Determination of trigger levels for groundwater quality in landfills located in historically human-impacted areas
Introduction
Groundwater often constitutes the main fresh water reservoir which is widely used for drinking, domestic, irrigation and industrial purposes. Its protection is important to ensure the fulfillment of human needs and, at the same time, to preserve its environmental values. In many countries worldwide, current national and supranational regulations try to protect groundwater resources in this perspective. For instance, the EU Water Framework Directive (EC, 2000) and Groundwater Directive (EC, 2006) aim to ensure a sustainable use of groundwater resources and to guarantee a good status of groundwater ecosystems by establishing specific measures to prevent pollution and quality deterioration.
One of the most relevant source of groundwater contamination around the world is constituted by landfills (Bjerg et al., 1995, Christensen et al., 1998, Christensen et al., 2000, Christensen et al., 2001, Han et al., 2016, Kjeldsen, 1993, Looser et al., 1999, MacFarlane et al., 1983, Rapti-Caputo and Vaccaro, 2006, Talalaj, 2014). Both unlined and lined landfills can impact groundwater by hazardous chemicals: the former due to direct leaks of leachate, the latter due to the failure of the liners (Han et al., 2014, 2016; Reyes-López et al., 2008). The EU Landfill Directive (EC, 1999) aims to prevent or reduce the negative effects of landfills on soils, surface water and groundwater. It establishes a list of requirements for a proper groundwater monitoring network in landfill sites, addressing the identification of sampling points, sampling frequency and parameters to be analyzed. Furthermore, it specifically imposes the definition of trigger levels for identifying significant adverse environmental effects on groundwater generated by the landfill. The trigger levels must be determined taking into account the specific hydrogeological and hydrochemical features of the site where the landfill is located. When a trigger level is reached and confirmed by repeating samplings, the landfill contingency plan and remediation actions should be adopted. The determination of trigger levels in landfills follows other research efforts aimed at providing groundwater quality threshold values for the management and protection of water resources, such as natural background levels and threshold values (Dalla Libera et al., 2017, Ducci et al., 2016, Hinsby et al., 2008, Rotiroti et al., 2015b) or environmental quality standards (Valsecchi et al., 2017).
The EU Landfill Directive does not specify how to calculate the trigger levels, however for newly constructed landfills, they could be easily derived from groundwater quality data of the area before the filling operations, if available. Conversely, the derivation of trigger levels becomes challenging when groundwater quality data prior to the construction of the landfill are missing and in the case of historically human-impacted areas, such as many urban environments (e.g. brownfield sites). Here, the baseline groundwater chemistry could be the product of existing and different (in space and time) anthropogenic influences on groundwater quality instead of natural processes. Therefore in these cases, high concentrations of pollution indicators measured downstream of a landfill could be the effect of historical groundwater pollution rather than leachate spills from the landfill itself and distinguishing between them is a key aspect.
The aim of this work is to present a methodology for determining trigger levels for groundwater quality in landfills located in areas where historical contaminations have already deteriorated groundwater quality and when groundwater quality data of the area before landfill construction are missing. The purpose is not only to meet the requirements of the EU Landfill Directive but also, in general, to provide a tool of wider and worldwide applicability for distinguishing between background existing contaminations and any contamination coming from a landfill, in order to better support landfill management and groundwater resources protection.
This methodology is based on multivariate statistical analysis of data measured from the existing network of wells/piezometers for monitoring the groundwater quality nearby the landfill. Several studies suggested the use of data-driven procedure in order to identify groups of well with similar hydrochemical features (Cloutier et al., 2008, Singh et al., 2005). Cloutier et al., 2008, Devic et al., 2014 successfully applied hierarchical clustering methods for the evaluation, interpretation and grouping of groundwater quality data since multivariate statistics are independent and quantitative methods. In particular, Güler et al. (2002) compared the performance of graphical and statistical methods for classifying water samples: the most efficient result was achieved by statistical clustering techniques, demonstrating that graphical techniques have limitations compared to multivariate statistics in the case of large data sets.
The presented methodology is applied to a case study in northern Italy. Here, a more recently constructed and currently used landfill is located in an area that was used in the past decades (before the implementation of environmental regulations) as an unregulated disposal site (no other possible historical contaminations of a different type affected the area). Therefore, the correct identification of the proper source of groundwater pollution that lowered the groundwater quality in the area (i.e. the more recent landfill or the older unregulated waste deposits) is challenging and requires specific tools of investigation and analysis.
Section snippets
Study area
The area under examination is located in an Alpine region in northern Italy. The study area corresponds to a dumping area (Fig. 1) that covers about 0.55 km2 and hosts: (a) a lined landfill constructed in the 1989 that is still to be filled (b) an old unlined landfill closed in the 90s and (c) other old smallest waste deposits whose the correct number and locations are unknown. The lined landfill is filled with municipal solid waste and sludge of wastewater treatment plants. It covers an area
Conceptual model
The hydrogeological information on the study area (Section 2.1; Fig. 1) indicates that the old unlined landfill is located upstream of the lined landfill, therefore it constitutes a potential source of groundwater contamination that could mask any leachate spills from the lined landfill. An overview of groundwater quality in the dumping area can be evinced from Fig. 2 that shows the mean values of COD and NH4-N in the monitoring network. These parameters can be considered as indicative of
Conclusions
This paper presented a methodology for calculating trigger levels for groundwater quality in landfills, focusing on the case of historically human-impacted areas where there are no data of groundwater quality prior to the construction of the landfill. The methodology was applied to a landfill in northern Italy that was build in an already contaminated area. More specifically, the study area was impacted by an old unlined landfill and some old unregulated and unmapped waste deposits.
The
References (46)
- et al.
Organic indicators of groundwater pollution by a sanitary landfill
Water Res.
(1986) - et al.
Characterization of the dissolved organic carbon in landfill leachate-polluted groundwater
Water Res.
(1998) - et al.
Characterization of redox conditions in groundwater contaminant plumes
J. Contam. Hydrol.
(2000) - et al.
Biogeochemistry of landfill leachate plumes
Appl. Geochem.
(2001) - et al.
Multivariate statistical analysis of geochemical data as indicative of the hydrogeochemical evolution of groundwater in a sedimentary rock aquifer system
J. Hydrol.
(2008) - et al.
Geostatistics as a tool to improve the natural background level definition: an application in groundwater
Sci. Total Environ.
(2017) - et al.
Natural and anthropogenic factors affecting the groundwater quality in Serbia
Sci. Total Environ.
(2014) - et al.
Combining natural background levels (NBLs) assessment with indicator kriging analysis to improve groundwater quality data interpretation and management
Sci. Total Environ.
(2016) - et al.
Evaluation of the impact of an uncontrolled landfill on surrounding groundwater quality, Zhoukou, China
J. Geochem. Explor.
(2014) - et al.
A review of groundwater contamination near municipal solid waste landfill sites in China
Sci. Total Environ.
(2016)
European case studies supporting the derivation of natural background levels and groundwater threshold values for the protection of dependent ecosystems and human health
Sci. Total Environ.
Groundwater pollution source characterization of an old landfill
J. Hydrol.
A review of approaches for the long-term management of municipal solid waste landfills
Waste Manage.
Landfill underground pollution detection and characterization using inorganic traces
Water Res.
Redox zones of a landfill leachate pollution plume (Vejen, Denmark)
J. Contam. Hydrol.
Migration of contaminants in groundwater at a landfill: A case study
J. Hydrol.
Geochemical evidences of landfill leachate in groundwater
Eng. Geol.
Assessment of groundwater contamination by landfill leachate: a case in México
Waste Manage.
COMPSEC, a new tool to derive natural background levels by the component separation approach: application in two different hydrogeological contexts in northern Italy
J. Geochem. Explor.
Pollutant sources in an arsenic-affected multilayer aquifer in the Po Plain of Italy: Implications for drinking-water supply
Sci. Total Environ.
Water quality assessment and apportionment of pollution sources of Gomti river (India) using multivariate statistical techniques—a case study
Anal. Chim. Acta
Deriving environmental quality standards for perfluorooctanoic acid (PFOA) and related short chain perfluorinated alkyl acids
J. Hazard. Mater.
Distribution of redox-sensitive groundwater quality parameters downgradient of a landfill (Grindsted, Denmark)
Environ. Sci. Technol.
Cited by (16)
Transport of pollutants in groundwater of domestic waste landfills in karst regions and its engineering control technologies
2023, Journal of Environmental ManagementTangerine, banana and pomegranate peels valorisation for sustainable environment: A review
2021, Biotechnology ReportsCitation Excerpt :These landfills represent serious threats to the environment [93–95]. Landfill sites can cause environmental pollution such as pollution of surface water, groundwater, air and soil [96–99]. Agricultural wastes in general contain a very important quantity of organic matter, after their disposal in landfills, the decomposition of agricultural wastes due to landfill microorganisms causes a change in their chemical composition resulting the production of many pollutants through leachates and landfill gases composed of CO2, CH4, CO, H2S and others [95,100].
Assessment of the environmental impact of sanitary and unsanitary parts of a municipal solid waste landfill
2020, Journal of Environmental ManagementCitation Excerpt :To better understand the sources and potential risks of soil pollution, the following methods were applied: geo-accumulation index (Igeo) (Müller, 1979), ecological risk index (ERi) (Hakanson, 1980), toxic equivalent factors and specific PAH ratios (Nisbet and LaGoy, 1992; Lima et al., 2005; Mzoughi and Chouba, 2011). These indices were all selected as appropriate quality assessment methods because they were previously used and validated by several other studies, are easily adjustable and adaptable, and are fairly easy to implement for development of overall landfill risk assessment methodology, in comparison to other methods such as multivariate statistical analysis (Stefania et al., 2018), analysis of tracers (Roy et al., 2014), microbiological analysis (Preziosi et al., 2019) etc. Monitoring results were also compared with the standard values from the appropriate national and international regulations.
Groundwater pollution assessment in landfill areas: Is it only about the leachate?
2020, Waste ManagementIdentification of groundwater pollution sources in a landfill site using artificial sweeteners, multivariate analysis and transport modeling
2019, Waste ManagementCitation Excerpt :This site, located in northern Italy, hosts an older unlined landfill and a newer lined MSW landfill, thus making the assessment of pollution sources a challenging task. A preliminary hydrochemical characterization of the area (Stefania et al., 2018a, 2019) showed that the old unlined landfill likely affects groundwater quality, however, other unknown sources have to be considered as well, and properly identified to address remediation strategies. The main aim of this work is to identify the sources of leachate pollution affecting the study area using a multi-methods approach, which integrates the use of artificial sweeteners as tracers with standard hydrochemical measurements, multivariate statistical analysis and transport modeling.