Groundwater is a precious natural resource. However, its vulnerability is often overlooked because in Western-Europe it is easy to use, cheap and abundant. But slowly our groundwater is turning grey: even when soil remediation and groundwater quality standards are formally met, groundwater is gradually impacted by decades of industrial and agricultural activities. Consequently, at numerous water production wells, quality has dropped below acceptable levels, already. This means that additional treatment steps are required before the groundwater can be used for industrial processes or drinking water purposes; with significant -financial- consequences for users. In this session we are zooming in on the origin of the problem, parties confronted with the problem and solutions.
The origin of the problem may be easily summarized as a result of wide-spread industrial and agricultural activities. As specific sources of contamination could be mentioned:
• the use of nutrients for fertilization and pesticides by farmers,
• residues of medicines, hormones, microplastics and Teflon coating flushed via the sewage system to surface waters by consumers,
• former landfills,
• other soil contaminations which are not complete removed,
By groundwater flow, contaminants migrate over time and cause deterioration of vast and growing volumes of groundwater. The process is facilitated by activities in the underground, like injudicious use of aquifer thermal energy storage (ATES) systems, which could perforate aquitards and enhance contaminant migration. See figure 1.
This is only one part of the story. As awareness on environmental issues evolved at the end of last century, many successful programs were carried out to protect the groundwater. Soil and groundwater remediation and emission restrictions contributed to that goal. Plans were made for smart combinations of activities such as ATES integrated with groundwater remediation. However, due to presumed enormous future costs, many actions needed were not taken. Policy changes often interfered with actual remedial and protection measures; on paper solutions were found but in reality, problems were not resolved. So, now we realize that our groundwater is going grey.