UK Coal Operations Limited Proposed extension of time for colliery spoil tipping Environmental Statement operations at Harworth Colliery No. 2 Spoil Heap TECHNICAL APPENDIX 6 – Hydrogeological and Hydrological Impact Assessment Hydrogeological and Hydrological Impact Assessment in support of an extension to Planning Permission for Harworth Colliery No 2 Spoil Heap Report ref: HC/HIA Final June 2013 Report prepared for: UK Coal Mining Ltd Harworth Park Blyth Road HARWORTH DN11 8DB BARKERS CHAMBERS • BARKER STREET • SHREWSBURY • UNITED KINGDOM • S Y 1 1 S B TEL : 01743 355770 FAX: 01743 357771 EMAIL : [email protected] Hydrogeological and Hydrological Impact Assessment in support of an extension to Planning Permission for Harworth Colliery No 2 Spoil Heap Report ref: HC/HIA Final June 2013 For Data Protection L Brown MSc FGS CGeol C C Leake BSc MSc FGS UK Coal Mining Ltd Hydrogeological Impact Assessment: Harworth Colliery No 2 Spoil Heap Final CONTENTS 1 INTRODUCTION 1 1.1 Background 1 1.2 Objectives 1 1.3 Data sources 1 1.4 Methodology of investigation 1 2 SITE SETTING 3 2.1 Location 3 2.2 Landform 3 3 BASELINE CONDITIONS 4 3.1 Background 4 3.2 Hydrology 4 3.2.1 Rainfall 4 3.2.2 Watercourses 4 3.2.3 Springs 5 3.2.4 Ponds and waterbodies 5 3.2.5 River flows 5 3.2.6 Surface water abstraction 5 3.2.7 Discharge consents 6 3.2.8 Surface water quality 7 3.3 Landfill sites 7 3.4 Protected sites and areas of ecological interest 8 3.5 Geology 9 3.5.1 Regional 9 3.5.2 Local geology 10 3.6 Hydrogeology 11 3.6.1 Aquifer status and regional context 11 3.6.2 Source Protection Zones 11 3.6.3 Aquifer characteristics 11 3.6.4 Groundwater abstractions 11 3.6.5 Groundwater levels and distribution 12 3.6.6 Groundwater quality 13 3.7 Spoil heap operation 13 3.8 Conceptual model 13 4 PROPOSED DEVELOPMENT 15 4.1 Operation 15 4.2 Restoration 15 4.3 Compliance with Mining Waste Directive 15 4.4 Water management during site operation 15 4.5 Water management post restoration 15 5 ASSESSMENT OF IMPACTS 16 5.1 Methodology 16 5.2 Catchment sensitivity 16 5.3 Potential impacts of renewed tipping 16 5.3.1 Groundwater levels and flow 16 5.3.2 Groundwater quality 17 5.3.3 Groundwater abstractions 17 Page i June 2013 P:\Projects\Harworth Colliery (1629)\Reporting\HIA Harworth Colliery Tip FINAL.doc UK Coal Mining Ltd Hydrogeological Impact Assessment: Harworth Colliery No 2 Spoil Heap Final 5.3.4 Surface water flows 17 5.3.5 Surface water quality 17 5.4 Potential impacts after restoration 18 5.4.1 Groundwater quality 18 5.4.2 Surface water quality 18 5.5 Cumulative impacts 18 6 MITIGATION MEASURES AND RESIDUAL IMPACTS 20 6.1 During tipping operations 20 6.2 Post-restoration 20 7 SUMMARY AND CONCLUSIONS 21 TABLES Table HC/HIA/T1 Long-term average monthly rainfall at the Wiseton raingauge 4 Table HC/HIA/T2 Summary river flow data 5 Table HC/HIA/T3 Licensed surface water abstractions 5 Table HC/HIA/T4 Discharge consents 6 Table HC/HIA/T5 Details of landfill sites within 3 km of site boundary 7 Table HC/HIA/T6 Details of wildlife sites within 3 km of site boundary 9 Table HC/HIA/T7 Summary of regional solid geology 10 Table HC/HIA/T8 Licensed groundwater abstractions 12 FIGURES Figure HC/HIA/01 Location of Harworth Colliery No 2 Spoil Heap Figure HC/HIA/02 Site setting Figure HC/HIA/03 Landform Figure HC/HIA/04 Surface water features Figure HC/HIA/05 Watercourses maintained by a Water Level Management Board Figure HC/HIA/06 Discharge consent Figure HC/HIA/07 Ecological and chemical status of rivers Figure HC/HIA/08 Landfills within 3 km of site boundary Figure HC/HIA/09 Sites of ecological interest Figure HC/HIA/10 Geology Figure HC/HIA/11 Groundwater levels and monitoring boreholes Figure HC/HIA/12 Groundwater level variations Figure HC/HIA/13 Site drainage Figure HC/HIA/14 Conceptual model APPENDICES Appendix HC/HIA/A1 Assessment methodology Appendix HC/HIA/A2 Summary geological logs Appendix HC/HIA/A3 Groundwater quality data Appendix HC/HIA/A4 Proposed site restoration Page ii June 2013 P:\Projects\Harworth Colliery (1629)\Reporting\HIA Harworth Colliery Tip FINAL.doc UK Coal Mining Ltd Hydrogeological Impact Assessment: Harworth Colliery No 2 Spoil Heap Final 1 INTRODUCTION 1.1 Background The No 2 Spoil Heap at Harworth Colliery is used for the disposal of colliery spoil originating from the mining activities at the colliery. The colliery, operated by UK Coal, has been in care and maintenance since 2006 and currently no spoil is being deposited. The current Planning Permission expires in June 2013 and UK Coal wishes to secure Planning Permission for future tipping to ensure that, in the event of mining re-commencing, work can start with no delays. Hafren Water has been commissioned to investigate potential impacts on the water environment arising from the continued use of the spoil heap and to support an extension to the Planning Permission for the site. 1.2 Objectives The principal objectives of this study are to: Determine baseline conditions in relation to the water environment at the No 2 Spoil Heap at Harworth Colliery, and its surroundings Identify any potential impacts of the proposed development Assess the magnitude and significance of potential impacts Derivation of appropriate mitigation measures for any identified potential impacts 1.3 Data sources The following sources of data were used in this study: British Geological Survey (BGS) 1:50,000 scale geological map, Sheet 101 East Retford Geological logs of nearby boreholes The physical properties of major aquifers in England and Wales. Allen JD, Brewerton LJ, Coleby LM, Gibbs BR, Lewis MA, MacDonald AM, Wagstaff SJ and Williams AT. Ordnance Survey (OS) Explorer 1:25,000 scale map, Sheet 279, Doncaster The Environment Agency (EA) Licensed abstractions Consented discharges Active and historical landfills Rainfall data Surface and groundwater water quality Natural England Sites of Special Scientific Interest Local Authorities (Daventry District Council) Private water abstractions UK Coal Mining Ltd 1.4 Methodology of investigation Baseline conditions of the water environment have been defined by the collation and analysis of Page 1 June 2013 P:\Projects\Harworth Colliery (1629)\Reporting\HIA Harworth Colliery Tip FINAL.doc UK Coal Mining Ltd Hydrogeological Impact Assessment: Harworth Colliery No 2 Spoil Heap Final existing data and field observations. The potential effects of the proposed development upon the extant water environment have been assessed by reference to the baseline data and a series of matrices (Appendix HC/HIA/A1), developed to ensure a rigorous and consistent approach to the assessment of potential impacts. Mitigation measures have been proposed where appropriate. Baseline conditions have been taken as those existing at the time of operation of the colliery when waste material was being placed on the spoil heap. Page 2 June 2013 P:\Projects\Harworth Colliery (1629)\Reporting\HIA Harworth Colliery Tip FINAL.doc UK Coal Mining Ltd Hydrogeological Impact Assessment: Harworth Colliery No 2 Spoil Heap Final 2 SITE SETTING 2.1 Location The Harworth Colliery No 2 Spoil Heap is located approximately 1 km south of the village of Harworth, Nottinghamshire (Figure HC/HIA/01) and centred on National Grid Reference (NGR) SK 61700 89900. The spoil heap covers an area of approximately 109 hectares (ha). Details of the immediate surroundings of the spoil heap are shown on Figure HC/HIA/02. The No 2 Spoil Heap (‘the site’) is bounded to the north by Selby Road with an industrial estate beyond, to the east by Blythe Road and agricultural land, to the south by agricultural land and to the west by the A1 with agricultural land beyond. The nearest residential properties are located in the village of Styrrup in the northwest, to the west of the A1, and to the southeast. Road access to the site is from an existing site entrance on Blythe Road. When operational, colliery waste is transported from the colliery by an elevated conveyor and placed in its final position by mobile plant. Waste in the form of slurry from the coal processing plant is transported by pipeline. 2.2 Landform The current landform is shown on Figure HC/HIA/03, as reported in the Aftercare Plan, August 2012. The natural ground around the spoil heap falls from around 35 m Above Ordnance Datum (mAOD) in the north to 15 mAOD in the south. The spoil heap rises to its highest point, approximately 77 mAOD, in the north of the site adjacent to the site at which spoil is deposited from the conveyor. The steep slopes (1 in 4 to 1 in 5) to the north and northeast of the peak have been planted with trees. To the east and northeast, the slopes are shallower (1 in 7) and grassed. These slopes have been restored in accordance with the restoration plan reproduced as Figure HC/HIA/A4.1 (Appendix HC/HIA/A4). Over the remainder of the site, the spoil heap rises to approximately 33 mAOD in the east, 36 mAOD in the west with a depression in the south of central area, previously occupied by a slurry lagoon when the site was operational. The peripheral slopes have, in the most part, been planted with trees, while the top is open exposed colliery spoil and unvegetated. Page 3 June 2013 P:\Projects\Harworth Colliery (1629)\Reporting\HIA Harworth Colliery Tip FINAL.doc UK Coal Mining Ltd Hydrogeological Impact Assessment: Harworth Colliery No 2 Spoil Heap Final 3 BASELINE CONDITIONS 3.1 Background Baseline (ie existing) conditions at the site are set out below and include information relating to the environmental setting as well as current activities at the site.