Hydrogeological Risk Assessment Proposal to Restore
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Environmental Statement Volume 3 – Hydrogeological Risk Assessment Proposal to Restore Rugeley ‘B’ Station Borrow Pit through Landfill using Pulverised Fuel Ash Rugeley Power Station May 2007 Document control sheet Form IP180/B Client: Rugeley Power Limited Project: Rugeley B Station Borrow Pit Landfill Job No: J24151C0 Title: Environmental Statement (Volume 3, Hydrogeological Risk Assessment) Prepared by Reviewed by Approved by ORIGINAL NAME NAME NAME S. Mannings & A. J. Oakeshott Parkes S. Mannings DATE SIGNATURE SIGNATURE SIGNATURE April 2007 REVISION 1 NAME NAME NAME J. Oakeshott S. Mannings S. Mannings DATE SIGNATURE SIGNATURE SIGNATURE May 2007 REVISION NAME NAME NAME DATE SIGNATURE SIGNATURE SIGNATURE REVISION NAME NAME NAME DATE SIGNATURE SIGNATURE SIGNATURE This report, and information or advice which it contains, is provided by Jacobs Ltd solely for internal use and reliance by its Client in performance of Jacobs Ltd’s duties and liabilities under its contract with the Client. Any advice, opinions, or recommendations within this report should be read and relied upon only in the context of the report as a whole. The advice and opinions in this report are based upon the information made available to Jacobs Ltd at the date of this report and on current UK standards, codes, technology and construction practices as at the date of this report. Following final delivery of this report to the Client, Jacobs Ltd will have no further obligations or duty to advise the Client on any matters, including development affecting the information or advice provided in this report. This report has been prepared by Jacobs Ltd in their professional capacity as Consulting Engineers. The contents of the report do not, in any way, purport to include any manner of legal advice or opinion. This report is prepared in accordance with the terms and conditions of Jacobs Ltd‘s contract with the Client. Regard should be had to those terms and conditions when considering and/or placing any reliance on this report. 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Contents 1 Introduction 1-1 2 Installation Description 2-1 2.1 Site Location 2-1 2.2 Historical Development and Existing Arrangement 2-1 2.3 Proposed Containment Engineering 2-1 2.4 Use of Cooling Water as a Waste Transport Medium 2-1 2.5 Operation 2-2 2.6 Future Scenario 2-2 3 Overview of Conceptual Site Model 3-1 3.1 Introduction 3-1 3.2 Pollution Source Term 3-1 3.3 Pollution Pathway – Landfill Liner 3-2 3.4 Receptors 3-3 3.5 Numerical Modelling 3-4 3.6 Conclusion 3-5 4 Source Term Characterisation 4-1 4.1 Waste Types 4-1 4.2 Overview of Physio-Chemical Properties of PFA 4-1 4.3 Site-Specific PFA Analyses 4-5 4.4 Ash Supernatant Analyses 4-10 4.5 Model Source Term 4-12 5 Environmental Setting 5-1 5.1 Topography and Surrounding Land Uses 5-1 5.2 Historical Land Uses 5-1 5.3 Regional Geology 5-3 5.4 Ground Conditions in the Site Area 5-3 5.5 Hydrology 5-6 5.6 Hydrogeology 5-8 6 Assessment of Hydrochemical Conditions 6-1 6.1 Introduction 6-1 6.2 Monitoring 6-1 7 Hydrogeological Risk Assessment & Numerical Modelling 7-1 7.1 Introduction 7-1 7.2 Source-Pathway-Receptor Linkages 7-1 7.3 Source Characterisation 7-1 7.4 Groundwater and Surface Water Monitoring 7-2 7.5 Numerical Modelling 7-3 7.6 Modelling Scenarios and Assumptions 7-4 7.7 Model Results 7-6 7.8 Model Sensitivity 7-7 7.9 Model Summary 7-8 7.10 Hydrogeological Risk Assessment Summary 7-8 8 Requisite Surveillance 8-1 8.1 Introduction 8-1 8.2 Source Term and Leachate 8-1 8.3 Groundwater 8-2 8.4 Surface Water 8-3 8.5 Proposed Control & Trigger Levels 8-3 9 Conclusions 9-1 Appendix A - HRA Drawings Appendix B - Background Leachable Testing and Site Specific Certificates of Analysis Appendix C - Historical Plans Appendix D - Borehole Logs Appendix E - Pumping Tests Appendix F - Groundwater Level Data and Hydrographs Appendix G - Baseline Groundwater Quality Appendix H - Quantitative Risk Assessment Appendix I - Site Monitoring Plan 1 Introduction Rugeley Power Limited (the applicant) has submitted a full Planning Application to Staffordshire County Council (the Waste Planning Authority or ‘WPA’) for the restoration through landfill of the B Station Borrow Pit (the Borrow Pit). The Borrow Pit is located at the eastern end of the Rugeley Power Station site in Rugeley, Staffordshire, and would be infilled using Pulverised Fuel Ash (PFA) generated on-site as a by-product of coal combustion. It is estimated that the voidspace of the Borrow Pit is around 718,000 m3 which would cater for the disposal of approximately 1 Million tonnes PFA (assuming a density of 1.4 tonnes/m3). The proposed landscaping would consume an additional 600,000 tonnes PFA (assuming a density of 1.6 tonnes/m3), increasing the landfill’s total capacity to around 1.6 Million tonnes PFA. The proposal should be able to cater for the disposal of all of Rugeley’s unsold PFA until at least 2016. PFA is classified under the European Waste Catalogue (No. 10-01-02) as being “Solid, Non-Hazardous, Stable, Non-Biodegradable and Non-Reactive”. The proposal falls under Item 11, Schedule 2 of the Town and Country Planning (Environmental Impact Assessment) (England and Wales) Regulations 1999 (the EIA Regulations) and as such the Planning Application must be accompanied by an Environmental Statement (ES) to assess its potential environmental effects. The ES consists of three separate volumes, as follows: • Volume 1 Non Technical Summary; • Volume 2 Environmental Statement (Main Report); and • Volume 3 Hydrogeological Risk Assessment. The scope and content of the ES were agreed during pre-application meetings held with the WPA, which provided a ‘Scoping Opinion’ dated 5/12/2006 for the development under Regulation 10 of the EIA Regulations. This document is Volume 3, the Hydrogeological Risk Assessment, which provides an assessment of the likely risks posed by the landfill on groundwater and surface water quality. The Borrow Pit was excavated within fluvio-glacial sands and gravels and is approximately 11m deep. The Borrow Pit is currently flooded but would be dewatered and provided with an engineered basal and side slope liner composed of bentonite enriched soil (BES) of minimum 0.5m thickness. Due to the low level of environmental risk posed by the installation, it would be operated as a passive landfill. This report demonstrates that the installation would comply fully with the Groundwater Regulations 1998 and the Landfill Regulations 2002. The report has been prepared in general accordance with all relevant guidance provided by the Environment Agency for the landfill sector, including: • Hydrogeological Risk Assessments for Landfills and the Derivation of Groundwater Control and Trigger Levels, March 2003 • Guidance on landfill completion, February 2003 Rugeley Power Limited 1-1 Proposal to Restore Rugeley ‘B’ Station Borrow Pit through Landfill using Pulverised Fuel Ash Environmental Statement – Volume 3 ‘Hydrogeological Risk Assessment’ • Guidance on Monitoring of Landfill Leachate, Groundwater and Surface Water Issue 1 dated 28 Feb 2003 • Landfill Directive Regulatory Guidance Note 6.0 Interpretation of the Engineering Requirements of Schedule 2 of the Landfill Regulations 2002 Version 2 dated July 2004 • LFD Regulatory Guidance Note 11: The disposal in landfills for non- hazardous waste of; stable, non-reactive wastes, asbestos wastes; waste with high sulphate or gypsum contents The structure of this report is as follows: Section 2 provides a description of the installation; Section 3 summarises the conceptual site model; Section 4 characterises the source term represented by the repository; Section 5 describes the site environmental setting and the hydrogeological and hydrological conditions relating to the site and local surrounding area; Section 6 assesses the hydrochemical conditions relating both to groundwater and surface water resources located on site and in the local vicinity; Section 7 comprises the hydrogeological risk assessment, with the methodology and results of contaminant fate and transport modelling that has been carried out for the installation; Section 8 outlines the proposals for requisite monitoring of the installation in order to comply with the Groundwater Regulations and relevant guidance; Section 9 sets out the overall conclusions of the report. All drawings referred to in the report can be found in Appendix A. Rugeley Power Limited 1-2 Proposal to Restore Rugeley ‘B’ Station Borrow Pit through Landfill using Pulverised Fuel Ash Environmental Statement – Volume 3 ‘Hydrogeological Risk Assessment’ 2 Installation Description 2.1 Site Location The proposal site is located to the south-east of Rugeley Power Station (NGR 406930 316670) and covers approximately 87.3 hectares in total, of which approximately 6.3 hectares is occupied by the existing Borrow Pit. The installation will comprise a single discrete excavated cell. Drawing J24151C0/EIA/01 shows the site location and Drawing J24151C0/EIA/02-A the installation boundaries.