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REPORT OF THE NICOLE WORKSHOP: Operating windows for site characterisation - NICOLE Network for ...
REPORT OF THE NICOLE WORKSHOP:
Operating windows for site characterisation

                              25-27 May 2011

                              Copenhagen, Denmark

                              www.nicole.org

                              Compiled by Elze-Lia Visser, secretary
                              NICOLE Service Providers Group and
                              Hans-Peter Koschitzky, academic member
                              NICOLE Steering Group
REPORT OF THE NICOLE WORKSHOP: Operating windows for site characterisation - NICOLE Network for ...
Report of the NICOLE WORKSHOP: Operating windows for site characterisation

         Acknowledgements

         NICOLE gratefully acknowledges

         •    Grontmij for co organising the event
         •    The speakers and chairpersons for their contributions to the meeting and their comments on this
              report
         •    The members of the Organising Committee:
                 o Kristian Kirkebjerg, Grontmij, Denmark / chair Organising Committee
                 o Lucia Buvé, UMICORE, Belgium
                 o Wouter Gevaerts, Arcadis, Belgium
                 o Hans-Peter Koschitzky, VEGAS/University Stuttgart, Germany
                 o Sarah MacKay, WSP, UK
                 o Carla Schön, Electrolux, Sweden
                 o Mark Travers, Environ, France
                 o Elze-Lia Visser-Westerweele, NICOLE Service Providers Group, NL
         •    The NICOLE secretariats

             NICOLE is a network for the stimulation, dissemination and exchange of knowledge about all
             aspects of industrially contaminated land. Its 120 members of 20 European countries come from
             industrial companies and trade organisations (problem holders), service providers/ technology
             developers, universities and independent research organisations (problem solvers) and
             governmental organisations (policy makers).
             The network started in February 1996 as a concerted action under the 4th Framework
             Programme of the European Community. Since February 1999 NICOLE has been self supporting
             and is financed by the fees of its members.
             More about NICOLE on www.nicole.org
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Report of the NICOLE WORKSHOP: Operating windows for site characterisation

         Contents
         1. Background                                                                                                                                           4

         2.      Strategies for characterisation                                                                                                                 5
              2.1. Make a conceptual site model ............................................................................................. 5

              2.2. Geophysics ........................................................................................................................... 5

              2.3. Non destructive field screening methods ............................................................................ 5

              2.4. Risk assessment volatile contaminants .............................................................................. 5

         3.      Field techniques                                                                                                                                6
              3.1. Purge and no-purge groundwater sampling ......................................................................... 6

              3.2. Sampling material in stockpiles ........................................................................................... 6

              3.3. Sampling in door air ............................................................................................................. 6

              3.4. Mass discharge from DNAPL zones ..................................................................................... 6

              3.5. Direct push techniques ........................................................................................................ 7

         4.      Isotope analysis and DNA-analysis                                                                                                               8
              4.1. Isotopes ................................................................................................................................ 8

              4.2. Natural attenuation of MTBE ............................................................................................... 8

              4.3. Biotraps ................................................................................................................................ 8

         5.      Forensics                                                                                                                                       9
              5.1. State of the art ..................................................................................................................... 9

              5.2. Pharmaceuticals .................................................................................................................. 9

              5.3. Tree sampling ....................................................................................................................... 9

         6.      Overall conclusions and recommendations                                                                                                         10
              6.1. General conclusions ........................................................................................................... 10

              6.2. Recommendations ............................................................................................................. 10

         Appendix 1. List of participants NICOLE Network Meeting on 24-27 May 2011,
         Copenhagen, Denmark                                                                                                                                     11

         Appendix 2 List of speakers NICOLE Network Meeting on 24-27 May 2011,
         Copenhagen, Denmark and provided links for more information on the subjects                                                                             13

         Appendix 3. Collated abstracts provided by speakers NICOLE Network Meeting on
         24-27 May 2011, Copenhagen, Denmark                                                                                                                     14

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         1. Background

         The NICOLE Network Meeting on 25-27 May 2011 explored the subject of Site Characterisation Tools,
         and updated us on where they can provide value in the management of contaminated sites. We have all
         heard anecdotally, or may have tried some of the myriad of new techniques and approaches being
         proposed around the industry. From forensics using isotopes and DNA, to new drilling methods and
         microbes - the range of options on offer may seem confusing.

         From the ongoing work with the Soil Directive it is evident that some sort of baseline and monitoring will
         be needed in the future and we find ourselves facing other new pieces of legislation such as the
         Industrial Emissions Directive (IED) which may also have potentially onerous baseline monitoring
         requirements. As such, our thoughts turn to the tools and methods we have for investigation, and
         thought it was time to update ourselves with a state of the art review.

         This meeting has drawn us away from the marketing literature and technique sellers, and via a walk
         through the site conceptual model, explored and contextualised techniques appropriateness – for
         example:
             • What technical conditions does it operate under – for example under what lithological or
                hydrogeological conditions can it actually operate and what are its limitations and ranges?
             • In what circumstances will it add value - so for example is it only really warranted in a detailed
                compliance defence, or will it help to speed up development or remediation?

         A programme of invited speakers reviewed the current and recent techniques and possibilities for site
         investigations such as drilling, sampling, in situ measurement and analysis for liquid, solid or gaseous
         contaminants in the subsurface. Moreover tracer tests, geophysics and last but not least plants as a
         pollutant diagnostic tool have been addressed. An entire days session was devoted to the development
         of advanced diagnostic techniques looking at forensics, DNA, isotopes, microbes, pharmaceuticals, and
         exploring some of the challenges in the analysis and the applicability both in corporate compliance
         work, and in remediation. The speakers explored the operating windows of the current and developing
         methods. The invited speakers presented lots of case studies also, showing where techniques are
         useful, applicable, appropriate and value for money.

         In this report you will find the conclusions of the Network meeting organised via 4 themes:
              1. Strategies for characterisation.
              2. Field techniques.
              3. Isotope analysis and DNA-analysis.
              4. Forensics.
         On each theme you will find a list of conclusions drawn from the different presentations in the NICOLE
         Workshop. In the appendix of this report the abstracts that have been provided by the speakers have
         been collated. From the NICOLE website www.nicole.org the presentations and the programme of the
         meeting can be downloaded. For further information on the presentations you can approach the
         speakers, their contact information is listed in the appendix to this report.

         This report reflects the conclusions of the NICOLE Workshop and the outcome of discussions. This
         document doesn't necessarily reflect the opinion of NICOLE and/or individual NICOLE members or
         member organisations.

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         2. Strategies for characterisation
         2.1.   Make a conceptual site model
            •   Heterogeneity in the soil must be taken into account in conceptualizing your site model.
            •   Work from macro scale into micro scale
            •   Choice of technologies for conceptualizing your situation is not “either … or ….” but “….and…..”.
            •   Take all results into account and try to visualize into a conceptual site model via an integrated
                approach.
            •   It all starts with understanding geology…..
            •   Key issue for all steps to follow is to develop and understand the conceptual site model.

         2.2.   Geophysics
            •   Different geophysical methods can be used before drilling to visualize (to get an idea of) soil
                properties.
            •   Can in some specific cases be used for imaging contamination (DNAPL source zones in specific
                situations), use with care and be aware of robustness of the (imaging) tools.
            •   In case of use for imagining contamination: additional information is always needed for
                interpretation. Inform yourself on the limitations of the specific methods.
            •   Can in some cases also be used for monitoring progress in remediation.

         2.3.   Non destructive field screening methods
            •   Non destructive methods can guide traditional sampling and as such optimize site investigation
                strategies (drilling campaigns, prioritization of investigation).
            •   Non destructive techniques can be divided in screening techniques (e.g. XRF, MIP, PID) and
                geophysical techniques (e.g.GPR, EM, Medusa).
            •   Can be quick method for determining the scale and boundaries of contamination.

         2.4.   Risk assessment volatile contaminants
            •   Risk assessment of contaminated soil vapour intrusion for existing buildings can be done by
                measurements; for new (to be developed) buildings modelling is the way of working; a lack of
                reliable parameters often causes a gap in necessary information.
            •   Models exist and differ from each other on used parameters and type of transport of the
                contaminant and give a large range of results.
            •   Choose your model site specifically.
            •   Communication on risk assessment needs attention.

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         3. Field techniques
         3.1.   Purge and no-purge groundwater sampling
            •   No purge sampling with Passive Diffusion Bags and Hydrosleeves has been tested in practice.
            •   No purge sampling can effectively be used for long term monitoring.
            •   No purge sampling can significantly differ from purged sampling, especially in low permeable
                zones and DNAPL zones.
            •   No purge sampling can give a better insight into the distribution of the contamination.
            •   Based on the results the interpretation can be that in source zones passive sampling (no purge)
                should be used for risk assessment instead of purged sampling: purging can mobilize free
                phase droplets (interpretation, not proven yet).
            •   In source zones purged sampling is to be used for remediation design.
            •   In plume zones (dissolved concentrations) either technique will work.
            •   More case studies are needed.
            •   Based on the significance of the results and the consequences they could have in practice
                investigation under controlled conditions (large scale in lab) is recommended.

         3.2.   Sampling material in stockpiles
            •   Sampling covers a wide field, two examples have been worked out on sampling granular
                material in stockpiles.
            •   Way of sampling adds to (un)certainty to results.
            •   Validation of the samples itself in practice is not feasible due to the huge amount of cost.
            •   Lot of work has been reported in international standards.
            •   Work in progress on decision support tool for reliable sampling.
            •   Numerical tools / concepts may be useful for interpretation data from groundwater / soil
                sampling.

         3.3.   Sampling in door air
            •   Indoor sampling of in door air is affected by many factors: weather, geology, building properties,
                characteristics of the pollutant and others.
            •   Risk assessment has to be based on average concentrations which needs measurements of
                indoor air over a longer period of time
            •   Several devices (more or less mobile) are available to do measurements during a short or longer
                period of time

         3.4.   Mass discharge from DNAPL zones
            •   Evaluating planes and mass discharge instead of point measurements is an effective way of
                characterizing the contamination and monitoring remediation.
            •   Reliable methods for quantification of mass discharge exist.
            •   Multi level sampling methods are needed to evaluate mass discharge in a control plane.
            •   Hydraulic conductivity is the main parameter influencing mass discharge calculations.
            •   Evaluation of the effective number of sampling wells related to the value of the mass discharge
                is subject to optimisation to save money and time.
            •   Uncertainty analysis of mass discharge is an important area for further development.

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         3.5.   Direct push techniques
            •   Can be used additionally to or instead of traditional sampling and is cost-efficient.
            •   Direct push technologies are very suitable for applying dynamic work plans.
            •   Give fast results that can be transformed into immediate action for further data acquisition,
                sampling or monitoring and remedial installations.
            •   Some Direct Push techniques are based on indirect measurements (parameters). These indirect
                measurements need to be calibrated with respect to the parameters of interest.
            •   Be careful in using equipment in multilayered aquifers: do not penetrate a sealing layer below a
                contamination to avoid cross contamination or worse creating spreading of contaminants in a
                less or not contaminated aquifer (which is also valid for every drilling).
            •   It should always be considered that the sealing of the probing holes for some Direct Push
                techniques are difficult or even not feasible.
            •   A well-versed team is a requirement for its reliable application and for the interpretation of the
                data.

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         4. Isotope analysis and DNA-analysis
         4.1.   Isotopes
            •   Isotope analysis is a powerful tool to evaluate natural and/or enhanced biodegradation of
                different contaminants (proof of degradation and degradation rates).
            •   Isotopes are sensitive parameters and experience is needed to be able to evaluate the
                outcome.
            •   Isotopes can be used to identify (additional) sources of contamination.
            •   Isotopes can be used to conceptualize your site model (e.g. flow paths, degradation pathways)

         4.2.   Natural attenuation of MTBE
            • Compound specific stable Isotope analysis (C and H isotopes) combined with DNA detection of
              key enzymes can provide quick and direct information on degradation of MTBE (potential for
              degradation, chemical or biological degradation, actual or historical degradation, degradation
              rate).
            • Molecular techniques (DNA and RNA) can be used to detect the presence or activity of MTBE
              degrading bacteria.
            • Outcome of isotope analysis and DNA detection needs validation with batch data and field data
              from contaminated site.

         4.3.   Biotraps
            • Biotraps are a passive sampling tool that collects microbes over time and mimics the
              environmental conditions in the soil.
            • Biotraps loaded with labelled compounds can be analysed using molecular and isotope based
              approaches and have proven to be a diagnostic tool for prediction of biodegradation to convince
              authorities on early close down without additional monitoring
            • The detailed strategy with contingency milestones in monitoring was agreed by the regulator on
              basis of molecular biological tools to support traditional lines of evidence

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         5. Forensics
         5.1.   State of the art
            •   Different methods exist for forensic studies on contaminants.
            •   Most common methods are fingerprinting, isotope analysis and evaluation of natural and
                anthropogenic tracers (e.g. additives).
            •   Can be used for finding sources of contamination (dating, localisation of spills), give insight in
                conceptual site model and indications for natural attenuation.
            •   Feasibility study and a careful assessment of accuracy and reliability of the results are
                recommended.

         5.2.   Pharmaceuticals
            •   Pharmaceuticals are emerging contaminants and emerging to be used as tracer for forensics
            •   Certain pharmaceutical tracers may be useful for forensic purposes in some cases
            •   Careful evaluation of expenses versus results to be obtained is basis for selection of this tool.
            •   Increased understanding of PPCP fate/transport remains key for usefulness.

         5.3.   Tree sampling
            • Tree sampling can be used for screening of certain contaminants and aging a contamination
            • Tree sampling and analysis provides additional information to other characterization results.
            • Trees accumulate contamination in sap and in xylem (tree sap is the fluid transported in xylem
              cells of a tree).
            • Phytoscreening focuses on the youngest tree rings (sap uptake of contaminants) and reflects
              the current state of contamination in the root zone.
            • Phytoscreening can be used for mapping certain contaminants.
            • Dendrochemistry focuses on the annual rings of the tree (xylem) which reflect the changes of
              the environment (contamination) in the root zone.
            • Dendrochemistry can be used for age dating of contamination (forensic, source identification).
            • Both tools request specialized use and evaluation. A few specialized laboratories are able to
              execute the rather expensive analysis.

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          6. Overall conclusions and recommendations

          6.1.   General conclusions
          The network meeting has shown a variety of possibilities to improve the conceptual model being the
          basis for all following actions and decisions (risk assessment, remediation, long term monitoring,
          baseline assessment....). Key conclusions from this meeting are:

             • Many tools and for a good result are available: you have to think about and use different tools to
               have good insight in your conceptual site model.
             • The key solution is the right combination and reasonable use of different tools.
             • All decisions for contaminated land management and remediation are made upon the data of
               the site investigations: be aware of the importance of your data!
             • It is possible to decide upon uncertainties, but always pose yourself the question: is the level of
               uncertainties the level you can manage?

          6.2.   Recommendations
          Review with respect to changes in legislation

             •   Changes in legislation urge us to review current and new technologies for site characterization
                 and monitoring.

          No purge sampling

             •   In source zones the usual purged sampling can be a better method for remediation design.
             •   For delineation of plumes both purged and no purge sampling methods give reliable results.
             •   For risk assessment no purge sampling could be the preferred method.
             •   More case studies are needed to prove of disapprove the above statements.
             •   Based on the significance of the results and the consequences it is recommended to start trial
                 investigations under controlled conditions (large scale in lab).

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          Appendix 1. List of participants NICOLE Network Meeting on
          24-27 May 2011, Copenhagen, Denmark
          Arakere, Suda                          LyondellBasell Industries                            USA
          Argyrou, Elli                          Adventus Europe                                      Greece
          Bakker, Laurent                        Tauw BV                                              NL
          Bastrup, John Ulrik                    GEO                                                  Denmark
          Bayersdorf, Hartwig                    Robert Bosch GmbH                                    Germany
          Beddow, Helen                          Nuvia Ltd.                                           UK
          Bell, Rob                              freelance journalist                                 UK
          Bjerg, Poul                            Technical University of Denmark                      Denmark
          Blom, Marianne                         ENVIRON Corporation                                  NL
          Boronat I Rodriguez, Jordi             MediTerra Consultors Ambientals, S.L.                Spain
          Burrows, Hazel                         BP International                                     UK
          Buvé, Lucia                            UMICORE                                              Belgium
          Camerani, Caterina                     AkzoNobel                                            Sweden
          Constant, Sébastien                    SPAQuE                                               Belgium
          Couto, Felipe                          Remedx                                               UK
          Darmendrail, Dominique                 Common Forum                                         France
          Davidsson, Lars                        WSP Environmental                                    Sweden
          Dixon, Nik                             Grontmij                                             Dixon
          Dörr, Helmut                           Dr. Dörr Consult GmbH                                Germany
          Dreiseitel, Martin                     F&R Worldwide, SRL                                   Romania
          Drenth, Eize                           Oranjewoud                                           NL
          Eisenmann, Heinrich                    Isodetect GmbH                                       Germany
          Ejdeling, Göran                        Sweco Environment AB                                 Sweden
          Euser, Marjan                          NICOLE Secretariat                                   NL
          De Fraye, Johan                        CH2M Hill                                            UK
          Garcia de la Rasilla, Mascha           Eurofins Analytico                                   NL
          Gevaerts, Wouter                       Arcadis Belgium NV                                   Belgium
          Gous, Danie                            Dow South-Africa                                     SA
          de Groof, Arthur                       Grontmij                                             NL
          Groot, Hans                            Deltares                                             NL
          Guibert, Pierre                        Environ                                              France
          Hallgren, Pär                          Sweco Environment AB                                 Sweden
          Hart, Catherine                        URS Nordic                                           Sweden
          van Hattem, Willem                     Port of Rotterdam                                    NL
          Heasman, Ian                           Taylor Wimpey UK Ltd                                 UK
          Held, Thomas                           Arcadis Consult GmbH                                 Germany
          Hertzmann, Daniel                      Sweco Environment AB                                 Sweden
          van Houten, Martijn                    Witteveen+Bos                                        NL
          Hübinette, Per                         Structor Miljö Göteborg AB                           Sweden
          Jacobsen, Frank                        Grontmij                                             Denmark
          Jacquet, Roger                         Solvay S.A.                                          Belgium
          Jubany, Irene                          Centre Tecnológic de Manresa                         Spain
          Kiilerich, Ole                         EPA Denmark                                          Denmark
          Kirkebjerg, Kristian                   Grontmij                                             Denmark
          Klaue, Bjorn                           Thermo Fisher Scientific                             Germany
          Kobberger, Gustav                      HPC                                                  Germany
          Kolle, Marcel                          Dura Vermeer Milieu                                  NL
          Koomans, Ronald                        Medusa Explorations BV                               NL
          Koschitzky, Hans-Peter                 University Stuttgart                                 Germany
          Langenhoff, Alette                     Deltares                                             NL
          Lee, Alex                              WSP Environmental                                    UK
          Liljemark, Anneli                      ÅF-Infrastructure AB                                 Sweden
          Lucassen, Pim                          Philips Real Estate                                  NL
          MacKay, Sarah                          WSP Environmental                                    UK
          Madarász, Tamás                        University of Miskolc                                Hungary
          Maurer, Olivier                        CH2M Hill France                                     France
          van de Meene, Chris                    SBNS                                                 NL

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          Menoud, Philippe                       DuPont de Nemours                                    Switzerland
          Merly, Corinne                         BRGM                                                 France
          Mezger, Thomas                         Akzo Nobel                                           NL
          Moll, Ulrich                           LyondellBasell Industries                            France
          Nguyen, Frédéric                       Université de Liège                                  Belgium
          Nielsen, Pernille                      MediTerra Consultors Ambientals, S.L.                Spain
          Van Nieuwenhove, Karel                 Antea Group                                          Belgium
          van Noord, Wilfred                     AkzoNobel                                            NL
          Ooteman, Kevin                         MWH                                                  NL
          Øster, Per                             A/S Dansk Shell                                      Denmark
          Pals, Jan                              SBNS                                                 NL
          Pellegrini, Michele                    Saipem                                               Italy
          Pentel, Robert                         GDF SUEZ                                             France
          Plaisier, Wim                          ARCADIS                                              NL
          van de Pol, Erwin                      Witteveen+Bos                                        NL
          Polenka, Miloš                         GEOtest a.s.                                         Czech Republic
          Polenková, Alena                       GEOtest Brno, a.s.                                   Czech Republic
          Van de Putte, Wouter                   MAVA                                                 Belgium
          Raben, Henry                           Tauw                                                 NL
          Rajala, Päivi                          Närings-, trafik-, och miljöcentralen                Finland
          van Riet, Paul                         Dow Benelux BV                                       NL
          Schelwald-van der Kleij, Lida          NICOLE ISG Secretariat                               NL
          Schmidtke, Joachim                     ENVIRON Germany GmbH                                 Germany
          Schön, Carla                           AB Electrolux                                        Sweden
          Schreurs, Jack                         Philips Environment & Safety                         NL
          Schrooten, Pieter                      ERM                                                  Belgium
          Sévêque, Jean-Louis                    UPDS                                                 France
          Shoesmith, Colin                       National Grid Property Ltd.                          UK
          Sinke, Anja                            BP International                                     UK
          Slenders, Hans                         Arcadis                                              NL
          Smeder, Maria                          Akzo Nobel AB                                        Sweden
          Smith, Jonathan                        Shell Global Solutions                               UK
          Sørensen, Majbrith                     Grontmij                                             Denmark
          Spence, Mike                           Shell Global Solutions (UK)                          UK
          Van Straaten, Mark                     MAVA                                                 Belgium
          Svensson, Håkan                        KemaktaKonsult AB                                    Sweden
          Svensson, Janna                        Sweco Environment AB                                 Sweden
          Thomas, Alan                           ERM UK                                               UK
          Torin, Lena                            Golder Associates AB                                 Sweden
          Törneman, Niklas                       Sweco Environment AB                                 Sweden
          Touchant, Kaat                         Vito                                                 Belgium
          Travers, Mark                          Environ                                              France
          Underwood, David                       Shell International Petroleum Company                UK
          Undi, Tilly                            TOTAL RM                                             UK
          Upton, Paul                            RSK Group Plc                                        UK
          Vanderhallen, Joris                    Port of Antwerp                                      Belgium
          Verhaagen, Paul                        Grontmij                                             NL
          Visser-Westerweele, Elze-Lia           NICOLE SPG Secretariat                               NL
          Voogd, Leon                            MWH                                                  NL
          van der Voort, Jack                    Ingenieursbureau Oranjewoud BV                       NL
          Waters, John                           ERM                                                  UK
          Williams, Stephen                      Thermo Fisher Scientific                             USA
          Wiltshire, Lucy                        Honeywell                                            UK

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          Appendix 2 List of speakers NICOLE Network Meeting on 24-
          27 May 2011, Copenhagen, Denmark and provided links for
          more information on the subjects

          Strategies for characterisation

          Wouter Gevaerts, ARCADIS, Belgium 

          Frédéric Nguyen – Université de Liège, Belgium 

          Henry Raben, Tauw, the Netherlands 

          Lena Torin, Golder, Sweden 

          Field techniques

          Wouter Gevaerts, ARCADIS, Belgium 

          Frank Lamé, Deltares, the Netherlands 

          Majbrith Sorensen, Grontmij, Denmark 

          Poul Bjerg, Technical University of Denmark 

          Hans-Peter Koschitzky, VEGAS, University Stuttgart, Germany 

          Isotope analysis and DNA-analysis

          Heinrich Eisenmann, Isodetect GmbH, Munich, Germany 

          Alette Langenhoff, Deltares, the Netherlands 

          Alex Lee, WSP, UK 

          Forensics

          Helmut Dörr, Dr. Dörr Consult, Germany 

          Joachim Schmidtke, Environ, Germany 

          Gustav Kobberger, HPC, Germany 

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          Appendix 3. Collated abstracts provided by speakers NICOLE
          Network Meeting on 24-27 May 2011, Copenhagen, Denmark

                                                 State of the art on geophysics

                                             Frédéric Nguyen, Université de Liège, Belgium

          A key element in the remediation of contaminated sites is the ability to map and characterize the
          contamination distribution, and to assess the efficiency of in-situ remediation actions at the site scale. These
          tasks are more or less difficult depending on the degree of heterogeneity of the subsurface.

          Geophysical mapping refers to the display of geophysical data and may provide qualitative information on
          contaminants, such as their location or extent. Geophysical mapping allows to reach a greater lateral
          coverage than drillings, with resolution ranging from a few centimeters up to several tens of meters,
          depending on the investigated depth. Generally, the resolution is inversely proportional to the investigated
          depth. Repeating a mapping in time may also provide information on the degradation of the contaminants if
          the degradation process affects the relevant physical property.

          Geophysical imaging, on the other hand, may provide information on the location at depths of contaminants
          in the subsurface, on their concentration and eventually on their degradation. However, the retrieved
          information is indirect. It goes through two main filters before delivering the desired property. The first one is
          related to the transformation of the acquired geophysical data (e.g. traveltime or resistance) to the spatially
          distributed geophysical properties (e.g. seismic velocity or bulk resistivity), usually refer to as images.
          Geophysical images are numerical models obtained by the optimization of a certain number of criteria. The
          most important one being that the model is able to reproduce the measured data. These models, as for all
          numerical models, suffer from uncertainties and may also exhibit numerical artifacts. Fortunately, these
          drawbacks can be avoided by designing properly the geophysical survey, and quantified using image
          appraisal tools such as the resolution/sensitivity matrix or the depth of investigation index. The second filter
          links the recovered geophysical property (e.g. magnetic susceptibility) to the parameter of interest (e.g. metal
          content). These petrophysical relationships are generally obtained at the laboratory scale, where the studied
          medium is well controlled and understood. When applied in-situ, the validity of these relationships which
          depend on the physico-chemical of the environment and on scaling laws has to be verified in order to avoid
          erroneous interpretation.

          This talk will give an overview of state-of-the art geophysical methods applied to contaminated sites in order
          to detect, map, characterize and monitor pollutants in the subsurface. We will review the relevance of
          geophysics depending on the target, and the limitations associated with the methods. Several relevant case
          studies will be presented and analyzed. We will also provide an overview of what to expect from geophysics
          in the future with a few research examples in the subfields of biogeophysics and hydrogeophysics.

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                   Current trends for tracer techniques in environmental hydrogeology

                                              Serge Brouyère, Université de Liège, Belgium

          Tracer techniques have been applied for years for the characterization of contaminant transport processes in
          groundwater, in different context ranging from the delineation of protection zones around groundwater
          catchment areas to the quantification of groundwater fluxes and hydrodispersive processes in variably
          saturated underground media.

          The objective of the talk is to present an overview on tracer techniques as applied to groundwater quality
          and pollution issues. A specific emphasis will be made on the applicability and potential of these techniques
          with respect to contaminated sites and on recent and ongoing technological developments of a single well
          tracer technique aiming at quantifying and monitoring groundwater and contaminant fluxes at such sites.

          The presented concepts will be illustrated using field results and associated modelling exercise.

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                          Direct push technologies: Overview, Applications and Limits

                                       Carsten Leven-Pfister, University Tübingen, Germany, and

                                     Hans-Peter Koschitzky, VEGAS, University Stuttgart, Germany

          Dr.   Carsten     Leven,    University    of     Tübingen,    Center             for     Applied   Geoscience   Hydrogeology
          D-72076 Tübingen, Germany. carsten.leven-pfister@uni-tuebingen.de

          Dr.-Ing. Hans-Peter Koschitzky, VEGAS, Research Facility for Subsurface Remediation, University of Stuttgart, D-70550
          Stuttgart, Germany, koschitzky@iws.uni-stuttgart.de

          Cost efficient and sustainable remediation, especially with innovative in situ remediation technologies,
          requires detailed knowledge of the subsurface in view of the pollutant distribution and the hydrogeology. So
          far commonly site investigations based on boreholes are used for the characterization of contaminated sites.
          In most cases these methods are time consuming, costly and as a consequence the site characterization is
          based only on a few drillings, i.e. investigations points, which results typically in insufficient information
          about the “real” extend and location of the contamination.

          An alternative approach for site investigation is the use of Direct Push (DP) technology. This technology
          refers to a growing family of tools used to obtain subsurface investigations by pushing and / or hammering
          small-diameter hollow steel rods into the ground. By attaching specialized probes to the end of the steel
          rods, it is possible to conduct high resolution logging of rock parameters as well as to collect soil, soil gas,
          and ground water samples. Using DP technology it is feasible to get very quick and on site information about
          the three-dimensional pollutant situation. This information serves as a basis for decision about the ongoing
          stepwise site investigation. So overall more information can be received at lower costs. Besides the broad
          applicability of DP technology, it also allows for a target-oriented installation of monitoring equipment.

          Due to the development of new powerful machines and tools, the application of DP technology increased
          strongly during the last years and became a viable alternative to conventional methods for site investigation.
          With the new generation of DP machines several sounding locations can be completed per day. Furthermore,
          under ideal conditions (e.g. soft, unconsolidated sediments) depths of more than 50 m can be reached.

          The presentation will give an overview about the various direct push technologies and will also show the
          benefits of these techniques for investigation of contaminated sites exemplary from case studies.

          DIETRICH, P. & LEVEN, C. (2006): Direct-Push Technologies. In: Kirsch, R. (Ed.): Groundwater Geophysics.
                 Springer. 321-340
          LEVEN, C. WEIß, H. KOSCHITZKY, H.-P. BLUM, PH. PTAK, TH. DIETRICH, P. (2010): Direct Push Verfahren, ISBN 978-3-
                 510-39014-4, altlastenforum Baden-Württemberg e.V., Schriftenreihe, Heft 14

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           Quantification of Mass Discharge from DNAPL sites in heterogeneous geological
                                               settings

                                                Poul Bjerg, Technical University of Denmark

          P. L. Bjerg (plb@env.dtu.dk), M. Troldborg, Ida Vedel Lange; Marta Santos; P. J. Binning (Department of Environmental
          Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark)

          DNAPL sources with chlorinated solvents are a major threat to groundwater. Contaminant discharge
          (mass/time) from contaminated sites is a useful metrics when evaluating the potential risk to downgradient
          receptors such as water supply wells and surface water bodies. A recent development is the coupling
          between contaminant source remediation and the plume response in order to assess the efficiency of site
          remediation and to optimize the resources spent to fulfill certain regulatory demands.

          In the field, the mass discharge migrating from a contaminant source is typically determined across a control
          plane located downstream of the source and perpendicular to the mean groundwater flow. The uncertainty in
          a field-estimated mass discharge is highly related to the degree of heterogeneity of the mass flux distribution
          at this control plane. The more heterogeneous the mass flux distribution is, the finer the monitoring
          resolution network should be to ensure that the unmeasured areas in the control plane do not influence the
          estimate significantly. However, at most non-research field sites the number of monitoring wells is limited.

          The degree of heterogeneity of the mass flux distribution at the control plane is caused by several factors,
          where spatially and temporally varying flow conditions and complex contaminant distribution in the source
          zone are considered most important. A quantification of the mass discharge and the associated uncertainty
          should therefore account for all these factors. However, it is not easy to describe and model the influence of
          such factors at a specific site, especially when data are sparse. Often the knowledge about e.g. the source
          and the geological and hydrogeological settings is limited, which makes it very difficult to conceptualize
          these elements and to incorporate them in a model. The previous studies of mass discharge uncertainty
          have not taken the influence of different conceptual site models into account.

          We present here the results of a major effort on development and application of mass flux estimates in
          engineering and regulatory practice. The activities are related to two DNAPL contaminated sites in Denmark.
          Mass flux fences have been established at both sites and detailed descriptions of geology and hydrogeology
          exist. The monitoring of the mass flux fences was completed at site A in 2008 as a part of the risk
          assessment. At site B the temporal and spatial variability of mass flux estimates were evaluated during 2008
          and 2009 by use of traditional wells (30 screens) and multi level samplers in the core of the plume (100
          sampling points). The mass flux dataset for both sites are used to develop and test various methods for
          quantification of mass discharge and related uncertainties.

          The presentation aims to give an overview of these activities and propose future challenges in the area.

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Report of the NICOLE WORKSHOP: Operating windows for site characterisation

                   Chlorinated solvent contamination, difficulties in understanding mass
                                         distribution, a case study
                                                         Pierre Guibert, Environ, France

          Pierre GUIBERT, ENVIRON(1), www.environcorp.com

          (1) ENVIRON France, Les Pléiades III - Bât. C - 320, avenue Archimède - 13857 Aix-en-

          Provence cedex 3 – pguibert@environcorp.com

          A past undetected leak from an underground solvent distribution tank system has lead to a significant
          subsoil contamination by trichloroethylene (TCE). Leak has been estimated at approximately several hundred
          tons of product over a 3-4 year period.

          Following detection of leak, pump & treat wells as well as SVE were installed on source area to recover
          product and mitigate exposure to on-site workers. Since, numerous site investigations and risk assessments
          were engaged both on-site and off-site to better understand contamination distribution and evaluate
          potential risks to third parties and the environment.

          These studies highlight that contamination is limited in the unsaturated zone, whilst important in the
          saturated zone and groundwater. TCE is observed as a dense non aqueous phase liquid (DNAPL) both on top
          as well as within a silt layer present on and off-site.

          Chlorinated solvents have migrated as a dissolved phase with the general flow of the shallow aquifer but
          more specifically as both dissolved and DNAPL via a preferential pathway composed of backfilled historic
          river bed, before flowing into the surrounding rivers. The dissolved plume extends beneath a mixed industrial
          estate composed of mixed traditional, industrial activities and local municipal services.

          This understanding of both the hydrogeological context and the distribution of the mass of DNAPLs was
          achieved after years of investigation programmes combined with the results of the remediation programme.

          Based on environmental media sampling at exposure endpoints (soil-gas, ambient air, groundwater, surface
          water) risks to human health and the environment are below applicable acceptable risk levels.

          DNAPL contamination within a complex hydrogeological context presents numerous challenges that will not
          permit full remediation thus making it difficult to prepare Remedial Action Plan (“Plan de Gestion de Site” -
          PGS), in accordance with French guidelines, which implies that source abatement must be achieved based
          on technical cost-benefit analysis.

          This project has highlighted the following challenges/difficulties associated with the presence of TCE as
          DNAPL in a complex hydrogeological context:
          • Numerous investigation techniques (monitoring wells, soil borings, soil gas borings, membrane interface
          probe borings, seismic refraction, tracer tests) were used to identify and delineate DNAPL mass and
          understand the complexity of the natural context. All of these studies present limitations and uncertainties
          making the characterization of DNAPL source area or confirmation of the actual presence of free product
          difficult even when suspected.
          • With the presence of significant DNPAL in a complex hydrogeologic context partial recovery of free product
          appears as the only technically feasible solution as long as human health and environmental risks are
          controlled.
          • Non-extracted DNAPL will continue to generate a dissolved phase that will maintain the
          environmental impact at a long-term steady state. Long-term monitoring of various environmental media and
          the installation of deed restrictions will be the key components associated with long term risk management
          of the contamination.

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Report of the NICOLE WORKSHOP: Operating windows for site characterisation

                                                         Sampling of vapour

                                               Majbrith L. Sørensen, Grontmij, Denmark

          The presentation will give an overview of sampling techniques for assessment of vapour intrusion in houses
          and buildings. The presentation will give an idea about errors and other factors that influence your results
          and thus your sampling scheme should reflect the present geology and hydrogeology.

              •   Description of various sampling schemes, focused on intrusion of chlorinated and other volatile
                  solvents.
              •   How are major and minor sources of error affect sampling and measurements. Absorbant media,
                  passive sampling, humidity, air pressure, geology.
              •   How sampling can affect risk assesment. When to sample or wait?
              •   Sampling with MIP, geoprobe and other field methods. Flux chamber and other quantitative
                  methods.
              •   Description of typical case where sampling method can be essential for results
              •   New upcoming sampling methods

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Report of the NICOLE WORKSHOP: Operating windows for site characterisation

          Risk Assessment of Vapour Intrusion, focused on Chlorinated Solvents

                                                          Lena Torin, Golder, Sweden

          Lena Torin, Golder Associates AB, Lilla Bommen 6, 411 04 Göteborg, Sweden

          lena_torin@golder.se

          The issue of soil vapour intrusion from volatile contaminants in soil and groundwater into buildings, and
          especially chlorinated solvent chemicals, is becoming increasingly important in the world. In order to predict
          which sites might have a vapour intrusion problem, several countries have developed models and/or
          demand that soil gas and indoor air is sampled at the site. The different European countries do not have the
          same view and approach to this issue and it’s therefore difficult to present a view of how risk assessment of
          vapour intrusion is done in Europe. The presentation will therefore focus on current best practice and what
          should be avoided.

          The presentation will give a short introduction on how risk assessment of vapour intrusion is done in general.
          The presentation will focus on vapour intrusion of chlorinated solvents as these chemicals make up most of
          the vapour intrusion problems. This is because chlorinated solvents can form large plumes within the
          groundwater, are persistent, have limited biodegradation in the vadose zone and are harmful to humans at
          very low concentrations.

          The presentation will cover the following topics:

          •      Quality control of sampling data and the importance of developing a conceptual site model to
                 understand variability and evaluate representative data for the risk assessment. What conditions
                 pose a risk for underestimating the risk?

          •      When and how to use toxicological reference values, guidelines and occupational exposure
                 standards. Trends and differences between countries. Since December 2010 the classification
                 and labeling of certain substances within the EC are harmonized in the CLP/GHS-database.

          •      How does the use of the building affect the risk assessment? The different exposures for
                 residential land use compared to commercial or industrial uses. What impact do building volume
                 and ventilation rates have?

          •      Differences between some vapour intrusion models with regard to parameters and how validated
                 they are against empirical sampling data. The largest collection of empirical data assembled is
                 the USEPA vapour intrusion empirical database (http://iavi.rti.org).

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Report of the NICOLE WORKSHOP: Operating windows for site characterisation

           Forensics - state of the art and possibilities in contaminated sites management

                                                   Helmut Dörr, Dr. Dörr Consult, Germany

          Dr. Helmut Dörr

          Dr. Helmut Dörr Consult, Germany – www.dr-helmut-doerr-consult.de

          The general applicability, the investigation strategy and the benefits of forensic methods in contaminated
          site management are discussed. Results are presented from a case study (TPH-, BTEX and PAH-
          contamination in soil and groundwater) at an industrial site occupied by various tenants over several
          decades. The results are discussed with respect to the objectives of forensics of identifying the polluter(s).

          The most common and approved forensic methods are the so-called fingerprinting, isotopic methods, the
          evaluation of multi-element distribution patterns and the investigation and interpretation of trace substances
          (e.g. additives) and environmental tracers.

          Forensic methods are particularly suitable for the dating and localization of spills containing mineral oil and
          aromatic hydrocarbons. The source of contamination can also be investigated for selected heavy metals and
          CHCs. Other methods such as the determination of isotope ratios of pure substances and elements (Sr, Nd,
          Pb and U) can be used for the differentiation of pollutant sources, to determine the region of their origin.
          Nitrogen, boron and chlorine isotopes can be used to distinguish natural from anthropogenic sources. The
          analysis of tree cores allows a dating of spills (phytoscreening, dendrochemistry and dendrochronolgy) under
          certain conditions.

          Forensic methods are not only suitable to identify polluters (location and date of spills) but can also add
          value in developing the site model for site specific risk assessment. Moreover, the identification and
          quantification of microbial decomposition potential can be a great benefit in the evaluation of cost efficient
          remediation strategies (MNA concepts).

          The application of forensic methods and interpretation of forensic data are demonstrated by a case study.
          TPH-, BTEX- and PAH - fingerprinting together with data for MTBE and other specific chemical substances
          (MEK, Bitrex, Cyclohexan and Sulfur were suspected from a Phase I investigation) allowed the identification
          of locations and dates of spills of gasoline, heating oil/diesel, and heavy oil spills with differing accuracies of
          discrimination. Additionally, CFCH-, SF6- and tritium analyses were evaluated to describe the hydrogeological
          structure (contaminant transport behaviour, mean residence time, infiltration rates) of the contaminated
          aquifer for a risk assessment process.

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Report of the NICOLE WORKSHOP: Operating windows for site characterisation

              Isotopes in contaminated sites management - principles and recommendations

                                         Heinrich Eisenmann, Isodetect GmbH, Munich, Germany

          The redevelopment of contaminated sites demands the application of efficient remediation technologies.
          Within this scope, the monitoring and enhancement of natural attenuation processes is a key strategy.
          However, clear evidence for biodegradation has to be provided. Isotope analysis delivers key information
          about contaminated sites. The isotope fingerprint of pollutants can allow discrimination of the initiators of
          groundwater contamination, while the enrichment of heavy isotopes by biological degradation can elucidate
          natural attenuation processes.

          In situ biodegradation at contaminated sites can be assessed by the enrichment of heavy stable isotopes
          (13C, 2H) in the residual pollutants. In many cases, even the quantification of biodegradation is possible,
          because of correlation to isotope enrichment. The appropriate isotope enrichment factor has to be selected
          according to the compound of interest and prevailing redox conditions (see www.isodetect.de). As a
          consequence, isotope monitoring can provide detailed information on natural attenuation processes by a
          single sampling campaign. The percentual decrease of contaminants caused by micobiological activity
          downstream from the source as well as biodegradation rates can be derived. This enables also the
          discrimination of non-sustainable processes that further diminish contaminant concentration such as
          dilution or dispersion.

          Numerous examples for successful isotope monitoring at sites contaminated with BTEX, MTBE or chlorinated
          ethenes have been described in scientific reports. As next, guidelines for this powerful exploring technique
          have been published by several environmental authorities. The presentation gives an overview about the
          state of the art in isotope monitoring of contaminated groundwater. In case studies, the quantification of
          biological attenuation of BTEX and chlorinated ethenes is demonstrated. For forensic purposes, the isotope
          fingerprint of pollutants can allow discrimination of the initiators of groundwater contamination. Finally, a
          variety of supplemental isotope surveys such as two-dimensional isotope monitoring (13C, 2H, 37Cl), isotope
          enrichment of electron acceptors (NO3 and SO4), and the exposition of isotope-labeled in situ microcosms
          (BACTRAPS) is shortly explained.

          •    Meckenstock, R., et al (2004) Stable isotope fractionation as a tool to monitor biodegradation in contami¬nated aquifers.
               J. Cont. Hydrol. 75: 215-255.
          •    US-EPA (2005) Monitored natural attenuation of MTBE as a risk management option at leaking underground storage tank
               sites. EPA/600/R-04/1/179. www.epa.gov/ada/download/reports/600R04179/600R04179-fm.pdf
          •    DECHEMA (2007) Held, T. et al.: Handlungsempfehlung: Mikrobiologische NA-Untersuchungsmethoden. www.natural-
               attenuation.de/media.php?mId=5623
          •    Fischer, A., Theuerkorn, K., Stelzer, N., Gehre, M., Thullner, M. Richnow, H.H. (2007) Applicability of Stable Isotope
               Fractionation Analysis for the Characterization of Benzene Biodegradation in a BTEX-con¬taminated Aquifer.
               Environmental Science & Technology 41: 3689-96.
          •    US-EPA (2008) A Guide for assessing biodegradation and source identification of organic ground water contaminants
               using compound specific isotope analysis (CSIA). EPA 600/R-08/148.
               www.epa.gov/ada/pubs/reports/600r08148/600R08148.html
          •    KORA (2008) Michels, J., Stuhrmann, J., Frey, C., Koschitzky, H.-P.: KORA Handlungsempfehlungen: Natürliche
               Schadstoffminderung bei der Sanierung von Altlasten. DECHEMA 2008. www.natural-
               attenuation.de/content.php?_document[ID]=6947&pageId=2647
          •    Eisenmann, H. Fischer A. (2010) Isotopenuntersuchungen in der Altlastenbewertung. Handbuch der Altlastensanierung
               60:3511.

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Report of the NICOLE WORKSHOP: Operating windows for site characterisation

              Closing down of remediation using Biotraps and DNA analysis – a case study

                                                              Alex Lee, WSP, UK

          Advanced diagnostics and forensic techniques are broadening the scope of site investigations and
          expanding the lines of evidence available to soil and groundwater practitioners, problem owners and
          regulators. Some of the more popular and widely available techniques include the following:

             Molecular Biological Tools – DNA / RNA analysis to characterise microbial populations and degradation
              processes. Can be used to provide clear lines of evidence to support theories of contaminant
              degradation via microbial processes;
             Compound Specific Isotope Analysis – analytical processes that analyse the molecular weighting of
              contaminant species in order to assess degradation processes. These analytical methods can be used
              to provide evidence of contaminant degradation;
             Groundwater tracers – tracers comprising DNA strands or physical dye tracers can be used to evaluate
              groundwater flow paths giving greater confidence and understanding of groundwater flow regimes

          We present a review of the above techniques and a summary of different situations where they have been
          used in real life cases. Concluding from the case studies, we suggest where the techniques can be useful –
          what ‘operating windows’ or situations are appropriate.

          We also use case studies to demonstrate the value to the problem owner and regulator that such techniques
          can bring in early close out of long term remediation schemes, saving time and money, but providing
          additional lines of evidence to allow regulatory close out.

          Rather than being ‘out of reach techniques’ which are only available to the few and at high cost, we show
          how some of the more useful and accessible emerging methods are being used routinely to close out long
          term monitoring programmes.

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                                Analytical challenges – It all starts with sampling

                                                               Frank P.J. Lamé

                                                       Deltares – The Netherlands

          In testing the environmental quality of a site, the investigation follows a series of steps: planning of the
          sampling campaign, fieldwork including sampling, packaging of the sampled material, sample selection
          for analysis, pre-treatment of the sample, extraction or destruction of the sample, chemical analysis and
          reporting. Each of these steps can give cause to errors, while every error can contribute to a biased
          result and consequently might result in an incorrect conclusion about the environmental quality of that
          site. High costs might be involved for remedial actions while there still is a lot of uncertainty about the
          nature, extent and level of contamination.

          Much emphasis is given to the analytical part of the characterization process: the reduction of the
          analytical error by means of e.g. calibration of the analytical equipment, blank samples, certified
          standards and round robin tests. Less attention is given to the origin of the analysed material, the
          sample, and the sampling strategy through which it was obtained.

          A site investigation is based on assumptions about the environmental quality of that site, wherein the
          assumptions are based on information obtained on the history of the site, the processes on the site and
          the risks for these processes to have either contaminated the soil and / or the groundwater. A
          conceptual model of the site builds up in the mind of the consultant, and during the investigation
          process, this conceptual model should develop to such a level that it is sufficiently clear to come to
          decisions about the site. National, as well as international standards (e.g. ISO 10381-5) provide
          guidance for the sampling of contaminated sites.

          As the sampling strategy is based on non-statistical information (the assumptions about the site), the
          accuracy of the overall process cannot be simply calculated. Indeed, the question arises if validation of
          the overall procedure is even possible.

          Another issue is the characterization of a lot or stockpile of soil or soil-like material. What is the
          environmental quality of that material and can it be reused safely, or is treatment necessary prior to its
          reuse? Is it even possible to obtain a reliable estimate of the mean concentration of such a, potentially
          highly heterogeneous, lot? How many samples should be taken and what size (mass / volume) should
          the samples have? How can you ensure that the 2 grams analysed for heavy metal content are actually
          representative for a soil lot of, for example 2000 tons? In such cases assumptions about the past of the
          material are of less relevance, at least for the sampling strategy to be applied. A statistically based
          approach van be used which allows at the same time the quantification of errors made. For the
          sampling of soil stockpiles, a unique validated sampling strategy has been developed.

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                         Pharmaceuticals in groundwater bodies as a forensic tool

                                                 Joachim Schmidtke, Environ, Germany

          Over the past decade, pharmaceuticals and personal care product (PPCP) compounds have been identified
          and studied as emerging pollutants. Although many studies have been conducted regarding the presence of
          PPCPs in sanitary wastewater and the environment, these studies have been primarily focused on evaluating
          the extent, fate, and toxicological significance of PPCP discharges. For comingled environmental
          contamination in areas where multiple potential sources exist, PPCPs also have the potential to serve as
          forensic indicators of contaminant sources. Because public use of many PPCPs can be tracked to a specific
          date of drug regulatory approval or initial date of manufacture and trends exist for use of certain popular
          products, PPCP data can also be utilized in age dating analyses.

          Ideal PPCP forensic indicators include persistent and mobile compounds that are in widespread usage in the
          population of interest. Wastewater sources that treat flow from multiple sources have an increased
          likelihood of the presence of a variety of indicator chemicals, although many compounds have also been
          identified in septic system discharges. Water quality studies conducted to identify the extent of the PPCP
          problem have detected a range of candidate compounds and have provided detection frequency data useful
          in selecting target compounds. Follow-on studies have provided additional data regarding of the persistence
          and fate of these compounds in surface and ground water environments, as well as survival in various
          wastewater treatment processes prior to discharge to the environment.

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Report of the NICOLE WORKSHOP: Operating windows for site characterisation

                                      Tree sampling for Environmental Forensics

                                       Jean-Christophe Balouet * & Gustav Kobberger **

          Two methods are presented, both based on chemical analyses of wood samples from trees:

          1. Phytoscreening
          Because trees uptake pollutants to which they are exposed, they can be used as indicators for pollutant
          releases in their vicinity. Soil and groundwater contaminants are uptaken and transported by sap in the
          outermost wood rings. These can easily be micro-sampled (0.2 g) and analyzed for the sap enriched
          contaminants. This method allows to qualitatively and quantitatively identify or exclude the presence of
          underground contaminants such as Chlorinated Hydrocarbons (PCE, TCE, DCE …). The correlation coefficient
          between tree and underground contamination is respectable (and up to 0.9). Whenever a site is properly
          vegetated, Phytoscreening can be used for a rapid identification or exclusion of contamination, for clarifying
          contaminant distribution by fast low cost measurements, for identification of release spots and delineation
          or monitoring of plumes. Being a standard method for CVOCs, BTEX and heavy metals (Cd, Cr, Cu, Hg, Ni, Pb,
          Zn) PIT currently investigates, if this method is also suitable for PAH, PCB and other organic compounds.

          2. Dendrochemical Age-Dating
          Due to their seasonal growth annual tree-rings represent a bio-archive of the past. During this growth
          process elements taken up with the sap from the rhizosphere are being built in and fixed to wood cells.
          Accordingly and besides heavy metals pollutant specific tracer elements such as Chlorine (for chlorinated
          organic compounds like PCE) or Chlorine and Sulfur (for Fuel Hydrocarbons) are built in and fixed to the wood
          cells. This growth related element incorporation exclusively takes place within the youngest annual ring with
          the resulting element concentration depending on the respective element availability in soil and
          groundwater. The change in concentration over all annual rings of a tree core sample from the stem can be
          gained for 30 elements with the help of energy-dispersive X-Ray-analysis (ED-XRF). The ED-XRF is supported
          by a line scanner allowing an equidistant scan of a complete wood core from its youngest to its oldest ring at
          increments of 50 µm. This process delivers the concentration profiles of 30 elements over the total life time
          of a tree can be obtained at a very high temporal resolution. Accordingly, concentration anomalies of
          pollutant specific elements (tracers such as Chlorine) can be dated exactly to reveal the beginning and
          duration of an underground impact (such as by PCE). In order to rule out or confirm the possibility of
          alternative sources for the Chlorine anomalies (e.g. road salt), allied element concentration profiles (e.g. K,
          Ca, Mg, S) are compared for Cl-synchronous anomalies (multi-element-analyses). Other potential
          (environmental) influences are assessed by comparison with a sample taken from a control tree in the
          vicinity outside of the polluted area. By this means tree core samples can be used as „proxy-recorders“
          documenting historic pollutant releases and impacts. If further historic data (e.g. documents) and
          information on soil and groundwater are considered, this method provides a reliable and very exact dating of
          the impact (by one 1 year) at the tree’s location. If more trees are available the spatiotemporal expansion of
          a plume as well as contaminant transport velocities can be revealed. This method is a powerful tool that
          provides an independent line of forensic evidence when attributing damages to polluters by exact age dating
          of impacts.

                   * Environment International, 2 ruelle du Hamet, 60129, France (jcbalouet@aol.com)
          ** HPC HARRESS PICKEL CONSULT AG, Kapellenstr. 45a, 65830 Kriftel, Germany (gkobberger@hpc-ag.de

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