Greenhalgh & Co.

Chartered Building Surveyors & Valuers

 

boltonsurveyors.org.uk

Greenhalgh & Co.

Chartered Building Surveyors & Valuers

21 Towncroft Lane

Bolton  BL1 5EN

Tel: +44 (0)1204 845382

Fax: +44 (0)1204 433968

Email: greenhalghco@btconnect.com

 

RICS Company No. 002973

 

Mine workings

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Mining Risk Assessment

 

Mining Risk Assessment is relatively new requirement for planning applications.

 

Between the 23rd June 2015 and the 3rd July 2015 the Coal Authority published a series of maps.

 

These maps are collectively referred to as Coalfield Plans for Local Planning Authority areas and are freely available on the internet and can be found at: https://www.gov.uk/government/collections/coalfield-plans-for-local-planning-authority-areas#coalfield-local-planning-authority-plans

 

These maps, along with the Coal Authority interactive map viewer give details of mining risk areas.

 

In essence areas of shallow coal workings, probable shallow coal working, mine shafts and coal crops, are considered the main potential risk area.  The risk primarily stems from the potential of subsidence or mining gas escape.... with subsidence being the main issue.

 

There are two different grades of risk: High Risk and Low Risk.

 

The High Risk Area (15% of the coalfield area) is where coal mining risks are present at shallow depth which are likely to affect new development.

 

The Low Risk Area (85% of the coalfield) is where past coal mining activity has taken place at sufficient depth that it poses low risk to new development

 

The risks are made up of the following:

Mine Entries with potential zone of influence

Past Surface Hazards

Past Shallow Coal Mine Workings

Mine Gas

Probable Shallow Coal Mine Workings

Geological features (fissures and break lines)

Workable Coal Seam Outcrops

Surface (Opencast) Mining


 

The mining risk assessment in the Northwest is typically undertaken as follows:

 

1) Identify the site location (latitude and longitude)

 

2) Obtain an Environmental and Coal Authority report

 

3) Conduct a ‘Walk-over’ survey to identify any evidence of previous mining related issues

 

4)  If any existing buildings exist measure them for structural movement in both the lateral and vertical plane.

 

5)  Assess any movement in existing buildings against what would be reasonable for the type and age of building given normal deterioration with age.

 

6)  Check the Environmental and Coal Authority report for likelihood of ground problems.

 

7)  Visual assess a sample of other buildings in the same risk area for signs of subsidence.

 

8)  Provide a risk assessment and if necessary a methodology of mitigating the risk of subsidence and mining gas invasion.