Guide to Groundwater Sampling
Why is Groundwater Sampling Essential?
Phases of Groundwater Sampling
1. Definition of the Hydrogeological Model
Before starting the sampling process, it is necessary to define the hydrogeological model of the study area. This is done by collecting and analyzing existing data, followed by direct field tests on the aquifer to identify key hydrogeological parameters, such as the direction of groundwater flow and the potential migration of pollutants.
2. Environmental Investigations and Piezometric Surveys
The most common environmental investigations are carried out using piezometers, which are observation wells for the aquifer. These tools allow you to:
• Measure the groundwater level directly.
• Collect samples for chemical-physical analyses.
Piezometers are made up of a tube sealed at both ends (removable at the top) and inserted into a sounding hole. To measure the depth of the water table relative to the topographic surface, a water level meter (freatimeter) is used. This measurement must be taken before any other operation to ensure its reliability.
3. Measurement of Chemical-Physical Parameters
During groundwater sampling, several essential parameters are analyzed:
• Temperature
• pH
• Dissolved oxygen
• Electrical conductivity
• Oxidation-reduction potential (ORP)
These measurements must be taken quickly to avoid alterations caused by exposure to the atmosphere, using equipment such as multiparameter probes.
4. Groundwater Sampling Techniques
To obtain a representative sample, it is necessary to purge the piezometer, removing either 3 to 5 times the volume of water present inside the piezometric tube or reaching the stabilization of the chemical-physical parameters.
Common sampling tools include:
• Submersible pumps
• Manual samplers (e.g., bailers)
The number of samples to be taken is determined based on the site characteristics and in agreement with the analytical laboratory.
5. Sample Preservation and Analysis
To ensure the reliability of the analysis, the samples must be properly preserved:
• Use suitable containers depending on the type of contaminant.
• Maintain a temperature of 4°C.
• Avoid exposure to heat sources and contamination.
The substances to be analyzed and the concentration limits are established by current regulations (Legislative Decree 152/2006 and Provincial Regulation D.G.P. 1072/2005 – Province of Bolzano). It is not always necessary to analyze all the compounds listed in the legislation; selection is made based on the site’s history and its environmental characterization.
Groundwater sampling is a critical step for environmental monitoring and the protection of water resources. If you need to carry out sampling and check the status of the groundwater at your site, contact us — we’ll send a qualified technician and handle the entire analysis process.