Percolation

Water

Prognosis

Research

Focus

BMBF-Research-Focus 'Percolation Water Prognosis' Concept and Current Activities Frank E. Oberacker* and Siegfried H. Eberle DVGW-TZW-HSL (Heinrich-Sontheimer-Laboratorium ffir Wassertechnologie - HSL, Technologiezentrum Wasser - TZW), Karlsruher Str. 84, D-76139 Karlsruhe, Germany * Corresponding author ([email protected])

Fig. 1 : Steps of the 'percolation water prognosis' [3]

1. Determination of the contaminant's source strength (' Quellst~irke'), which is defined as the total mass flow caused by natural leaching, which will be done normally in the laboratory. 2. Transport prognosis ('Transportprognose') of the contaminant passage through soil and the unsaturated zone into the groundwater. This step is done normally by computer modelling.

1

Introduction

The German Federal Soil Protection Act [1] has been effective since 1998. In this act, not only comprehensive provisions on the prevention of hazards caused by harmful soil changes (contaminated sites) are formulated, but also obligations to avoid future soil impacts arising from the application of mineral wastes or recycling products onto or into soils (precaution). The requirements needed for implementation of this act are specified by the Federal Ordinance on Soil Protection and Contaminated Sites (BBodSchV) of July 17, 1999 [2]. One aspect to be considered is the contaminant leaching from contaminated materials through soil and the unsaturated zone into the groundwater. A concept for evaluating this pathway was developed by a joint working group of'Bund' (Federal) and ' L/inder' (State) Governments [3-5], which is called 'Sickerwasserprognose' (percolation water prognosis). This 'percolation water prognosis' may be divided into two steps (Fig. 1):

24

The place of assessment (' Ort der Beurteilung' ) for the 'percolation water prognosis' is the transition area between the unsaturated and the saturated zone. At this point, either the contaminant concentration or the mass flow can be used for decision. Official authorities have to decide whether a specific material can be safely deposited on a specific site by comparing the results of the 'percolation water prognosis' (step 1 + 2) with the threshold values ('Geringf%igkeitsschwellen') defined by law. In drawing up this concept, it soon became obvious that reliable methods are not available for determining the source strength or setting up the transport prognosis. In recognition of the considerable research needs and the lack of a scientific basis for these methods, the Federal Ministry for Education and Research (BMBF) initiated the BMBF-research-focus 'percolation water prognosis'. Following its public announcement in September 1999 [6], about 100 project proposals were submitted. The Project Agency for Water Technology and Disposal at the Research Centre in Karlsruhe (FZK-PtWT + E) was made responsible for handling and evaluating the proposals. In the meantime, 41 projects are supported with a total budget of about 11 million Euro [7].

JSS - J Soils & Sediments 2 (1) 24 - 28 (2002) 9 ecomed publishers, D-86899 Landsberg. Germany and Ft Worth/TX, USA o Tokyo, Japan 9 Mumbai, Indien | Seoul, Korea

Research Focus

Percolation Water Prognosis

Within this BMBF-research-focus, the scientists shall work out a better scientific basis of the methods, which are needed to carry out the 'percolation water prognosis'. Main requirements for these methods are to be valid on the one hand, but also practicable and generally accepted on the other. It is planned that detailed instructions of these methods will be included in the amendment of the BBodSchV in the year 2005.

.,

.om the resoaro, area.:

i

Waste materials (9) Engineering consultants (51 HydrogeologylHydrology (7) Soil science (5) I I Water chemstrylAnalytics (6) Building materials (2) [

After consulting several experts and representatives of the responsible official authorities, the range of materials was delimited to mineral wastes like demolition waste materials, ashes, slags, contaminated soils, etc. 2

Fig. 2: Structure of the BMBF-research-focus 'percolation water prognosis'

Structure

The programme is executed by engineering consultants and scientists originating from different research areas like waste materials, hydrogeology / hydrology, soil science, mineralogy / geochemistry, water chemistry / analytics, building materials and mathematics / physics. Each participant

focusses either on methods to determine the material's source strength or on improving existing models, which describe contaminant transport through soils {Fig. 2). A list of all project partners engaged in the BMBF-research-focus is given in Table 1.

Table 1 9 List of projects united in the BMBF-research-focus 'percolation water prognosis' (granted or about to be granted) 1

Project-No.

Recipient

02WP0299

Development of a method for the 'percolation water prognosis' exemplary for not-easily volatilized organic contaminants from treated soils Prognosis of the contaminant input into groundwater with percolation water Determination of the source strength from fine grained or compacted materials to predict the contaminant input into groundwater ('percolation water prognosis') Determination of the time-dependent course of the source strength by lysimeter experiments in the field

2

02WP0288

Technische UnivereitAt Braunschweig HPC GmbH Harburg

3

02WP0287

Fachhochschuie MOnster

4

02WP0286

Landesumweltamt NRW Essen

5

02WP0 t 98

6

02WP0200

Eberhard-Karls-Universit~it T0bingen Institut for Wasserforschung GmbH Dortmund

7

02WP0199

8

02WP0201

9

02WP0261

10

02WP0t 57

11

02WPOt 92

12

02WP0242

13

02WP0220

14

02WP0216

15

02WP0217

f6

02WP0205

17

02WP0206

18

02WP0203

Title

Development and validation of a model for the estimation of the contaminant concentration at the point of assessment Part 1 : Determination of the retention under conditions of non-equilibrium Development and validation of a model for the estimation of ... Part 2: Determination of the source strength and parameterisation of the contaminant output from anthropogenic material piles/deposits via particles Johannes GutenbergDevelopment and validation of a model for the estimation of ... Part 3: Evaluation of Universit~t Mainz mobilization, transport and retention of colloidal and suspended particles in soil DVGW e.V. Bonn Development and validation of a model for the estimation of ... Part 4: Examination of the significance of microbial degradation for the transport of persistent organic contaminants in the unsaturated zone Ruprecht-Karls-Universitat Development and validation of a model for the estimation of ... Part 5: Assessment and Heidelberg quantification of preferential pathways in coarsely structured materials Technische Universit~it Dresden Computerized advice system for the 'percolation water prognosis' COMBESICK Part 1 : Development of a test for the assessment of the source strength to predict the contaminant ~nput into groundwater with percolation water Technische Universit~it Dresden Computerized advice system for the 'percolation water prognosis' CQMBESlCK Part 2: Development of the electronic data processing tools for the conversion and evaluation of the results Dr. Kemmesies und Partner, Computerized advice system for the 'percolation water prognosis' COMBESICK Part 3: Gunzenhausen Integration of reality-simulating modules TU Hamburg-Harburg Development of quality criteria for percolation water models and evaluation of existing models Rheinisch-Westf~lische Prognosis of the contaminant input into groundwater with percolation water Part 1: Technische Hochschule Development of a method for the transport prognosis via iterative simulation of transport Aachen ~rocesses Rheinisch-Westf~lische Prognosis of the contaminant input into groundwater with percolation water Part 2: Technische Hochschule Examination and evaluation of the influence of macropores on the percolation water Aachen transport in the unsaturated zone Georg-August-Universit~t Contaminant output from weakly contaminated wastes, recycling products and contaminated G6ttingen materials - Lysimeter experiments and comparison with known methods of prognosis Bundesanstalt for Development of a method to quantify contaminant concentrations in percolation water on Geowissenschaften & Rohstoffe the basis of chemical and physical pedotransfer functions Hannover Ludwig-Maximilians-Universit~t Examination of the prognosis quality derived from leaching tests of the mobilization of M0nchen oxyanions from steel slags in regards of concentrations in percolation water and transport into groundwater

JSS - J Soils & Sediments 2 (1) 2002

25

Percolation Water Prognosis

Research Focus

Table 1: List of projects united in the BMBF-research-focus 'percolation water prognosis' (granted or about to be granted) (cont'd)

Project-No. Recipient I9

Title

02WP0196

Universit~t Stuttgart

20

'Percolation water prognosis' via laboratory experiments for transferring the practical relevance Part 1 : Determination of source strengths and factors for up-scaling 02WP0197 I Dresdner Grundwasser'Percolation water prognosis' via laboratory experiments ... Part 2: Development of a forschungszentrum e.V. Dresden computer-based expert system for the reproducible determination of migration parameters in the laboratory to predict the composition of percolation waters

21

02WP0186

Hochschule Bremen

22

02WP01 75 : Techn. Universitb.t ML~nchen

23

02WP0174

AGROLAB GmbH Langenbach

24

02WP0165

Technische Universit~.t M0nchen

25

02WP0166

Rheinisch-Westf~Iische Technische Hochschule Aachen

26

02WP0158 ' Technische Universitat Bergakademie Freiberg

Development of a test method for the determination of the source strength of materials contaminated with heavy metals and following transport modelling

27

02WP0156

28

02WP0142

Johannes-GutenbergUniversit~t Mainz Universit~t Bremen

29

02WP0141

CUTEC GmbH Clausthal

Simulation of the formation of secondary minerals in mineral residues and soil layers in contact with percolation water Prediction of the source strength: Standardized laboratory experiments for verification and sensitivity analysis of a computer model to be used in practice Prediction of the contaminant input into groundwater with percolation water

30

02WP0122

Georg-August-Universit~.t G6ttingen

31

02WP0118

32

02WP0117

33

02WP0t 05

34

02WP0082

35 I 02WP0089 36 37

02WP0088 02WP0081

38

02WP0143

39 ] 02WP0219 40

02WP0218

41

02WA0071

Development and test of an outdoor-simulating set-up to determine the maximum percolation water output of PAH from contaminated wastes Statistical evaluation of combinations of chemical and mineralogical methods for the 'percolation water prognosis' Development and verification of a test method for the determination of percolation water concentrations below contaminated areas in the unsaturated zone Concept for the evaluation of the leaching behaviour of mineral building materials with percolation and groundwater Part 1: Determination of the source strength for soils and groundwaters in contact with bedding materials, jetcrete or concrete for subterraneous curtains Concept for the evaluation of the Ieaching behaviour of ... Part 2: Determination of the source strength for soils and groundwaters in contact with concrete foundations and sol] injections

9 of methods for determining the source strength of ashes and slags. Evaluation and optimisation of existing computer models for unsaturated soils in regards of their applicability for the 'percolation water prognosis' Universit~t Bayreuth 'Percolation water prognosis': Optimisation of percolation methods for determining the source strengths of contaminated natural and anthropo-technogenic dumping materials Friedrich-Alexander-Universit~t Mathematic modelling to identify the source strength of contaminants and to predict their Erlangen-NOrnberg transport behaviour into groundwater G.E.O.S. mbH Freiberg Analysis and modelling of microbial processes/interactions with organic and anorganic materials and their influence on the mobilization/fixation of contaminants Technische Universit&t Development of a method to quantify the source strength of granular materials Part 1 : Hamburg-Harburg Influence of COn concentration on the mobilization of anorganic contaminants Universit~t Fridericiana zu Development of a method to quantify the ... Part 2: Influence of redox conditions, DOC and Karlsruhe (TH) temperature on the mobilization of anorganic contaminants DVGW e.V. Bonn Development of a method to quantify the ... Part 3: Mobilization of organic contaminants Eberhard-Karls-Universit~.t Distinguishing equilibrium - non-equilibrium conditions in percolation experiments for the T0bingen leaching of organic contaminants: Examination of materials and model development BAM Berlin Preparation of reference materials for research purposes in the BMBF-research-focus 'percolation water prognosis' GSF-Forschungszentrum Central experiments with sand iysimeters fiIled by hand for verification of the quantitative GmbH Neuherberg prognosis of contaminant input into groundwater with percolation water Forschungszentrum JQlich Central experiments with monolithic loess lysimeters for verification of the quantitative GmbH JQlich prognosis of contaminant input into groundwater with percolation water DVGW e.V. Bonn Scientific co-ordination and interpretation of the results of the BMBF-research-focus 'percolation water prognosis'

Particular attention will be paid to the validation of the results. As a basis for this, some core projects were set up to determine transferability and possible areas of application of the developed methods. Comparability will be ensured by preparing reference materials, which are provided to all participants to be included in their research. The results obtained by the different methods, used by the participants to determine the source strength of the reference materials will be used to identify the controlling key factors. In an additional approach, these reference materials are filled in large lysimeters, which are expected to deliver sets of data close to nature and will be used for validation of the proposed transport models. The research-focus will be accompanied by an advisory board and a scientific co-ordination. Furthermore, concern will be

26

drawn to the harmonization of soil and water related regulations on an EU-wide basis. The board consists of experts of the relevant scientific disciplines and representatives of official authorities and includes Prof. F6rsmer (Technical University of Hamburg-Harburg, focus on source strength) and Prof. Grathwohl (University of Tiibingen, focus on transport prognosis), who represent the participating projects. It will give executive advice to the BMBF and shall promote a broad consent on quality and applicability of the investigated methods. Scientific co-ordination is carried out by the Heinrich-Sontheimer-Laboratory (HSL) in Karlsruhe (project-no: 02WA0071). It serves as the interface between the single and the core projects, summarizes the actual progress and informs the advisory board on a regular basis. Work-

JSS - J Soils & Sediments 2 (1) 2002

Research Focus

shops and meetings are organised and a database will be created to store and interpret the results. 3

Current Activities

3.1

Reference materials

The reference materials were introduced into the procedure as a common basis, on which a validation of the developed methods will be feasible, and on which applicability limits may be identified. Obviously, it will not be possible to apply one single method to all materials (from finely grained soils to slags or coarsely grained demolition waste) and all contaminants (heavy metals, oxyanions, polar and non-polar organic substances). Because every participant will have to use the reference materials (RM) listed in Table 2, a quantity of 6 tons each has been prepared by the Federal Institute for Material Research and Examination in Berlin (BAM, project-no: 02WP0143). 3.2

Lysimeter experiments

The lysimeter experiments are intended to validate the different models developed within the research-focus. They are planned to deliver close-to-nature data for the contaminant transport in different soils (sand, loess) exposed to natural precipitation (Fig. 3). Two sets of four lysimeters each have been installed at two institutions. They are located at the Research Centre in J~lich (project-no: 02WP0218), where monoliths of loess are used, and at the GSF Research Centre in Munich (project-no: 02WP0219), where the used sand is filled in manually. The following operation scheme is applied: 1. The lysimeters are exposed to natural rainfall. An additional irrigation system guarantees a minimum annual precipitation of 900 mm. 2. The source strength is derived from layers of the reference materials (50 cm), which are poured onto the soil

Percolation Water Prognosis

filling of the lysimeters. They are covered by a 30 cm layer of quartz sand. 3. Time-dependent sampling of the percolation water is done at three depths using ceramic suction cups, as well as at the bottom of the lysimeters; water content and matrix potential are measured continuously at the same depths. 4. By using hydrologic tracers (bromide, D20), as well as by continuously weighing the lysimeters the water flow is observed. 5. In order to follow the contaminant transport in addition to the source strength studies of the reference materials, two 'indicator substances' (isoproturon, difluoro benzoic acid) are applied to the lysimeters at the beginning of the experiments. Important parameters (conductivity, pH, redox potential) and main ions (Ca, Mg, Na, NH4, CI, SO4, NO3) are determined, as well. Special attention has been paid to really acquire all parameters, which are necessary for transport modelling. This operation data including the actual rainfall will be given to the participants focussing on the transport prognosis, whose improved models should be able to predict the real contaminant transport in the lysimeters. Their calculated results are reported to the co-ordinator. By comparing the predicted and the real contaminant transport, the performance of the different models will be evaluated. 3.3

Database

A central database will be created at the HSL, where the relevant information about materials, contaminants, leaching methods and transport models gained by the participants is stored. Substantial features of data analysis will be integrated to compare the different methods/models and to identify relevant parameters, which have to be considered either for determining the source strength or for setting up the transport prognosis.

Table 2: Reference materials (RM) prepared for examination by the participants of the BMBF-research-focus 'percolation water prognosis' Type

Origin

Contaminants

'RM Boden'

Contaminated soil from a former tar work site

PAH, mineral oil hydrocarbons, phenolics

2 mm

'RM HMVA'

Ash rubbish incineration plant

heavy metals

4 mm

'RM Bauschutt'

Concrete/brick scraps, asphalt-containing break-up of roads and gypsum plaster board residues from a demolition waste recycling work

PAH, heavy metals, salts

4 mm

Grain size

This database will probably be given to official authorities, who have to deal with the 'percolation water prognosis'. On the one hand, the database will be useful in evaluating different cases, on the other hand, double work will be avoided. 3.4

Fig. 3: Schematic set-up of the core lysimeter experiments

JSS - J Soils & Sediments 2 (1) 2002

Projects focussing on the source strength

Participants focussing on the source strength are looking at the leaching of different contaminants from different materials using different methods (Table 3). Important aspects concerning the methods are the kind of leaching solution to be used (for example distilled water, rain water, drinking water), the sample pretreatment (for example drying, size reduction) and the temperature at which the extractions should be car-

27

Percolation Water Prognosis

Research Focus

Table 3: Research aspects of the projects focussing on 'source strength' Contaminants examined Organics: PAH, mineral oil hydrocarbons, phenolics, benzene, toluene, xylene, PCB, chlorinated aromatic compounds, tributyl tin Building material additives; polyacrylates, naphthalenesulfonate, sulfonated naphthaleneformaldehyde-condensates Heaw metals: Cd, Cr, Cu, Ni, Pb, Zn; Oxyanions: Cr, Mo, V, As, Sb Others" alkali metals, sulfate, fluoride, cyanide, TOC, etc.

Materials examined Reference materials: RM Boden, RM MVAs, RM Bauschutt Contaminated soil and demolition waste materials: break-up of roads, tar and coal containing soils, pile materials, dredging sludges, washery slacks, harbour muds Building materials: concrete, jetcrete, bedding materials, soil injections Ashes/Slaqs_: fly ashes, ashes of rubbish incineration, blast furnace slags, granulated lead works slags Others: moulding sands, sewage sludge, rotting residues of mechanical-biological waste processing, tyres, DSD plastic recycling materials, etc.

Methods used Soil saturation extract, 1:2-leaching, DEV $4, pHstat, leaching with NH,NOa, DIN 19734 (Cr), CEN TC 292, Swiss method, TCLP (US-EPA) Tank-/trough method, cascade test, sequential extraction, column tests (DIN V 19736) Triaxial tests, (field)-Iysimeter experiments Hydrogeochemical modelling

Influences considered Material properties: grain size, bulk density, degree of consolidation, heterogeneity, aging of materials, secondary mineral formation, structure of aggregates Leachinq solution: Oz/CO2 concentration, redox potential, ionic strength, temperature, complexing agents, natural soil DOC Flow conditions: saturated, unsaturated, stop flow design, circuit design, flow velocity, degree of saturation, liquid-/solid-ratio, contact time Others: equilibrium/non-equilibrium, up-scaling, microbial activity, colloid formation, pressure

Table 4: Research aspects of the projects focussing on 'transport prognosis' Methods used Determination of parameters: (field)-Iysimeter, laboratory column arrangements (saturated, unsaturated, depthdependent sampling), batch tests, diffusion cells, field research, material characterization, characterization of the microbial inventory, tracer experiments, x-ray tomography, interpretation of groundwater recharge studies and mapping of eroded areas, pedotransfer functions Modelling: integration of routines for special processes in existing models, numeric simulations (Taylor, Monte Carlc etc.), sensitivity analysis, parameter studies, creating of databases (for contaminants, soil types, soil textures etc. creating of expert systems

Influences considered Regarding contaminants: sorption, diffusion, degradation processes, source strengths, equilibrium/non-equilibrium, contaminant distribution between mobile / immobile water and solid phase, particle-bound transport RegaLding soils: layering, soil properties (pH, TOC, texture, sesquioxide and clay content, etc.), gas phase Regarding water balance: rain characteristics, hydraulics, groundwater level, degree of water saturation, unsteady flow, preferential flow / matrix flow Others: uncertainty of input data, effects of microbial processes (sulfate reduction, sulfide oxidation, etc.) on the mobility of anorganic contaminants, complexing agents, up-scaling

References

ried out (influence on microbial degradation, diffusion, etc.). The aim is to select specific procedures, which can be applied in most cases. Criteria will be worked out which outline the fields of application for the different methods.

[1]

3.5

[3]

Projects focussing on the transport prognosis

Participants focussing on the transport prognosis are looking at the contaminant transport in the unsaturated zone from different perspectives, consider possible influences and use models with different degrees of complexity (Table 4). Major efforts will be taken to simplify the developed models, so that they are applicable in practice but still satisfy scientific criteria. Therefore, one of the participants (projectno: 02WP0220) is doing parameter studies with the highly sophisticated model HYDRUS-2D to identify the parameters, which at least have to be considered. It is intended to establish quality criteria, which can be used to evaluate existing, less complex models in terms of their applicability for the 'percolation water prognosis'. Important aspects concerning the contaminant transport are weighing the influence of preferential flow and the temperature at which the necessary data has to be gained. Also, all participants should agree on a kind of representative soil profile, which could be referred to in the future, in case a standard ' percolation water prognosis' has to be carried out.

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Models used ' Hydrus-2D, Richy, PHREEQC, SISIM, TENSIC, SIWAPRO, SMART, etc. I Further models see: [9-10]

[2]

I4] [5] [6]

[7] [8]

Bundes-godenschutzgesetz (BBodSchG): Gesetz zum Schutz vor sch/idlichen Bodenver~inderungenund zur Sanierung yon Altlasten. BGBI. I, 502ff (17.03.1998) Bundes-Bodenschutz- und Altlastenverordnung (BBodSchV): BGBI. I, 1554ff (16.07.1999) L/inderarbeitsgemeinschaftWasser(LAWA),Bund-/L/inderarbeitsgemeinschaft Bodenschutz (LABO), L~inderarbeitsgemeinschaft Abfall (LAGA):Gefahrenbeurteilung yon Bodenverunreinigungen/ Altlasten als Gefahrenquelle ftir das Grundwasser ( l 7.06.1998) L~nderarbeitsgemeinschaft Wasser (LAWA): Geringfiigigkeitsschwellen (Priifwerte) zur Beurteilung yon Grundwassersch~iden und ihre Begr6ndung (21.12.1998) L/inderarbeitsgemeinschaft Wasser (LAWA): Grunds~itze des Grundwasserschutzes bei Abfallverwertung und Produkteinsatz (27.01.1999) Bundesministerium ftir Bildung und Forschung (BMBF): Bekanntmachung iiber die F6rderung yon FuE-Verbundvorhaben zum Thema: 'Prognose des Schadstoffeintrages in das Grundwasser mit dem Sickerwasser ('Sickerwasserprognose')' sowie Erl/iuterungen zur BMBF-Ausschreibung 'Sickerwasserprognose'. Bundesanzeiger (21.09.1999) Rudek R, Eberle SH (2001): Der F6rderschwerpunkt 'Sicke'rwasserprognose' des Bundesministeriums for Bildung und Forschung Ein Uberblick. Altlastenspektrum 6/2001 Ebede SH, Oberacker FE (2001): Die 'Sickerwasserprognose' Spagat zwischen wissenschaftlicher Genauigkeit und praktikablem Vollzug. Altlastenspektrum 6/2001

[91 http://www'umwelt'sachsen'de/Ifug/dasima/ [! O] Reinsrorf F, Snsse~ B, Marre D, Grathwohl P, Walther W (2001): Modelle zur Sickerwasserprognose. Bodenschutz 1/2001

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