Contaminated land investigation: detailed inspection of former Wisbech Canal, Norfolk Prepared for Borough Council of King’s Lynn and West Norfolk King’s Court Chapel Street King’s Lynn Norfolk PE30 1EX Report reference: 60319R1D1. November 2010 Copyright 2010 ESI Confidential Prepared by ESI Ltd New Zealand House, 160 Abbey Foregate, Shrewsbury, SY2 6FD, UK Tel +44(0)1743 276100 Fax +44 (0)1743 248600 email [email protected] Registered office: New Zealand House, 160 Abbey Foregate, Shrewsbury, SY2 6FD. Registered in England and Wales, number 3212832 Contaminated land investigation: detailed inspection of former Wisbech Canal, Norfolk This report has been prepared by ESI Ltd. (ESI) in its professional capacity as soil and groundwater specialists, with reasonable skill, care and diligence within the agreed scope and terms of contract and taking account of the manpower and resources devoted to it by agreement with its client, and is provided by ESI solely for the internal use of its client. The advice and opinions in this report should be read and relied on only in the context of the report as a whole, taking account of the terms of reference agreed with the client. The findings are based on the information made available to ESI at the date of the report (and will have been assumed to be correct) and on current UK standards, codes, technology and practices as at that time. They do not purport to include any manner of legal advice or opinion. New information or changes in conditions and regulatory requirements may occur in future, which will change the conclusions presented here. This report is confidential to the client. The client may submit the report to regulatory bodies, where appropriate. Should the client wish to release this report to any other third party for that party’s reliance, ESI may, by prior written agreement, agree to such release, provided that it is acknowledged that ESI accepts no responsibility of any nature to any third party to whom this report or any part thereof is made known. ESI accepts no responsibility for any loss or damage incurred as a result, and the third party does not acquire any rights whatsoever, contractual or otherwise, against ESI except as expressly agreed with ESI in writing. Principal Author(s) Andy Tait/Andy Singleton Checked by: Lisa Murray Reviewed by: Hannah Fraser Confidential Prepared by ESI Ltd New Zealand House, 160 Abbey Foregate, Shrewsbury, SY2 6FD, UK Tel +44(0)1743 276100 Fax +44 (0)1743 248600 email [email protected] Registered office: New Zealand House, 160 Abbey Foregate, Shrewsbury, SY2 6FD. Registered in England and Wales, number 3212832 Contaminated land investigation: detailed inspection of former Wisbech Canal, Norfolk Page i CONTENTS 0. EXECUTIVE SUMMARY .......................................................................................... 1 1. INTRODUCTION ....................................................................................................... 3 1.1 Background ............................................................................................................... 3 1.2 Objectives ................................................................................................................. 3 1.3 Scope of work ........................................................................................................... 3 1.4 Relevant Legislation .................................................................................................. 4 1.5 Report structure ........................................................................................................ 4 2. SITE LOCATION AND HISTORY ............................................................................. 6 2.1 Site location and setting ............................................................................................ 6 2.2 History of the Site ...................................................................................................... 6 3. CONSULTATIONS .................................................................................................... 9 4. ENVIRONMENTAL SETTING ................................................................................. 11 4.1 Current land use and general site setting ............................................................... 11 4.2 Geology ................................................................................................................... 11 4.3 Hydrogeology .......................................................................................................... 12 4.4 Hydrology and drainage .......................................................................................... 13 4.5 Waste management/landfill sites ............................................................................ 13 4.6 Ecology and wildlife................................................................................................. 13 5. SITE INVESTIGATION WORKS ............................................................................. 14 5.1 Summary of NCC ground gas monitoring (1992 to present) ................................... 14 5.2 NCC 2009 ground gas investigations ...................................................................... 14 5.3 Summary of the NPL site investigation works (2009) ............................................. 15 5.4 Summary of Kings Lynn and West Norfolk Council site investigation works (2010) 15 5.5 ESI site investigation works (2010) ......................................................................... 15 5.5.1 Purpose of the site investigation ......................................................................... 15 5.5.2 Drilling activities .................................................................................................. 16 5.5.3 Soil and water sampling and testing ................................................................... 21 5.5.4 Ground gas measurements ................................................................................ 23 Report Reference: 60319R1 Report Status: Final Contaminated land investigation: detailed inspection of former Wisbech Canal, Norfolk Page ii 6. SITE INVESTIGATION RESULTS .......................................................................... 24 6.1 Geology ................................................................................................................... 24 6.1.1 Made Ground ...................................................................................................... 24 6.1.2 Natural deposits .................................................................................................. 24 6.2 Hydrogeology .......................................................................................................... 24 6.2.1 Groundwater levels ............................................................................................. 24 6.3 Soil quality data ....................................................................................................... 27 6.4 Leachability test results ........................................................................................... 29 6.5 Groundwater quality data ........................................................................................ 30 6.5.1 ESI monitoring data ............................................................................................ 30 6.5.2 NCC monitoring data .......................................................................................... 31 6.6 Soil gas results ........................................................................................................ 32 6.6.1 ESI monitoring data ............................................................................................ 32 6.6.2 NCC monitoring data .......................................................................................... 33 7. CONCEPTUAL MODEL .......................................................................................... 34 7.1 Conceptual ground model ....................................................................................... 34 7.2 Conceptual exposure model ................................................................................... 35 7.2.1 Sources ............................................................................................................... 35 7.2.2 Pathways ............................................................................................................ 36 7.2.3 Receptors ............................................................................................................ 37 7.3 Pollutant linkages .................................................................................................... 38 8. HUMAN HEALTH RISK ASSESSMENT ................................................................. 41 8.1 Methodology ........................................................................................................... 41 8.1.1 Risk screening .................................................................................................... 41 9. SOIL GAS RISK ASSESSMENT ............................................................................ 48 9.1 Methodology ........................................................................................................... 48 9.2 Risks posed by bulk gases (pollutant linkage: PL11) .............................................. 48 10. CONTROLLED WATERS RISK ASSESSMENT .................................................... 51 10.1 Methodology ..........................................................................................................