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BRINGING GROUNDWATER QUALITY RESEARCH TO THE WATERSHED SCALE Edited by Neil R. Thomson IAHS Publ. 297 (July 2005) ISBN 1-901502-18-X, 576 + xiv pp. Price £85.00

Sustainable economic growth requires plentiful supplies of high-quality water. This has placed pressure on groundwater resources globally and forced the international groundwater science, engineering and regulatory community to recognize the current limitations of research and resource management. Integrated and technically feasible approaches tackling local issues and watershed-scale concerns concurrently are required. These were considered by GQ2004 (Waterloo, Canada) and this collection of papers comprises a reviewed selection from the conference.

Abstracts of the papers in this volume can be seen at:

www.iahs.infowith information about other IAHS publications

and IAHS activities

The introductory contributions include global and several national perspectives, followed by sections dealing with: – Contaminant input processes – Site characterization – Management and decision making – Natural attenuation processes and applications – In situ remediation – Flow and transport modelling at the national, the watershed and smaller scales

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The GQ Series

Contents

Contents

Preface by Neil R. Thomson & James F. Barker v

1 Groundwater Quality

A global inventory of groundwater quality: first results Jasper Griffioen, Rianne Brunt, Slavek Vasak & Jac Van Der Gun

3

Groundwater quality in Canada: a national overview Suzanne Lesage

11

Cumulative factors affecting groundwater quality in domestic wells in Finland Kirsti Korkka-Niemi

19

Urbanization of rural watersheds in the region of Waterloo: implications for water quality Randy L. Stotler, Jon Paul Jones, Shaun K. Frape, Robert J. Drimmie, Craig T. Johnston & Ian Judd-Henry

29

Burial sites and their impact on groundwater Julian Trick, Ben Klinck, Patricia Coombs, Dave Noy & Geoff Williams

36

Quality of water from hand-dug wells, boreholes, and streams in two localities in southwest Nigeria: implications for incidence of water borne diseases Samson Ayanlaja, O. O. Kehinde-Phillips, Francis Ogunkolo, Bunmi Dada & B. A. Senjobi

44

Groundwater quality trend detection at the regional scale: effects of spatial and temporal variability H. P. Broers, J. Rozemeijer, M. Van De Aa, B. Van Der Grift & E. A. Buijs

50

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2 Contaminant Input Processes

Evaluating diffuse groundwater pollution trends—a key chal-lenge for the new EC water directives Stephen Foster

63

Indicators for assessing transport of oil sands process-affected waters Michael MacKinnon, Grey Kampala, Bill Marsh, Phil Fedorak & Selma Guigard

71

Herbicide runoff on a pastoral hill slope—a case study Karin Müller, Roland Stenger & Anis Rahman

81

Dynamics of groundwater recharge through structured soils and the influence on water quality Edwin Cey, David Rudolph & René Therrien

89

Assessing water travel times during riverbank filtration Melissa Dawe & Kerry MacQuarrie

97

Investigating surface water–groundwater interactions with the help of sewage indicators in Berlin, Germany Gudrun Mass-mann, Uwe Dünnbier, Janek Greskowiak, Andrea Knappe & Asaf Pekdeger

103

Fate and transport of phage as surrogates for viral pathogens in UK aquifers Eadaoin Joyce, Katie Collins, Aidan Cronin, Joerg Rueedi, Steve Pedley, Alwyn Hart, John Tellam & Richard Greswell

113

Effects of macropore flow on solute transport in a vadoze zone under repetitive rainfall events Fumi Sugita, Tokuo Kishii & Mi-chael English

122

Factors controlling the chemistry of shallow groundwater in dif-ferent geological and hydrological environments Irén Varsányi, Hélène Pauwels & Lajos Ó.Kovács

130

Impact of a polluted stream on its adjacent aquifer: the case of the Alamar zone, Tijuana, Mexico Fernando T. Wakida, Luis E. Ponce-Serrano, Eulalia Mondragon-Silva, E. Garcia-Flores, David N. Lerner & Guillermo Rodríguez-Ventura

141

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The influence of relative permeability heterogeneity on DNAPL releases G. P. Grant, J. I. Gerhard & B. H. Kueper

148

3 Site Characterization

Characterization of Quaternary gravel aquifers and their imple-mentation in hydrogeological models Uli Maier, Andreas Becht, Boris Kostic, Claudius Bürger, Peter Bayer, Georg Teutsch & Peter Dietrich

159

Geostatistical evaluation of high frequency hydraulic property and groundwater quality data collected by the Waterloo Profiler Shane McDonald, Jeff Groncki & Susanne Biteman

169

Quantification of PCE mass flow rates for source zone identifica-tion Sebastian Bauer, Marti Bayer-Raich, Christian Kolesar, Dietmar Müller, Thomas Holder & Thomas Ptak

176

Characterization of transport processes in a heterogeneous aquifer using electrical resistivity tomography (ERT) Kerstin Müller, Jan Vanderborght, Andreas Englert, Andreas Kemna & Harry Vereecken

182

Contaminant retardation by double-porosity diffusive exchange in the Chalk: implications for monitoring William Burgess, John Barker, Sally Watson & Ben Fretwell

191

Real and apparent thickness relationship for gasoline and gaso-hol contamination Alexandra Finotti, Nelson Caicedo, Everton De Oliveira & José Luiz Zoby

197

Detection and characterization of a vinyl chloride plume inside an urbanized area Alessandro Gargini & Monica Pasini

203

Wettability effects on the natural remobilization of mixed DNAPL pools James W. Roy, James E. Smith & Robert W. Gillham

212

4 Management and Decision Making

Impacts of changing agricultural land-use practices on municipal groundwater quality: Woodstock, Ontario Claus P. Haslauer, David L. Rudolph, Neil R. Thomson, Rob Walton & Mar-

223

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garet Misek-Evans

Developing a farm wellhead protection plan Hugh Simpson & James Myslik

234

Managing basin-wide groundwater quality changes resulting from enhanced groundwater recharge programs N. Thomas Sheahan, W. Greg Hamer & David S. Gould

241

Risk-based design of cost-efficient remediation strategies at megasites Fabio Serapiglia, Judith Sievers & Michael Finkel

249

IMS—A risk-based management approach for megasites, ex-ample Bitterfeld megasite, Germany Jochen Großmann, Judith Sievers, Antje Ritter & Martin Keil

256

Macro and micro scale evaluation of contaminant plumes at Ab-erdeen Proving Ground Donald J. Green

262

5 Natural Attenuation Processes and Applications

SIReN: Site for innovative research on monitored natural attenu-ation Sarah Macnaughton, Richard Swannell, Gordon Lethbridge, Phil-ippa Scott, Graham Norris, Nicola Harries, Alwyn Hart & Jonathan Smith

269

Assessing measurements of first-order degradation rates through the virtual aquifer approach Sebastian Bauer, Christof Beyer & Olaf Kolditz

274

Investigations of a large TCE plume discharging to surface water Steven Chapman, Beth Parker & John Cherry

282

Assessment of stable carbon isotopes as a tool for assessing MTBE biodegrada-tion at a field site Luis E. Lesser, Gerard Spinnler, Paul C. Johnson & Ramon Aravena

290

Natural attenuation of volatile hydrocarbons in the unsaturated zone—modelling for the Værløse field site Uli Maier, Uli Mayer & Peter Grathwohl

296

Fate and transport of naphthenic acids in groundwater Francoise Gervais & James Barker

305

Wetlands as natural reactive barriers: the hydrological and geomorphological landscape perspective Seiichiro Ioka & Norio Tase

311

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Steady state plumes: transverse mixing in aquifers, numerical experiments and field scale predictions for natural attenuation Uli Maier, Hermann Rügner & Peter Grathwohl

317

Modelling a controlled-sourced, multichemical plume undergoing natural attenu-ation Caitlin Martin, Hugh McCreadie, John W. Molson & Jim Barker

326

Tracing landfill leachate impacts on groundwater using DOC geochemistry and δ13C measurements Hossein Mohammadzadeh, Ian Clark & Gilles St-Jean

332

Natural attenuation of N-S-O heteroaromatic compounds in groundwater: chem-ical analyses, reactive transport experiments and field studies Matthias Piepenbrink, Martina Krüger, Thomas Ptak & Peter Grathwohl

338

6 In Situ Remediation

In situ groundwater clean-up of MTBE by photocatalysis May Chan, Alex Orlov, Richard Lambert & Rod Lynch

349

Spatial variations in MTBE-biodegradation activity near a biobar-rier in Port Hueneme, California Luis E. Lesser & Paul C. Johnson

358

Sequential reactive barrier remediation of ammonium-contamin-ated groundwater using polymer mats Bradley M. Patterson, Michelle E. Grassi, Blair Robertson, Gregory B. Davis & Allan J. McKinley

367

Separating the kinetic and sorption parameters of nitroaromatic compounds in contact with granular iron Melissa Marietta & John F. Devlin

376

Investigation of the performance of organic carbon permeable reactive barriers using dissolved gas analysis Randi L. Williams, K. Ulrich Mayer, Rich T. Amos, David W. Blowes & Carol J. Ptacek

383

Adsorption of natural organic matter and its effects on TCE degradation by iron PRBs Stefano Marconetto, Lai Gui & Robert Gillham

389

In situ chemical oxidation test of organic solvents with po-tassium permanganate Salvador Jordana, Jordi Guimerà, Josep A. Domènec & Josep M. Subirana

398

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A meso-scale constructed wetland for the remediation of chlorobenzene contaminated groundwater Arno Kaschl, Andrea Schultz, Carsten Vogt, Falk Dorusch, Peter Popp, Helko Borsdorf, Eberhard Küster, Peter Kuschk, Matthias Kästner & Holger Weiß

404

On-site landfill leachate management in a headwater catchment Brian Beatty & Joanne Thompson

412

Surfactant enhanced air sparging in Borden sand Gordon H. Brown, Michael D. Annable, Jaehyun Cho & Heonki Kim

418

Remediation of bromate contaminated groundwater Ray Butler, E. Cartmell, A. Godley & L. Lytton

426

Remediation of groundwater contaminated by trichloroethylene using groundwater extraction and effects of natural attenuation Nobuyuki Egusa, Tatemasa Hirata, Masanori Yoshioka & Osami Nakasugi

433

7 Flow and Transport Modelling

Pesticide transport in groundwater at the national scale: coup-ling an unsaturated zone model with a groundwater flow model Aaldrik Tiktak, Ton Van Der Linden & Gerard Uffink

441

Stochastic modelling of well head protection zones in highly het-erogeneous aquifers Monica Riva, Laura Guadagnini, Eugeniu Martac & Thomas Ptak

449

An adaptive hybrid method of characteristics technique for solv-ing solute transport problems Jianmei Cheng, Danhong Huang & Jianming Chen

458

Modelling groundwater/surface water interactions using MOD-FLOW-WhaT R. Brad Thoms & R. L. Johnson

466

A fully-coupled approach to evaluate the effectiveness of tile-drain systems to control drainage water and salinity George B. Matanga, Claire Jacquemin &Don Demarco

473

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How old is the water? Simulating groundwater age at the water-shed scale J. W. Molson & E. O. Frind

482

Large-scale groundwater flow and transport modelling: method-ology and application to the Meuse Basin, Belgium Philippe Or-ban, Serge Brouyere, Horatiu Corbeanu & Alain Dassargues

489

Delineation of well head protection areas for wells in Urmia Plain, Iran, using WhAEM2000 K. Badv & M. Deriszadeh

496

Surface and groundwater qualities in an urbanized catchment: scenario from a developing country Moshood N. Tijani & Shin-Ichi Onodera

506

Applying a laboratory-scale biodegradation concept to model field-scale reactive transport with advanced numerical methods Sascha E. Oswald, Ian A. Watson, Roger S. Crouch & Steven A. Banwart

517

Numerical simulation of density-driven permanganate oxidation of trichloroethylene DNAPL in a sandy aquifer Thomas H. Henderson, K. Ulrich Mayer, Beth L. Parker & Tom A. Al

525

An object-oriented groundwater/river model Olaf Kolditz, Martin Beinhorn & Rudolf Liedl

531

Key word index 541

Author index 545

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Preface

Sustainable economic growth requires a plentiful supply of high-quality water. This requirement has placed tremendous pressure on groundwater resources throughout the world, and has forced the international groundwater science, engineering and regulatory community to recognize the current limitations of research and resource management. The deterioration of groundwater quality, the presence of pathogens and chemical contaminants in surface water and groundwater, and the maintenance of aquatic habitat are challenges that require an integrated and technically feasible approach. This approach requires us to concurrently address local issues and the larger scale water management concerns typically encountered at the watershed or basin scale. Some important issues that will need to be addressed are:

– cost effective technologies to control and remediate contamination;– tools to comprehensively manage water quality at the watershed scale;– development and testing of investigative tools and methods;– optimal instrumentation approaches to monitor groundwater and surface water at

the watershed scale;– understanding the important chemical, biological, and physical processes

controlling natural and anthropogenic contaminants;– development of simulation models to investigate behaviour and perturbations to

the system;– assessment of best management practices; – improvement in analytical tools;– development of risk and cost-benefit relationships;– understanding the role of wetland and riparian zones to treat surface water; and– strategies to ensure early detection of potential non-point pollution problems.

This publication comprises the proceedings of the GQ2004 International Conference of Groundwater Quality: Bringing Groundwater Quality Research to the Watershed Scale, held at Waterloo, Canada, 19–22 July 2004. It continues the series established by previous conferences, GQM’93 (held in Estonia in 1993), GQ’95 (held in the Czech Republic in 1995), GQ’98 (held in Germany in 1998, and GQ2001 (held in the UK in 2001). The objective of GQ2004, a research-based conference, was to provide an international forum to discuss advances in groundwater quality research at the watershed scale. Integration of groundwater and surface water quality research and consideration of complex megasites, widely distributed and persistent chemicals and pathogens were emphasized.

This volume contains 67 peer-reviewed papers from the conference based on both oral and poster presentations. The papers presented at the conference were selected by

The conference proceedings volumes are all available from IAHS Press, Wallingford, UK. Groundwater Quality Management (GQM’93), ed. by K. Kovar & J. Soveri. IAHS Publ. 220 (1994) Groundwater Quality: Remediation and Protection (GQ’95), ed. by K. Kovar & K. Krásný. IAHS Publ. 225 (1995) Groundwater Quality: Remediation and Protection (GQ’98), ed. by M. Herbert & K. Kovar. IAHS Publ. 250 (1998) Groundwater Quality: Natural and Enhanced Restoration of Groundwater Pollution (GQ2001), ed. by S. F. Thornton &

S. E. Oswald. IAHS Publ. 275

the conference organizers and the Scientific Advisory Committee from over 220 submitted abstracts. The papers in this volume are separated into seven sections reflecting aspects related to the objective of this conference. The first section deals with general trends in groundwater quality beginning with a global perspective followed by national perspectives from Finland, Canada, Nigeria, and The Netherlands. Section 2 focuses on processes related to contaminant input to ground-water systems with contributions dealing with diffuse groundwater pollution, dynamics of groundwater recharge through fractures, the fate and transport of surrogates for viral pathogens, and factors controlling nitrate concentration in shallow groundwater. Site characterization is the topic of the third section which contains papers on the geostatistical evaluation of hydraulic properties, the use of electrical resistivity tomography to characterize transport processes, contaminant retardation in the UK chalk, and the wettability effects on the natural remobilization of mixed DNAPL pools. Section 4 contains papers on management and decision making for megasites, enhanced groundwater recharge programmes, and agricultural environments. Papers dealing with the application and processes relating to natural attenuation are contained in Section 5 with contributions on methods to assess first-order degradation rates, the use of wetlands as a natural reactive barrier, the natural attenuation of N-S-O heteroaromatic compounds, and steady-state plumes. Section 6 contains in situ remediation contributions on the clean-up of MTBE by photocatalysis, the performance and assessment of permeable reactive barriers, surfactant enhanced air sparging, and the use of constructed wetlands. The final section, Section 7, deals with flow and transport modelling and contains contributions on modelling pesticide transport, stochastic modelling of wellhead protection zones, simulating groundwater age at the watershed scale, and applying lab-scale biodegradation concepts to a field scale-reactive transport model.

Neil R. ThomsonDepartment of Civil Engineering, University of Waterloo

Waterloo, Ontario, Canada N2L 3G1

James F. BarkerDepartment of Earth Sciences, University of Waterloo

Waterloo, Ontario, Canada N2L 3G1

The Editor would like to acknowledge the diligence and cooperation of the reviewers for their peer review of the papers, and the conference authors for their patience and cooperation during the editing process. Also, the Editor would like to thank Donna Armbrost, Blythe Reiha, and Heather Thomson for their assistance with the editing and review process.

The conference was organized by the following committee:

James Barker (Chair) Department of Earth Sciences, University of Waterloo

Leanne GelsthorpeCRESTech, Waterloo

Lorraine Albrecht (Secretariat)Department of Earth Sciences, University of Waterloo

Chris Hanton-Fong Department of Earth Sciences, University of Waterloo

David Blowes Department of Earth Sciences, University of Waterloo

Suzanne LesageHealth Canada, Ottawa

Mary Ellen PattonDepartment of Earth Sciences, University of Waterloo

Mark ServosCanadian Water Network, Waterloo

Tony Endres Department of Earth Sciences, University of Waterloo

Ed Sudicky Department of Earth Sciences, University of Waterloo

Mike English Geography and Environmental Studies, Wilfrid Laurier University, Waterloo

Neil ThomsonDepartment of Civil Engineering, University of Waterloo

The conference organizers would like to thank the following sponsors for their support:

National Water Research Institute, Environment CanadaCanadian Water Network, A Centre of the Canadian Network of Centres of ExcellenceCRESTech, A Division of the Ontario Centres of ExcellenceInternational Association of Hydrogeologists, Canadian National Chapter

They also thank the members of the Scientific Advisory Committee, who were:

Poul Bjerg (Denmark) David Lerner (UK)Stephen Foster (UK) Huub Rijnaarts (The Netherlands)Peter Grathwohl (Germany) Yoram Rubin (USA)Charles Harvey (USA) Frank Schwartz (USA)Ron Harvey (USA) Georg Teutsch (Germany)Susan Hubbard (USA)

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------Bringing Groundwater Quality Research to the Watershed Scale (Proceedings of GQ2004, the 4th International Groundwater Quality Conference, held at Waterloo, Canada, July 2004). IAHS Publ. 297, 2005, 3-10.

A global inventory of groundwater quality: first results

JASPER GRIFFIOEN1, RIANNE BRUNT1, SLAVEK VASAK2 & JAC VAN DER GUN2

1 Netherlands Institute of Applied Geoscience TNO, PO Box 80015, 3508 TA Utrecht, The [email protected] International Groundwater Resources Assessment Centre (IGRAC), PO Box 80015, 3508 TA Utrecht, The Netherlands

Abstract Groundwater quality is deteriorating worldwide due to anthropogenic impacts and it may be limited naturally as well. We present a first overview of groundwater quality at a global scale as part of the Global Groundwater Information System of the International Groundwater Resources Assessment Centre. The groundwater quality overview consists of 11 attributes that refer to individual compounds, occurrence of anthropogenic pollution and other quality problems. It considers individual countries or other large administrative units and is qualitative because source material is qualitative. The latter complicates intercomparison and limits true insight into the current status. However, global patterns can be recognized. A need exists to transform the insights per country into hydrogeochemical insights in order to identify the poor-quality regions within an identified country as well as to identify probable problem areas in not-yet identified countries. Such a process-based probability approach is developed for F-rich groundwater.Keywords contamination; environmental state; fluoride; groundwater quality; hydrogeology; risk


Groundwater quality in Canada: a national overview

SUZANNE LESAGENational Water Research Institute, Environment Canada, 867 Lakeshore Rd, Burlington, Ontario L7R 4A6, Canada. [email protected]

Abstract In Canada, drinking water quality is largely under provincial jurisdiction, with the Federal Government being responsible for the First Nations and Inuit as well as trans-boundary issues. The Guidelines for Canadian Drinking Water Quality set out the basic parameters that every water system (public, semi-public and private) should strive to achieve in order to provide a clean, safe and reliable drinking water supply. Because of the vast surface water resources in the country, public perception is often biased into thinking that these are sufficient. However, more than 30% of the Canadian population uses groundwater as their drinking water source. Until the recent worldwide trend in drinking bottled water, there was little interest in assessing the overall extent and quality of this resource in Canada. The advent of large bottling operations, with the associated problems in aquifer capacity and boundary issues, has changed the situation. The mapping of aquifers has been undertaken by Natural Resources Canada, whereas groundwater quality is a shared responsibility between Environment and Health Canada. A national survey of Federal contaminated sites was completed and an action plan for remediation is in place. A survey was conducted to delineate the magnitude of the threats to groundwater resources and to

mailto:[email protected]

use the information in integrated watershed management plans. Key words Canada; legislation; national overview; survey


Cumulative factors affecting groundwater quality in domestic wells in Finland

KIRSTI KORKKA-NIEMIDepartment of Geology, University of Turku, FIN-20500 Turku, [email protected]

Abstract Groundwater quality in domestic wells in Finland is described using a database of 1421 wells. Statistical evaluation of the water quality variables and background data points to a combination of specific extra-regional (geology, marine influence, atmospheric deposition), regional (aquifer type) and site-specific factors (pollution, land use) which together are manifested as cumulative effects operating at particular locations. All the layers of factors are represented to various extents in each well. According to the principal component analysis, the strongest modifier of well water quality seems to be an extra-regional or regional factor, and the site-specific factor seems to be of minor significance.Key words drinking water; Finland; groundwater; water analysis; water quality


Urbanization of rural watersheds in the region of Waterloo: implications for water quality

RANDY L. STOTLER1, JON PAUL JONES1, SHAUN K. FRAPE1, ROBERT J. DRIMMIE1, CRAIG T. JOHNSTON2 & IAN JUDD-HENRY3

1 Department of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, [email protected] Stantec Consulting Ltd, 49 Frederick Street, Kitchener, Ontario N2H 6M7, Canada3 Saskatchewan Research Council, 125-15 Innovation Drive, Saskatoon, Saskachewan S7N 2X8, Canada

Abstract Currently, the Regional Municipality of Waterloo (RMOW), Canada, derives about 90% of its water supply from groundwater. During the last five years, the population has grown by 8% per year, with development occurring on formerly agricultural land. Over the last 10 years, geochemical sampling in production, domestic, and monitoring wells across the RMOW, focusing on nitrate and chloride, has provided a background data set to evaluate changes to groundwater quality as development encroaches rural watersheds. Samples were taken in rural, urban, and rural residential (areas with relatively dense concentrations of both individual domestic wells and septic systems) environments. Typically, chloride levels are highest in urban areas and along highways in rural areas; nitrate levels are highest in rural and rural residential areas. Results in some recently urbanized sections indicate a reduction in nitrate concentrations,


with little impact yet observed from road salt, but additional sampling is needed to assess long-term trends.Key words nitrate; non-point source pollution; road salt; urbanization; Waterloo Moraine, Canada


Burial sites and their impact on groundwater

JULIAN TRICK, BEN KLINCK, PATRICIA COOMBS, DAVE NOY & GEOFF WILLIAMSBritish Geological Survey, Keyworth, Nottingham NG12 5GG, [email protected]

Abstract Historical evidence suggests that aquifers underlying burial grounds are at risk from the decay products associated with the breakdown of the human body. However, until recently research into the potential problems has been sparse. The British Geological Survey has investigated two burial sites overlying major sandstone aquifers in the UK to try and quantify the risks. A study of a 19th century burial ground showed possible evidence of a retarded high salinity plume, but transport modelling suggested solutes would reach the water table within 20 years and thus the burial ground no longer presents a source of contamination. A study of a modern working cemetery demonstrated that even with an unsaturated zone thickness of between two and three metres there is an impact of the burials on groundwater quality at the site , particularly from pathogenic bacteria. The survival of pathogenic bacteria in the sub-surface is poorly understood and requires further investigation. However, risk to drinking supplies can be mitigated by careful consideration of the local geological and hydrogeological conditions.Key words bacteria; burial; cemetery; decay; decomposition; groundwater; hydrogeology


Quality of water from hand-dug wells, boreholes, and streams in two localities in southwest Nigeria: implications for incidence of water borne diseases

SAMSON AYANLAJA, O. O. KEHINDE-PHILLIPS, FRANCIS OGUNKOLO, BUNMI DADA & B. A. SENJOBIDepartment of Soil Science and Farm Mechanization, College of Health Sciences, Olabisi Onabanjo University PMB 2002, Ago-Iwoye, [email protected]

Abstract Ago-Iwoye environ spans an area of 900 km2 with a population of a half million people, 10% of which are university students who live, and source domestic water from hand-dug wells and boreholes in the community. Water samples were collected from 27 hand-dug wells, eight boreholes, and five streams and analysed for cations, anions, and coliform bacteria. The university clinic records were examined for the number of students treated for malaria, typhoid fever, dysentery and cholera as a proportion of all patients treated during 2003. The concentration of nitrate is higher in some samples than the WHO’s maximum permitted level, while 28 of the



40 samples had detectable coliform bacteria (Enterobacteriaceae family) counts, suggesting faecal contamination. Fifty percent of all ailments reported to the clinic were water related. Adequate sanitation and protection of domestic water sources from contamination should be vehemently pursued. Key words domestic water sources; quality; sanitation; water borne diseases


Groundwater quality trend detection at the regional scale: effects of spatial and temporal variability

H. P. BROERS1, J. ROZEMEIJER1, M. VAN DER AA2, B. VAN DER GRIFT1 & E. A. BUIJS1

1 Netherlands Institute of Applied Geoscience TNO–National Geological Survey, PO Box 80015, 3508 TA Utrecht, The [email protected] Technical Soil Protection Committee, Ministry of Environment and Housing, Postbus 30947, 2500 GX Den Haag, The Netherlands

Abstract The EU Directives require the aggregation of trends in individual monitoring points to areas or groundwater bodies. This aggregation is delicate because spatial variations in solute inputs, groundwater age and reactive processes are large, and temporal variations due to climatological factors largely influence the time series at shallow depths in the aquifers. In principle, the monitoring of the recently infiltrated uppermost groundwater yields the fastest response to changes in agricultural practices. However, the trend analysis results and model results both indicated that trend monitoring using the uppermost groundwater suffers from large temporal and spatial variability. In our case, this seriously hampered the detection of trends that are due to changing agricultural practice. Trend analysis results from the configurations with deeper permanent screens showed less temporal variability, but the trend results only became meaningful when the age of the groundwater was considered. Tritium-helium age dating showed that variations in groundwater age at 7–12 m depth are larger than theoretically expected. Therefore, scaling of the time series according to the recharge year of the groundwater was profitable. Using the tritium-helium age scaling, the concentration time series confirmed the impacts of increasing manure loads between 1950 and 1990 and indicated the first signals of improvement after 1990. The trend reversal was apparent for indicators which behave conservatively in groundwater. Trend reversal for retarded pollutants may take much longer to be detected; reactive processes have large effects on trend detection.Keywords groundwater age; spatial and temporal variability; trend analysis; tritium-helium


Evaluating diffuse groundwater pollution trends—a key challenge for the new EC water directives

STEPHEN FOSTER

President, Internation Association of Hydrogeologists, c/o British Geological Survey, Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB, UK [email protected]

Abstract This paper is not intended to be a systematic guide to emerging European Community (EC) framework legislation governing groundwater, nor a scientific review of diffuse groundwater pollution. It is situated more at the technical–regulatory interface, looking at the challenge of evaluating the risks of diffuse groundwater pollution and the effectiveness of pollution control measures. These generic aspects of the practical implementation of the EC Water Directives should be of interest to all concerned with groundwater resource management and protection.Key words diffuse sources; European Community; groundwater; water quality trends


Indicators for assessing transport of oil sands process-affected waters

MICHAEL MACKINNON1, GREY KAMPALA2, BILL MARSH3, PHIL FEDORAK3 & SELMA GUIGARD3

1 Syncrude Research Department, 9421-17 Ave, Edmonton, Alberta T6N 1H4, [email protected] Syncrude Canada Ltd. Mildred Lake Site, Fort McMurray, Canada3 University of Alberta, Edmonton, Alberta, Canada

Abstract In the Athabasca oil sands, bitumen production using caustic warm-water extraction leads to large quantities of fluid tailings. The resulting tailings require storage in above-grade deposits or secure settling basins. Significant changes in groundwater systems occur from disruption during mining or changes in hydrology with tailings deposition. Intentional release into local groundwater systems is not practiced and release by seepage is minimized by engineering means. Waters produced from oil sands processing have unique properties that can be used as indicators of interaction with surface and groundwaters. In this paper, water from an above-grade tailings sand deposit is examined as a recharge into a surface water drainage system. The changes in water properties occurring during seepage of this process-affected water are examined, and analytical tools for better estimating the attenuation processes in receiving aquatic systems are described. Key words ammonia; attenuation; boron; oil sand; groundwater; naphthenic acids; salts; transport


Herbicide runoff on a pastoral hill slope—a case study

KARIN MÜLLER1, ROLAND STENGER2 & ANIS RAHMAN1

1 AgResearch Ltd, Ruakura Research Centre, East Street, Hamilton, New [email protected] Lincoln Environmental, Private Bag 3062, Hamilton, New Zealand



Abstract Runoff and herbicide loss from pastoral land were studied at the plot and hill slope scale. Rainfall was simulated 24 h after application of 2,4-D and MCPB in winter and spring, respectively. Average MCPB concentrations, normalized by the concentration applied, were twice the normalized 2,4-D concentrations, reflecting the higher mobility of MCPB. On the hill slope scale 7 and 4% of the applied 2,4-D and MCPB, respectively, were exported. Herbicide loss was determined by runoff volume, which was six times higher in winter. Saturation excess with a variable contributing area was identified as the main runoff generating process. The initial depth of a perched water table in the convergent footslope explained the different seasonal runoff responses. Event-averaged concentrations were similar on both scales. Runoff and herbicide loss displayed high spatial variations due to the heterogeneity of soil properties, and the influence of (micro-) topography on re-infiltration and return flow.Key words 2,4-D; MCPB; return flow; saturation excess; subsurface flow; variability


Dynamics of groundwater recharge through structured soils and the influence on water quality

EDWIN CEY1, DAVID RUDOLPH1 & RENÉ THERRIEN2

1 Department of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada [email protected] Department of Geology and Geological Engineering, University of Laval, Québec G1K 7P4, Canada

Abstract Using numerical simulations, the influence of fractures on groundwater recharge dynamics was examined under variably-saturated conditions. Hypothetical groundwater recharge events were simulated for a simple variably-saturated porous block containing a single vertical rough-walled fracture. Results indicate that moisture and solute exchange between the fracture and the matrix limit the rate and depth of penetration of surface infiltration. Large infiltration volumes might be required to overcome matrix storage and initiate fracture flow at depth. Once fracture flow is initiated, it controls the vertical flux of a surface applied tracer. The overall results illustrate the complexity associated with the migration of contaminant species in low permeability sediments with significant macroporosity.Key words groundwater recharge; macropores; numerical modelling; vadose zone


Assessing water travel times during riverbank filtration

MELISSA DAWE & KERRY MACQUARRIEDepartment of Civil Engineering, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick E3B 5A3, [email protected]


Abstract Riverbank filtration is a process that can lead to passive removal of natural organic matter, organic contaminants and pathogenic microbes. Quantification of water travel time between rivers and well fields is of interest because of the strong influence travel time has on the extracted water quality. In this study of a heterogeneous sand and gravel aquifer, travel time during riverbank infiltration is being assessed using environmental tracers and hydraulic measurements. Vertically discrete water temperature time series have been obtained beneath the riverbed infiltration area. Groundwater temperatures show significant seasonal variations (from 22°C to close to 0°C) that lag river water temperature changes. Hydraulic heads and groundwater samples for radon-222 have been collected from sub-riverbed piezometer nests. As expected, groundwater radon-222 exhibited an increase (up to 29 Bq l -1) relative to river water. Average linear velocities from radon-222 ingrowth calculations and preliminary temperature time series modelling range from 0.7 to 5.0 m day-1, and 0.1 to 2.6 m day-1, respectively. These results compare favourably to typical velocities used in slow sand filtration for drinking water treatment.Key words environmental tracers (radon-222, water temperature); infiltration velocity; riverbank filtration; river–groundwater interactions


Investigating surface water–groundwater interactions with the help of sewage indicators in Berlin, Germany

GUDRUN MASSMANN1, UWE DÜNNBIER2, JANEK GRESKOWIAK3, ANDREA KNAPPE4 & ASAF PEKDEGER1

1 Free University of Berlin, Hydrogeology Group, Malteserstr. 74-100, D-12249 Berlin, [email protected] Berlin Water Company, Laboratory, Germany3 Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany4 Alfred-Wegener-Institute Potsdam, Germany

Abstract In Berlin, 70% of the drinking water is derived from bank filtrate or artificially recharged water. Because the surface water system contains elevated proportions of secondary treated municipal sewage, a number of sewage indicators from various sources can be detected in the bank filtrate. An artificial recharge (AR) site and a bank filtration (BF) site in Berlin Tegel are introduced and compared in terms of their hydrogeological and hydrochemical properties. Because of a permanent clogging layer and the geological properties, travel times are slower at the BF site and the hydrochemical conditions are more reducing. First estimates for the reaction rate constants of oxygen and nitrate are obtained with exponential data fitting. Some of the effects of the different redox conditions on minor substances such as drug residues are highlighted. Key words artificial recharge; bank filtration; tracers; wastewater


Fate and transport of phage as surrogates for viral pathogens in UK aquifers


EADAOIN JOYCE1, KATIE COLLINS1, AIDAN CRONIN1, JOERG RUEEDI1, STEVE PEDLEY1, ALWYN HART2, JOHN TELLAM3 & RICHARD GRESWELL3

1 Robens Centre for Public and Environmental Health, Building AW Floor 2, University of Surrey, GU2 7JJ, UK [email protected] Science Group, Air, Land & Water, Environment Agency, Olton Court, 10 Warwick Road, Solihull, West Midlands B92 7HX, UK3 School of Earth Sciences, University of Birmingham, B15 2TT, UK

Abstract The management of water quality in urban aquifers is a complex task with multiple pollution sources and within these multiple sources of microbial contamination (e.g. sewers, cemeteries, landfills, etc.) in combination with potentially complex dynamic hydrogeology and water flows. Further complications arise from likely large variability in the source loadings as well as a paucity of reliable information needed to assess the fate and transport of pathogens in groundwater systems. Proper management of urban groundwater requires a detailed understanding of: (a) concentrations of microorganisms in sources, mainly leaky sewers, (b) mechanisms and volumes of sewer exfiltration, (c) fate and transport characteristics of the microbes once in the groundwater, and (d) the levels of microorganisms that are typically picked up in urban water monitoring programmes and the subsequent threat posed to public health. Only by examining these key issues can we determine the role and capacity for natural attenuation mechanisms to limit the survival and spread of pathogens in groundwater and hence mitigate the effects of these pathogens. The authors have sought to address these issues by: (a) investigating the fate and transport of bacteriophage as analogues of viral pathogens in field-scale tracing work; (b) characterizing typical sewer bacterial and viral concentrations and gaining a better understanding of the mechanisms of sewer exfiltration; (c) characterizing the geology and hydrogeology of key urban research sites in three UK cities; and (d) frequent temporal and spatial monitoring of water quality at the research sites. The research is presented here to help guide future urban groundwater management, as well as deal with associated rural groundwater problems in the UK such as large-scale burial of animal carcasses.Key words bacteriophage; groundwater; sandstone; UK; viruses


Effects of macropore flow on solute transport in a vadoze zone under repetitive rainfall events

FUMI SUGITA1, TOKUO KISHII2 & MICHAEL ENGLISH3

1 Chiba University of Commerce, Konodai 1-3-1, Ichikawa, Chiba, [email protected] National Institute of Earth Science and Disaster Prevention, Tennodai 3-1, Tsukuba, Ibaraki, Japan3 Wilfrid Laurier University, Waterloo, Ontario, Canada

Abstract An experimental apparatus was employed to measure the effects of macropore flow on solute transport during repetitive rainfall–infiltration events. The effects of macropore flow were classified into three categories depending on rainfall amount relative to evaporation and storage change during a period of interest. Macropores were found to contribute to faster infiltration under heavy rainfalls, while they contribute to larger vertical dispersion in all rainfalls including light rains which do not initiate macropore flow. Rainfall intensity has an influence on the onset of the macropore flow. Macropore flow in high antecedent soil water content conditions causes


greater vertical spreading of the solute due to little lateral infiltration from macropores into matrix. Key words macropores; solute movement; rainfall–infiltration experiments


Factors controlling the chemistry of shallow groundwater in different geological and hydrological environments

IRÉN VARSÁNYI1, HÉLÈNE PAUWELS2 & LAJOS Ó.KOVÁCS3

1 University of Szeged, Dept. of Mineralogy, Geochemistry and Petrology, H-6701 Szeged, PO Box 651, [email protected] BRGM, Water Division, 3 av. Cl. Guillemin, F-45060 Orléans, France3 Hungarian Geological Survey, H-1440 Budapest, PO Box 17, Hungary

Abstract Chemical composition and water stable isotope data of shallow groundwater were studied in two areas with different geological and hydrogeological features. One was a sedimentary area in the Pannonian Basin (Hungary), the other was Coët-Dan catchment underlain by Brioverian (Late Proterozoic) pyrite-bearing schists in Brittany (France). Temporal and spatial variability of dissolved compounds and relationships between relevant components were used to determine the major processes influencing the chemical composition, particularly the NO3

-

content, of shallow groundwater. In the sedimentary aquifer organic matter, in the basement aquifer pyrite, provide electrons for reduction and/or denitrification. In spite of the difference in geology, the importance of groundwater flow in controlling the chemical composition, including NO3

-, was established in both study areas.Key words basement aquifer; hydrogeology; nitrate; redox processes; sedimentary aquifer; shallow groundwater


Impact of a polluted stream on its adjacent aquifer: the case of the Alamar zone, Tijuana, Mexico

FERNANDO T. WAKIDA1, LUIS E. PONCE-SERRANO1, EULALIA MONDRAGON-SILVA1, E. GARCIA-FLORES2, DAVID N. LERNER3 & GUILLERMO RODRÍGUEZ-VENTURA1

1 Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Calzada Tecnológico 14418, Mesa de Otay, CP 22390 Tijuana BC México [email protected] Laboratorio ambiental SIGMA, Blvd. Bellas Artes # 17606-B. Frac. Garita de Otay, CP 22505 Tijuana, BC Mexico 3 Groundwater Protection and Restoration Group, Civil & Structural Engineering, University of Sheffield, Mappin St, Sheffield S1 3JD, UK

Abstract The Alamar Creek is part of the Tijuana River basin, a basin shared by Mexico and the United States. The study area is located in the east side of the city of Tijuana, Baja California,

Mexico, with an approximate area of 9 km2. It encompasses a suburban area with a mix of land uses: sewered and unsewered residential areas and small-scale horticulture. The objective of this study is to investigate the present level of contamination of the alluvial aquifer system adjacent to the Alamar Creek and to make a preliminary evaluation of the connection between surface and groundwater pollution. Water analysis has shown that groundwater quality in the aquifer is poor. Groundwater pollution in the alluvial aquifer system of the Alamar zone is attributed largely to the infiltration of polluted water from the stream and the lack of sewerage.Key words Alamar Creek; groundwater pollution; Mexico; river–aquifer interaction; suburban area; Tijuana; urban river


The influence of relative permeability heterogeneity on DNAPL releases

G. P. GRANT1, J. I. GERHARD1 & B. H. KUEPER2

1 Institute for Infrastructure and Environment, University of Edinburgh, Edinburgh EH9 3JL, [email protected] Department of Civil Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada

Abstract Predictions of dense non-aqueous phase liquid (DNAPL) releases are sensitive to the nonwetting phase relative permeability–saturation (kr,N–S) constitutive relationships employed in numerical models. In this study, hysteretic kr,N–S curves were measured for a variety of sands, revealing trends in kr,N–S function shapes that were correlated to sand type. To explore the significance of this conclusion, numerical simulations of a fixed volume DNAPL release were conducted using 10 realisations of a spatially correlated, random permeability field. Simulations assuming homogeneity of relative permeability were compared to those employing the determined functional dependence of relative permeability on porous media properties. The simulations demonstrate both temporal and spatial sensitivity. The time for DNAPL migration to cease is shorter, and the ultimate extent of DNAPL invasion is greater, in those simulations using the traditional assumption that kr,N–S is uniform and not correlated to porous media type.Key words constitutive relationships; DNAPL release; relative permeability; simulations; temporal and spatial sensitivity


Characterization of Quaternary gravel aquifers and their implementation in hydrogeological models

ULI MAIER, ANDREAS BECHT, BORIS KOSTIC, CLAUDIUS BÜRGER, PETER BAYER, GEORG TEUTSCH & PETER DIETRICH Center for Applied Geoscience, University of Tübingen, Sigwartstraße 10, D-72076 Tübingen, [email protected]

Abstract Aquifer analogues of Quaternary gravel deposits at two research sites in SW Germany

were assembled. Detailed 2-D and 3-D sedimentological models were developed in the mesoscale (tens of metres) from sedimentological, hydrogeological, and geophysical surveys. Data from field investigations were integrated in facies models using ArcInfo GIS and GoCAD, respectively, delineating sedimentary structures and providing a database for hydraulic properties. A method was developed to convert these data into groundwater flow models using MODFLOW 2000 and related software. These were utilized to obtain bulk hydraulic flow and transport properties of the investigated sites. Key words aquifer analogue; heterogeneity; gravel deposit; GoCAD; MODFLOW 2000; transport characteristics


Geostatistical evaluation of high frequency hydraulic property and groundwater quality data collected by the Waterloo Profiler

SHANE McDONALD1, JEFF GRONCKI2 & SUSANNE BITEMAN3

1 Malcolm Pirnie, Inc., 630 Freedom Business Center, Suite 300, King of Prussia, Pennsylvania 19406, USA [email protected] Malcolm Pirnie, Inc., 155 East Woodfield Rd, Suite 680, Schaumburg, Illinois 60173, USA 3 Malcolm Pirnie, Inc., 1500 Abbott Rd, Suite 210, East Lansing, Michigan 48823, USA

Abstract Waterloo Profiler subsurface investigations generate large volumes of aquifer property and water quality data. This paper presents how data collected by Waterloo Profiler were evaluated using transition probability geostatistics and zonal kriging to assess contaminant distribution in a heterogeneous 300-foot (~100 m) thick sand aquifer. Index of hydraulic conductivity (Ik) was measured continuously, and groundwater samples were collected every 10 feet vertically to characterize aquifer heterogeneities. Stratigraphy was interpreted by comparing Ik to stratigraphic descriptions, then creating a three-dimensional framework of aquifer and contaminant heterogeneities using advanced geostatistical methods and Markov chain analyses. Markov chain analyses use transition probabilities to predict stratigraphic changes in lithofacies. The water quality data was differentially interpolated within the three-dimensional framework using zonal kriging. The results are detailed with three-dimensional aquifer and contaminant plume visualizations. These visualizations incorporate our geological understanding and are more easily understood than the simple graphical representations. Key words data visualization; geostatistics; groundwater sampling; Markov chain; stratigraphy; transitional probability analyses; Waterloo Profiler; zonal kriging


Quantification of PCE mass flow rates for source zone identification

SEBASTIAN BAUER1, MARTI BAYER-RAICH2, CHRISTIAN KOLESAR3, DIETMAR MÜLLER3, THOMAS HOLDER1 & THOMAS PTAK1

1 Center for Applied Geoscience, University of Tübingen. Sigwartstrasse 10, D-72076 Tübingen, [email protected] UmweltForschungsZentrum, Theodor-Lieser-Straße 4, D-06120 Halle, Germany3 Federal Environment Agency Austria, Spittelauer Lände 5, AT-1090 Vienna, Austria

Abstract The integral groundwater investigation method is used for the quantification of PCE and TCE mass flow rates at an industrialized urban area in Linz, Austria, a densely populated industrial and urban area. In this approach, pumping wells positioned along control planes perpendicular to the groundwater flow direction are operated for a time period of the order of days and sampled for contaminants in the pump discharge. The concentration time series are used to determine contaminant mass flow rates, mean concentrations and the plume shapes as well as positions at the control planes. It was possible to identify active contaminant sources and to exclude some of the suspected source zones. The individual source strength was quantified in terms of mass flow rates at the control planes. Key words integral investigation; mass flow rate; PCE; numerical model


Characterization of transport processes in a heterogeneous aquifer using electrical resistivity tomography (ERT)

KERSTIN MÜLLER, JAN VANDERBORGHT, ANDREAS ENGLERT, ANDREAS KEMNA & HARRY VEREECKENAgrosphere Institute (ICG IV), Forschungszentrum Jülich GmbH, 52425 Jülich, [email protected]

Abstract Tracer experiments were carried out for the characterization of the spatial and temporal variability of transport processes in heterogeneous aquifers. At the Krauthausen test site (Germany) two large scale tracer experiments were conducted to investigate the potentiality of electrical resistivity tomography (ERT) for imaging subsurface transport. First, a CaCl2 tracer solution with a higher electrical conductivity (EC) than the groundwater was injected. One year later, the same experiment was repeated using a “negative” tracer with a smaller conductivity than the groundwater. With ERT, changes in bulk electrical conductivity of the aquifer were monitored, and translated to groundwater EC using calibration relations that were determined in laboratory measurements on aquifer sediments. The salt tracer showed a density driven drift to the middle and lower parts of the aquifer while the “negative” tracer moved primarily through the upper and middle parts. The comparison between ERT and local breakthrough curves derived from multilevel groundwater sampling showed that resistivity tomograms are an appropriate surrogate for traditional concentration maps. Key words electrical resistivity tomography; heterogeneous aquifers; tracer tests


Contaminant retardation by double-porosity diffusive exchange in the Chalk: implications for monitoring



WILLIAM BURGESS1, JOHN BARKER1, SALLY WATSON1 & BEN FRETWELL2

1 Department of Earth Sciences, University College London, London WC1E 6BT, [email protected] ENTEC UK, Shrewsbury, UK

Abstract Intergranular porosity of the UK Chalk aquifer is up to 40%, but fracture porosity is seldom greater than 3%. At least 90% of Chalk groundwater occurs as essentially immobile porewater. Immobile porewater also occurs as residual saturation for several metres above the water table. The quality of mobile groundwater in fractures is substantially moderated by diffusive exchange with porewater. Pollutant retardation and dispersion by double-porosity diffusive exchange in the Chalk have been quantified in relation to: (a) extensive (30 km2) pollution from disposal lagoons for coalfield brine, and (b) the “seasonally unsaturated zone” above a plume of contaminated groundwater. Semi-analytical models incorporating Fickian diffusion successfully reproduce observed porewater contaminant profiles in both cases. Forward modelling indicates that release of contaminants back to mobile groundwater will occur over several decades. Results emphasise that diagnosis of the quality status of double-porosity aquifers requires attention to porewater chemical profiles, particularly where historical pollution sources exist.Key words Chalk; double porosity; diffusion; groundwater quality; monitoring; porewater


Real and apparent thickness relationship for gasoline and gasohol contamination

ALEXANDRA FINOTTI1, NELSON CAICEDO2, EVERTON DE OLIVEIRA3 & JOSÉ LUIZ ZOBY3

1 Departamento de Engenharia Química, Universidade de Caxias do Sul, PO Box 1352, Caxias do Sul, RS, 95001-970, [email protected] Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul, PO Box 15029, Porto Alegre, RS, 91501-970, Brazil3 Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, Cidade Universitária, São Paulo, SP, 05508-080, Brazil

Abstract Petroleum product releases from gas stations or petroleum facilities pose a great concern for groundwater in urban aquifers. The use of ethanol as an oxygenate in gasoline to improve air quality affects the behaviour of the free phase in the subsurface. A mathematical relationship between real and apparent free phase thicknesses is proposed in this work for gasoline subsurface contamination. The equation is based on hydrostatics, capillary pressure and fluid densities. The equation has been validated at the laboratory scale using gasohol (24% by volume of ethanol) and gasoline. The equation fits the data produced by the two gasoline experiments better than the gasohol experiments. This difference appears to be related to the mass transfer of ethanol from gasohol to water, since ethanol partitions preferentially to water.Key words gasohol; gasoline; mathematical relationship; real and apparent thickness


Detection and characterization of a vinyl chloride plume inside an urbanized area

ALESSANDRO GARGINI & MONICA PASINIEarth Sciences Department, University of Ferrara, Corso Ercole I d’Este, 32, I-44100 Ferrara, [email protected]

Abstract The paper deals with a sandy confined aquifer of alluvial origin contaminated by vinyl chloride and located in the Po Valley immediately to the south of the Po River and 5 km to the north of the city of Ferrara (northern Italy). The investigation identified, inside a mainly urbanized area, a plume with a length of 1.7 km and a maximum width of 0.3 km with vinyl chloride (VC) concentrations of up to more than 11 000 ppb and total absence of other chlorinated ethanes, ethenes, and ethylene. To optimize the VC analysis, short-term low-flow purging using peristaltic and inertial pumps were used to collect samples.Key words confined aquifer; direct-push; inertial pump; Po River; Po Valley; plume; vinyl chloride


Wettability effects on the natural remobilization of mixed DNAPL pools

JAMES W. ROY1, JAMES E. SMITH 2 & ROBERT W. GILLHAM1

1 Department of Earth Sciences, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canadajwroy@sciborg. uwaterloo. ca2 School of Geography and Geology, McMaster University, Hamilton, Ontario, L8S 4M1, Canada

Abstract Although commonly considered immobile, certain multicomponent DNAPL pools may remobilize simply through compositional changes caused by the preferential dissolution of components of higher solubility. This process, termed natural remobilization, was previously demonstrated for open pools and pools within porous media in a 2-dimensional flow cell. The potential for remobilization is controlled by the capillary pressure at the pool boundaries and the displacement pressure of the capillary barrier. These parameters will be affected by the change in fluid properties (primarily density) and the loss of pool height occurring during dissolution, as well as hysteretic and wettability effects. Using these two sets of experiments and an additional visualization within a glass capillary, it was determined that enhanced contact-angle hysteresis, associated with a change in wettability reduces the potential for natural remobilization for certain pools within porous media. However, it increases the potential for remobilization for open pools. Keywords dissolution; DNAPL (dense non-aqueous phase liquid); groundwater; wettability



Impacts of changing agricultural land-use practices on municipal groundwater quality: Woodstock, Ontario

CLAUS P. HASLAUER1, DAVID L. RUDOLPH1, NEIL R. THOMSON2, ROB WALTON3 & MARGARET MISEK-EVANS3

1 Department of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada [email protected] Department of Civil Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada 3 Country of Oxford, Woodstock, Ontario N4S 1H6, Canada

Abstract The primary groundwater supply for the City of Woodstock, Ontario is drawn from a well field situated in a rural setting outside the city limits. Nitrate concentrations in several of the wells have exceeded the Ontario Drinking Water Guidelines leading to significant concern regarding the long-term water quality of this key supply. The source of nitrate may be related to historical agricultural land-use practices. In an attempt to reduce nitrate levels in the municipal wells, nutrient loadings on the agricultural land within the immediate vicinity of the well field are being significantly reduced through alternative cropping and fertilizing practices. To evaluate the success of these pro-active agricultural land-use practices a multi-faceted investigative approach has been adopted. A key component of this approach involves a detailed hydrogeologic investigation to: (a) improve the conceptual model of the groundwater flow system; (b) estimate the nitrate mass present in the subsurface; and (c) quantify the spatial nitrate mass loading from the agricultural land under investigation. In concert with these data, a three-dimensional flow and transport model is currently under development with the objective of predicting the magnitude and timing of the influence of these land-use changes on the nitrate concentrations extracted by the municipal well field. This paper presents an outline of the novel land-use management strategy employed by the County of Oxford, which oversees the City of Woodstock water supply, hydrogeological details of the various field investigations, and preliminary field results.Key words agriculture; City of Woodstock, Canada; field investigations: hydrogeologic conceptual model; municipal groundwater; nitrate


Developing a farm wellhead protection plan

HUGH SIMPSON1 & JAMES MYSLIK2

1 Environmental Management Unit, Resources Management Branch, Ontario Ministry of Agriculture & Food, 1 Stone Road West, Guelph, Ontario N1G 4Y2, Canada [email protected] Engineering and Technology Unit, Resources Management Branch, Ontario Ministry of Agriculture & Food, Wellington Place, RR#1, Fergus, Ontario N1M 2W3, Canada

Abstract Groundwater drawn from private wells is usually the only drinking water supply for farm and other rural use. Farmers have a personal interest and valuable role in ensuring that their actions and land-use activities within their property boundaries do not impair the quality or quantity of recharge to their water supplies. A farm wellhead protection plan can be used to help manage and protect groundwater supplies within the farm boundary. Widespread adoption of this approach can also result in a cumulative benefit to the community. This paper describes a risk


assessment approach that can be used to develop and implement a farm wellhead protection plan. This plan addresses farm-specific concerns, such as nutrient management, as well as concerns common to both farm and non-farm situations, such as fuel storage and maintaining well yield.Key words farm; groundwater; Ontario, Canada; risk assessment; wellhead


Managing basin-wide groundwater quality changes resulting from enhanced groundwater recharge programs

N. THOMAS SHEAHAN1, W. GREG HAMER1 & DAVID S. GOULD2

1 Geomatrix Consultants, Inc., 250 East Rincon Street, Suite #204, Corona, California 92879, USA [email protected] Crescenta Valley Water District, 2700 Foothill Boulevard, La Crescenta, California 91214, USA

Abstract Crescenta Valley Water District (District) supplies groundwater from the Verdugo basin to the heavily-developed Verdugo Valley, California, USA. Prior to the 1980s, most domestic wastewater was disposed of through individual wastewater (IW) systems, which recharged the basin, but also increased nitrate (NO3) concentrations. Since the 1980s, the IW systems have been replaced with sewers, which now carry high-NO 3 wastewater out of the basin, but reduce recharge. Increasing demands for groundwater has prompted development of recharge programmes. Recharge may detrimentally affect groundwater quality due to chemical interaction, flow direction changes, and rising groundwater levels. This paper presents the demographic and hydrogeological conditions of the Verdugo basin, the presence of high NO3 in the basin, the need for recharge to meet demand, available sources of recharge water, water quality problems that may result, and seven management techniques for avoiding, reducing, or mitigating water quality impacts while optimizing recharge and beneficial use of the basin. Key words groundwater; nitrate (NO3); recharge; reclaimed water; rising water table; storm water; Verdugo basin; wastewater; water capture; water quality management


Risk-based design of cost-efficient remediation strategies at megasites

FABIO SERAPIGLIA1, JUDITH SIEVERS2 & MICHAEL FINKEL1

1 Centre for Applied Geosciences, University of Tuebingen, Sigwartstr. 10, 72076 Tuebingen, [email protected] GICON GmbH, Tiergartenstr. 48, 01219 Dresden, Germany

Abstract Remediation planners and decision makers at megasites are usually confronted with vast and complex distributions of pollutants in soil and groundwater. Due to the size of the problem and a typically scarce database on hydrogeological and geochemical parameters, megasites represent a particular challenge; and specifically adapted methods are required to assist site managers in the design of effective cleanup solutions. The proposed methodology is based on


a system dynamics modelling approach where the system is represented by a risk based source-pathway–receptor concept and the dynamics predominantly by a mass flux model. Effects of possible remedial actions, either tackling the contaminant source or managing the groundwater plume, are described as mass flux change over time. The concept allows for a straightforward check of effects (risk reduction) and costs of any particular remediation scenario. Working on a relatively high abstraction level and making use of various simplified analytical relationships, quick information on economic as well as technical feasibility of possible scenarios is provided.Key words cost efficiency; megasites; remediation technologies; risk reduction; site management


IMS—A risk-based management approach for megasites, example Bitterfeld megasite, Germany

JOCHEN GROẞMANN1, JUDITH SIEVERS1, ANTJE RITTER1 & MARTIN KEIL2

1 GICON – Großmann Ingenieur Consult GmbH, Tiergartenstraße 48, 01219 Dresden, [email protected] Landesanstalt für Altlastenfreistellung (LAF), Maxim-Gorki-Str. 10, 39108 Magdeburg, Germany

Abstract The management of contaminated megasites requires an integrated risk-based approach to achieve cost-effective risk reduction in compliance with the regulations of the European Water Framework Directive. Megasites are characterized by complex site-specific conditions in which a complete removal of contamination is neither technically nor economically feasible. Previous work regarding the difficulty in managing four exemplary megasites constituted the basis for the development of the Integrated Management System (IMS) tool. This tool facilitates the management of megasites by offering a guideline, which includes all the essential steps for determining an appropriate remediative action plan satisfying the interests of all involved stakeholders. Within this paper, the IMS is presented and applied to the Bitterfeld megasite in Saxony-Anhalt, Germany.Key words Bitterfeld, Germany; contaminated site management; groundwater contamination; integrated management system; megasites; risk-based approach; risk cluster; risk management zone


Macro and micro scale evaluation of contaminant plumes at Aberdeen Proving Ground

DONALD J. GREENUS Army Garrison Aberdeen Proving Ground, IMNE-APG-SHE-R, APG, Maryland 21010, [email protected]

Abstract Aberdeen Proving Ground (APG) is a 123 square mile US Army Installation located on four peninsulas that project into the Chesapeake Bay in Maryland, USA. APG is listed on the US Environmental Protection Agency’s National Priority List of the most significant contaminated

sites within the US. The installation lies within the Atlantic Coastal Plain characterized by a com-plex mix of sand and clay lenses interspersed with paleochannels. Twenty-five distinct plumes of groundwater contamination have been identified. Concentrations of contaminants range from 1 to 2 660 000 ug l-1 and consist of volatile organic compounds, explosive compounds, chemical warfare agent breakdown products, metals and perchlorate. The majority of the contaminants discharge to surface water. However, two municipal water supply systems and one Army water supply have been impacted by these contaminant plumes. The APG Installation Restoration Programme has developed an overall groundwater decision logic to address these diverse contaminant plumes. Due to the geological and chemical heterogeneity of the individual contaminant plumes, a site-specific evaluation of each plume is also required. Factors effecting the site specific evaluation include: aquifer classification, types of contaminants, concentration of contaminants, toxicity of contaminants, sources, DNAPL presence, proximity to receptors and hydrogeology. At present APG is operating three pump and treat systems, a phytoremediation site, and removing contaminants from a 1-MGD municipal water supply system. Feasibility studies to evaluate the cost of cleaning up an additional 12 plumes are being conducted and five plumes are being further characterized. Key words aquifers; groundwater; pump and treat; volatile organic compounds


SIReN: Site for innovative research on monitored natural attenuation

SARAH MACNAUGHTON1, RICHARD SWANNELL1, GORDON LETHBRIDGE2, PHILIPPA SCOTT2, GRAHAM NORRIS3, NICOLA HARRIES3, ALWYN HART4 & JONATHAN SMITH4 1 AEA Technology, 329 Harwell, Didcot, Oxfordshire OX11 0QJ, [email protected] Shell Global Solutions, PO Box 1, Chester CH1 3SH, UK3 CL:AIRE, 5th Floor, 2 Queen Anne's Gate Buildings, Dartmouth Street, London SW1H 9BP, UK4 The Environment Agency, Olton Court, 10 Warwick Road, Olton, Solihull B92 7HX, UK

Abstract Natural attenuation processes are well documented for unconsolidated sands. However, monitored natural attenuation (MNA) has not been well documented in sandstone common in the UK. SIReN is an initiative between Shell Global Solutions, Environment Agency, CL:AIRE and AEA Technology established to provide: (a) a study of MNA in UK hydrogeology (made ground, potentially dual-porosity aquifer); (b) a site for co-ordinated research into MNA; (c) a contribution towards defining an operating window for MNA in the UK; (d) a cost-effective MNA strategy for “mega” sites, addressing the challenges of multiple sources/co-mingled plumes. SIReN has a 50-year history of petrochemicals manufacture. Contaminants include BTEX, styrene and naphthalene. Site characterization detected co-mingled plumes in shallow groundwater, and found evidence of penetration to the sandstone aquifer. A number of research projects are ongoing, covering a broad range of themes, including: “Smart” monitoring/site investigation; decision-making tools for MNA; and specific remediation technologies. Site characterization as well as initial findings from research are presented with discussion of MNA strategy for complex “mega” sites.


Key words co-mingled plumes; mega-sites; monitored natural attenuation; research facility


Assessing measurements of first-order degradation rates through the virtual aquifer approach

SEBASTIAN BAUER, CHRISTOF BEYER & OLAF KOLDITZCenter for Applied Geoscience, University of Tübingen, Sigwartstrasse 10, D 72076 Tübingen, [email protected]

Abstract The principal idea behind the “virtual aquifer” is to simulate and evaluate investigation strategies for contaminated sites by modelling typical contamination scenarios. In this paper, first-order degradation rates using various methods were the focus of study. A virtual reality of a contaminated aquifer was generated by simulating the spreading of a plume, originating from a defined source zone, subject to first-order degradation. This plume was investigated through monitoring wells placed along the plume centre-line. Using information such as head measurements, concentration and hydraulic conductivity, first-order degradation rates were calculated and compared to the true predefined value. This comparison was conducted for varying degrees of heterogeneity, represented by ln(KF), randomly distributed conductivity fields. It was found that when heterogeneity was increased, “measured” degradation rates overestimated the true degradation rate by several orders of magnitude. The range of degradation rates obtained roughly corresponds to the range stated in literature values. Key words first-order degradation; modelling; natural attenuation; virtual reality


Investigations of a large TCE plume discharging to surface water

STEVEN CHAPMAN, BETH PARKER & JOHN CHERRYDepartment of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, [email protected]

Abstract Detailed depth-discrete monitoring along cross sections of a large TCE plume in a surficial sand aquifer at an industrial facility in Connecticut, USA, show a persistent plume extending 700 m from the DNAPL source zone to a mid-size river. Aquifer monitoring where the plume enters the river shows low maximum TCE concentrations (tens of µg l -1) and similarly low concentrations of the TCE degradation product, cDCE. Therefore, based only on groundwater considerations, the plume appears to undergo strong natural attenuation, with reduction of plume concentrations by more than four orders of magnitude between the source zone and river, resulting in almost no contaminant discharge via groundwater to the river. However, groundwater– surface water interactions exert a strong influence on the down gradient half of the plume, where part of the plume discharges to a pond and small streams flowing to the river. Pond and stream monitoring show that roughly half of the plume mass discharge ends up being

transported to the river via stream flow, with the other half lost from the hydrological system primarily by mass transfer from surface water to the atmosphere. River monitoring shows no detectable TCE or degradation products, indicating that, overall, attenuation processes in groundwater and surface water prevent river impacts.Key words chlorinated solvents; plume attenuation; stream discharge; surface water interaction; transects; trichloroethylene


Assessment of stable carbon isotopes as a tool for assessing MTBE biodegradation at a field site

LUIS E. LESSER1, GERARD SPINNLER2, PAUL C. JOHNSON1 & RAMON ARAVENA3

1 Arizona State University, Department of Civil and Environmental Engineering PO Box 875306, Tempe, Arizona 85287-5306, USA. [email protected] Shell Global Solutions Shell Global Solutions (US) Inc. Westhollow Technology Center, PO Box 4327, Houston, Texas 77210, USA.3 University of Waterloo Earth Sciences Department, 200 University Ave. W., Waterloo, Ontario N2L 3G1, Canada.

Abstract Stable carbon isotope techniques have been suggested as diagnostic tools for assessing hydrocarbons biodegradation. The objective of this study was to determine if isotope fractionation can be used as a reliable indicator of MTBE biodegradation, whether natural or engineered. The MTBE plume at Naval Base Ventura County (Port Hueneme, California, USA) offers a unique setting to study the fate of MTBE using stable carbon isotopes. Dramatic decreases in MTBE concentrations as a result of biodegradation have been well documented at this site. MTBE stable isotope fractionations were tracked along with MTBE concentrations. Laboratory-scale microcosms show 6‰ enrichment on MTBE-13C under aerobic conditions. However, limited fractionation was detected in field samples.Key words biobarrier; biodegradation; fractionation; MTBE, Port Hueneme; stable isotopes; microcosms


Natural attenuation of volatile hydrocarbons in the unsaturated zone—modelling for the Værløse field site

ULI MAIER1, ULI MAYER2 & PETER GRATHWOHL1

1 University of Tübingen, Department of Applied Geology, Sigwartstr. 10, D-72076 Tübingen, [email protected] Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver V6T 1Z4, Canada

Abstract Numerical simulations were performed in order to assess the diffusive spreading of


volatile fuel constituents and their biodegradation in the unsaturated zone for the Værløse field test site, Denmark. Modelling results illustrate that the attenuation rates depend mainly on distribution parameters such as Henry’s law constant of the fuel constituents, on the biological degradation rate constant, on soil water content and temperature. The measured field data of 14 NAPL compounds, oxygen and reaction products can be reproduced by the model MIN3P. The emission into groundwater could be estimated after the processes in the unsaturated zone were quantified. Key words biodegradation; gasoline hydrocarbons; meteorological data; natural attenuation; unsaturated zone; transient conditions; vapour diffusion; well controlled field experiment


Fate and transport of naphthenic acids in groundwater

FRANCOISE GERVAIS & JAMES BARKERDepartment of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, [email protected]

Abstract Naphthenic acids (NAs) are naturally occurring carboxylated alkanes and cycloalkanes which are concentrated in wastewater during processing of the Athabasca oil sands, Alberta, Canada. The wastewater is stored in ponds that cover over 30 km 2. Preliminary studies of three aquifer segments potentially impacted by such water sought to understand the attenuation of NAs via biodegradation and sorption during groundwater flow. Laboratory microcosms and batch sorption experiments suggest that only biotransformation will alter the pattern of NA isomer distribution, mainly by a reduction in the relative proportion of lower molecular weight NAs with C < 14. Examination of the field data reveals that, in some monitoring points, apparent attenuation of NAs with C < 14 is greater than that for conservative chemicals, suggesting that some attenuation beyond dispersive dilution may be occurring. However, only in one plume is biotransformation implicated in the attenuation of NAs. Key words Athabasca oil sands; fate; groundwater; naphthenic acids; oil sands; transport


Wetlands as natural reactive barriers: the hydrological and geomorphological landscape perspective

SEIICHIRO IOKA1 & NORIO TASE2

1 Terrestrial Environment Research Center, University of Tsukuba, Ibaraki 305-8577, [email protected] Geoenvironmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan

Abstract To explore the relationships between groundwater biogeochemistry and the water table configuration in a convex slope-wetland plot in Tsukuba upland, Japan, detailed measurements were conducted along a vertical section near the break-in-slope of the water table. The results indicate that a NO3

- reduction zone is located locally in the Younger Loam Formation near the interface underlying the sand and gravel layer at the point where the water table gradient

dramatically deceased. Additionally, a significant chemical gradient of decreasing SO42-

concentration and increasing Mn concentration in groundwater was observed at this point. This study suggests that the hydrological landscape based on land-surface form, hydraulic properties and climatic setting in this region is a strong indicator of the effective area of this subsurface wetland as a natural reactive barrier.Key words chemical gradient; convex slope-wetland plot; hydrological landscape; Japan; subsurface wetland; water table gradient


Steady state plumes: transverse mixing in aquifers, numerical experiments and field scale predictions for natural attenuation

ULI MAIER, HERMANN RÜGNER & PETER GRATHWOHLCentre for Applied Geoscience, University of Tübingen, Sigwartstraße 10, D-72076 Tübingen, [email protected]

Abstract Scenario specific modelling to predict the length of steady state contaminant plumes in groundwater was performed. Small transverse vertical dispersivities t result in extremely steep concentration profiles of solutes in groundwater and were found to be a controlling mechanism for the external supply of electron acceptors to plumes of easily biodegradable organic com-pounds. Scenario specific modelling using the codes MIN3P and BIONAPL as well as a simpler 1-D model yielded an empirical relationship for the plume length, depending on t, the aquifer thickness M and reaction stoichiometry. For simple conditions (homogeneous aquifer, fully contaminated aquifer thickness), the simulation of the 2-D scenario in a vertically oriented 1-D model was facilitated. Thus, if t is known, the length of plumes of easily biodegradable contaminants in groundwater can be predicted. These results were tested at the field site “Osterhofen”, situated on periglacial gravel deposits from the last alpine glaciation period in southwest Germany. An ammonium plume extending from a former landfill was investigated using integral measurements at two consecutive control planes. Fitting the measured mean concentrations yielded t = 3.2 cm and the plume was found to cease after 570 m, proving Natural Attenuation as an appropriate remediation measure at the site. Key words Damköhler number; groundwater plumes; natural attenuation; reactive transport modelling; transverse mixing


Modelling a controlled-sourced, multichemical plume undergoing natural attenuation

CAITLIN MARTIN1, HUGH McCREADIE2, JOHN W. MOLSON3 & JIM BARKER1

1 Department of Earth Science, University of Waterloo, 200 University Ave., Waterloo, Ontario N2L 3G1, [email protected] Water Management Consultants, Waterloo, Ontario, Canada


3 Ecole Polytechnique, Montreal, Quebec, Canada

Abstract In the summer of 1991, a coal tar creosote source was emplaced below the water table at CFB Borden, hydraulically upgradient of an existing extensive piezometer array. Multiple organic plumes developed from this source under natural gradient conditions, and several chemicals were monitored over the 13 years of the study. The vast amount of data collected offered an opportunity to create a groundwater model of a well-studied site and compare the results of this model to the observed field measurements. The naphthalene plume from this source was modelled with Visual MODFLOW and RT3D, using three electron acceptors. The modelled plume matched observations closely in extent, character, and behaviour. Present work includes using the model BIONAPL/3D to simulate the transport and degradation of several chemicals simultaneously. Results from these simulations show that the more comprehensive BIONAPL model may allow for a better understanding of the processes at work in the creosote plume.Key words BIONAPL; coal tar creosote; RT3D; Visual MODFLOW


Tracing landfill leachate impacts on groundwater using DOC geochemistry and δ13C measurements

HOSSEIN MOHAMMADZADEH1,2, IAN CLARK1 & GILLES ST-JEAN1

1 Ottawa-Carleton Geosciences Centre, University of Ottawa, 140 Louis Pasteur, Ottawa, Ontario K1N 6N5, [email protected] Department of Geology, Faculty of Sciences, Ferdowsi University of Mashhad, Iran

Abstract Impacts of landfill leachate threaten water resources, although distinguishing it from natural sources of solutes, can be enigmatic. To monitor impacts on natural waters and to trace biogeochemical reactions, geochemical methods are complemented by stable isotope analysis of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in a study of the Trail Road Landfill (TRL) site, located about 25 km to the west of the city of Ottawa, Canada. DOC and DIC were characterized using liquid chromatography, a Total Carbon Analyzer (TCA) and a Continuous-Flow Isotope Ratio Mass Spectrometry (CF-IRMS). Data show landfill leachate impact on downgradient groundwater. Leachate DOC and DIC concentrations are about 249 mg l -1 and 662 mg l-1, respectively. An average of –24.8‰ was found for 13CDOC of the leachate at the collection station. The 13CDOC show a tendency to increase with distance from the landfill site toward the dewatering pond. An inverse correlation of 13CDOC with DOC concentration indicates biodegradation of the DOC in the plume. In order to better characterize the biogeochemical evolution of DOC in a leachate plume, we have developed a new approach focusing on the compound specific 13C analysis of DOC. High Performance Liquid Chromatography (HPLC) is used to separate acetate fractions. Fraction selection was based on the detection of discrete peaks of acetate. DOC concentration and 13CDOC of acetate fraction are measured separately on the TCA and CF-IRMS, which are about 23 mg l-1 and –16.87‰, respectively. The DOC concentration and the 13C value of acetate fraction, which shows a specific amount for DOC and 13C, can be used as a tracer for the leachate derived DOC and acetate in downgradient leachate-contaminated groundwater. Key words DOC; isotope; leachate; Trail Road Landfill


Natural attenuation of N-S-O heteroaromatic compounds in groundwater: chemical analyses, reactive transport experiments and field studies

MATTHIAS PIEPENBRINK, MARTINA KRÜGER, THOMAS PTAK & PETER GRATHWOHLCenter for Applied Geoscience, University of Tübingen, Sigwartstrasse 10, D-72076 Tübingen, [email protected]

Abstract: N-S-O heteroaromatic compounds are toxic and potentially carcinogenic substances, which can typically be found in groundwater at tar oil contaminated sites. Most of these substances are not yet routinely monitored. The few existing field studies show a relatively high persistence coupled with a high mobility, resulting in extended contaminant plumes. This paper is presents results of: (a) an optimized chemical analysis of N-S-O heteroaromatic compounds; (b) transport experiments of selected compounds at laboratory scale; and (c) the quantification of the in situ natural attenuation-potential at field-scale. The quantification of N-S-O heteroaromatic compounds in groundwater required the improvement of existing analytical techniques. It turned out that sample preparation via SPE followed by measurement via GC-MS delivered the most reliable results. Laboratory column experiments to determine the transport behaviour of selected N-S-O heteroaromatic compounds were conducted using an online-monitoring set-up, which was able to detect the anticipated small retardation factors of these compounds. Independently obtained parameter sets were used to simulate the measured breakthrough curves, employing an Lagrangian stochastic transport model. The quantitative determination of the natural attenuation potential of N-S-O heteroaromatic compounds at a tar oil contaminated field site in southern Germany is performed using an integral investigation approach.Key words chemical analyses; integral investigation approach; natural attenuation; N-S-O heteroaromatic compounds; reactive transport experiments; transport modelling


In situ groundwater clean-up of MTBE by photocatalysis

MAY CHAN1, ALEX ORLOV2, RICHARD LAMBERT2 & ROD LYNCH1

1 Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ, [email protected] Cambridge University Chemistry Department, Lensfield Road, Cambridge CB2 1EW, UK.

Abstract An attractive route for removing organics from groundwater is to use a process which is capable of mineralising contaminants, that is decomposing them, for example, to carbon dioxide, hydrogen ions and water. Photocatalysis is a process which involves illumination of a catalyst surface with UV light, and which is capable of mineralising organic contaminants. In this study, which is a collaboration between Engineering and Chemistry Departments at Cambridge, this clean-up process was tested on water contaminated with MTBE. Results are also presented of a laboratory study of an in situ reactor, buried in soil, simulating clean-up of a moving plume of MTBE-contaminated water. The process was shown to decompose MTBE effectively, and for the


in situ reactor, the radius of influence was evaluated under various conditions. It was also found that the rate of clean-up can be increased using a novel gold-modified titanium dioxide catalyst.Key words groundwater clean-up; groundwater remediation; MTBE; photocatalysis


Spatial variations in MTBE-biodegradation activity near a biobarrier in Port Hueneme, California

LUIS E. LESSER & PAUL C. JOHNSON Arizona State University, Department of Civil and Environmental Engineering, PO Box 875306 Tempe, Arizona 85287-5306, [email protected]

Abstract MTBE has been found to be resistant to natural attenuation processes at many sites creating very large plumes. In Port Hueneme, California, a long MTBE plume has been extensively characterized. In this plume, MTBE-degrading cultures were injected more than four years ago and this biobarrier has been effective in degrading MTBE. The objective of this study was to determine the current spatial distribution of the microbial activity along the biobarrier, and to determine which portions of the aquifer are actively degrading MTBE. The approach used was to collect discrete soil aquifer samples and groundwater near the biobarrier. Microcosms were prepared and MTBE was periodically monitored for any degrading activity. The main result from this study was the recognition of heterogeneous MTBE-degrading activity zones throughout the biobarrier. Of special interest is that well oxygenated zones, where no MTBE is presently being biodegraded, showed a high MTBE-degrading activity.Key words MTBE; Port Hueneme, California; biobarrier; biodegradation; microcosms


Sequential reactive barrier remediation of ammonium-contaminated groundwater using polymer mats

BRADLEY M. PATTERSON1, MICHELLE E. GRASSI1,2, BLAIR ROBERTSON1, GREGORY B. DAVIS1 & ALLAN J. MCKINLEY2

1 CSIRO Land and Water, Private Bag No. 5, Wembley 6913, Western Australia, [email protected] School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia

Abstract Large-scale column experiments and a pilot-scale field trial were undertaken to evaluate the potential of in situ polymer mats (installed in series) as permeable reactive barriers within a “treatment wall” remediation system to induce sequential bioremediation of ammonium-contaminated groundwater. The first upgradient polymer mat was used to deliver oxygen via

diffusion to induce bacterial nitrification of the ammonium to nitrite/nitrate as the groundwater moved past, and the downgradient polymer mat was used to deliver ethanol, to induce bacterial denitrification of the nitrite/nitrate to produce nitrogen gas. In these large-scale column experiments, nitrification rates increased and stabilized over the six-month experiment, with stable nitrification half-lives in the range 0.06–0.25 days. Based on the mass of ammonium converted and oxygen aqueous solubility data, nitrification most likely occurred in a biologically active zone at the polymer wall/aqueous interface. When ethanol was delivered via the downgradient polymer mat, denitrification half-lives in the range 0.12–0.34 days were observed. Nitrification/denitrification rates were maintained for groundwater flow rates up to 300 m year -1, suggesting oxygen and ethanol delivery rates via the polymer mats were sufficient not to limit nitrification or denitrification. In the pilot-scale field trial, a 7-m deep treatment wall was constructed with 10-m wide impermeable wings either side of a 0.75-m wide permeable reactive zone “flow-through box” containing an oxygen and an ethanol delivery polymer mat. Sequential remediation of ammonium was observed with a >90% reduction in total N. The location and rate of nitrification (half-life of 1.2 days) suggested nitrification may not have occurred at a discrete biologically active zone. An average denitrification half-life of 0.4 days was similar to laboratory column results.Key words permeable reactive barrier; ammonium; nitrate; contaminated groundwater; polymer mat


Separating the kinetic and sorption parameters of nitroaromatic compounds in contact with granular iron

MELISSA MARIETTA & JOHN F. DEVLINDept of Geology, University of Kansas, 1475 Jayhawk Blvd, Lindley Hall rm. 120, Lawrence, Kansas 66045, [email protected]

Abstract Two nitroaromatic compounds, 4ClNB and 4AcNB, were reduced with granular iron in batch tests and columns tests with a range of initial concentrations from about 20 M to 400 M. The batch test data were interpreted using the Langmuir-Hinshelwood rate law to obtain an estimate of the sorption parameter J, and the column test data were interpreted with the KIM equation to obtain estimates of a second sorption parameter, Cmax, and a kinetic rate constant, k for each compound. This methodology made it possible to obtain unique estimates of all three parameters without an extraction procedure. The results indicated that the iron surface sorbs the two compounds similarly but is more reactive to 4AcNB (higher k) than 4ClNB, which is consistent with expectations based on one-electron reduction potentials. Further work is needed to continue validation of the procedure and verify the accuracy of the parameter estimates.Key words granular iron; nitroaromatics; sorption; Langmuir-Hinshelwood kinetics


Investigation of the performance of organic carbon permeable reactive barriers using dissolved gas analysis

RANDI L. WILLIAMS1, K. ULRICH MAYER1, RICH T. AMOS1, DAVID W. BLOWES2 & CAROL J. PTACEK2,3

1 Department of Earth & Ocean Sciences, The University of British Columbia, 6339 Stores Rd, Vancouver, British Columbia V6T 1Z4, [email protected] Department of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada3 National Water Resources Institute, Environment Canada, Burlington, Ontario L7R 4A6, Canada

Abstract The strongly reducing nature of treatment materials may lead to gas production in permeable reactive barriers (PRBs), potentially resulting in the formation of gas bubbles and ebullition. Dissolved gas data were collected at the Nickel Rim Mine organic carbon PRB near Sudbury, Ontario, Canada, during July 2003. Concentrations of dissolved Ar, CH4, CO2, H2, H2S, N2, and O2 were determined on-site using gas chromatography and a headspace technique. Within the barrier, elevated CH4 and CO2 concentrations were observed, while Ar and N2 concentrations were depleted in comparison to atmospheric levels, indicating that degassing is occurring within the barrier. Gas bubble formation can be used to help delineate the processes occurring in PRB systems. Analysis of dissolved gas data provides additional information to determine dominant terminal electron accepting processes (TEAPs), to delineate rates of microbially mediated sulfate reduction, and to identify zones of preferential flow. Key words dissolved gases; permeable reactive barriers (PRBs); terminal electron accepting processes (TEAPs)


Adsorption of natural organic matter and its effects on TCE degradation by iron PRBs

STEFANO MARCONETTO1, LAI GUI2 & ROBERT GILLHAM2

1 Department of Georesources, Politecnico di Torino, Turin, [email protected] Department of Earth Sciences, University of Waterloo, Waterloo, Ontario N2L 6C1, Canada

Abstract The effects of natural organic matter (NOM) on reactivity of granular iron toward trichloroethene (TCE) degradation were examined. Column experiments showed significantly lower TCE degradation rates in the presence of both humic (HA) and fulvic (FA) acids. At 15 mg l-1 of HA or FA, the TCE degradation decreased by a factor of 4 and 5, respectively. The greater effect of FA on the degradation rate was not directly correlated with the total amount of NOM adsorbed. The strongest influence took place at the beginning of the sorption processes of NOM onto the iron. Electrochemical experiments indicated that NOM had little or no effect on iron corrosion potential. These observations suggest competition exists between TCE and NOM for occupation of reactive sites and possible interaction between TCE and NOM in solution with consequent limitation of TCE degradation. These results provide useful information for designing granular iron permeable reactive barriers (PRBs) in aquifers hydrologically connected with swamps, wetlands, and possibly landfill sites.Key words degradation rates; fulvic acid (FA); granular iron; humic acid (HA); natural organic matter (NOM); PRBs; sorption; trichloroethylene (TCE)



In situ chemical oxidation test of organic solvents with potassium permanganate

SALVADOR JORDANA1, JORDI GUIMERÀ1, JOSEP A. DOMÈNEC2 & JOSEP M. SUBIRANA2

1 ENVIROS-Spain, S.L., Pg. de Rubí, 29-31, ES-08197-Valldoreix (Barcelona), Spain jordi.guimera@ enviros.biz2 Junta de Residus, Dr. Roux 80, ES-08017 Barcelona, Spain

Abstract A pilot test was conducted in an aquifer polluted (500 50 10 m) by organic chlorinated solvents (PCE, TCE, DCE) consisting of a concentrated injection of KMnO4 and long-term pumping from a borehole 11.8 m downstream. The reactant slug was 10 kg of commercially available KMnO4 injected over 3.2 h along with 680 l of water. The extraction rate was maintained constant for 10 days at a 410 m3 day-1. During the observation period, the concentration of PCE decreased from 900 to 200 ppb, while TCE and cis- and trans-DCE decreased by more than one-order of magnitude. After the dilution of the oxidant plume, concentrations increased again to original values. The results of this pilot test are optimistic regarding the use of this method for full-scale application at this site.Key words ethylenes; in situ chemical oxidation


A meso-scale constructed wetland for the remediation of chlorobenzene contaminated groundwater

ARNO KASCHL1, ANDREA SCHULTZ1, CARSTEN VOGT2, FALK DORUSCH1, PETER POPP3, HELKO BORSDORF3, EBERHARD KÜSTER4, PETER KUSCHK5, MATTHIAS KÄSTNER5 & HOLGER WEIẞ1

1 Department of Groundwater Remediation, UFZ Centre for Environmental Research Leipzig/Halle, Permoserstr. 15, D-04318 Leipzig, [email protected] Department of Environmental Microbiology, UFZ Centre for Environmental Research Leipzig/Halle, Permoserstr. 15, D-04318 Leipzig, Germany3 Department of Analytical Chemistry, UFZ Centre for Environmental Research Leipzig/Halle, Permoserstr. 15, D-04318 Leipzig, Germany4 Department of Ecotoxicology, UFZ Centre for Environmental Research Leipzig/Halle, Permoserstr. 15, D-04318 Leipzig, Germany5 Department of Bioremediation, UFZ Centre for Environmental Research Leipzig/Halle, Permoserstr. 15, D-04318 Leipzig, Germany

Abstract Rising groundwater levels in Bitterfeld, Germany, will transport organic contaminants near the ground surface in the future, so that the construction of near-natural wetlands may present an effective remediation approach. A 2 6 m pilot plant was built to investigate the fate of monochlorobenzene (MCB), one of the main pollutants at the site, in a wetland system. MCB concentrations were reduced from ~10–15 mg l-1 at the inlet to ~1–3 mg l-1 after passage through the soil filter. A zonation in the vertical and horizontal direction was apparent for MCB, sulfate, iron(II) and pH. Aerobic MCB-degrading microbial communities were enriched from the pilot plant and showed degradation of MCB in microcosms down to oxygen-limited conditions of 0.5


mg O2 l-1. Volatilization may also constitute a significant process as indicated by the results of active and passive gas sampling at the surface of the soil filter. Overall, constructed wetlands have a high potential for the remediation of chlorinated solvents, but more research is needed to move away from a black box approach and understand the relevant attenuation processes.Key words anaerobic–aerobic interface; Bitterfeld; constructed wetland; enhanced attenuation; Germany; microbial degradation; multi-level sampling; Phragmites; volatilization


On-site landfill leachate management in a headwater catchment

BRIAN BEATTY & JOANNE THOMPSONBeatty & Associates Limited, 18 King Street East, Bolton, Ontario L7E 1E8, [email protected]

Abstract By current environmental standards, the Innisfil landfill would not have been approved. It was placed in worked-out sand pits, within 30 m of a headwater tributary of Lovers Creek, a high-quality, cold water stream. A leachate plume from the closed landfill radiates outward towards a wetland that provides baseflow to the on-site tributary stream. Development of a leach-ate management system involved three phases of activity: (a) land acquisition for leachate attenuation, landfill contouring to minimize infiltration and installation of a trench collection system; (b) leachate characterization and installation of a pumping well collection system; and (c) design and implementation of an in situ effluent disposal system that utilized the natural attenuation capacity of the site. The disposal system involves the direction of effluent to two on-site infiltration basins located to achieve contaminant attenuation both in the groundwater regime and in the headwater discharge area. Monitoring for over five years has demonstrated effective on-site management using natural attenuation with no need for costly off-site leachate treatment and disposal. Key words effluent disposal systems; leachate management; rapid infiltration basins


Surfactant enhanced air sparging in Borden sand

GORDON H. BROWN1, MICHAEL D. ANNABLE1, JAEHYUN CHO1 & HEONKI KIM2

1 Department of Environmental Engineering Sciences, University of Florida, Gainesville, Florida 32611, [email protected] Department of Environmental System Engineering, Hallym University, Chuncheon, Gangwon-do, 200-702, Korea

Abstract The application of surfactants can enhance in situ air sparging methods for NAPL remediation. The work presented here demonstrates that lowering the surface tension between air and water allows greater desaturation of water saturated media in one-dimensional physical


models. Laboratory Tempe pressure cell, column, and batch experiments were conducted with natural media from Canadian Forces Base (CFB) Borden, Ontario, Canada. The results show that desaturation increased as surface tension decreased for 2.0 mm glass beads and Borden sand. Anionic surfactant sorption to the natural aquifer material was significant. The goal of this work was to evaluate the feasibility of conducting a pilot field test of this technology at CFB Borden. Keywords air sparging; desaturation; NAPL; remediation; surfactant; VOCs


Remediation of bromate contaminated groundwater

RAY BUTLER1, E. CARTMELL1, A. GODLEY2 & L. LYTTON3

1 School of Water Sciences, Cranfield University, Bedfordshire MK43 0AL, [email protected] WRc Swindon, Frankland Road, Blagrove, Swindon, Wiltshire SN5 8YF, UK3 Veolia Water, Blackwell House, Three Valleys Way, Bushey, Hertfordshire WD23 2LG, UK

Abstract Bromate is classed by the World Health Organization as a “possible human” carcinogen, with drinking water limits of 10 µg l -1 now implemented in areas including the UK, United States and Canada. Concentrations within a recently discovered UK groundwater bromate plume exceed these guidelines. However, knowledge on bromate remediation is restricted to low-level potable water contamination (10–60 µg l-1) as a by-product of ozonation. The current project is examining a potential groundwater remediation methodology utilising biological bromate reduction to bromide by augmentation of indigenous microbial populations. Initial trials have focused on a glucose-enhanced anaerobic suspended-growth chemostat system. A maximum bromate reduction of 0.7 mg l-1 was obtained under carbon excess conditions at 10°C, with specific reduction rates (≤2.83 µmol Br/Ab600 h-1) low compared to denitrification (≤305 µmol N/Ab600 h-1). However, further studies investigating optimized conditions have now produced an enhanced culture capable of reducing over 30 mg l-1 bromate within a 40 h retention time. Work is now planned or underway to investigate potential process efficiencies for both in situ and ex situ applications, and to isolate and characterize bacterial strains possessing a putative bromate reduction pathway.Keywords bromate; bioremediation; chemostat; groundwater


Remediation of groundwater contaminated by trichloroethylene using groundwater extraction and effects of natural attenuation

NOBUYUKI EGUSA1, TATEMASA HIRATA1, MASANORI YOSHIOKA2 & OSAMI NAKASUGI3

1 Wakayama University, 930 Sakaedani, Wakayama 640-8510, Japan

egusa @ sys.wakayama-u.ac.jp 2 Hyogo Prefectural Institute of Public Health and Environmental Sciences, 3-1-27 Kotohiramachi, Sumaku, Kobe 654-0037, Japan3 National Institute of Environmental Studies, 16-2 Onogawa, Tsukuba 305-0053, Japan

Abstract This paper evaluates the effects of the pump-and-treat technique and natural attenuation to treat trichloroethylene (TCE) at a contaminated site. Groundwater contamination at this site was discovered about 20 years ago. The cause of the contamination was the leakage of TCE from an underground pipeline at a factory. At the factory, soil removal and pump-and-treat techniques were conducted to remediate the unsaturated zone and the aquifer, respectively. Consequently, the pump-and-treat method which operated for 14 years succeeded in the decontamination of groundwater. In the meantime, dichloroethylene (DCE) was detected in the aquifer, and the estimated first-order rate constants for the degradation of TCE and DCE were 1.5–15.0 10-3

day-1 and 3.1–31.0 10-3 day-1, respectively. This result implicitly indicates that DCE degraded faster than TCE, and the anaerobic oxidation of DCE contributed to the faster degradation of DCE than TCE in this aquifer.Key words natural attenuation, first-order rates; pump-and-treat; remediation; trichloroethylene


Pesticide transport in groundwater at the national scale: coupling an unsaturated zone model with a groundwater flow model

AALDRIK TIKTAK, TON VAN DER LINDEN & GERARD UFFINKNetherlands Environmental Assessment Agency, PO Box 303, 3720 AH Bilthoven, The [email protected]

Abstract Evaluation of the leaching potential of a pesticide and its metabolites is a crucial part of European registration procedures. So far, these procedures consider the movement into the shallow groundwater only. An important question is whether processes in the saturated zone can reduce the concentration in deeper aquifers to levels below a target value, for instance the drinking water limit. To investigate this problem, a spatially distributed model of pesticide leaching from soils was combined with a regional-scale groundwater flow and transport model. The combined model was used to simulate the concentration of a commonly used mobile herbicide in deeper aquifers. Results indicate that the herbicide concentration in the shallow groundwater often exceeds the target value. Due to dispersion, concentrations generally decrease with depth, but the reduction in concentrations is not sufficient to lower the concentration below the drinking water limit of 0.1 g l-1.Key words GeoPEARL; groundwater contamination; modelling; observations; pesticides


Stochastic modelling of well head protection zones in highly heterogeneous aquifers

MONICA RIVA1, LAURA GUADAGNINI1, EUGENIU MARTAC2 & THOMAS PTAK2

1 Dipartimento I.I.A.R., Politecnico di Milano–P. Leonardo Da Vinci n. 32, I-20133 Milano, [email protected] Geosciences Center, University of Göttingen, Goldschmidtstrasse 3, D-37077 Göttingen, Germany

Abstract The assessment of well head protection zones is strongly related to spatial variability of hydrogeological properties. To set up a numerical model for probabilistic wellhead protection zone delineation, field and laboratory scale experiments for subsurface investigation were performed at the “Lauswiesen” site in southern Germany. At this site, spatial variations of hydraulic conductivity mainly dominate flow and transport processes. By means of a multivariate cluster analysis, three different types of aquifer materials (facies) were identified to characterize the heterogeneity of the aquifer lithology. Spatial variability of each material type was separately analysed by a geostatistical procedure based on indicator variography. Three-dimensional (3-D) recombined distributions of the identified clusters were used to reconstruct the internal aquifer architecture. Then, 3-D time related mean well head protection zones and their associated uncertainty were obtained by a Monte Carlo stochastic simulation procedure.Key words multivariate cluster analysis; probabilistic capture zones; stochastic processes; well head protection


An adaptive hybrid method of characteristics technique for solving solute transport problems

JIANMEI CHENG1, DANHONG HUANG1 & JIANMING CHEN2

1 Department of Hydrogeology & Water Resources, China University of Geosciences, Wuhan, Hubei, 430074,[email protected] Department of Earth Sciences, University of Waterloo, Waterloo, Ontario, Canada

Abstract This paper outlines a proposed method for solving the advection–dispersion equation by using an adaptive hybrid method of characteristics (MOC) combined with a finite element method (FEM). The introduction of the hydrodynamic derivative separates the advection part of the equation from the dispersion part. The advection portion can then be solved by using the adaptive hybrid MOC, which could be either: (a) a combination of MOC with modified method of characteristics (MMOC); (b) a combination of high-order interpolation with linear interpolation based on MMOC; or (c) a moving point method dependent on the relative concentration gradient, DCe. This approach was validated against a variety of existing analytical and numerical solutions. Key words adaptive hybrid method of characteristics; advection–dispersion equation; finite element method; high interpolation; linear interpolation; MOC; MMOC; moving particle


Modelling groundwater/surface water interactions using


MODFLOW-WhaT

R. BRAD THOMS1 & R. L. JOHNSON1

Center for Groundwater Research, OGI School for Science and Engineering, OHSU, 20000 NW Walker Rd, Beaverton, Oregon 97006, [email protected]

Abstract The three-dimensional (3-D), modular finite-difference groundwater model MODFLOW has been modified to simulate 3-D variably saturated flow (using Richard’s equation) and 2-D overland flow (using the kinematic wave approximation). Surface and subsurface flow are coupled at the iteration level and are contained within the MODFLOW finite difference grid. This approach treats the surface/subsurface flow as an integrated system which is solved by an implicit finite difference formulation that uses Picard iterations to reach convergence based on a head criterion. The resulting modifications retain the modular structure of the MODFLOW code and preserve the model’s existing capabilities as well as its compatibility with commercial pre/post processors. Two conjunctive surface/subsurface flow simulations are presented; a soil flume experiment and a watershed flowpath simulation. The simulation cases both verify the model’s performance and demonstrate the model’s ability to capture seasonal groundwater/surface water interactions. The overall success of the model in simulating conjunctive surface/subsurface flow, mixed boundary conditions and variable soil types demonstrates its utility for future hydrologic investigations.Key words MODFLOW; overland flow; Richard’s equation; variably saturated


A fully-coupled approach to evaluate the effectiveness of tile-drain systems to control drainage water and salinity

GEORGE B. MATANGA1, CLAIRE JACQUEMIN1 & DON DEMARCO3

1 US Department of Interior, Bureau of Reclamation, 2800 Cottage Way, MP-740, Sacramento, California 95825-1898, [email protected] HydroGeoLogic, Inc., 145 Columbia Street West, Suite 5, Waterloo, Ontario N2L 3G2, Canada

Abstract On the western side of California’s San Joaquin Valley, tile drains are often installed beneath agricultural lands to control water logging and salinity in the plant root zone, and contamination of shallow groundwater. A numerical model, HydroSphere, with capability to simulate water flow and solute transport in fully-coupled subsurface/tile-drain systems, has recently been developed. In this model, the three-dimensional (3-D) form of the Richard’s equation is used to account for flow through the subsurface, and 1-D continuity and momentum equations, to account for flow of drainage water through the tile drains. Solute transport throughout the integrated system is accounted for using various forms of the advection–dispersion equation. Lateral inflow of drainage water from the subsurface along the axes of tile drains is spatially variable. Discharge through the drains is therefore a function of longitudinal distance along the axes. The continuity equation and various forms of the momentum equation provide various methods for routing discharge through the tile drains. A drainage water and salinity management option known as Integrated on-Farm Drainage Management (IFDM) system is currently undergoing demonstration at Red Rock Ranch, San Joaquin Valley. The IFDM



system and application of HydroSphere to evaluate its effectiveness to control drainage water and salinity will be discussed. Key words integrated subsurface surface water; modelling; salinization; tile drains


How old is the water? Simulating groundwater age at the watershed scale

J. W. MOLSON1,2 & E. O. FRIND1

1 Dept of Earth Sciences, Univ. of Waterloo, Waterloo, Ontario N2L 3G1, Canada [email protected] Dept. of Civil, Geological & Mining Engineering, Ecole Polytechnique, Montreal, Quebec H3C 3A7, Canada

Abstract A three dimensional direct-age finite element simulation model was developed based on advective–dispersive transport with a zero-order source term (after Goode, 1996). The approach provides a continuous distribution of groundwater age, and accounts for age mixing. The model is applied to predict and visualize the steady state age distributions which evolve within natural and stressed (pumped) watershed-scale flow systems, including the major well fields within the multi-aquifer Waterloo Moraine. The age of the pumped water is compared with estimates based on particle tracking, with both methods showing characteristic age distributions controlled by the regional hydrogeologic structure. Key words groundwater age; groundwater protection; numerical modelling


Large-scale groundwater flow and transport modelling: methodology and application to the Meuse Basin, Belgium

PHILIPPE ORBAN, SERGE BROUYERE, HORATIU CORBEANU & ALAIN DASSARGUES Hydrogeology, Dept of Georesources, Geotechnologies and Building Materials (GeomaC), University of Liège, Liège, [email protected]

Abstract To meet the requirements of the EU Water Framework Directive, an integrated water management project named PIRENE was initiated by the Walloon Region of Belgium. A partner of this project, the Hydrogeology Group of the University of Liège, is in charge of the development of a physically based transient groundwater flow and transport model for the Walloon part of the Meuse Basin (approximately 17 000 km2). To face the problems associated with this large-scale model, a general approach has been developed that combines a hydrogeological database and GIS systems to manage data. Techniques of spatial discretization have been applied that optimize the number of unknowns. For modelling groundwater flow and transport on a large scale, a new numerical approach called the Hybrid Finite Element Mixing



Cell (HFEMC) has been implemented in the 3-D simulator SUFT3D.Key words database; flow; GIS; groundwater; HFEMC; large-scale modelling; Meuse Basin, Belgium; transport


Delineation of well head protection areas for wells in Urmia Plain, Iran, using WhAEM2000

K. BADV & M. DERISZADEHDepartment of Civil Engineering, Urmia University, Urmia, [email protected]

Abstract Well head protection areas (WHPAs) were delineated around water supply wells in Urmia plain, Urmia City, Iran. The WhAEM2000 (V.2.1.0) computer model based on the analytic element method was used, and 2-year time of travel WHPAs were delineated for pumping wells drilled in the basin of the Shahr-Chai River located in Urmia plain. Steady state flow was applied for the model of the unconfined aquifer, which was subsequently calibrated to observed water elevations. In the confined aquifer the groundwater does not interact with the surface waters and no recharge penetrates into the aquifer. Hence, uniform flow was applied to create a model for the confined aquifer. No calibration was implemented due to the lack of hydraulic data and the hypothesis testing method was used. The delineated WHPAs indicated that if most of the residential lands in Urmia City were contaminant sources, water pumped from the supply wells would be threatened.Key words analytic element method; Iran, Urmia plain; well head protection area; WhAEM2000


Surface and groundwater qualities in an urbanized catchment: scenario from a developing country

MOSHOOD N. TIJANI1, 2 & SHIN-ICHI ONODERA2

1 Department of Geology, University of Ibadan, Ibadan, [email protected] Biogeochemistry Laboratory, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima, 739-8521, Japan

Abstract Quality assessment of groundwater, surface water and bottom sediment samples within Ibadan metropolis, SW Nigeria were undertaken with respect to major and trace element concentrations. TDS are generally low, with average values of 516 and 373.5 mg l-1 for surface- and groundwater respectively, representing low solubility characteristic of the Precambrian Basement Complex setting. The groundwater system is characterized by Ca-Mg-HCO3 due to geogenic weathering-dissolution reactions while the surface water system is dominated by Na-Ca-Cl-HCO3 facies indicating interplay of secondary anthropogenic inputs and the primary geogenic character. A clear indication of urbanization effects on the water quality is revealed by


the NO3 contamination with values of 17.2–412 mg l-1 and 22.8–366 mg l-1 for groundwater and surface water, respectively, exceeding the WHO limits in >50% of the analysed samples. Trace elements (Pb, Zn, Cu, and Cd) are generally below the recommended WHO limits in both surface and groundwater. However, the stream sediment samples are relatively enriched compared to background concentrations with enrichment factor (EF) of about 70 (Hg), 2.2 (As) and 0.35 (Pb), while Muller’s geoaccumulation index of 6.9 (Hg), 0.8 (As) and 1.7 (Pb) also underlies water quality problems associated with metal speciation in drainage systems.Key words enrichment/anthropogenic factor; Ibadan metropolis; Nigeria; shallow groundwater; stream sediment; surface water; trace/heavy metals; water quality


Applying a laboratory-scale biodegradation concept to model field-scale reactive transport with advanced numerical methods

SASCHA E. OSWALD1,2, IAN A. WATSON2, ROGER S. CROUCH2 & STEVEN A. BANWART2

1 Centre for Environmental Research UFZ Leipzig-Halle, Theodor-Lieser-Strasse 4, D-06120 Halle/Saale, [email protected] Groundwater Protection and Restoration Group, Department of Civil and Structural Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK

Abstract Biodegradation is an important factor contributing to the natural and enhanced attenuation of organic contaminants in groundwater. A biodegradation concept was developed by detailed modelling of a laboratory microcosm experiment, tested, and then transferred from laboratory scale into a field-scale reactive transport model. Two-dimensional and three-dimensional simulations were performed for this non-linear multicomponent reactive transport system, and a high degree of grid refinement was required at the plume fringes. Computations were based on the partial differential equation toolbox, Unstructured Grids (UG), which allows applying advanced numerical tools including adaptive remeshing and parallel processing. The two-step kinetic biodegradation concept with separate fermentation and respiration steps, and with hydrogen and acetate as intermediate species, allowed for good reproduction of detailed field data and identification of important biodegradation processes. The results showed that plume core processes can be as important as plume fringe processes based on a 47 year cumulative mass balance.Key words field simulation; grid adaptation; laboratory microcosm; natural attenuation; parallel processing; phenol; scale transfer; two-dimensional


Numerical simulation of density-driven permanganate oxidation of trichloroethylene DNAPL in a sandy aquifer

THOMAS H. HENDERSON1, K. ULRICH MAYER1, BETH L. PARKER2 & TOM A. AL3

1 Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia V6T 1Z4, [email protected] Department of Earth Sciences, University of Waterloo, 200 University Ave. W., Waterloo, Ontario N2L 3G1, Canada3 Department of Geology, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick E3B 5A3, Canada

Abstract Numerical models of permanganate oxidation of chlorinated solvents TCE and PCE have been developed to integrate field-measured data, test conceptual models, and assist in the design of field experiments. The reactive transport code MIN3P was modified to simulate geochemical reactions in variable-density flow systems. Three-dimensional simulations were created of a pilot-scale permanganate oxidation trial. In this experiment, the density of the permanganate solution was the primary mechanism driving the migration of the oxidant. Reaction by-products and geochemical parameters were monitored using depth-discrete nested sampling points over an eight-month period. Chemical processes simulated in the model include DNAPL dissolution, permanganate oxidation of TCE and aquifer organic carbon, calcite dissolution, and precipitation of manganese oxides. The model generally reproduces the field-measured movement of the oxidant, the production of chloride, and the destruction of TCE DNAPL.Key words chemical oxidation; density-driven flow; permanganate; reactive transport


An object-oriented groundwater/river model

OLAF KOLDITZ, MARTIN BEINHORN & RUDOLF LIEDLChair of GeoSystemsResearch, Center of Applied Geosciences, University of Tübingen, Sigwartstrasse 10, D-72076 Tübingen, [email protected]

Abstract In this paper we present a model for coupled groundwater and river flow which is developed based on object-oriented programming concepts. The groundwater model is three dimensional (3-D) and accounts for confined as well as unconfined flow. Additionally density effects resulting from salinity and heat variations can be taken into consideration. The river model is based on averaged 1-D Saint-Venant equations. The coupling between the two hydraulic systems can be treated in two different ways. First, in the framework of finite element technology, the groundwater body (represented by 3-D prismatic elements for aquifers/aquitards and 2-D quad elements for faults) and the river stream (represented by 1-D line elements) are coupled directly, i.e. having common mesh nodes. Second, groundwater and river systems can be coupled in the framework of the multi-continuum concept (i.e. each hydraulic system is represented by an individual continuum which are coupled via transfer functions). The second approach has advantages concerning numerical stability, but transfer functions must be given for water exchange between both compartments, which are difficult to obtain experimentally. Here the direct coupling concept is presented. The groundwater–river model is based on data from the Jordan Valley area. The focus of this paper is the technical background for coupled hydrosystem modelling, such as data import, consistent geometric modelling, meshing of heterogeneous systems, object-orientation for coupled processes and user interfaces.Key words coupling techniques; groundwater–river hydraulics; object-orientation; user interface


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