Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, Kgs Lyngby 2800, Denmark; Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya, C. Jordi Girona 1-3, Barcelona 08034, Spain.
Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, Kgs Lyngby 2800, Denmark.
J Contam Hydrol. 2019 Feb;221:35-49. doi: 10.1016/j.jconhyd.2018.11.002. Epub 2018 Nov 14.
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.
受污染场地对地下水资源构成重大威胁。与大量受污染场地相比，水管理部门可用于场地调查和清理的资源有限。个别场地的数值输运模型需要大量数据，并且在设置方面需要大量的工作，因此，对于管理数千个受污染场地来说，它们可能过于昂贵而无法实用。因此，广泛使用基于污染物输运模型解析解的简单工具来评估（在早期阶段）一个场地是否可能对地下水构成威胁。我们提出了一种由五个不同模型组成的工具，这些模型代表了常见的地质环境、污染物途径和输运过程。该工具采用简化方法，对含水层的污染水平进行初步、保守、快速和廉价的估算。这对于风险评估应用程序或选择和优先考虑应进行进一步调查的场地非常有用。该工具基于稳态半解析模型，模拟从源头到下游地下水的不同污染物输运情景，包括非饱和和饱和输运过程。模型结合了文献中现有的垂直（从源头到含水层顶部）和水平（在含水层内）输运的解析解。还考虑了净补给引起的向下迁移以及垂直弥散和稀释羽流的增加的影响。最后，我们说明了该工具在丹麦两个受污染场地的初步评估中的应用，并将模型结果与现场数据进行了比较。比较表明，采用保守的、通常是非特定场地的参数选择进行初步评估，与观察到的总体趋势在定性上是一致的，并提供了污染的保守估计。
