A simple contaminant fate and transport modelling tool for management and risk assessment of groundwater pollution from contaminated sites.

Contaminated sites pose a significant threat to groundwater resources. The resources that can be allocated by water regulators for site investigation and cleanup are limited compared to the large number of contaminated sites. Numerical transport models of individual sites require large amounts of data and are labor intensive to set up, and thus they are likely to be too expensive to be useful in the management of thousands of contaminated sites. Therefore, simple tools based on analytical solutions of contaminant transport models are widely used to assess (at an early stage) whether a site might pose a threat to groundwater. We present a tool consisting of five different models, representing common geological settings, contaminant pathways, and transport processes. The tool employs a simplified approach for preliminary, conservative, fast and inexpensive estimation of the contamination levels of aquifers. This is useful for risk assessment applications or to select and prioritize the sites, which should be targeted for further investigation. The tool is based on steady-state semi-analytical models simulating different contaminant transport scenarios from the source to downstream groundwater, and includes both unsaturated and saturated transport processes. The models combine existing analytical solutions from the literature for vertical (from the source to the top of the aquifer) and horizontal (within the aquifer) transport. The effect of net recharge causing a downward migration and an increase of vertical dispersion and dilution of the plume is also considered. Finally, we illustrate the application of the tool for a preliminary assessment of two contaminated sites in Denmark and compare the model results with field data. The comparison shows that a first preliminary assessment with conservative, and often non-site specific parameter selection, is qualitatively consistent with broad trends in observations and provides a conservative estimate of contamination.

[1]  Philip J Binning,et al.  A risk assessment tool for contaminated sites in low-permeability fractured media. , 2011, Journal of contaminant hydrology.

[2]  J. Feyen,et al.  Dispersivity Estimates from a Tracer Experiment in a Sandy Aquifer , 2000 .

[3]  A. V. Luikov,et al.  Analytical Heat Diffusion Theory , 1969 .

[4]  J. N. Petersen,et al.  Analytical solutions for multiple species reactive transport in multiple dimensions , 1999 .

[5]  H. Vereecken,et al.  Review of Dispersivities for Transport Modeling in Soils , 2007 .

[6]  P. L. Bjerg,et al.  Role of diffusion in chemical oxidation of PCE in a dual permeability system. , 2007, Environmental science & technology.

[7]  Daniel M. Tartakovsky,et al.  A Bayesian approach to integrate temporal data into probabilistic risk analysis of monitored NAPL remediation , 2012 .

[8]  H. Mosbaek,et al.  Transport of hydrocarbons from an emplaced fuel source experiment in the vadose zone at Airbase Vaerløse, Denmark. , 2005, Journal of contaminant hydrology.

[9]  R. Gillham,et al.  Field experiments in a fractured clay till: 1. Hydraulic conductivity and fracture aperture , 1993 .

[10]  Eliezer J. Wexler,et al.  Analytical solutions for one-, two-, and three-dimensional solute transport in ground-water systems with uniform flow , 1989 .

[11]  Matthew J. Simpson,et al.  Exact series solutions of reactive transport models with general initial conditions , 2014 .

[12]  Bruce Hunt,et al.  DISPERSIVE SOURCES IN UNIFORM GROUND-WATER FLOW , 1978 .

[13]  Felipe P. J. de Barros,et al.  A divide and conquer approach to cope with uncertainty, human health risk, and decision making in contaminant hydrology , 2011 .

[14]  Huu Hao Ngo,et al.  Industrial metal pollution in water and probabilistic assessment of human health risk. , 2017, Journal of environmental management.

[15]  B. Sleep,et al.  The spatial distribution of eubacteria and archaea in sand-clay columns degrading carbon tetrachloride and methanol. , 2007, Journal of contaminant hydrology.

[16]  Melissa A Harclerode,et al.  Early decision framework for integrating sustainable risk management for complex remediation sites: Drivers, barriers, and performance metrics. , 2016, Journal of environmental management.

[17]  J. Bear.  Dynamics of Fluids in Porous Media , 1975 .

[18]  S. Attinger,et al.  Transport of a decay chain in homogenous porous media: analytical solutions. , 2001, Journal of contaminant hydrology.

[19]  D. DeGroot,et al.  Chloride Dispersion across Silt Deposits in a Glaciated Bedrock River Valley. , 2014, Journal of environmental quality.

[20]  Peter Friis-Hansen,et al.  Risk-based economic decision analysis of remediation options at a PCE-contaminated site. , 2010, Journal of environmental management.

[21]  O. Paladino,et al.  Analytical Solutions of Three‐Dimensional Contaminant Transport Models with Exponential Source Decay , 2018, Ground water.

[22]  Richard Boyle,et al.  The rationale for simple approaches for sustainability assessment and management in contaminated land practice. , 2016, The Science of the total environment.

[23]  P. Binning,et al.  Review of reactive kinetic models describing reductive dechlorination of chlorinated ethenes in soil and groundwater , 2013, Biotechnology and bioengineering.

[24]  R. Baker,et al.  Evaluation of Volatilization as a Natural Attenuation Pathway for MTBE , 2004, Ground water.

[25]  R. Baciocchi,et al.  Role of natural attenuation in modeling the leaching of contaminants in the risk analysis framework. , 2013, Journal of environmental management.

[26]  John A. Cherry,et al.  Diffusive Disappearance of Immiscible‐Phase Organic Liquids in Fractured Geologic Media , 1994 .

[27]  T. P. Clement,et al.  Analytical solutions for sequentially coupled one-dimensional reactive transport problems – Part I: Mathematical derivations , 2008 .

[28]  V. Cvetkovic,et al.  Evaluation of Risk from Contaminants Migrating by Groundwater , 1996 .

[29]  M. Rivett,et al.  Transport of a dissolved-phase plume from a residual solvent source in a sand aquifer , 1994 .

[30]  Fengjun Zhang,et al.  Sorption of chlorinated solvents and degradation products on natural clayey tills. , 2011, Chemosphere.

[31]  P. L. Bjerg,et al.  Concurrent ethene generation and growth of Dehalococcoides containing vinyl chloride reductive dehalogenase genes during an enhanced reductive dechlorination field demonstration. , 2008, Environmental science & technology.

[32]  Walter A Illman,et al.  A semi-analytical solution for simulating contaminant transport subject to chain-decay reactions. , 2013, Journal of contaminant hydrology.

[33]  T. P. Clement,et al.  Analytical solutions for sequentially coupled one-dimensional reactive transport problems – Part II: Special cases, implementation and testing , 2008 .

[34]  Yoram Eckstein,et al.  Use of Weighted Least‐Squares Method in Evaluation of the Relationship Between Dispersivity and Field Scale , 1995 .

[35]  John A. Cherry,et al.  Ground‐Water Contamination from Two Small Septic Systems on Sand Aquifers , 1991 .

[36]  Peter Kjeldsen,et al.  Unsaturated zone leaching models for assessing risk to groundwater of contaminated sites. , 2009, Journal of contaminant hydrology.

[37]  A. Fiori,et al.  Uncertainty quantification of adverse human health effects from continuously released contaminant sources in groundwater systems , 2016 .

[38]  J. F. Devlin,et al.  Application of new point measurement device to quantify groundwater-surface water interactions. , 2018, Journal of contaminant hydrology.

[39]  N. Basu,et al.  Flux-based assessment at a manufacturing site contaminated with trichloroethylene. , 2006, Journal of contaminant hydrology.

[40]  P. Binning,et al.  GrundRisk - Coupling of vertical and horizontal transport models , 2017 .

[41]  J. D. Colthart,et al.  Aerobic Biodegradation of Benzene, Toluene, and Xylene in a Sandy Aquifer—Data Analysis and Computer Modeling , 1989 .

[42]  W. J. Alves,et al.  Analytical solutions of the one-dimensional convective-dispersive solute transport equation , 1982 .

[43]  Philip John Binning,et al.  Application of Bayesian geostatistics for evaluation of mass discharge uncertainty at contaminated sites , 2012 .

[44]  D. T. Snow,et al.  Anisotropie Permeability of Fractured Media , 1969 .

[45]  C. Welty,et al.  A Critical Review of Data on Field-Scale Dispersion in Aquifers , 1992 .

[46]  R. Bossi,et al.  Preferential flow and pesticide transport in a clay‐rich till: Field, laboratory, and modeling analysis , 2002 .

[47]  Olaf A Cirpka,et al.  Stochastic evaluation of mass discharge from pointlike concentration measurements. , 2010, Journal of contaminant hydrology.

[48]  James N. Petersen,et al.  Development of analytical solutions for multispecies transport with serial and parallel reactions , 1999 .

[49]  H. Fischer.  Mixing in Inland and Coastal Waters , 1979 .

[50]  Dirk Schulze-Makuch,et al.  Longitudinal dispersivity data and implications for scaling behavior , 2005, Ground water.

[51]  Valerio Cozzani,et al.  Impact of Hydrogeological Uncertainty on Estimation of Environmental Risks Posed by Hydrocarbon Transportation Networks , 2017 .

[52]  P. L. Bjerg,et al.  Field evaluation of biological enhanced reductive dechlorination of chloroethenes in clayey till. , 2010, Environmental science & technology.