This page is blank BRITISH GEOLOGICAL SURVEY In association with Roger Tym and Partners TECHNICAL REPORT WN/95/3 A geological background for planning and development in Wigan Volume 1: A geological foundation for planning Editors: A Forster, A Arrick, MG Culshaw and M Johnston Authors: A Forster, M Stewart, DJD Lawrence, A Arrick, CS Cheney, R SWard, JD Appleton, DE Highley, AM MacDonald, and Editors PD Roberts A Forster, A Arrick, MG Culshaw and M Johnston Authors A Forster, M Stewart, DJD Lawrence, A Arrick, CS Cheney, R SWard, JD Appleton, DE Highley, AM MacDonald, and PD Roberts Maps and diagrams used in this report are based on Ordnance Survey mapping. Bibliographic reference FORSTER, A, and others. 1995. A geological foundation for planning. Vol. 1 ofA geological background for planning and development in Wigan. FORSTER, A, ARRICK, A, CULSHA W, M G, and JOHNSTON, M (editors). British Geological Survey Technical Report, No. WN/95/3. Disclaimer This Technical Report was produced under contract with the Department of the Environment. The views expressed are those of BGS and do not necessarily reflect those of the Department of the Environment or any other government department. © Crown copyright 1995 Published with the permission of the Controller of Her Majesty's Stationery Office. Keyworth, Nottingham British Geological Survey BRITISH GEOLOGICAL SURVEY The full range of Survey publications is available through Keyworth, Nottingham NG12 5GG the Sales Desks at Keyworth and at Murchison House, "B' 0115-936 3100 Telex 378173 BGSKEY G Edinburgh, and in the BGS London Information Office in Fax 0115-9363200 the Natural History Museum Earth Galleries. The adjacent bookshop stocks the more popular books for sale over the Murchison House, West Mains Road, Edinburgh EH93LA counter. 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"B' 01232-666595 Fax 01232-662835 Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OXI0 8BB "B' 01491-838800 Telex 849365 HYDROL G Fax 01491-692345 Parent Body Natural Environment Research Council Polaris House, North Star Avenue, Swindon, Wiltshire SN21EU 'fi" 01793-411500 Telex 444293 ENVRE G Fax 01793-411501 C011tents 1 Digest 12 Made ground and landfill (Map 6) 49 2 Executive summary 2 Introduction 49 Form of modification 49 3 Statement of limitations 4 Classification of waste material 49 4 Introduction 5 Made ground - general waste 50 Aims and objectives 5 Made ground - mining waste 52 Information sources 5 Engineered earthworks 53 Database 6 Disturbed ground 53 5 Geographical background 7 13 Gases and leachates 54 Location 7 Gases - nature and hazards 54 Topography 7 Migration processes and pathways 54 Geomorphology 7 Gas accumulation 55 History of development 7 Non-geological sources 55 Agriculture and soil types 7 Geological sources 56 6 Planning background 8 Susceptibility classification: 'natural' methane and Ground characteristics and the planning system 8 carbon dioxide 57 Development plans 8 Factors influencing vulnerability to landfill Development control 8 gas 57 Government policy advice and guidance 8 Susceptibility classification: Geologic radon The planning system and information on ground potential 58 conditions 9 Limitations of radon potential classification 61 Availability and sensitivity of ground condition Leachates 61 data 9 Factors influencing vulnerability to landfill Use of data to secure grants for land leachates 61 reclamation 10 14 Previous and present industrial land uses (Map 7) 63 7 Bedrock geology (Map 2) 11 Introduction 63 Introduction 11 Sources of information 63 Upper Carboniferous 13 Classification of industrial use 63 Permo-Triassic 16 Implications for planning 64 Structure 17 Limitations to use of Map 7 64 8 Superficial geology (Map 3) 20 Potentially harmful element contamination 64 Introduction 20 Conclusions 66 Summary of Quaternary history 20 15 Engineering geology (Map 8) 68 Superficial deposit thickness and rockhead Classification and material characteristics 68 topography 22 Engineering rocks 69 Details of Superficial Deposits 22 Engineering soils 70 9 Hydrology and hydrogeology (Map 4) 24 Landslides 72 Introduction 24 Acknowledgements 73 Surface water 24 Glossary 74 Groundwater 25 References 76 Aquifer recharge 28 Past groundwater abstraction and water levels 29 Appendices Groundwater chemistry 34 I Database structure and user's guide 79 II Details of opencast coal sites worked in the Wigan 10 Minerals resources (Map 5) 37 Metropolitan Borough 85 Opencast coal 37 Glass sand 37 Clay 37 FIGURES Sand (aggregate) 38 Sandstone 39 1 Location of the study area 6 Peat 39 2 Simplified bedrock geology (reduction of Map 2) 11 11 Coal mining (Map 9) 40 3 Generalised vertical section (from Map 2) 12 Introduction 40 4 Correlation of the Coal Measures classification History of mining and mining methods 40 schemes 15 Hazards associated with old mineworkings 43 5 Major faults in the Wigan area 18 Site investigation in areas of suspected shallow 6 Graben structure in the bedrock below the Wigan mineworkings 48 area 19 Preventive and remedial techniques for mining 7 Disposition of superficial deposits in the Wigan area subsidence 48 (inset from drift map) 20 8 Underlying rockhead surface in the Wigan area 21 27 Factors to be considered when assessing vulnerability 9 Cross section of buried river channel 21 to landfill gas 58 10 Superficial deposit thickness contours 22 28 Factors to be considered when assessing vulnerability 11 River hydrograph for gauging station at SD 5870 0611 to landfillieachates 62 on the River Douglas 25 12 Glacial sands and gravels may form perched aquifers with water levels close to ground level 27 TABLES 13 Averaged monthly climatic data, (for the period between 1961 to 1992), for the Wigan area, provided Classification of surface water (National Rivers from the Meteorological Office MORECS Authority, 1990 Survey) 25 system 28 2 Summary of the hydrogeological properties of the 14 Groundwater abstraction and water levels before lithological units in the Wigan area 26 mining 30 3 Coal seams shown on British Coal plans known to have 15 Groundwater abstraction and water levels at the been mined in the Wigan Metropolitan Borough 40 maximum development of mining 31 4 Classifications used for distinguishing between 16 Groundwater abstraction and water levels; the current landfills on Map 6 'The distribution of made and situation 32 worked ground' 51 17 Groundwater abstraction from the Coal Measures 33 5 Radon potential classification for The Natural 18 Groundwater abstraction from the Permo-Triassic Contamination Review of Great Britain (adapted from strata 33 Appleton and Ball, 1995) 59 19 Rising water-levels to the west of the Winwick fault, 6 Geologic radon potential classification based on towards Ashton-in-Makerfield 34 concentration of radon in soil gas and rock/soil 20 Zones of different groundwater chemistry in the permeability (adapted from Appleton and Ball, Permo-Triassic aquifer south of Wigan 35 1995) 59 21 Shaded areas show where coal seams crop out near 7 Summary of radon in soil gas concentrations for the surface in the Wigan area and coal is likely to Wigan survey 60 have been mined at an early date 41 8 Radon potential of superficial and bedrock geological 22 Diagrammatic cross section of bell pits found in units in the Wigan area 60 opencast sites 42 9 Summary statistics for all radon measurements 61 23 Examples of different patterns of 'pillar and stall' 10 The range of concentrations of the constituents of working exposed during the excavation of opencast leachate from landfills containing municipal wastes sites in the Wigan area 44 (Anon, 1986b; concentrations in mg/l) 62 24 Workings found during the construction of the new 11 Statistical summary of stream sediment data from the public swimming baths showed 75% extraction and Wigan area 65 good parallel alignment of the stalls in a seam dipping 12 Statistical summary of <150 ]Jm soil data from the towards the north-east at about 1 in 12 45 Wigan area 66 25 Illustration of the types of artificial superficial 13 Statistical summary of stream water data from the deposits in the Wigan area and the symbols used to Wigan area 67 indicate them on Map 6 50 14 Geological materials classified on the basis of their 26 Potential pathways for the migration of landfill gases engineering geological behaviour with regard to land and leachates 56 use and construction 68 1 Digest This report, commissioned by the Department of the • the potential for groundwater contamination; Environment, provides concise, accessible data on the • the presence of mineral resources; geology of the Wigan Metropolitan Area and their impli­ cation for planning and development in the area. The • the presence of geological faults. report comprises two volumes: The report includes ten applied geological maps of the • Volume I: 'A Geological Foundation for Wigan Metropolitan Area at a scale of 1:25 000 on the Planning', concerns technical' matters and describes themes of: the geological data collected.