Management of process arisings from tunnels and other earthworks: A guide to regulatory compliance

Transcription

1 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance A report prepared by Beyond Waste in association with Environmenta Geotechnics and commissioned by The Pipe Jacking & Tunneing Research Group

2 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance IFC Beyond Waste in Association with Environmenta Geotechnics Beyond Waste Ltd, Yew Tree House, Lewes Road, Forest Row, East Sussex, UK. Te: +44 (0) Fax: +44 (0) Website: Discaimer This guide contains simpified guidance on compex and changing egisation, and does not constitute ega advice. Whist the authors have endeavoured to ensure it is current at the date of competion (May 2005), neither the authors nor the Pipe Jacking & Tunneing Research Group can be hed iabe for errors and omissions; compiance with the aw remains the reader s responsibiity. If you have concerns over compiance, you must seek professiona advice and / or contact the Environment Agency. Use of the information contained herein for pubications and reports shoud incude an acknowedgement to Beyond Waste Ltd as the source of the data. BEYOND WASTE ALL RIGHTS RESERVED. About the Authors Principa Author: Aan Potter Beyond Waste Aan Potter is the founder of Beyond Waste, a dynamic research and consuting organisation created in order to make an active contribution to the goba transition from a waste economy to a resource economy. From origins within academia (SPRU) he has acquired neary 20 years practica experience of waste and resource reguation and management issues in a variety of capacities (industry, oca government, and the Environment Agency). He speciaises in providing reguatory compiance and strategic advice to a range of cients primariy with waste management interests. Aan is a chartered waste manager and a member of the United Kingdom Environmenta Law Association. Technica Author: Prof Stephan Jefferis Environmenta Geotechnics Ltd. Prof Stephan Jefferis is visiting professor in the University of Oxford and a director of Environmenta Geotechnics Limited. He has over thirty years experience in the design of surry systems and materias for soi modification. He has worked on tunneing surries since their first appication in the UK.

3 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance

4 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 2 PIPE JACKING AND TUNNELLING RESEARCH GROUP The Pipe Jacking and Tunneing Research Group was formed in 1986 by the Pipe Jacking Association to co-ordinate research into pipe jacking and tunneing. The group brings together representatives from industry and academia and its roe is to act as a ead co-ordinator for the management of research into a broad range of industry issues. The group seeks to identify issues and areas for research and work with seected research contractors to obtain funding from research councis and industry partners. The Pipe Jacking Association has contributed over 300,000 directy to the research projects isted beow. Current members of the Group are: Geotechnica Consuting Group Pipe Jacking Association Severn Trent Water Thames Water University of Cambridge Department of Engineering University of Oxford Department of Engineering Science Co-opted member: Sud Chemie Research carried out by the Pipe Jacking Association and the Pipe Jacking and Tunneing Research Group Project Contractor Competed Pipe Jacking: State of the Art Review (PJA) CIRIA 1983 Laboratory mode testing of pipes and packing materias Oxford University 1989 Monitoring of fu-scae pipe jacks on active sites Oxford University 1992 Further site monitoring of pipe jacks and ground movements Oxford University 1996 Finite Eement Anaysis and mode testing of pipes Oxford University 1996 Prototype testing of improved micro-tunneing pipes Oxford University 1997 Mitigating the disruption caused by utiity street works (PJA) TRL 2001 Soi conditioning and ubrication for pipejacking Oxford University 2001 Soi conditioning and ubrication in tunneing, pipejacking and microtunneing Oxford /Cambridge Universities 2005 Surry management and disposa of semi-iquid spoi (Scoping study) CIRIA/Newcaste University 2005 Management of process arisings from tunnes and other earthworks Beyond Waste/Environmenta Geotechnics 2005

5 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 3 ACKNOWLEDGEMENTS This report has been prepared with the support of the Pipe Jacking and Tunneing Research Group. Particuar thanks are due to the project steering group that guided the contractors in their work under the chairmanship of Ian Staney (Johnston Microtunneing) consisting of the foowing individuas: G Monteith A Moss R Socombe (Barhae Construction) (Deta Civi Engineering) (Herrenknecht) Particuar thanks are due to Andrew Marsha of the Pipe Jacking Association for administering the project. And to Simon Rutedge BSc (Hons) MSc LLM who provided peer review of the ega content. This report draws on materia avaiabe on the websites of a range of governmenta agencies. Where text has been directy ifted from those sites acknowedgment is given. Crown Copyright may appy. Where Crown Copyright appies materia is reproduced with the permission of the Controer of HMSO and the Queen s Printer for Scotand.

6 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 4 EXECUTIVE SUMMARY Environmenta considerations now exert major contros on construction processes both from a technoogy seection and project cost point of view. A particuar environmenta chaenge for the pipe jacking and tunneing industries reates to the management of the excavated arisings from tunne works in genera and from surry tunneing (the most widey used procedure for sma projects) and earth pressure baance (EPB) tunneing in particuar. This is argey due to their high moisture content. Whie these arisings may be reused as a virgin materia, in practice, much materia has been andfied. The stage-wise impementation of the EU Landfi Directive with its progressive ban on the disposa of iquid wastes to andfi couped with the escaating price of andfi is acting as a catayst to change management practices. Under the directive, disposa of hazardous iquid waste to andfi is now banned and disposa of a iquids to andfi wi be banned by If any spoi is so wet as to be cassified as iquid then disposa to andfi wi not be permitted. If cement or simiar materias are added to wet arisings to soidify them it is necessary to consider whether the eevation of ph coud render the resuting materia a hazardous waste. This report is a response from the pipe jacking and tunneing industries to the chaenge of the Directive. Its primary purpose is to set out the egisation reating to the management of arisings from tunneing works. To provide a context, the report first deveops estimates of the annua quantities of arisings from the two main types of tunneing procedure used for pipe jacking, surry tunneing and earth pressure baance tunneing. Indicative moisture contents of the arisings are aso deveoped. The materias contain significanty more water than woud be present in an in-situ soi thus making them potentiay difficut to manage. The quantities of arisings from pipe jacking operations are shown to be very sma from a UK perspective and indeed, even if they were a regarded as waste, they woud represent just 0.05% of waste produced by construction and demoition activities when compared with nationa arisings data. The report then addresses the current egisative framework for management of materias that may be deemed to be waste. It highights opportunities and threats to the industry and seeks to ay out ceary and concisey a step by step route map to enabe producers to navigate through the compex web of egisation to achieve reguatory compiance. A word of warning however, waste management egisation is in a constant state of evoution and hence this report represents a snap shot of the situation refecting the current understanding at the time of reporting (May 05). The project was funded by the Pipe Jacking & Tunneing Research Group but we beieve the content is reevant across the construction and reated industries. We commend it to a readers with an interest in securing the future of the sector.

7 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 5 FOREWORD This guide is intended to provide the pipe jacking and tunneing community with guidance on the management of materias arising from the pipe jacking and tunneing processes. The principa audience of the report is the community itsef to ensure compiance with the diverse reguatory requirements reating to management of materia when it becomes waste and importanty aso to encourage the community to think about how waste produced from their activities might be minimised. The guide may be of wider interest to other payers in the construction and demoition fied as we as the reguatory bodies themseves. As the report identifies materias arising from the sector s activities are reativey sma in voume and reativey benign in nature. However, we are aso seeing a tightening of reguatory requirements, which impinge on the industry to a significant extent. If arisings cannot be managed and disposed of somehow utimatey the processes coud grind to a hat. In order to ensure that the arisings from tunneing operations are not automaticay considered as waste and hence subject to the fu weight of the reguatory requirements, the terms used to describe the materias generated during the tunneing process need to be chosen carefuy. This may mean a departure from previousy accepted terminoogy. For exampe Environment Agency Guidance states that recycing is something, which is ony carried out on waste. 1 Hence care shoud be taken in the use of the term recyce or even reuse when referring to the further use of a materia for a different purpose. Providing the hoder has not decided to discard an item or materia then it remains a useabe product (See Section 7.2.1). A gossary of non-waste terms for what otherwise might oosey be referred to as the waste from tunneing processes therefore needs to be deveoped. The first few entries are beow and are used throughout this report. Waste Associated Term Spoi from the tunneing machine New term Process arisings Note: The OE dictionary defines spoi as a waste materia brought up during the course of an excavation or a dredging or mining operation. Process arisings impies that the materia is retained as part of an overa process and hence may not be decared waste unti it has been ejected from the process. This guide addresses the issue of defining the process boundary in a subsequent section. Waste disposa Materia management Note: The use of the term disposa automaticay cassifies a materia as waste. Ceaned surry after passage through soid/iquid separation pan Returned surry from the soid/iquid separation pant Note: Promotes the idea of cycic use and avoids suggestion that the surry is contaminated A use of the term contaminated shoud be avoided in reation to process arisings uness the arisings have genuiney been contaminated with contaminants such as ubricating ois, fues or materias that may be cassed as hazardous. The intention here is not to avoid the proper reguatory processes but to ensure that the optima route through to compiance is identified for any arisings such that the reguatory contros encountered are proportionate to the risk posed by the materias concerned. 1 A Simpe Guide To Assist Community Sector Reuse/Refurbishment Organisations In Compying With Waste Reguations. Produced By The Environment Agency And The Community Waste Sector November 2003.

8 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 6 INDEX 1 INTRODUCTION 8 2 TUNNELLING TECHNIQUES FOR WET GROUND 8 3 THE SLURRY TUNNELLING PROCESS SLURRY COMPONENTS, DENSITY AND FLOW RATE SLURRY PROCESSING LIQUID SLURRY MANAGEMENT 10 4 EARTH PRESSURE BALANCE (EPB) TUNNELLING 10 5 QUANTITIES OF SOIL AND PROCESS ARISINGS PROCESS ARISINGS FROM A SINGLE PROJECT THE NATURE OF THE PROCESS ARISINGS Process arisings from coarse scaping screens Process arisings from the dewatering screens Process arisings from the fines remova equipment DRYING OF WET PROCESS ARISINGS 13 6 MATERIALS USED IN THE TUNNELLING PROCESS GENERAL CONSTRUCTION AND PLANT CHEMICALS USED IN THE TUNNELLING PROCESS ph High ph Low ph Handing Hazardous Materia 15 7 LEGAL FRAMEWORK LEGAL CONTEXT IS THE MATERIAL WASTE? Has the item been discarded? IF THE MATERIAL IS CLASSED AS WASTE AT WHICH POINT IS IT DEEMED TO BECOME WASTE? UNDER WHAT CIRCUMSTANCES MIGHT IT CEASE TO BE WASTE? WASTE MANAGEMENT OPTIONS Reduction Reuse Recovery Disposa Casses of andfi Prohibition on iquids Pre-treatment 21 8 ASSOCIATED REGULATORY REQUIREMENTS THE DUTY OF CARE SPECIAL WASTE Proposas for repacing the Specia Waste Reguations European Waste Cataogue LANDFILL TAX AGGREGATES LEVY 25 9 DECISION FRAMEWORK 25 APPENDIX 1 Pipe jacking and sma diameter EPB tunneing. Exampe figures for arisings 28 APPENDIX 2 Extract of Sectora Guidance from NetRegs 31 APPENDIX 3 European Court of Justice Judgements: The Definition of Waste 31 APPENDIX 4 Extracts of The Waste Management Licensing Reguations 1994 (SI 1994 No. 1056) 34 APPENDIX 5 Extract of The Landfi (Engand and Waes) 37 APPENDIX 6 Extract from The Landfi Tax (Quaifying Materia) Order

9 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance A report prepared by Beyond Waste in association with Environmenta Geotechnics and commissioned by The Pipe Jacking & Tunneing Research Group

10 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 8 1 INTRODUCTION This is the fina report for the project on tunneing arisings management. Sections 2 to 6 set out the basics of the tunneing processes, the materias that may be used, the quantities of process arisings that can be expected from sma diameter tunneing in the UK and the division of these arisings between soids and water from the ground and from the tunneing process itsef. Sections 7 to 9 set out the ega framework for management of process arisings. 2 TUNNELLING TECHNIQUES FOR WET GROUND The Pipe Jacking Association (PJA) pubication, An introduction to pipe jacking and microtunneing design, identifies a range of excavation methods for wet ground as shown in Tabe 1 When tunneing in wet ground, that is at or beow the groundwater eve, it is necessary to imit or prevent groundwater entry into the tunne. From Tabe 1 the five principa approaches to achieving this are: 1) Seaed face using surry for process arisings conveyance; 2) Seaed face with earth pressure baance; 3) Chemica stabiisation of the ground using grouts; 4) Dewatering with deep wes or wepoints; 5) Air pressure to counteract water pressure. Process arisings from natura ground stabiised by cement or chemica grouts require specia consideration in reation to their future management or use. This may require specific advice from the manufacturer of the grout. It shoud be noted that many stabiisation grouts are markedy akaine (for exampe, sodium siicate and cement) and this can be a cause for concern as regards cassification of the materia for use or management of the materia as a waste. Tabe 1 Pipe Jacking Excavation Methods For Wet Ground (Soi Types: Wet Cohesive; Wet Non-Cohesive; Wet Mixed And Fi Conditions) Excavation Pipeine Length Ground Support Remarks method Interna Diameter Open hand shied mm Generay up to Chemica stabiisation Subject to ground 200m Suspension grouts conditions, depth, We points inter-jacks, ubrication Deep wes and economics Cutter boom shied Not appicabe Backacter mm Generay up to Chemica stabiisation Subject to ground 500m Suspension grouts conditions, depth, We points inter-jacks, ubrication Deep wes and economics TBM mm Generay up to Chemica stabiisation Subject to ground 500m Suspension grouts conditions, depth, We points inter-jacks, ubrication Deep wes and economics Surry machine mm Generay up to In-buit method Subject to inter-jacks, 500m ubrication and economics Earth pressure mm Generay up to Partiay in-buit pus: Limited by water baance 500m Chemica stabiisation pressure head, Suspension grouts inter-jacks, ubrication We points, Deep wes and economics Air pressure shied m Generay up to In-buit method Subject to inter-jacks, 500m ubrication and economics Microtunneing mm Generay up to Dependent on type Subject to inter-jacks, 250m of machine ubrication, economics and guidance system

11 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 9 3 THE SLURRY TUNNELLING PROCESS As a tunneing machine excavates soi at the tunne face, the process arisings must be transported to the surface for management. In a surry tunneing machine, this is achieved by using a surry as a carrier. This surry circuates in a continuous oop from the tunneing machine to the soid/iquid separation pant and back to the machine. The various stages of the process are: 1. returned surry is pumped to the machine; 2. in the machine, the process arisings are incorporated into the surry; 3. the soi aden surry is pumped to the surface separation pant; 4. in the soid/iquid separation pant, soids are separated out; 5. the surry, after separation, is returned to the machine. The principa roe of the surry is to carry the cut soi from the excavation face to a separation pant which is normay ocated on the surface. In this roe, the surry is a carrying fuid carrying the soi from the tunne excavation face to the separation pant where the soi is removed and the surry then returned to the face. The surry is designed to operate in a cosed oop and is repeatedy recyced through the tunneing machine and separation pant. 3.1 Surry Components, Density And Fow Rate In many grounds, the initia surry wi be simpy water. In use, it wi pick up fines from the excavated ground and wi become somewhat more viscous and denser than water. In other grounds especiay where the ground is rather coarser it may be necessary to add bentonite cay to the surry to improve its abiity to sea the face. In fine sois, proprietary chemicas may be added to the surry to imit soi dispersion and prevent the surry becoming too viscous and dense. Typicay, the density of the surry returned to the machine wi be ess than about 1.05 t/m 3. If this density cannot be achieved in the separation pant then buid up of fines in the surry is ikey to occur. The surry fow rate must be matched to the tunneing machine design. The pipeine from the tunneing machine to the separation pant is typicay at east 100 mm in diameter and the fow veocity has to be at east 1.5 m/s to ensure satisfactory soi conveyance. This combination of fow veocity and pipe diameter gives a minimum fow rate of about 100 m 3 /hr. However, in practice, higher fow rates are used to prevent cogging of the face of the tunneing machine and typicay fow rates wi be in the range 150 to 250 m 3 /hr.

12 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance Surry Processing Remova of the transported soids from the surry is an integra part of surry tunneing operations. In coarse sois, this may be reativey straightforward but probems with the separation of sits and cays (in genera materia finer than about 100 microns) can be a imiting factor to the use of surry machines. Typicay, a soid/iquid separation pant wi invove three eements: a coarse or scaping screen, a hydrocycone / dewatering screen combination unit and a fines remova system such as a centrifuge or fiter bet press. A typica schematic diagram for the separation pant is shown in Figure 1 on page 11. It shoud be noted that separation pants can vary significanty between projects. The openings of the coarse screen wi depend on the partice size expected of the tunneed soi. Typicay, the screen might have an opening of 5 to 10 mm and may be protected by a heavier, coarser pre-screen. The hydrocycone/dewatering screen unit typicay consists of one or more hydrocycones mounted over a dewatering screen (smaer hydrocycones can remove finer soids, they have a finer cut, but are more easiy bocked). Often a singe arge and one or more sma hydrocycones wi be used. The size of the sma hydrocycones, and therefore their cut, may be imited by the opening of the coarse screen. The underfow orifice of hydrocycones is easiy bocked by oversize materia and the smaer the hydrocycone the smaer the underfow orifice. The hydrocycones concentrate the soi soids into their underfow by centrifuga action and this concentrate is discharged onto the dewatering screen where a cake shoud buid up. The dewatering screen is vibrated so as to move the soids aong the screen to a discharge point. The materia that first buids on the screen wi be coarser than the screen opening but finer materia wi become trapped in the voids of this coarser materia so that the combination of screen pus bed provides a system that can remove materia significanty finer than the screen openings. This requires that a reasonabe bed of soi buids up on the screen the presence of some appropriatey sized materia is essentia to the effective operation of the pant. Typicay, the bed wi be a few centimetres deep though this wi depend on the pant used and the operating conditions. If there is insufficient materia in the concentrated underfow from the hydrocycones then the combination of hydrocycones and dewatering screen wi not be effective and ony materia coarser than the screen opening wi be removed. The hydrocycone/dewatering screen unit is designed to recyce ; the underfow from the coarse screen drops into a divided tank from which the hydrocycones draw their feed and to which they return their ceaned overfow. In fine sois or in mixed grounds where the face incudes a significant amount of fines, it wi be necessary to incude a fines separation device in the separation circuit. For sma diameter tunneing machines, this usuay wi be a centrifuge. For arger machines and/or major projects, one or more fiter bet presses sometimes are used. The probem with both centrifuges and fiter bet presses is that they cannot take the fu fow from the tunneing machine. Centrifuges and fiter bet presses therefore are operated off-ine to the main fow circuit and are used to poish the surry and prevent accumuation of fines in the circuit. Because of the imited fow capacity of centrifuges they may be kept running after tunneing is compete for the day the running time for the centrifuge may be greater than that for the tunneing machine. 3.3 Liquid Surry Management At the end of a project, some surry wi remain in the system and a management procedure for this remaining surry is necessary. Current procedures incude: Extended centrifuge treatment (with the addition of foccuants) to convert the surry to effectivey water and a centrifuge paste. The water then may be discharged to fou sewer with a trade effuent consent. Discharge to sewer is not considered in this guide. As the surry is basicay a suspension of natura soi in water with a sma amount of treatment chemicas it may be possibe to manage it by appication to and. If the surry cannot be treated to aow discharge of the water fraction to sewer or spread on and it may be soidified by the addition of cement or other soidification materia to produce a soid mass that may be andfied though the soidified materia wi have to meet waste acceptance criteria for the appropriate cass of andfi if it is to be consigned to andfi. Re-use of the soidified materia may be difficut if it is cassed as waste (see ater). 4 EARTH PRESSURE BALANCE (EPB) TUNNELLING In some grounds, the excavated materia may be removed from the tunneing machine by a screw conveyor. However, the pressure in the face of the machine must be reated to the earth pressure so as to prevent the inward movement of the soi in the tunne face. This requires that a pug of soi is deveoped in the screw. In wet and permeabe grounds,

13 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 11

14 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 12 this pug of soi must aso prevent the uncontroed escape of groundwater. Hence the presence of this pug of materia is essentia to the tunneing operation. It may be possibe to form the necessary pug with the soi naturay present in the ground especiay if it incudes a significant proportion of cohesive materia. In other sois it can be necessary to modify the soi with chemica additives typicay water-soube poymers which work synergisticay with the fines to produce a conditioned soi. In noncohesive sois such as sands, foam may be used in pace of poymers. Earth pressure baance (EPB) tunneing may be used on arger diameter tunnes, as soi must be removed mechanicay, aong the tunne, after discharge from the screw conveyor (rather than pumped in a surry). 5 QUANTITIES OF SOIL AND PROCESS ARISINGS At a meeting of the project steering group on 30 September 2004, members of the group estimated the amount of pipe jacking that was undertaken in the UK per year. An initia estimate of 5 km of 1.8 m outside diameter pipe jack was proposed. This gives a soi voume of 12,700 m 3 /year or mass of perhaps 22,300 tonnes/year. After some discussion, this was revised to 30,000 tonnes/year. This is the input of soi. The output of process arisings produced by the tunneing process is greater than this because the process arisings from the tunneing have an average moisture content higher than that of the soi in the ground. Treatment chemicas aso may be added but quantities are ikey to be sma compared with the quantity of soi though they may have important impacts on the management of the process arisings. It aso was estimated that the distribution of excavation procedure between surry tunneing and EPB tunneing was 95% by surry and 5% by EPB machine. In order to quantify the process arisings from pipe jacking and sma diameter tunneing operations the tabes in Appendix 1 have been prepared. These show some exampe figures and assumptions for soi type and separation pant performance. It must be emphasised that these are indicative figures ony. It woud appear that size distributed efficiency data (grade efficiency data) are not avaiabe for the separation pant used by the pipe jacking and tunneing industry and refinement of the figures using existing separation pant computer simuation procedures is not practicabe at the present time. The resuts of the cacuations are summarised in Tabe 2 beow (see aso Tabe 9 of Appendix 1). Tabe 2 Summary Of Estimated Annua Soi Excavation Data And Process Arisings (Combined Output From Surry Tunneing and EPB machines) Summary of soi excavated and Soi excavated Process arisings Extra materia process arisings for management generated generated per year Mass Voume Mass Voume Mass Voume Tonne m3 Tonne m3 Tonne m3 Soids 20,690 7,807 20,690 7, Water 9,310 9,310 15,722 15,722 6,411 6,411 Tota process arisings 30,000 17,118 36,411 23,529 6,411 6,411 Soids content 69% 57% Per cent extra materia 21% 37% Tabe 2 shows that because of water in the process arisings, the amount of process arisings to be managed may be perhaps 21% greater than the weight of soi excavated or 37% over the voume excavated. As a resut, athough the tota mass of soi excavated may be of the order of 30,000 tonne/year, the quantity of process arisings generated per year may be of the order of 36,400 tonne/year (it shoud be noted that the surry separation pant and EPB performance figures may be reativey optimistic and the actua quantity of process arisings may exceed the excavated soi quantity by a significanty greater margin). In overa waste management terms the quantity of process arisings generated by pipe jacking and sma diameter tunneing is reativey modest athough of course a major issue for the industry especiay as some of the process arisings may be very wet. 5.1 Process Arisings From A Singe Project A singe pipe jacking or sma diameter tunneing project may ast perhaps two to three months with perhaps 500 to 750 tonnes of soi excavated per month and a tota of 1,500 tonnes for the whoe job. For a surry tunneing project the quantity of process arisings generated may be over 17% greater than this by mass or 30% by voume (see Appendix 1, Tabe 10). For an EPB machine the amount of process arisings generated wi be very significanty greater than the amount of soi (97% by mass, 170% by voume see aso Appendix 1, Tabe 10).

15 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance The Nature Of The Process Arisings As discussed above the process arisings from pipe jacking and sma diameter tunneing machines wi incude arisings from each of the separation stages: Process arisings from coarse scaping screens From the exampe figures set out in Appendix 1, Tabe 6, 7% by mass (5% by voume) of process arisings produced from surry tunneing might be from the coarse scaping screen. As this materia is reativey coarse, the amount of water adhering to it wi be sma and the moisture content may be quite ow, perhaps 10% if the materia is non-porous grave. Moisture contents may be higher if the coarse process arisings are porous materia for exampe, cay or mudstone chippings. Management of this materia wi be reativey straightforward and its further use is to be preferred. For exampe, if it were free from adhering cay and did not contain soft materia (e.g. umps of cut cay), it coud be used as aggregate. This raises issues regarding aggregate evy which is deat with in Section 8.4. If not, options for use incude: restoration on inert sites (andfi tax exempt), use on andfis (andfi tax exempt), use under an exemption as part of a construction project, use on an existing site as a fi materia aways assuming that the materia is appropriatey free from contamination (See Later) Process arisings from the dewatering screens From the exampe figures in Appendix 1, Tabe 6, 58% by mass (51% by voume) of process arisings produced from surry tunneing might be from the dewatering screens. This is a substantia proportion of the process arisings produced. If there is a significant amount of sand or coarse sit in the tunne face the process arisings may be useabe as a construction soi. If the face contains finer materia, process arisings may be rather wetter perhaps a moisture content of 60 to 70%. If the screens are operating effectivey management of this materia can be reativey straightforward and again use is to be preferred. However, dewatering screens cannot aways be operated effectivey. For effective operation, there must be sufficient coarse materia to buid a bed on the screen and this bed must be sufficienty permeabe to aow dewatering. In reguatory terms this suggests that the presence of coarse materia is an integra part of the operation and hence it is not a waste at this point. A soi with ony cay and sit-sized fines may pass through the screens argey untreated and as a consequence overoading of the surry with fines may occur. Screens aso can be overoaded, the bed becomes too thick and dewatering becomes inefficient so that wet process arisings pus surry are discharged from the screen Process arisings from the fines remova equipment From Appendix 1, Tabe 6, 36% by mass (44% by voume) of process arisings produced from surry tunneing might be removed in the fines unit. This wi be a wet and difficut materia. Often it wi be a sticky (viscous) semi-fuid. If vibrated, for exampe, in transport it may iquefy and/or some of the iquid content may be iberated. The fines paste is difficut to further dewater uness it can be spread and aowed to dry naturay. It is the most difficut fraction of process arisings requiring management. It aso shoud be noted that in some grounds the fines remova equipment may not remove sufficient fines to prevent their buid up in the surry. If this occurs, fines-rich surry may have to be removed (bed) from the circuit. Formery this woud have been deat with as iquid waste. 5.3 Drying Of Wet Process Arisings On occasion and with cement weather conditions, process arisings may be eft to dry prior to subsequent management. Storage of the process arisings can raise questions in reation to icensing of the storage site if the materia is deemed to be a waste. 6 MATERIALS USED IN THE TUNNELLING PROCESS A wide range of materias may be used on a tunneing project and therefore may be represented in the materia generated. These may be divided into those that are derived from the genera construction and mechanica processes on the site (e.g. use of mechanica pant), and those specific to the tunneing process. Waste from offices, from washing and toiet faciities shoud be managed through proper contractor s practice and is not considered in this guide.

16 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance Genera Construction And Pant This may incude: Spied and/or contaminated fue ois Lubricating ois and greases (residua) Cooants e.g. antifreeze iquids and water contaminated with any of the materias used on site or vehice wash-down etc. Used spi kits for hydrocarbons and other chemicas Cement powder (residua) Hardened cement and concrete (residua) 6.2 Chemicas Used In The Tunneing Process Treatment chemicas may be added at severa ocations in the tunneing process: 1) at the face to reduce torque e.g. foams; 2) as additives to the ubricants injected around the pipes there may be some eakage into the tunne face; 3) in surry machines as additives to change the properties of the surry, e.g. to inhibit the dispersion of fines and so prevent overy dense/viscous surries deveoping; 4) in a surry separation pant as a pre-treatment (coaguation and foccuation) prior to centrifuge or fiter bet press treatment; 5) in EPB machines to improve the fow or pug formation in the screw conveyor; 6) to dry process arisings from the surry separation pant or from an EPB machine to faciitate easier management; 7) grout to treat oose or difficut ground which is then excavated by the machine. Concentrations of treatment chemicas (e.g. organic poymers) in a tunneing surry or treated soi from an EPB machine generay wi be sma and are unikey to exceed about 1% by weight of water and can be much ess. Thus if, for exampe, the process arisings are very wet and consist of equa quantities (by mass) of excavated soi and a surry, the overa treatment chemica content of the process arisings is unikey to exceed 0.5%. Coaguants and foccuants added prior to centrifuging may be added at doses of a few grams per dry tonne of process arisings (equivaent to a few ppm). Aso, it shoud be noted that many of the treatment chemicas wi bind strongy to fine sois; indeed they may be designed to do so. Therefore the eachabe chemica content of the process arisings may be ess than the amount of chemicas added (though aowance wi need to be made for organics naturay present in the soi). Bentonite cay may be added as a surry forming materia. It is a natura cay, but it may have been treated with sodium carbonate and sma amounts of organic poymers. Concentrations may range up to about 5% depending on the source and quaity of the cay. In use it may be necessary to add further sodium carbonate to maintain the cay in the sodium form. Sodium bicarbonate may be added if cement is present in the surry. Soi containing grouts used for ground treatment wi require specia consideration as quantities of treatment chemicas are ikey to be much greater than in any other process arisings. For exampe, the quantity of grout injected into a ground to strengthen or water tighten it may be perhaps 5 to 30% of the voume of soi. Arisings other than soi from the tunneing process may incude: Bentonite; Hardened cement (e.g. from cement grout); Proprietary grouts; Empty bags and drums (e.g. treatment chemica, cement, bentonite or grout containers). There aso may be some hydrocarbon contamination of the process arisings through eakage of hydrauic ois and greases. 6.3 ph Many of the treatment chemicas tend to be of near neutra ph and thus their use shoud not generate concerns about the ph of the resuting process arisings. However, some caution is necessary as discussed in the foowing sections High ph sodium bentonite typicay wi have a ph in the range 9.5 to Thus, pipe ubricants and bentonite based surries may have phs of up to about Speciay formuated ubricants may have higher (or ower) phs;

17 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 15 fresh concrete or cement grout wi have a ph of about 13.5 thus cement containing process arisings can have a high ph; if a machine drives through concrete (e.g. weak concrete at a shaft entry/exit the process arisings wi be of potentiay high ph; siicate based grouts are of high ph and excavation through siicate grouted soi wi give high ph process arisings; some surry forming poymers perform better at high ph so akais may be added to the surry Low ph Excavation in peat can produce ow ph process arisings. ph vaues may be as ow as 3 though 4 to 5 is more typica. Many deep cays contain some pyrite (iron suphide). On exposure to air, the pyrite can oxidise to suphuric acid and suphates. In the ground, the soi may be of near neutra ph but after exposure to atmospheric oxygen the ph may reduce significanty Handing Hazardous Materias The Environment Agency hosted NetRegs website incudes the foowing advice A Safety Data Sheet must accompany any materia suppied to you that has potentiay hazardous properties. The Safety Data Sheet gives information on how chemicas shoud be handed, stored and disposed of. If a Safety Data Sheet does not accompany the deivery, contact the suppier and ask for it. Suppiers who fai to provide adequate information for the safe use of their products are in breach of the aw. Materias that have hazard abes and are controed by COSHH shoud be signed out of your storage area and signed back in after use regardess of the quantity eft in the container. This aso appies to materias signed out for use on remote sites. This web based resource aso provides outine guidance for the sector. This is reproduced in Appendix 2. 7 LEGAL FRAMEWORK 7.1 Lega Context The guide covers egisation that is appicabe to the UK as a whoe. However, this has been impemented in different ways between Engand and Waes, Scotand and Northern Ireand. The guide appies to the Engand and Waes ega situation as the defaut. Whie the genera principes are common, contractors working in Scotand and Northern Ireand shoud seek specific advice from the oca reguator (Scottish Environmenta Protection Agency and DoE Environment and Heritage Service Northern Ireand respectivey) Is the materia waste? Waste is defined in Artice 1(a) of the Waste Framework Directive as any substance or object which the hoder discards or intends, or is required to discard. The Directive defines THE HOLDER as being either the producer or the person now in possession of the object. This is important because it is the hoder s decision or intention that is fundamenta in deciding whether something has been or wi be discarded. Where the hoder is not the producer the intention or actions of the origina producer are aso reevant. In contracting situations the producer is normay taken to be the tunneing contractor. The hoder coud either be the tunneing contractor or a main contractor or even the cient for the project. Current practice is that the tunneing contractor is responsibe for the arisings as waste. The Government issued guidance on the interpretation of the definition of waste in 1994 (Government Circuar 11/94, Annex 2). However, since then there have been a number of judgements by the European Courts and our nationa Courts on the interpretation of the definition, which are not refected in the Government s guidance. The Government is revising that guidance to take these judgements into account. However the Government defers to the courts as the fina arbiter of the meaning of aw. The courts have identified various factors, which are reevant, and others, which are ess reevant, in determining whether or not something is waste. However, most of these factors are ony indicative and the Courts tend to emphasise that each decision must be made based on a the facts of the case before it whist having regard to the aim of the 2 Basic Guidance for management of waste for the sector is given on the Environment Agency hosted NetRegs website this is reproduced in Appendix 2.

18 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 16 Directive: the protection of human heath and the environment against harmfu effects caused by the coection, transport, treatment, storage and tipping of waste. That having been said, the findings of specific cases are having increasingy profound effects on the appication of the aw across the board so the specific nature of judgements shoud not be taken to mean they do not have wider appication. A recent exampe is the Van de Wae judgement which suggests that materia insitu is waste if it has become contaminated whereas previousy the view has been taken that materia needs to have been excavated before it coud be deemed waste. This judgement has profound impications for the identification of the hoder of the waste because of course if the interpretation appies widey it woud mean the and owner woud be the keeper of the waste in the first instance and any subsequent operations invoving the materia woud be viewed as waste management operations. A summary of the most significant judgements is incuded at Appendix Has the item been discarded? This requires that the intention of the hoder be determined. THE HOLDER is the producer or the person in possession. Has that person discarded the item, or are they intending to or being required to discard it? Whie this guide provides guidance on interpretation utimatey it is the responsibiity of THE HOLDER to determine whether they are handing waste. Whie the Environment Agency, as the authority responsibe for enforcing waste management egisation in Engand and Waes, may advise of its opinion as to whether or not something is waste, it is possibe to take a different view. Utimatey it is a matter for the courts to decide. The Environment Agency has produced some guidance 4 (fundamentas) as foows: on the matter which outines a number of usefu points 1. Just because someone ese has a use for an item does not mean that it is not waste. 2. Just because money changes hands for the item does not mean that it is not waste. 3. Just because an item doesn t work and needs repair does NOT mean that it IS waste. 4. The more that has to be done to an item to make it suitabe for use then the more ikey it is to be waste. 5. Recycing is something which is ony carried out on waste Step 1: Expore the scope for defining the waste producer through the contract. 7.3 If the materia is cassed as waste at which point is it deemed to become waste? At the tunne face? When suspended in the surry? When subjected to processing to remove it from the tunneing cyce? When deposited as a soid/semi soid? This is an important question as it determines the process boundary. So for exampe, if the materia was deemed to have been discarded at the tunne face then a subsequent processing may be subject to waste management icensing egisation. It may be more desirabe to extend the process boundary to cover the fu operation so that the materia is deemed to be waste (if it is so deemed) ony once it has eft the site of production. In the case of tunneing arisings the presence of materia at the face can perform a function in the tunneing operations and hence it coud be argued that at this point the materia has not been discarded. It is ony at the point at which the materia has been removed from the process and a determination made as to whether it woud be of any subsequent use that the materia woud then be deemed to be waste. The determination as to whether the materia is or is not waste may depend on the consistency (wetness) of the materia at this time. Step 2: Determine the process boundary and estabish when the materia arising woud be deemed to be discarded. 7.4 Under What Circumstances Might It Cease To Be Waste? A further important question is that once a materia is deemed to be waste under what circumstances might it cease to be waste? Case aw suggests that the waste must have been subject to a recovery operation. 3 The European Commission document entited "Towards a thematic strategy on the prevention and recycing of waste" recognised the difficuties that the definition of waste can pose and indicated its wiingness to enter into debate on the issue. There is work ongoing on this point. 4 A Simpe Guide To Assist Community Sector Reuse/Refurbishment Organisations In Compying With Waste Reguations. The Environment Agency & The Community Waste Sector Nov 2003.

19 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 17 What constitutes a recovery operation in this case? Recovery operations are defined in the Waste Framework Directive and the meaning has been further defined by Case Law at the European Court of Justice. See Appendix 3 for outine criteria that woud quaify a process as a recovery operation. 7.5 Waste Management Options If a materia has been cassed as waste, consideration needs to be given to the management options avaiabe. The Government Waste Strategy 2000 presents a hierarchy of waste management options as foows: 1. Reduction 2. Reuse 3. Recycing & Composting 4. Recovery incuding therma processing 5. Disposa Appying the hierarchy to the management of tunneing waste a number of options emerge. These are further expanded upon beow Reduction The opportunities to reduce production of arisings are imited in a tunneing environment as the process necessariy requires the conversion of insitu materia into oose materia. However as stated above there is sti some scope to avoid the materia being defined as waste by extending the process boundary such that the materia does not become cassed as waste. The ony viabe reduction method identified once it is a waste is to reduce the water content of the arisings. Step 3: Consider a opportunities to reduce the quantity of waste requiring management. A producer is required to provide a written description of the nature of the waste to go for onward management. This description must provide as much information as someone ese might need to hande the waste safey. It must describe the waste by reference to the appropriate 6 digit code/s in the European Waste Cataogue (EWC) (See Section 8.2.2). The EWC is intended to provide a method of identifying the type of waste according to the process or industries from which they arise. The code assigned may determine the management routes avaiabe particuary if the code appies to inert or potentiay hazardous waste. As is the case for tunneing arisings where there is no specific code it is necessary to identify the code that achieves the best fit. The most appropriate Chapter for tunneing arisings woud be under Chapter 17 (Construction and Demoition Wastes (incuding excavated soi from contaminated sites). Within this the most appropriate code woud appear to be: SOIL (INCLUDING EXCAVATED SOIL FROM CONTAMINATED SITES), STONES AND DREDGING SPOIL * soi and stones containing dangerous substances soi and stones other than those mentioned in The presence of an asterisk aows for the possibiity of the waste being hazardous. Cassification as hazardous waste imposes additiona reguatory burdens and is to be avoided if possibe. The Environment Agency Guidance 5 that gives its interpretation of the cassification of hazardous waste states in the case of Chapter that: These categories incude such a broad range of potentiay hazardous wastes that they shoud be considered under a the hazards H1 to H14. If the chemica constituents of the waste are unknown, it shoud be treated as hazardous uness tested. Definitions of the hazards H1 to H14 can be found in the Agency s Technica Guidance. Hence a precautionary approach is proposed with a presumption to a Chapter waste that is unknown being cassed as hazardous if there is any reason to indicate the waste may be hazardous uness the fu range of testing has been appied. This means that particuar care shoud be taken if tunneing in potentiay contaminated conditions, with the need to ensure that any additives 6 or spiages do not render the waste hazardous. 5 Environment Agency Technica Guidance WM2: Hazardous Waste: Interpretation of the definition and cassification of hazardous waste (June 2003). 6 The Environment Agency Guidance WM2 states on additives in reation to driing muds: Many recipes for driing muds are unique to the company or individua in charge of the operation: it is difficut to be prescriptive about ikey hazards. Even supposedy ow toxicity water-based muds may contain ecotoxic additives (H14). If the chemica constituents of the mud are unknown, any additives shoud be assessed to determine any potentia hazard.

20 Management of process arisings from tunnes and other earthworks: A guide to reguatory compiance 18 Step 4: Determine Appropriate Cassification of Waste Reuse For unavoidabe arisings (re)use is, in principe, the most desirabe outcome. Essentiay natura materia is being excavated which is then used for purposes for which other materias woud otherwise have to be used. Exampes of this incude: Use on-site where for exampe, engineering fi is required and a materias baance has been undertaken. If it is simpy deposited on the site, this may constitute disposa by andfi under which circumstances a forma permit woud be required. It is unikey that this woud be a favoured option under these circumstances. The key here is to avoid the materia being cassed as waste or demonstrating that the use of the materia may be cassed as a recovery operation. Use esewhere via sae as product. The viabiity of this option depends on whether the materia is cassed as waste and if so that it has been subject to a recovery operation and so is no onger to be cassed as waste. As the definition of waste suggests, a key determinant is the intention of producer. So it may be argued that if there was premeditation concerning the use of the materia once it had been extracted for exampe, if a materia is excavated and sod on, it may not be deemed to be waste at a. However, if the materia is simpy given away then it may be deemed to be waste as it might be impied that the intention of the producer is to discard it. Just because a receiver may have a use for the waste does not mean that it is not waste. As one judgement put it one man s waste may be another man s treasure.* This woud normay require identifying receivers that are prepared to pay the market rate for such materia as an aternative to primary materias. If it is to be used for infi purposes the existence of panning permission for the deveopment may aso provide evidence of egitimacy. Storage on-site pending disposa for onger than one year coud be construed to constitute a disposa by andfi requiring a fu permit. Storage for an indefinite period woud ikey to be deemed to be abandonment and may render those responsibe iabe to prosecution for iega waste disposa and possiby a requirement to remove the waste. Step 5: Review contract arrangements such that opportunities for reuse of materia arisings can be egitimatey considered to enabe use as a product Recovery This woud cover use esewhere in a recovery operation exempt from waste management icensing. The Waste Management Licensing Reguations 1994 incude specific exemptions from icensing for the appication of certain waste to and under particuar circumstances and subject to certain contros. These are known as the Paragraph 7 (spreading on agricutura and), 9 (and restoration) and 19 exemptions (gof courses and transport faciities etc). The fu text is reproduced in Appendix 4. These have been revised recenty and more forma registration procedures have been introduced. From 1st October 2005 if you wish to rey on such an exemption you must seek registration from the Environment Agency. This wi require you to obtain, compete and submit a form aong with: (a) (b) (c) (d) a notice of reevant particuars and such other information as the authority reasonaby requires in reation to the activity; such pans and other documents as the authority reasonaby requires; specify the quantity of waste to be disposed of or recovered; and a cheque to cover a registration fee. The registration is renewabe on an annua basis with payment of an annua fee. There is a fine ine between reuse of tunneing arisings for fi etc and the use of tunneing waste in recovery operations and in practice they may amount to very simiar activities. However if the materia is cassed as tunneing waste the operator shoud notify the Environment Agency of the activity and go through the necessary registration procedure. Athough an activity may be exempt from icensing, it is sti subject to statutory contros to prevent environmenta poution and harm to human heath. It is an offence to carry out an exempt activity without it being registered or to carry out an activity in breach of registration obigations. * The Government funded Waste & Resources Action Programme (WRAP) has undertaken some pioneering work deveoping Quaity Protocos for the production of aggregates from inert waste. The Quaity Protocos provide a route for producers of recyced and secondary aggregates to demonstrate that their product has been fuy recovered and is no onger a waste.