D Barr

J R Finnamore

R P Bardos

J M Weeks

C P Nathanail

CIRIA C575 London 2002

Biological methods for assessment and remediation ofcontaminated land: case studies

6 Storey's Gate, Westminster, London SW1P 3AUTELEPHONE 020 7222 8891 FAX 020 7222 1708EMAIL enquiries@ciria.org.uk WEBSITE www.ciria.org.uk

Biological methods for assessment and remediation of contaminated land: case studies

Barr D, Finnamore J R, Bardos R P, Weeks J M, Nathanail C P

Construction Industry Research and Information Association

CIRIA C575 © CIRIA 2002 ISBN: 0 86017 575 8

Published by CIRIA, 6 Storey's Gate, Westminster, London SW1P 3AU.

All rights reserved. No part of this publication may be reproduced or transmitted in anyform or by any means, including photocopying and recording, without the writtenpermission of the copyright-holder, application for which should be addressed to thepublisher. Such written permission must also be obtained before any part of thispublication is stored in a retrieval system of any nature.

This publication is designed to provide accurate and authoritative information in regardto the subject matter covered. It is sold and/or distributed with the understanding thatneither the author(s) nor the publisher is thereby engaged in rendering a specific legalor any other professional service. While every effort has been made to ensure theaccuracy and completeness of the publication, no warranty or fitness is provided orimplied, and the author(s) and publisher shall have neither liability nor responsibility toany person or entity with respect to any loss or damage arising from its use.

2 CIRIA C575

Keywords

contaminated land, environmental good practice, ground engineering,sustainable construction, ground investigation and characterisation

Reader interest

Landowners anddevelopers, environmentalhealth and contaminated landofficers, planning officers,environmental andengineering consultants.

Classification

AVAILABILITYCONTENTSTATUSUSER

UnrestrictedGuidance documentCommittee guidedLand owners, developers, consultantsand contractors

CIRIA C575 3

Executive summary

Biological processes to treat contaminated land (bioremediation) have had widespreaduse in North America, several countries in mainland Europe, and in the UK.

The general technical consensus is that remediation (biological or otherwise) shouldusually take place in a risk management context to break pollutant linkages. Riskassessment is the defining discipline for this management approach. Conventionalapproaches to risk assessment are based on evaluations of contaminant toxicity andexposure to organisms (a function of bioavailability). The evaluations are informed byconceptual site models developed using site investigation data. Typically estimations oftoxicity and bioavailability are generic in nature, based on overall assumptions. Theseassumptions necessarily have to be rather conservative in order to provide an acceptablelevel of protection for all types of site and contamination problems. Biological techniqueshave begun to be used as tools to provide site specific estimates of bioavailability andecotoxicity, for use in risk assessment. This approach is very much still in its infancy,although a notable example from Canada described in this report, shows an applicationin a commercial redevelopment context. There is great interest in developing thesebiological test methods further as they are seen as potentially offering a more directappraisal of risks.

Bioremediation techniques include monitored natural attenuation (MNA), biosparging,groundwater recirculation, landfarming, biopiles, bioreactors, phytoremediation,treatment beds and windrows. These rely on naturally occurring processes: biodegradation,transformation, mobilisation and accumulation/immobilisation to interrupt pollutionlinkages. The majority of techniques are based on microbial biodegradation, howeverthe use of plants is emerging, for example to extract contaminants.

While biological remediation treatments are mediated by living organisms, theirimplementation is dependent on physical and chemical processes. All of them dependon the movement of water and/or air to stimulate the desired biological activity, andusually to also bring organisms into contact with contaminants or vice versa. They canbe applied in situ, ie directly to unexcavated ground, or ex situ to excavated orextracted materials. The engineering interventions needed for in situ processes includeinstalling wells, actively pumping/flushing/venting/sparging (air or water), introducingamendments that are passively dissipated in the ground environment, conditioningwater for recirculation or addition, for example by adding nutrients, and making use ofthe growth habit of plants.

Ex situ processes make use of similar interventions, with the main difference being thatexcavated soils can be mixed, which can assist process control. Mixing in situ isrestricted to cultivation of surface layers or mixing materials in columns.

This report includes a series of case studies showing that bioremediation can cost-effectively treat a range of contaminants under redevelopment, transaction or proactiverisk management scenario. The case studies selected are representative of many of thetechnologies in commercial use in the UK.

The detailed case studies include:

� MNA to demonstrate the long-term protection of a river from nitrobenzene, benzene,toluene, ethylbenzene, xylenes (BTEX) and dimethylphenol in groundwater.

� Biosparging to treat BTEX, phenol and polynuclear aromatic hydrocarbons (PAHs)in groundwater at a former gas works.

� Recirculation of groundwater through a bioreactor/aerator/nutrient dosing chamberto treat aviation fuel and diesel in soil and groundwater beneath an air force base.

� Landfarming at a former fuel distribution facility to prevent leaching ofhydrocarbons into a trout river.

� Windrows to treat a range of petroleum hydrocarbons including diesel, BTEX andPAH at two sites.

� Treatment beds at an oil shale refinery to degrade tar, PAH and aliphatic hydrocarbons.

The case studies illustrate a number of benefits of bioremediation. In most cases risk isreduced permanently as contaminants are destroyed. These case studies illustrate thecommercial and competitive use of bioremediation in the face of more conventionalremediation alternatives, such as excavation and removal to landfill.

The case studies also illustrate that bioremediation systems are often simple to installand operate, run on a year round basis and offer the scope to reuse treated soils on site.Space permitting, rapid turnaround is possible for ex situ bioremediation � in one casea windrow based technology achieved the specified remedial goals in 41 days.

Biological methods are also increasingly being used to assess ecological and human healthrisks. A broad battery of ecotoxicity tests accredited to international standards is availablein the UK. Acute exposure of ecological receptors to contamination at a site can beestimated within 24 hours while chronic exposure requires up to 28 days. Ecotoxicologicaltests provide a direct measure of ecotoxicity (avoiding the need to model harm toreceptors) and account for all known or unknown toxic components in the soil.

Commercial application in the UK has been limited to monitoring bioremediationprogress and measuring bioavailability of soil contaminants for human health riskassessment purposes. In the latter case, this reduces the conservatism in the moretraditional chemical-based approach to human health exposure assessment.

Ecotoxicological test methods offer the scope for cost savings on contaminated landprojects by using relatively cheap biological tests to screen for contamination and helpfocus subsequent more expensive chemical sampling and analysis. It may also bepossible to demonstrate that a contaminated site does not need remediation by showingthat the bioavailability of the contaminants to receptors is low.

4 CIRIA C575

CIRIA C575 5

Acknowledgements

CIRIA�s research programme on contaminated land aims to provide guidance for theconstruction industry, its clients and other interested parties and consists of a series ofcollaborative research projects and publications dealing with the various aspects oftreating and reusing land that is either derelict or contaminated or both.

Mr D Barr and Mr J R Finnamore of WSP Environmental, Dr R P Bardos of r3Environmental, Dr J M Weeks of WRc-NSF and Dr C P Nathanail of Land QualityManagement at the University of Nottingham wrote this report under contract toCIRIA. Additional contributions were provided by Mr M Lambson from BP AmocoGroup, Dr P Morgan of Geosyntec, Dr D Jenkins and Mr I Viney of WSP Remediation,Ms A Barnes of LQM and Professor C Thompson from Alcontrol.

Following CIRIA�s usual practice, the research project was guided by a SteeringGroup, which comprised:

Dr M Dyer (chairman) University of Durham

Dr D Ashton Environment Agency

Mr G Bowden Welsh Development Agency

Mr R Dunn AEA Technology

Dr D Evans Golder Associates

Ms V Fogleman Barlow Lyde & Gilbert

Dr T Kearney Environment Agency

Mr M Lambson BP Amoco Group

Mr G Lethbridge Shell Global Solutions

Dr S MacNaughton DTI BioWise

Mr A Mercer DTI BioWise

Mr R Murray-Smith Astra Zeneca

Mr M Perkins Halcrow Group

Mr K Potter ICI C & P

Prof W Radley EB Nationwide

Mr S Redfearn The BOC Foundation

Ms A Sheffield Shanks Waste Solutions

Dr C Warman Entec UK

Mr R Winson DTI Biotechnology Directorate

CIRIA�s research manager for this project was Ms J C T Kwan.

The project was financially supported by:

AEA TechnologyAstra ZenecaThe BOC FoundationBP Amoco GroupCIRIA Core MembersDTIEB NationwideShanks Waste SolutionsShell Global Solutions.

CIRIA and the authors gratefully acknowledge the support of these fundingorganisations and the technical help and advice provided by the members of thesteering group. Contributions do not imply that individual funders necessarily endorseall views expressed in published outputs.

The co-operation of the following organisations in providing case studies for inclusionin this report is gratefully acknowledged.

AEA Technology Arcadis Geraghty and Miller InternationalBio-Logic Remediation BP Amoco GroupCEH Monks WoodGolder Associates LimitedKomex EuropeLattice PropertiesQDSRemediosShanks Waste SolutionsURS Dames & MooreWSP Remediation

A number of other individuals and organisations assisted in the preparation of thisreport, for example by volunteering case studies for inclusion, allowing access to casestudy information, and by attending a consultee workshop on the project.

6 CIRIA C575

Note

Recent Government reorganisation has meant that DETR responsibilities have beenmoved variously to the Department of Trade and Industry (DTI), the Department forthe Environment, Food and Rural Affairs (DEFRA), and the Department for Transport,Local Government and the Regions (DTLR). References made to the DETR in thispublication should be read in this context.

For clarification, readers should contact the Department of Trade and Industry.

CIRIA C575 7

Contents

List of tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9List of figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10List of boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Acronyms and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

PART A OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.2 Aims of the report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231.3 Scope of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241.4 Report structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

PART B BIOREMEDIATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.1 Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.2 Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.3 Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

3 Case studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393.2 Monitored natural attenuation (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413.3 Monitored natural attenuation (B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463.4 Biosparging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503.5 Groundwater recirculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553.6 Landfarming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 3.7 Windrows (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653.8 Windrows (B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 703.9 Other technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

4 Factors to consider in the selection and implementation of bioremediation technologies on contaminated sites . . . . . . . . . . . . . . . . . . 794.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 794.2 Technical suitability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 824.3 Integration with other remediation techniques . . . . . . . . . . . . . . . . . . . . 884.4 Legal and regulatory acceptability . . . . . . . . . . . . . . . . . . . . . . . . . . . . 884.5 Stakeholder interests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 904.6 Costs and benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.7 Practicalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 934.8 Health and safety issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 984.9 Wider environmental impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 994.10 Quality control and assurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1004.11 Procurement and contractual arrangements . . . . . . . . . . . . . . . . . . . . . 102

5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

PART C BIOLOGICAL TEST METHODS . . . . . . . . . . . . . . . . . . . . . . . . . 1096 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

6.1 The role of biological test methods on contaminated sites . . . . . . . . . . 1116.2 Techniques for assessing ecological effects of contaminated sites . . . . 1136.3 Toxicity tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1146.4 Single and multiple species assays and test systems . . . . . . . . . . . . . . 1156.5 Tests of soil function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1166.6 Tests of microbial function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1166.7 Biosensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1176.8 Measurement of in situ soil processes . . . . . . . . . . . . . . . . . . . . . . . . . 117

7 Case studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1197.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1197.2 Microbial biomass, BIOLOG and bait lamina . . . . . . . . . . . . . . . . . . . 1197.3 Biomarkers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1277.4 In situ bioassays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1307.5 Ex situ bioassays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

8 Factors to consider in the selection and use of biological test methods toassess ecological risk on contaminated sites . . . . . . . . . . . . . . . . . . . . . . . 1338.1 Business drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1338.2 A framework for ecological risk assessment . . . . . . . . . . . . . . . . . . . . 1358.3 Selecting appropriate biological test methods and approaches . . . . . . . 143

9 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155Appendix A Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167Appendix B Biological test methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

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List of tables

1.1 Perceived constraints to using bioremediation, and possible counter arguments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2.1 Fundamental bioremediation processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.2 Broad categories of in situ bioremediation technologies . . . . . . . . . . . . . . . . 322.3 Phytoremediation variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363.1 Summary of the bioremediation case studies . . . . . . . . . . . . . . . . . . . . . . . . . 393.2 Cost comparison of remedial options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453.3 Summary of natural attenuation monitoring data case study results (B) . . . . . 483.4 Summary of biosparging monitoring data hydraulically down gradient of

treatment zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533.5 Summary of monitoring data for groundwater recirculation case study . . . . . 583.6 Remedial target concentrations for windrows case study (B) . . . . . . . . . . . . . 723.7 Cost comparison of remedial options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 734.1 Typical data requirements for screening the viability and feasibility of

bioremediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814.2 Relative biodegradability of groups of contaminants . . . . . . . . . . . . . . . . . . . 824.3 Ideal contaminant and environmental characteristics for application of

bioremediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 834.4 Interventions that can be used to effect bioremediation processes . . . . . . . . . 874.5 Costs of bioremediation case studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 924.6 Equipment and site facility requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 954.7 Waste arisings and abatement measures for bioremediation technologies . . . 974.8 Health and safety hazards associated with bioremediation . . . . . . . . . . . . . . . 984.9 Insurable risks on bioremediation projects . . . . . . . . . . . . . . . . . . . . . . . . . 1047.1 Summary of biological test method case studies . . . . . . . . . . . . . . . . . . . . . 1197.2 Soil pH, organic content, C:N ratio and cadmium, copper, lead and zinc

content at six locations along a transect from Avonmouth smelter . . . . . . . . 1207.3 Bait lamina average feeding activity (%) and feeding category (%) . . . . . . . 1258.1 Eco-receptor sites listed in Part IIA EPA 1990 . . . . . . . . . . . . . . . . . . . . . . . 1358.2 Examples of possible factors to be used to prioritise sites . . . . . . . . . . . . . . 1378.3 Examples of ecosystem protection goals, assessment endpoints, effects

endpoints and effect measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1418.4 Benefits and limitations of different approaches to ERA . . . . . . . . . . . . . . . 147 8.5 Costs of tests performed with invertebrate species . . . . . . . . . . . . . . . . . . . 1508.6 Costs of chronic sediment toxicity test using Hetercypris incongruens . . . . 1508.7 Practical considerations for terrestrial toxicity test methods . . . . . . . . . . . . 151

List of figures

1.1 Categories of remediation approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.1 A pollutant linkage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.2 Categories of bioremediation techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312.3 Treatment bed and bunded treatment area . . . . . . . . . . . . . . . . . . . . . . . . . . . 332.4 Windrow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342.5 Biopile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343.1 Site plan for MNA case study (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413.2 Conceptual model showing plume migrating towards river . . . . . . . . . . . . . . 423.3 Monitoring data along length of plume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443.4 Site plan for MNA case study (B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463.5 Groundwater monitoring results for MNA case study (B) . . . . . . . . . . . . . . . 493.6 Example of biosparging system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.7 Site plan showing treatment zone and key monitoring wells . . . . . . . . . . . . . 513.8 Treatment process used during biosparging at a former gasworks site . . . . . . 523.9 Monitoring results down gradient of treatment zone . . . . . . . . . . . . . . . . . . . 533.10 Example of groundwater bioreactor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553.11 Treatment process used in the groundwater recirculation case study . . . . . . . 573.12 Example of landfarming (pilot scale) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603.13 Site plan of the landfarming treatment area . . . . . . . . . . . . . . . . . . . . . . . . . . 613.14 Site model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623.15 Mean TPH concentrations in soil and leachate samples . . . . . . . . . . . . . . . . . 633.16 View of windrows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653.17 Example of windrow turning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 663.18 Windrows at Norwich Riverside . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 703.19 Commercial scale bioreactor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 763.20 Total PAH and benzo(a)pyrene degradation during laboratory test . . . . . . . . 774.1 Framework for selecting and implementing remediation technologies . . . . . . 804.2 Example of a stepwise sequence of biodegradation . . . . . . . . . . . . . . . . . . . . 846.1 Categories of biological test methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1146.2 Luminescence from bacterial expression of the Lux gene . . . . . . . . . . . . . . 1177.1 Avonmouth smelter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207.2 BIOLOG plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1227.3 Bait lamina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1237.4 Utilisation of BIOLOG substrate guilds by bacterial communities of

Avonmouth soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1247.5 Mean feeding activity at Avonmouth test sites, as shown by bait lamina

tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1257.6 Test site on gas works in East London . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1277.7 Enclosed earthworm bioassay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

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7.8 Neutral red retention timing assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1297.9 Mean (SEM) percentage total immune activity in earthworms

(Lumbricus terrestris) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1307.10 Mean (��SEM) total cholinesterase activity in earthworms (Lumbricus

terrestris) exposed in situ to soils at four field sites . . . . . . . . . . . . . . . . . . . 1308.1 Framework for ecological risk assessment . . . . . . . . . . . . . . . . . . . . . . . . . 1368.2 Relationship between intensity of impact of a contaminated site and the

response of an ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

List of boxes

2.1 Risk management approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.2 The use of hyperaccumulators in phytomining . . . . . . . . . . . . . . . . . . . . . . . 373.1 Degradation of nitroaromatic compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . 434.1 The evolution of mobile plant licensing in the UK . . . . . . . . . . . . . . . . . . . . 904.2 Verification and validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1006.1 The use of biological test methods in site characterisation and pollutant

mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1116.2 The use of biological test methods to monitor the progress of

bioremediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1136.3 Bioassays, biomarkers and bioindicators . . . . . . . . . . . . . . . . . . . . . . . . . . . 1157.1 Gram stains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 7.2 Doelman thresholds for alterations in microbial community structure . . . . . 1237.3 Neutral Red Retention Time assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1298.1 Estimating ecological effects and exposure . . . . . . . . . . . . . . . . . . . . . . . . . 1428.2 Factors to consider in the use of biomarkers and bioindicators . . . . . . . . . . 1448.3 Factors to consider in the use of microcosms and mecocosms . . . . . . . . . . . 1458.4 Factors to consider in the use of biosensors . . . . . . . . . . . . . . . . . . . . . . . . . 1458.5 Example of ecosystem recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Glossary

acute toxicity Identifies the concentration of a substance that results inadverse effects from short-term doses. Typical experiments kill50 per cent of the test animals (LD50 or LC50); this providesan indication of lethal concentrations at short-term exposure.

aeration Incorporation of air into a liquid or solid material by exposure(passive), mixing, agitation, chemical means or directinjection with the aim of transferring oxygen to the material.

aerobe An organism that can grow in the presence of air.

anaerobe An organism that can grow in the absence of oxygen or air.

anaerobic respiration Use of inorganic electron acceptors, other than oxygen, asterminal electron acceptors for energy yielding oxidativemetabolism. Examples include nitrate respiration.

assessment endpoint Explicit expressions of the environmental value that is to beprotected. Assessment endpoints should be defined in termsof the valued ecological entity (species, ecological resourceor habitat type) and a characteristic of the entity to protect egreproductive success.

attenuation Reduction in contaminant concentration, availability ortoxicity through biological, chemical and physical processes.

bioaccessibility The fraction of a substance that is available for absorption byan organism.

bioaccumulation Accumulation of environmental contaminant, such as heavymetals, within the cells of living organisms.

bioassay Biological tests using specific organisms to quantify thetoxicity of contaminated soil and water samples.

bioaugmentation Addition of specifically prepared cultures of organisms tocarry out specific functions such as biodegradation, in theenvironment.

bioavailability The fraction of a substance which can be absorbed by thebody through the gastrointestinal system, the pulmonarysystem and the skin. By its definition, bioavailability alsoincludes the process of bioaccessibility.

biodegradation Decomposition of a compound into smaller chemical subunits through the action of organisms, typicallymicroorganisms (bacteria, fungi and actinomycetes).

Bioindicators Multiple measures of organism health to environmentalstressors, which include several levels of biologicalorganisation and time scales of response. Because organismsare subjected to a variety of stressors in their environment,multiple measures of health are needed to help identify andseparate the effects of man-induced stressors (such ascontaminants) from the effects of natural stressors (such asfood and habitat availability).

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biological oxygen Measure of the biodegradable organic pollution presentdemand in a watercourse. (Measured mg/l). A high level of organic

matter (with high BOD) in effluent stimulates microbialgrowth, which in turn removes oxygen from water necessaryto sustain aquatic environment.

biomarkers of effect Biological test that provides a biological response that can berelated to an exposure to, or toxic effect of chemicals.

biomarker of exposure Biological test that provides a measure of the concentrationof one or more chemicals in the tissue of selected plants oranimals. Biomarkers of effect and exposure are generallyused to indicate exposure of organisms to contaminants atlower levels of biological organisation, while bioindicatorsare typically used to reflect effects of stressors on biologicalsystems at higher levels of organisation.

bioremediation The elimination, attenuation or transformation of polluting orcontaminating substances by the use of biological processes,to minimise the risk to human health and the environment(BBSRC, 1999).

biosensor Analytical device containing a biological material that acts asa sensing element. When exposed to a contaminant, thesensing element generates an information-linked response,which can be obtained via a suitable transducer.

bioslurping Simultaneous withdrawal of non aqueous phase liquid(NAPL), groundwater and/or soil gas from the groundwaterlayer using a single pump.

biosparging Injecting a gas (usually air) under pressure into the saturatedzone to provide oxygen (or an alternate electron acceptor) tofacilitate microbial degradation of contaminants in groundwaterand saturated soil.

biostimulation Addition of nutrients, oxygen and/or water to stimulatemicroorganisms in contaminated soils, to enhance biologicalprocesses.

biotransformation Conversion of a contaminant to a less toxic and/or lessmobile form.

bioventing The process of supplying oxygen in situ to oxygen deprivedsoil microorganisms by forcing air through unsaturatedcontaminated soil at low flow rates. This stimulatesbiodegradation and minimises stripping volatiles into theatmosphere.

co-metabolism A process in which a compound is fortuitously degraded byan enzyme or co-factor produced during microbialmetabolism of another compound.

contaminated land �...Any land which appears to the local authority in whosearea it is situated to be in such a condition, by reason ofsubstances in, on or under the land, that:a) significant harm is being caused or there is a significant

possibility of such harm being caused orb) pollution of controlled waters is being, or is likely to be

caused�(EPA 1990; Section 78A[2]).

discharge consent Authorisation issued by the regulatory authorities(Environment Agency, SEPA) permitting discharge oreffluent into controlled waters to prevent pollution.

ecological risk Qualitative and/or quantitative analysis of the actual orassessment potential effects of contamination on ecological receptors

other than humans and domesticated species (US EPA, 1997).

ecosystem A living entity of populations co-existing as a unit, with thecapacity to interact with one another and their physical andchemical environments.

ecosystem engineers Organisms with sufficient numerical and biomass densities toexert a predominant influence in the formation andmaintenance of soil structure.

ecotoxicology The study of the toxic effects of agents on living organisms.

effect endpoint Measurable biological response to a stressor that can berelated qualitatively or quantitatively to the characteristicchosen as the assessment endpoint.

electron acceptor Compound that is reduced in a metabolic redox reaction.

endpoint See assessment or effect endpoints.

exposure Concentration or amount of an agent that reaches a specifiedreceptor or component of the receptor (eg organ, tissue or cell).

fermentation Microbial metabolism in which a particular compound is usedboth as an electron donor and an electron acceptor resultingin the production of oxidised and reduced daughter products.

fertiliser Any organic or inorganic material of natural or syntheticorigin (other than liming materials) added to a soil to supplyone or more elements essential to plant growth.

hyperaccumulation For some plants accumulation of metals appears to be anactive process possibly related to a tolerance mechanism fortheir survival on contaminated sites. For such plants leafconcentrations of heavy metals can reach high levels (forexample around 1 per cent for zinc or manganese, and 0.1 per cent for cadmium, on a dry matter basis). In Europethese plants tend to be members of the Brassicaceae and aregenerally found on �naturally� contaminated soils, such asserpentine soils. These plants are referred to as�hyperaccumulators� to distinguish the nature of their metalaccumulation from passive accumulation processes takingplace in say SRC.

indicator species Species that can be used as a early indicator ofenvironmental degradation to a community or an ecosystem(see bioindicator).

keystone species Species that interact with a large number of other species in acommunity. Because of the interactions, the removal of thisspecies can cause widespread changes to community structure.

mesocosm Experimental, field-based subsets of naturally occurringenvironments in which the response of more than one bioticspecies to contaminants is measured.

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metabolic by-product A product of the biologically mediated reaction between anelectron donor and an electron acceptor. Metabolic by-products include volatile fatty acids, daughter products ofchlorinated aliphatic hydrocarbons, methane and chloride.

microcosm Experimental, laboratory-based subsets of naturally occurringenvironments in which the response of more than one bioticspecies to contaminants is measured.

micro-nutrient Nutrient required at very low concentrations, possibly toxicat higher concentrations.

microorganisms Includes bacteria, fungi, algae, protozoa and viruses.

mineralisation The breakdown of organic matter to inorganic materials(such as carbon dioxide and water) by microorganisms.

mobile plant licence Waste management licence issued under Section 35(1) of theEnvironmental Protection Act 1990 authorising the treatmentor disposal of specified waste by specified plant(Environment Agency Guidance on the application of WMLto remediation, V2.0, 2001).

monitored natural Monitoring of soils or groundwater to confirm whetherattenuation natural attenuation processes are acting at a sufficient rate to

ensure that the wider environment is unaffected and thatremedial objectives will be achieved within a reasonabletimescale; this will typically be less than one generation or30 years (modified from Environment Agency, 2000).

nitrate respiration The use of nitrate as a terminal electron acceptor foranaerobic respiration. This process occurs under anaerobic ormicroaerophilic conditions. Not all bacteria are capable ofthis form of metabolism and the nitrate may not be reducedcompletely to nitrogen gas (stopping at nitrite, for example).

organisational level See trophic level.

phytodegradation A process in which plants are able to degrade organicpollutants through metabolic processes.

phytoextraction Use of plants to remove contaminants, such as metals, thatthey have accumulated from the environment, especially soil.

phytomining Use of phytoextraction to extract inorganic elements ofeconomic value.

phytoremediation The use of plants for in situ risk reduction for contaminatedsoil, sludges, sediments and groundwater, throughcontaminant removal, degradation, or containment.

phytostabilisation Use of soil amendments and plants to reduce bioavailabilityand offsite migration of contaminants.

phytostimulation Stimulation of microbial biodegradation of contaminants(organics) in the root zone. eg via protecting and supportingmicrobial communities; by soil aeration as a result of rootgrowth; and by transport of water to the area.

plant Equipment or machinery used in an industrial process, factoryor other industrial premise (Environment Agency Guidanceon the application of WML to remediation, V2.0, 2001).

recalcitrant Resistant to biodegradation or some other process.

redox potential The oxidation-reduction potential of an environment.Measures the tendency of the environment to be reducing(donate electrons) or oxidising (accept electrons).

redox ameliorants Reagents added to the subsurface to change the ambient redoxconditions, eg to support enhanced aerobic biodegradation.

residual Amount or concentration of contaminants remaining incontamination specific media following remediation.

rotorvation Soil cultivation process.

site licence Waste management licence issued under Section 35(1) of theEnvironmental Protection Act 1990 authorising the deposit,disposal, treatment, or keeping of specified waste onspecified land (Environment Agency, 2001).

stressor Any physical, chemical or biological entity that can inducean adverse ecological response. For land contamination, theprincipal stressor is typically chemical in nature.

test battery A combination of biological test methods carried out onmultiple species as part of an ecological risk assessment.

toxicity The adverse effects to a living organism an agent has aninherent capacity or potential to cause. The result may be death,damage to structure or loss of function. See also acute toxicity.

trade effluent Permit/authorisation issued by the sewerage undertakerdischarge (England & Wales) or water authority (Scotland) allowing

discharge of trade effluent to public sewer.

trophic level Describes the residence of nutrients in various organismsalong a food chain ranging from the primary nutrientassimilating microorganisms to predatory carnivorous animals.

uncertainty Situation where the future or current status of a parameter ofconcern is not known and cannot be measured.

vadose zone Unsaturated zone of soil above the groundwater, extendingfrom the bottom of the capillary fringe to the soil surface.

validation Confirmation of the likely performance of a particularremedial approach, for example supporting evidence ofverified performance on other sites.

verification Confirmation that predicted levels of performance have beenachieved, for example that a particular level of riskmanagement for a site has taken place.

warranty An express or implied statement forming part of a contractthat a particular state of affairs exists. It is normally qualifiedby a letter of disclosure that describes why, in certain cases,the warranty is not true (Finnamore et al, 2000).

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Acronyms and abbreviations

ASTM American Society for Testing and Materials ATP Adenosine triphosphateAWCD Average well colour developmentBBSRC Biotechnology and Biological Sciences Research CouncilBGL Below ground levelBOD Biochemical oxygen demandBTEX Benzene, toluene, ethylbenzene, xylenesCDM Construction (Design and Management) Regulations 1994ChE Cholinesterase activityCIRIA Construction Industry Research and Information AssociationCLEA Contaminated land exposure assessmentCmic Carbon content in non-resting microbial biomassCorg Organic carbon contentCOD Chemical oxygen demandCOMAH Control of Major Accident Hazards Regulations 1999COTC Certificate of technical competenceCPL Contractors pollution liability InsuranceDEFRA Department of Environment, Food and Rural AffairsDETR Department of the Environment, Transport and the Regions

(formerly DOE and now DEFRA)DNA Deoxyribonucleic acidDNAPL Dense non-aqueous phase liquidDO Dissolved oxygenDOE Department of the Environment (now DEFRA)DRO Diesel range organicsDTA Direct toxicity assessmentEA Environment AgencyEC European CommunityEcD Ecological doseEHO Environmental health officerEPA 1990 Environmental Protection Act 1990EQS Environmental quality standardERA Ecological risk assessmentERT Enchytraeid reproduction testEU European UnionGAC Granular activated charcoalGC-FID Gas chromatography-flame ionisation detectorGLP Good laboratory practiceGMO Genetically modified organismsHS(G) Health and Safety GuidanceHSE Health and Safety ExecutiveICE Institute of Civil EngineersICRCL Interdepartmental Committee on the Redevelopment of Contaminated LandIPC Integrated pollution controlIPPC Integrated pollution prevention and controlIR Infra-red spectrometryISM Integrated soil microcosm

ISO International Standards OrganisationLCA Life-cycle assessmentLNAPL Light non-aqueous phase liquidLOEC Lowest observed effect concentration MAFF Ministry of Agriculture Fisheries and Food (now part of DEFRA and

other government departments)MIRR Maximum initial respiratory responseMNA Monitored natural attenuationMPL Mobile plant licenceMTBE Methyl-tertiary butyl etherMW Molecular weightNAPL Non-aqueous phase liquidNOEC No observed effect concentrationNOAEL No observed adverse effect levelNOEL No observed effect levelNPK Nitrogen, phosphorus, potassium fertiliserNRA National Rivers Association (now the Environment Agency)NRR Neutral red retention OECD Organisation for Economic Co-operation and Development OFA Overall feeding activityORC® Oxygen release compoundPAH Polynuclear aromatic hydrocarbonsPBTK Physiologically based toxicokineticPBET Physiologically based extraction testPCB Polychlorinated biphenylPCR Polymerase chain reactionPEC Predicted environmental concentrationPI Professional indemnity insurancePL Public liability insurancePLFA Phospholipid fatty acidPNEC Predicted no effect concentrationPPC Pollution Prevention ControlPPE Personal protective equipmentQSAR Quantitative structure activity relationshipsRNA Ribonucleic acidSBET Simple bioavailability extraction testSEPA Scottish Environment Protection AgencySIR Substrate-induced respirationSQS Soil quality standardsSRC Short rotation coppiceSSSI Site of special scientific interestSSTL Site specific target levelSVE Soil vapour extractionSVOC Semi volatile organic compoundsTME Terrestrial model ecosystemTPH Total petroleum hydrocarbonsUBA Umweltbundesamt (German Environmental Protection Agency)UST Underground storage tankVOC Volatile organic compoundWAMITAB Waste management industry training advisory boardWML Waste management licenceWRA Water Resources Act, 1991

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Part AOverview

CIRIA C575 21

1 Introduction

1.1 BACKGROUND

1.1.1 Bioremediation

Past industrial activities, such as waste disposal, industrial process wastes and mining,have left the UK with a legacy of soil and groundwater contamination. The risks thatboth existing and new contamination present to human health and the natural and builtenvironments can be managed by a variety of biological, physical and chemicalremediation technologies � see Figure 1.1.

Figure 1.1 Categories of remediation approaches

Engineered containment techniques and landfill continue to be the favoured treatmentoptions in the UK, being used at least as part of the remediation strategy in 94 per centand 75 per cent of all remediation projects respectively (Environment Agency, 2000b).Of the alternative, process-based technologies, bioremediation has emerged as a viable,cost-effective option for which there is a growing track record of successfulimplementation in the UK.

Bioremediation involves the elimination, attenuation or transformation of polluting orcontaminating substances by the use of biological processes, to minimise the risk tohuman health and the environment (BBSRC, 1999). Bioremediation technologiesexploit the ability of various naturally occurring microorganisms (including bacteriaand fungi) and higher organisms (including plants) to degrade pollutants and/or renderthem virtually harmless, for example, by immobilisation. The technologies offer arange of potential advantages over the more traditional approaches of landfill andcontainment, including:

� permanent reduction in risk � destructive bioremedial processes destroycontaminants rather than transferring them from one medium or site to another

� cost effectiveness � treated soils can often be retained on site, avoiding or reducinghaulage and disposal costs

TREATMENTOPTIONS

CONTAINMENT SEPARATION DESTRUCTION

Excavate and dispose

��on-site landfill��off-site landfill

Hydraulic��separation��plume containment��hydraulic gradient

management

Chemical��stabilisation

Physical��cover��vertical barriers��liners��solidification��vitrification

Physical��soil washing��thermal desorption��steam stripping��vacuum extraction��solvent extraction��particle separation

Physical��incineration

Chemical��dechlorination

Biological��landfarming ��treatment beds��biosparging ��windrows��bioventing ��biopiles��redox ameliorants ��bioreactors��phytoremediation ��biorestoration��hyperaccumulation��ground water pumping and recirculation��biological permeable reactive barrier walls��monitored natural attenuation

� sustainability � bioremediation processes are, in the main, not energy intensive andreduce transport requirements.

The following regulatory and economic developments and environmental pressures arelikely to reinforce further the merits of using bioremediation:

� the EC Landfill Directive (1999/31/EC) requires sustainable remedial treatmentssuch as pre-treatment of waste, which means that it may be more economic andpractical to treat and retain contamination on site

� increasing pressure from the general public and other stakeholders to avoid lorrymovements on large earthwork projects

� increasing cost of landfill caused, for example, by reduction in licensed landfillspace and the imposition of, and increases in the rate of, the landfill tax

� implementation of the Part IIA Contaminated Land regime, which is likely to leadto more businesses undertaking proactive risk management on contaminated sites.

Despite the arguments for using bioremediation, the uptake of technologies has beenrelatively slow in the UK. This has been due in part to a number of perceived constraintssurrounding the use of bioremediation. As discussed in Table 1.1, the actual constraintsare often far less challenging and in many circumstances can be effectively overcome.

Table 1.1 Perceived constraints to using bioremediation, and possible counter arguments

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Perceived constraint Comment

Bioremediation technologies andexpertise are notavailable in the UK

Estimates suggest that the number of bioremediation projects that had been conducted in the UKby mid 1999 were between 100 and 200 for ex situ techniques and 30 for in situ methods (Jefferiset al,1999). There are a number of contracting businesses offering bioremediation as one of manytechnology options in the UK. A few companies specialise in bioremediation and a small numberprovide niche services on specific bioremediation techniques.

Bioremediation doesnot work

There is growing evidence that contaminants, such as vinyl chloride, that were once consideredvirtually non-degradable can be degraded under the right conditions. As the science underpinningbioremediation improves and technologies develop, there is increasing scope to manipulateoperating conditions to suit the specific project requirements and achieve a successful outcome.Bioremediation principles have been successfully used in domestic and industrial wastewatertreatment for many decades.

The financial sectorwill not agree tobioremediation

Institutional barriers arise through the reluctance of funders and investors to bear unwarrantedproject risks and uncertainty. In the financial sector, bioremediation technologies are less wellunderstood than excavation and disposal and this can lead to a perception of �higher risk, greateruncertainty� in bioremediation meeting its remedial goals. This perception can promote excavationand disposal ahead of bioremediation, even if the project economics favour the latter. Otherstakeholders with a capacity to influence technology selection may hold similar perceptions. Thegrowing track record of successful bioremediation should go some way to alleviating the concernsof stakeholders and promoting appropriate use of bioremediation technologies.

Bioremediation is tooslow The majority of remediation undertaken in the UK proceeds through planning and land

development, where rapid timeframes are typically set for completing the remediation works.While this is often a valid constraint, space permitting and other factors being favourable,bioremediation can treat contaminants in weeks. Section 3.8 describes a case study wherebioremediation was effectively integrated into a brownfield redevelopment programme.

Licensing is problematic It is generally agreed that the licensing of bioremediation techniques through Mobile Plant

Licensing has become more streamlined (Viney, pers. comm.). A relatively high proportion (41 per cent) of the total MPLs that had been issued to November 2001 were for bioremediationprocesses (Environment Agency, www.environment-agency.gov.uk)

CIRIA C575 23

1.1.2 Biological test methods

Land is an important resource that fulfils a number of essential functions, includingproviding a reserve of potable water and raw materials, acting as a support medium forplant growth and a protective filter for groundwater resources, providing a structuralbase on which to build, supporting recreation and maintaining habitats and biodiversity.Land quality reflects the capacity to maintain these functions, which in turn depends onthe complex chemical, biological and physical properties and interactions of the keyconstituents of land, ie soil, water, air and biota. It is recognised that soil is a limitedresource, which is readily damaged. This has led to concerns about sustainable use ofthe land, and the potential impacts of contamination on soil function, terrestrialecosystems and biodiversity (Environment Agency, in preparation).

Biological test methods � including bioassays, biosensors, microcosms, mecocosmsand biomarkers � provide a means of assessing the potential or actual impact ofcontamination on terrestrial ecological receptors. The assessment can be made at a soilfunction/quality/structure, individual species, and to a lesser degree, population,community or ecosystem level. The application of biological tests has been limited toresearch projects. The use of bioassays and biomarkers in national ecological riskassessment strategies is, however, increasingly seen as a useful supplement to chemicalanalysis in decisions related to contaminated land (Ferguson et al, 1998).

The lack of commercial use of biological test methods reflects the immaturity ofecological risk assessment (ERA) on contaminated sites in the UK. This stems fromgaps and uncertainties in the science, policy and regulation underpinning ERA. Thefollowing aspects, for example, will need to be addressed and clarified if ERA is toform a defensible component of the overall risk assessment process on contaminatedsites in the future:

� standardisation of biological test methods� definition of criteria by which to judge significance of harm to ecological receptors� agreement of thresholds, if any, for acceptable harm to ecological receptors� valuation of ecological receptors� selection of appropriate receptors to be protected� differentiation between contaminant-related stress and other environmental stressors� development of procedures for undertaking ecological risk assessment.

1.2 AIMS OF THE REPORT

The primary objective of this report is to promote and provide guidance on appropriateselection and performance of bioremediation techniques and biological test methods oncontaminated sites. It aims to do so by:

� describing a selection of case studies where biological test methods andbioremediation technologies have been used successfully to assess and/or managethe risks posed by land contamination

� using the case studies to highlight the actual, rather than the perceived, constraintsto using biological methods, demonstrating circumstances where the constraintsmay or may not be overcome on a site specific basis

� demonstrating the benefits that were generated by using biological methods.

Target readership

The report is targeted at developers, environmental regulators, consultants, contractorsand other practitioners involved in contaminated projects, as well as owners ofcontaminated sites planning to take remedial action in advance of property transactions,as a precursor to redevelopment or as part of a proactive environmental risk managementstrategy.

1.3 SCOPE OF THE REPORT

The report is focused on case studies covering bioremediation and ecotoxicological riskassessment of contaminated sites.

1.3.1 Bioremediation

The bioremediation sections of the report are centred on a series of case studies ofrecently completed, commercial, full-scale technology applications in the UK. Theseinclude in situ bioventing, groundwater recirculation and biosparging, ex situ biopiles,windrows, landfarming and treatment beds. The case studies cover treatment of soiland groundwater contaminated by a range of mainly organic contaminants. The contextof remediation includes brownfield development, property transactions and proactiveenvironmental management. All case studies represent �successful� projects from atleast one stakeholder�s perspective.

The report provides objective assessments of the success of bioremediation in terms ofwhether the original management objectives and remedial goals were met for each casestudy. It is not intended to verify the technologies, relying instead on the judgement ofthose involved directly in the projects. It is also not intended to assess theappropriateness of the management objectives and remedial goals, although commentsare provided on outdated practices where these could have a material impact on thesuccess of a project under the current regulatory and risk management regimes.

Guidance is provided on screening bioremediation technologies for viability as a standalone risk management solution or a component in an integrated remedial approach.The guidance is focused on the broad range of factors that should be considered duringthe screening process, and is designed to provide the basis on which to proceed, or not,to the next step of evaluating bioremediation and other potential remedial options inmore detail. Detailed evaluation and subsequent design and implementation phases areoutside the scope of this report, and the reader is directed to Model Procedures (DETR1999, in preparation) for the management of contaminated land, and guidance onspecific technologies.

1.3.2 Biological test methods

The biological test method sections focus on the use of biological assays, microcosmsand biomarkers to provide data and information to support the assessment of ecologicalrisk on contaminated sites. The report addresses methods of data collection, but theapplication of these data for ecological risk assessment purposes is beyond the scope ofthis report.

Microorganism, plant and invertebrates tests are covered in this report, but for ethicalreasons, tests on organisms from higher organisational levels are excluded. Theemphasis of the case studies is on research-based applications since these currentlypredominate in the UK. A single example of a commercial application is drawn fromCanada. The UK applications are drawn from three sites and cover examples from allof the main test method categories � in situ and ex situ bioassays, biomarkers,

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biosensors, and bioavailability tests. The review of test methods looks at their potentialfor commercial application.

Guidance is provided in terms of highlighting key factors to be considered in thegeneral design of an ecological risk assessment strategy, and selecting appropriatebiological tests to fit within that strategy. It does not provide a manual for conductingecological risk assessment. A suggested framework for assessing ecological risks isincluded, although this is likely to evolve in the future in the light of studies beingundertaken by the regulatory bodies and the industry. The framework and guidance isdesigned for use on all contaminated sites, not just those designated ContaminatedLand sites under Part IIA of EPA 1990.

1.4 REPORT STRUCTURE

This report is divided into three parts A to C.

Part A Overview provides the background to the project including the objectives,context and method and approach.

Part B Bioremediation provides an introduction to the theory of bioremediation,detailed or summarised descriptions of the following case studies, guidance onselection of bioremediation techniques and conclusions.

Technology Sections

Monitored natural attenuation 3.2, 3.3Biosparging 3.4Groundwater recirculation/bioreactor 3.5Landfarming 3.6Windrows 3.7, 3.8Biopiles 3.9.1Redox amelorants 3.9.2Phytoremediation 3.9.3

Part C Biological test methods provides an introduction to the theory ofecotoxicology, brief descriptions of the following case studies, guidance on selection ofappropriate biological test methods and conclusions. Detailed descriptions of severalspecific test methods are provided in Appendix B.

Test method Sections

Microbial biomass, BIOLOG and bait lamina 6.2Biomarkers 6.3In situ bioassays 6.4Ex situ bioassays 6.5