range of drilling methods including ‘top hammer’ rotary percussive, down hole hammer, eccentric drilling systems, rock roller and pcd’s. A range of flush methods are also used including air, high pressure air, water, air/water mist, foam, grout, polymers and muds. In addition our drilling rigs are equipped with sophisticated cuttings collection systems which also allow configuration for wellhead blow out prevention and gas protection. Mini rigs are available for use in areas of difficult access or size/weight restriction.

We have available a wide range of grout mixing and pumping plant for mineworkings treatment schemes, much of which are bespoke items designed and manufactured in-house, including;

• Grout mixing equipment from 0.5m3 including high shear mixers for clay based grouts
  
• Computer controlled continuous batching plants with outputs of up to 150m3/hr which are used for both bulk infilling schemes and also for central batching on large mine workings treatment sites which ensures control of deliveries, quality, and environmental risks, reduction of material storage and access requirements
  
  

• Automated and completely sealed/dust free grout batching plant up to 30m3/hr for specialist or sensitive situations
  
• Mobile, hydraulically operated grout agitation/pumping units which can be strategically placed or moved as work proceeds, outputs up to 100m3/hr
• Full range of grout pumping and monitoring equipment including Gardner-Denver grout pumps and high output trailer mounted concrete pumps (electrically operated) which have enabled grout infill materials to be pumped up to 3000mwith stage pumping units
  
• Establishment of conveyor systems to transport granular infill materials in sensitive or inaccessible locations