Groundwater Contamination
We assess the relationship between potential contamination sources, subsurface characteristics, and aquifer behavior to understand how contaminants may reach, migrate through, or persist within the groundwater system.
A potential source does not necessarily mean the aquifer is affected
For a substance to reach groundwater, there must be a connection between its point of origin, the soil, the subsurface, and the aquifer system. Understanding that pathway is essential to assess whether a risk exists and which areas may warrant closer attention.
It starts with a potential origin
Fuel, wastewater, chemicals, waste, and other activities may represent potential sources of contamination, depending on their characteristics, management, location, and site conditions.
The subsurface controls movement
Soil, the unsaturated zone, geology, fractures, and the presence of water determine whether a substance can move deeper and how readily it may do so.
Aquifers may include sensitive features
Wells, springs, and groundwater abstraction areas may be relevant when they are hydrogeologically connected to the location of a potential contamination source.
A contaminant's pathway depends on subsurface conditions
A substance released at the surface may infiltrate and move through soil and the unsaturated zone before reaching the water table.
Retention, degradation, dispersion, and transport processes may occur along the way. Their behavior depends on the characteristics of the geological medium, groundwater, and the substance involved.
Therefore, the presence of a potential source does not, by itself, demonstrate aquifer contamination. The conditions that could enable or restrict contaminant movement must be evaluated.
Distance alone does not explain risk
A source close to a well does not necessarily present the same conditions as another source at the same distance in a different geological setting.
Proper interpretation requires consideration of groundwater depth, groundwater flow direction, geological materials, permeability, fractures, and the properties of the substance involved.
Assessment involves more than identifying a source and measuring distance. We need to understand whether a plausible hydrogeological pathway exists between the potential source and the groundwater resource we seek to protect.
Factors controlling potential groundwater impacts
We examine the characteristics of the potential source, the properties of the substance involved, and the hydrogeological conditions that determine whether a possible pathway to the aquifer or relevant water abstractions exists.
Origin and characteristics of potential contamination
We examine where the source is located, the activity generating it, how it is managed, and any history of spills, leaks, infiltration, or other conditions that could allow substances to enter the subsurface.
Properties influencing mobility
Where information is available, we consider the properties of the substance involved, since solubility, persistence, density, and other characteristics can affect how it moves or remains in the subsurface.
Soil and subsurface between the source and aquifer
We assess the thickness, composition, permeability, and other properties of the materials separating the ground surface from groundwater, which may delay, alter, or facilitate substance movement.
Geology, fractures, and preferential pathways
We consider geological units, structures, fractures, and permeability contrasts that can control water movement and create preferential transport pathways in the subsurface.
Groundwater levels and flow direction
Groundwater depth and the spatial distribution of hydraulic heads help us interpret where a substance could move after reaching the saturated zone and which areas are hydrogeologically connected.
Wells, springs, and other features of interest
We identify water abstractions and hydrogeological features whose locations and connections to the system may be relevant to assessing potential impacts and prioritizing investigation or protection.
What happens if a substance reaches groundwater?
Once a substance reaches the saturated zone, its movement may depend on groundwater flow direction and velocity, geological properties, and the characteristics of the contaminant.
Transport is not necessarily uniform. Advection, dispersion, diffusion, retention, and transformation may affect how substances are distributed and their concentrations.
Understanding these processes helps assess possible transport pathways and identify wells, springs, or other receptors requiring more detailed evaluation.
Risk depends on how several factors are connected
A potential source can present very different conditions depending on the substance, groundwater depth, geology, and receptor locations.
We therefore integrate these elements into a single conceptual model rather than examining each variable in isolation.
The presence of a potential source is only the starting point. A hydrogeological assessment seeks to determine whether a plausible pathway exists, what conditions control movement, and which receptors may be relevant within the system.
We reconstruct the connection between the source and groundwater system
The investigation begins by identifying what happened, where the potential source is located, and how the hydrogeological setting functions. This information supports an interpretation that guides the necessary checks and technical studies.
We identify the source and its history
We review the activity carried out, substances involved, facility locations, past leaks or spills, existing management systems, and other information that helps reconstruct the potential source of contamination.
We interpret subsurface conditions
We integrate geology, topography, groundwater levels, well records, unsaturated-zone conditions, and likely groundwater flow direction to identify possible migration pathways.
We verify relevant conditions
When warranted, we supplement the interpretation with field reconnaissance, measurements, monitoring points, sampling, or other targeted studies to verify the identified conditions.
We first develop a hydrogeological hypothesis
Not every situation requires an extensive sampling or drilling campaign at the outset. The investigation is designed around an initial interpretation of the source, transport medium, and potential receptors.
This approach focuses verification efforts where they provide useful information and allows the conceptual model to be progressively refined as new data become available.
The investigation should follow the potential contamination pathway. The goal is to determine which connections are hydrogeologically plausible and obtain the information needed to confirm, rule out, or delineate the situation under investigation.
Assessing situations that may compromise groundwater
Hydrogeological investigation helps determine whether a potential source may be connected to an aquifer, identify sensitive receptors, and define what additional information is needed to guide decisions.
Investigating a potential contamination source
Following a spill, leak, or substance loss, we can assess its location, subsurface conditions, and relationship to groundwater to determine which migration pathways require evaluation.
Gas stations and storage systems
Tanks, piping, and fuel-handling areas may call for a hydrogeological assessment to understand site conditions and potential connections to wells, springs, or the aquifer.
Treatment and infiltration systems
Septic systems, treatment plants, drainage systems, and other disposal methods can be assessed in relation to groundwater depth, ground permeability, and aquifer vulnerability.
Industry, workshops, and substance handling
Facilities using or storing chemicals, oils, solvents, or other substances may require an assessment of their location and site-specific hydrogeological conditions.
Assessing potential impacts on wells or springs
When a potential source is near a water abstraction point, we assess spatial relationships and hydrogeological connectivity to determine whether further investigation or control measures are needed.
Defining monitoring and control points
When ongoing follow-up is needed, hydrogeological interpretation helps select monitoring locations and parameters consistent with groundwater flow direction.
Not all situations require the same level of intervention
A potential source may require only an initial assessment or, depending on conditions, a more detailed investigation involving measurements, sampling, or monitoring.
Hydrogeological analysis supports a proportionate sequence of work and focuses efforts on the pathways and receptors that are genuinely relevant.
An effective investigation should focus on plausible hydrogeological connections. Understanding the source, pathway, and receptors helps determine the actions, studies, or controls actually needed in each case.
Technical studies to investigate potential impacts
Depending on the source, hydrogeological conditions, and receptors involved, the assessment can be expanded through targeted studies addressing aquifer sensitivity, substance transport, or groundwater protection.
Contaminant Transport Assessment
Examines how a substance could migrate from a potential source toward groundwater, considering the unsaturated zone, geological characteristics, groundwater flow, and potential receptors.
Explore this studyAquifer Vulnerability Assessment
Assesses how susceptible an aquifer is to substances entering from the surface, considering the natural characteristics of the soil, subsurface, and groundwater.
Explore this studyWater Source Protection Zone Delineation
Identifies areas requiring attention around abstraction points or other relevant hydrogeological features, using technical criteria related to groundwater system behavior and protection.
Explore this studyThe investigation is defined by the question we need to answer
A potential contamination source does not automatically mean every type of study is necessary. The scope depends on the existing information and conditions identified at the site.
Depending on the case, we may begin by assessing aquifer sensitivity, investigate a potential transport pathway in greater depth, or define protection measures around a receptor.
The investigation should build on the available evidence. The goal is to select the study needed to confirm, rule out, or delineate a potential impact, without unnecessary analyses unrelated to actual site conditions.
Do you need to assess a potential groundwater impact?
We can review the history of the potential source, site hydrogeological conditions, and the locations of wells, springs, or other receptors to determine the appropriate level of investigation.