A Geological Background for Planning and Development in Wigan
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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 2: A user’s guide to Wigan’s ground conditions Editors: A Forster, A Arrick, M G Culshaw and M Johnston Authors: A Arrick, A Forster, D F Clark, M Stewart, and D J D Lawrence Editors A Forster, A Arrick, M G Culshaw and M Johnston Authors A Arrick, A Forster, D F, Clark, M Stewart, and D J D Lawrence Maps and diagrams used in this report are based on Ordnance Survey mapping. Bibliographic reference ARRICK,A, and others. 1995. A user’s guide to Wigan’s ground conditions. Vol. 2 of A geological background for planning and development in Wigan. FORSTER, A, ARRICK,A, CULSHAW,M G, and JOHNSTONM (editors). British Geological Survey Technical Report, No. WN/95/3. Disclaimer This Technical Report was produced under contract with the Departmentof 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. 0 Crown copyright 1995 Published with the permission of the Controller of HerMajesty’s Stationery Office. Keyworth, Nottingham British GeologicalSurvey BRITISH GEOLOGICAL SURVEY The full range of Survey publicationsis available through Keyworth, NottinghamNG 12 5GG the Sales Desksat Keyworth and at Murchison House, e 01 15-936 3100Telex 378173 BGSKEY G Edinburgh, and in the BGS London Information Officein FaxOl15-9363200 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. Most BGS booksand reports are listed in HMSO’s Sectional List 45,and can be bought from HMSOand e 0131-667 1000 Telex727343 SEISED G Fax0131-6682683 through HMSO agentsand retailers. Maps are listed in the BGS Map Catalogue, and can be bought from BGS approved stockists and agents as well as direct from BGS. London Information Officeat the Natural History Museum, Earth Galleries, Exhibition Road, South Kensington, The British Geological Survey carries out the geological London SW7 2DE survey of Great Britainand Northern Ireland (the latter as %T 0171-5894090 Fax0171-5848270 an agency service for the governmentof Northern Ireland), TF 0171-938 9056/57 and of the surrounding continental she& as well as its basic research projects. It also undertakes programmesof St Just, 30 Pennsylvania Road, Exeter EX4 6BX British technical aid in geology in developing countries as eFax01392-437505 01392-78312 arranged by the Overseas Development Administration. Geological Surveyof Northern Ireland, 20 College The British GeologicalSurvey is a component bodyof the Gardens, Belfast BT9 6BS Natural Environment Research Council. 01232-666 595 Fax01232-66283501232-666595 Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB 01491-838800849365Telex HYDROLG Fax 0 149 1-692345 Parent Body Natural Environment Research Council Polaris House, North Star Avenue, Swindon, Wiltshire SN2 1EU e 01793-41 1500 Telex444293 ENVRE G Fax 01793-41 1501 Contents Executive summary 9 Locations of new development 34 Introduction 1 Derelict land 34 Aims and objectives 1 Development costs 36 Statement of limitations 1 10 Economic development - attracting investment 38 Database 2 11 Key geological factors in planning and Characteristics of the study area 3 development 40 Location 3 Introduction 40 Topography 3 Shallow mining as a potential undermining Industrial history 3 hazard 40 Land use 4 Potential for contaminated land 40 Geology 4 Potential for groundwater contamination 4 1 Planning and development issues 6 Mineral resources 4 1 Ground conditions and the planning system 6 Major faults 42 Different perspectives on ground conditions 7 Limitations of mapping 42 Protection of natural resouces 10 Risks of groundwater contamination 10 TABLES Movement of groundwater table 13 Contaminated and rehabilitated land 16 1 Water quality classification 10 Contaminated land 16 2 Hydrogeological units and characteristics 14 Rehabilitation of despoiled areas 19 3 Types of contamination which may occur in the Landfill, leachates and gases 21 Wigan area 17 Existing landfill sites 21 Geology and slope stability 30 Prospects for new landfill sites 22 Characteristics of rocks and soils 3 1 Lateral spread of leachates and gases 23 Subsoil and foundations 32 Minerals and environmental planning 25 Excavations 33 Mineral resources 25 Derelict land in Wigan, 1974-1988 (in hectares) 34 Mining subsidence 26 Derelict land in Wigan, 1992 (in hectares) 34 Other general ground condition factors 29 Flooding 29 Slope stability 30 Subsoil 32 Ease of excavation 32 EXECUTIVE SUMMARY 1. This is the second volume of a two volume report implications of possible subsidence), landfill sites resulting from a Department of the Environment brief to (often on the site of previous mineral extraction), and provide concise, accessible data on the geology of the derelict land (usually the result of industrial Wigan area and to derive from this the implications for processes). planning and development in the area. The study com- menced in September 1992 and was completed in June 6. Within the context of thesediffering perspectives, 1995. Its findings are published in two volumes: the specific ground conditions applying in the Wigan area are detailed in Chapters 4-8 of this volume and Maps 1-9 0 Volume 1: ‘A geological foundation for planning’ of this report. These are presented with area-wide or concerns technical matters and describes the general ground conditions first, following through to more geological data collected and presents them in a detailed site-specific conditions, as follows: comprehensive and structured format. 0 groundwater protection 0 Volume 2: ‘A user’s guide to Wigan’s ground conditions’ seeks to apply the geological data 0 contaminated land and rehabilitation described in the technical volume to the workings of 0 the local planning system and to consider their landfill, leachates and gases implications for future planning and land use. 0 mineral resources and subsidence 2. The study area for this project is that of the Metro- 0 flooding, slope stability, subsoil and ease of politan Borough of Wigan, comprising about 200 square excavation kilometres and a population of just over 300 000. This area has a long history of human occupation, of mining activity 7. In each of these sections, this report follows a com- and of industrial development. These factors have all been mon format. First we examine the significance of a specific related to, and have often been directly dependent upon, ground condition in the Wigan area. This is followed by an the local geology as outlined in Chapter 2 of this Volume. outline of the key indicators which can be used to evaluate the impact of this condition. The locations where the 3. Geology, or ground conditions in their widest sense, ground condition might be found and suggested appro- interact with the local planning system in several ways. priate action to be undertaken are then covered. Fiaally, Ground conditions can increase development costs; they each section concludes with suggested reading material can be the underlying basis of areas of attractive landscape and a list of initial contacts for further local information. and environment which the planning system seeks to pro- tect; they can include valuable minerals whose future 8. The latter parts of this volume, Chapters 9 and 10, possible exploitation should not be sterilised by permitting seek to draw together Wigan’s individual ground con- development on the surface. ditions and to outline how in combination these conditions will, could or should affect future planning decisions for 4. These apparently straightforward interactions are, in development, redevelopment and conservation. These reality, at least partly dependent upon the different per- effects are only one of a large number of ‘material con- spectives of various interest groups. The public planning siderations’ in the planning process in Wigan. As such they sector, developers/landowners, and groups with a specific are analysed in the wider context of the planning and interest in environmental conservation do not always view economic factors which operate in the local area. This the relative importance and consequences of ground con- analysis is considered in terms of ditions in the same light. An individual site may be an important environmental resource for one group, a valu- the current extent of derelict land in Wigan able mineral resource for another group, or an area for 0 the means of and proposals for remediation of such economic regeneration and new jobs by a third group. land 5. The views, of representatives of each of these groups 0 the impact of adverse ground conditions on in the Wigan area were sought at an early stage of this development costs study as summarised in Chapter 3. Although there was 0 the relationship between ground conditions, divergence of opinion in some areas, there was common economic development policies and potential grant agreement that: aid Data on ground conditions in Wigan were not easily 9.Finally, Chapter 11, summarisesthe five applied available, incomplete or not reliable, and not geological factors or ground conditions which are con- publicly available (or perceived as being so). There sidered to be particularly significant in the Wigan area. was general agreement that improved and more These are highlighted in combination on Map 10 in order accessible data were needed. to present a consolidated representation of applied geologi- Certain ground conditions were particularly cal resources and constraints. These key factors are sum- important in the area, namely mined ground (with marised in the following five paragraphs. 10. Shallow mining as a potential undermining hazard pollution of groundwater. These features thus represent Coal has been mined in the Wigan area for hundreds of both major resources and significant constraints to years and much early mining, for which records are absent development.