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Northern Foundations Ltd Geotechnical and Environmental Ground Investigations
18 Ashbourne Drive, High LaneStockport SK6 8DB
Tel: 01663 764929Fax: 01663 810150
CM 9347
LAND TO THE REAR OF
11 BRIERLEY GREEN
BUXWORTH
HIGH PEAK
COAL MINING
RISK ASSESSMENT
CONTENTS
1. INTRODUCTION 1.1. Commission 1.2. Site Location 1.3. Proposed Development 1.4. Scope of the Coal Mining Risk Assessment
2. SOURCES OF INFORMATION USED TO INFORM THIS REPORT 2.1. Coal and Brine Report 2.2. Documented Geology 2.3. Available Historical Information
3. SITE DESCRIPTION
4. IDENTIFICATION AND ASSESSMENT OF SITE SPECIFIC COAL MINING RISKS
5. MITIGATION STRATEGY PROPOSED
6. CONCLUSION
FIGURES
Figure 1 Site Location Map
Figure 2 Site Photographs
APPENDICES
Appendix 1 Coal Authority Report
3
COAL MINING RISK ASSESSMENT
FOR
LAND TO THE REAR OF
11 BRIERLEY GREEN
BUXWORTH
HIGH PEAK
1. INTRODUCTION
1.1. Commission
Mr John F Lomas has submitted a planning application for the proposed development for
two detached houses on the land to the rear of 11 Brierley Green, Buxworth.
Northern Foundations Ltd have been commissioned to prepare a Coal Mining Risk
Assessment Report of the proposed development site, in order to provide the Local
Planning Authority with information on coal mining and an assessment of its impact on
land stability.
1.2. Site Location
The site was situated within Brierley Green, a locality within the village of Buxworth,
High Peak. The property was located directly to the west of Dolly Lane and
approximately 55m north of the B6062. The Manchester to Sheffield railway was
located approximately 105m to the south of the site. The attached Site Location Map
(Figure 1) indicates the general location of the investigation area.
The approximate Ordnance Survey grid reference for the investigation area is 402502,
382435.
1.3. Proposed Development
At the time of the report, the planning application was for proposed outline permission
for the construction of two detached houses on land located to the rear of 11 Brierley
Green, Buxworth, with modified vehicle access and parking areas.
1.4. Scope of the Coal Mining Risk Assessment
The purpose of this Coal Mining Risk Assessment Report is to:
• Present a desk-based review of all available information on the coal mining issues
which are relevant to the application site;
• Use that information to identify and assess the risks to the proposed development
from coal mining legacy, including the cumulative impact of issues;
4
• Set out appropriate mitigation measures to address the coal mining legacy issues
affecting the site, including any necessary remedial works and/or demonstrate
how coal mining issues have influenced the proposed development; and
• Demonstrate to the Local Planning Authority that the application site is, or can be
made, safe and stable to meet the requirements of national planning policy with
regard to development on unstable land.
2. SOURCES OF INFORMATION USED TO INFORM THIS REPORT
This risk assessment of coal mining issues has been based on the following obtained
sources of information:
• The Coal Authority Mining Report, dated 14 May 2014 Reference
51000542183001.
• Geological information obtained from the British Geological Survey Sheet 99
Chapel-en-le-Frith.
• Coal mining and geological information obtained from the Geological Survey of
Great Britain, 6 inches to 1 mile scale, Sheet SK 08 SW.
• A Site history based on limited historical Ordinance Survey mapping of the area.
2.1. Coal and Brine Report
A copy of the Coal Authority Mining Report has been obtained and is attached in
Appendix 1. This report indicated that the property lies outside any defined brine
extraction area.
Unrecorded Shallow Workings and/or Mine Entries:
The Coal Authority Mining Report states that the property is in an area where the Coal
Authority believe there is coal at or close to the surface and that this coal may have been
worked at some time in the past.
Recorded Mine Entries:
The Coal Authority Mining Report states that there is 1 mine entry within, or within 20
metres of, the boundary of the property, the approximate position of which is shown on
their attached plan. The Coal Authority disclosed the following information:
402382-014. Records indicate that the entrance to this mine adit has been filled at some
time in the past to an unknown specification.
In addition, the Coal Authority Mining Report stated that according to the records in their
possession, the property is not within the zone of likely physical influence on the surface
5
from past recorded underground workings, and that the property is not within the likely
zone of influence on the surface from any present underground coal workings. The site
is not located within an area that has been subject to past or present opencast working.
The Authority is not aware of any evidence of damage arising due to geological faults or
other lines of weakness that have been affected by coal mining. There is no record of a
mine gas emission requiring action by the Coal Authority within the boundary of the
property. No notice of the risk of the land being affected by subsidence has been given
under section 46 of the Coal Mining Subsidence Act 1991.
The property has not been subject to remedial works, by or on behalf of the Authority,
under its Emergency Surface Hazard Call Out procedures. The Coal Authority has not
received a damage notice or claim for the property since 31 October 1994. There is no
current Stop Notice delaying the start of remedial works or repairs to the property. The
Authority is not aware of any request having been made to carry out preventive works
before coal is worked under section 33 of the Coal Mining Subsidence Act 1991.
It should be noted that the Coal Authority believes reserves of coal exist in the local area
which could be worked at some time in the future.
Additional Comments:
In addition, in the report stated that, in view of the mining circumstances, a prudent
developer would seek appropriate technical advice before any works are undertaken.
Therefore, if development proposals are being considered, technical advice relating to
both the investigation of coal and former coal mines and their treatment should be
obtained before beginning work on site. All proposals should apply good engineering
practice developed for mining areas.
Please refer to the full report obtained from the Coal Authority (see Appendix 1).
2.2. Documented Geology
The Geological Survey map for this area is Sheet 99 Chapel-en-le-Frith; reference was
also made to the Geological Survey Sheet SK 08 SW. The following information was
supplied by the British Geological Survey:
Drift: Till, Devensian – Diamicton (Glacial Boulder Clay)
Solid: North section of site: Pennine Lower Coal Measures Formation -
Mudstone, Siltstone and Sandstone (formerly Lower Coal Measures)
6
South section of site: Millstone Grit Group – Mudstone, Siltstone And
Sandstone
The map indicated that the site is intersected by a geological Solid boundary associated
with a fault; the fault was indicated as uncertain and as passing through the central
section of the site in a generally east to west direction, with the down throw to the
north. The rock to the north of the fault was shown as Pennine Lower Coal Measures
Formation, and the rock to the south was predicted to be Millstone Grit.
The predicted line of the Yard coal crop was indicted as uncertain and in close proximity
to the east boundary of the site at its closest point; the dip of the seam was indicated as
generally westerly in this locality, and would therefore dip below the site. The Sheet SK
08 SW notes the Yard coal seam as 36 inches thick and at a depth of 36 feet, in the
abandoned Air Pit coal mine.
The following sketch plan indicates the main features shown on the Geological Survey
Sheet SK 08 SW:
2.3. Available Historical Information
Reference has been made to several Ordnance Survey maps dated from 1876/77 to
present. The early maps indicated no significant development in the area of the
investigation and adjacent land. The 1898-99 Ordnance Survey map indicated several
buildings located in the plot directly to the north of the site, which were labelled
‘Colliery’; the map also indicated an embankment in the north section of the footprint.
By the time of the 1921 survey, the Colliery was not shown.
7
3. SITE DESCRIPTION
At the time of the Report, the property generally comprised grass covered agricultural
pastureland. The property had an access route from the east boundary of the site from
Dolly Lane, and a small area of gravel was noted adjacent to this gate in the north east
corner of the site. Dolly Lane passed along the length of the east boundary. The north
boundary was formed by a stonewall and several mature trees were noted close to this
boundary. The plot directly to the north of the site was vacant, generally overgrown
with weeds and mixed vegetation, with uneven ground levels, and was generally
surrounded by woodland and mature trees.
Residential properties were noted approximately 30m to 35m south of the southern
boundary of the site, and the nearest residential property was noted on Dolly Wood Close
approximately 18m east of the site.
The site area was noted to be generally sloping, with slightly uneven levels in parts; a
high point was noted in the north west corner of the site and a low point along the south
boundary. No surface water features were noted on or adjacent to the site.
Site photographs taken in May 2014 are presented in Figure 2.
4. IDENTIFICATION AND ASSESSMENT OF SITE SPECIFIC COAL MINING RISKS
The table below summarises the potential risks associated with coal mining legacy for the
proposed development site, identified from the compiled information:
Coal Mining Issue Yes No Risk Assessment
Underground coal mining (recorded at shallow depths)
Underground coal mining (probable at shallow depths) Risk of mining subsidence, and to building stability
Mine entries (shafts and adits) Risk of mining subsidence, and to building stability
Coal mining geology (fissures)
Record of past mine gas emissions
Recorded coal mining surface hazard
Surface mining (opencast workings)
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Underground Coal Mining (Probable at Shallow Depths)
The Coal Authority Report obtained for this site has indicated that ‘the property is in an
area where the Coal Authority believe there is coal at or close to the surface. This coal
may have been worked at some time in the past’. Extrapolation of the Geological Survey
information would infer that the Yard coal seam passed below the northern section of the
site at depths varying from approximately surface level to approximately 11m below
ground level. Accordingly, it is our opinion that there is a risk for unrecorded shallow
workings and/or mine entries in the northern section of the site; this would apply to the
section north of the uncertain fault line which is predicted to pass across the site in a
general east west direction. Accordingly, it is our opinion that there would be risks
specific to abandoned coal workings. These risks include the potential for:
• Coal mining subsidence
• Collapse of shallow mine workings
• Increased depths of made ground
Mine Entries (Shafts and Adits)
The Coal Authority Mining Report indicated that there is a mine entry within 20 metres of
the north boundary of the property, the approximate position of which is shown on their
attached plan. The Coal Authority records indicated that the entrance to this mine adit
has been filled at some time in the past to an unknown specification. Accordingly, it is
our opinion that there is a risk from the recorded mine entry, predicted to be within 20m
of the northern site boundary; this would apply to the north section of the site. There is
also a possibility of unrecorded mine entries. Accordingly, it is our opinion that there
would be risks specific to abandoned coal workings. These risks include the potential for:
• Coal mining subsidence
• The collapse of, or risks of entry to, mine entries including shafts and adits
• Increased depths of made ground
Note: An ‘adit’ is a mine entry in the form of a passage for access or drainage, driven at
a shallow angle (usually below the horizontal), often in a hillside.
5. MITIGATION STRATEGY PROPOSED
Underground Coal Mining (Probable at Shallow Depths)
The compiled data has indicated that there is a risk for unrecorded shallow workings
below the northern section of the site. Depending on the location of the predicted fault,
it may be possible to reduce risk to future buildings by locating the new construction to
the south section of the site. In any event, we would recommend that a ‘Phase 1 Desk
9
Study’ should be undertaken which should include the assessment of additional and more
detailed information that can be obtained from the Coal Authority. It is expected that
this would be followed by a subsequent intrusive investigation, the scope of which would
be determined by the findings of the ‘Desk Study’; we would expect this to include a
borehole investigation and may include deep rotary boreholes. Subsequent to the
completion of the investigation, appropriate technical advice and good engineering
practice should be adopted for development. The recommended mitigation measures
should be incorporated into the proposed development and appropriate design
construction methods for future buildings should be adopted.
Mine Entries (Shafts and Adits)
As the Coal Authority Report indicated that the recorded mine entry is not within the site
boundary, and appears to be approximately 13m to 18m north of the northern boundary,
it is possible that the risk to the buildings from this particular adit could be mitigated by
limiting new construction to the southern section of the site.
General Recommendations:
The Coal Authority have stated that ‘All proposals should apply good engineering practice
developed for mining areas.’ Accordingly, the foundations proposals should have regard
to good engineering practice in mining areas, which may include the adoption of
appropriate foundation design such as stiff foundations that would span potential
10
differential movements, and may incorporate piling. With regard to good engineering
practice in mining areas, reference should be made to the CIRIA Special Publication 32
"Construction over abandoned mine workings"; appropriate advice should be sought from
a Consulting Engineer.
The Coal Authority Permission
Prior written permission from The Coal Authority is required for intrusive activities which
will disturb or enter any coal seams, coal mine workings or coal mine entries (shafts and
adits). Further information on The Coal Authority’s permissions process can be found at:
www.coal.gov.uk/services/permissions/index.cfm
As the project is still at application for outline planning, no applications have been made
to The Coal Authority for written permission for further intrusive activities and/or site
investigation works, at this stage.
6. CONCLUSION
The Coal Mining Risk Assessment has indicated that the property is in an area where the
Coal Authority believe there is coal at or close to the surface which may have been
worked at some time in the past. Without appropriate technical advice and good
engineering practice, building over or within the influencing distance of shallow workings
could raise significant safety and engineering risks.
In addition, The Coal Authority believe there is a mine entry within 20 metres of the
north boundary of the property. Building over or within the influencing distance of a
mine entry raises significant safety and engineering risks, and as a general precautionary
principle, should wherever possible be avoided. However, as the adit is not within the
site area, we believe that appropriate positioning of the proposed buildings would help to
mitigate this risk.
Not withstanding the above, we would recommend that a ‘Phase 1 Desk Study’ should
be undertaken and should include assessment of additional information that can be
obtained from the Coal Authority. The scope of any recommended subsequent intrusive
investigations would be determined by the findings of this ‘Desk Study’, and may include
deep rotary boreholes.
We would consider that the above findings would not preclude the proposed
development of the site, and that the recommended ‘Phase 1 Desk Study’, with
11
subsequent intrusive investigation and technical recommendations can be made part of
Planning Conditions for the development.
As a standard procedure, we would advise that, in the case of any significant new
information coming to light in future studies, in any intrusive investigations, and during
future works, then the coal mining risks should be reassessed and appropriate measures
should be adopted.
P. R. JACKSON BSc (Hons) CEng FGS MBCS
On behalf of Northern Foundations Limited
USE OF REPORT
The work and the report are prepared specifically for the Client’s Project and the
recommendations may not be appropriate to alternative schemes. For this reason the
copyright and licence to use shall remain vested in Northern Foundations Ltd who
disclaim all responsibility or liability (whether at common law or under the express or
implied terms of the contract between Northern Foundations Ltd and the Client) for any
loss or damage of whatever nature in the event that this report is relied on by a third
party or used in circumstances or for projects for which it was not originally
commissioned or where the records and results contained therein are interpreted by
anyone other than Northern Foundations Ltd.
This report remains the property of Northern Foundations Ltd until complete
reimbursement for the report and services provided by Northern Foundations Ltd has
been received by Northern Foundations Ltd. Accordingly, Professional Indemnity
Insurance will not be available to the Client for the report and services provided by
Northern Foundations Ltd., until complete reimbursement for this report and services has
been received by Northern Foundations Ltd.
All Intellectual Property Rights in the Report and Services shall remain owned by Northern
Foundations Ltd or our Suppliers.
FIGURE 1 – Site Location Map
Site Land to Rear of 11 Brierley Green, Buxworth, High Peak Job No 9347 Client Mr John Lomas Date May 2014
SITE PLAN
Northern Foundations Ltd
FIGURE 2 – Site Photographs
Site Land to Rear of 11 Brierley Green, Buxworth, High Peak Job No 9347
Client Mr John Lomas Date May 2014
Site Photographs
1. From south east corner of site, looking north west
2. From north east corner of site, looking south
3. From north east of site, looking south west
4. From north east of site, looking west
5. The adjacent plot north of the site, looking west
6. The north east corner of site, looking west
Northern Foundations Ltd
APPENDIX 1 – Coal Authority Report
