Contaminant Transport Assessment
At Geo Costa Rica, we conduct contaminant transport assessments to estimate how and how long a substance may take to migrate from a potential contamination source to groundwater and, where applicable, to a well, spring, or other sensitive receptor.
Assessing the potential migration of contaminants toward groundwater
A contaminant transport assessment estimates the potential pathway and travel time of a substance from a source at the surface or underground to the aquifer and, where relevant, a receptor such as a well or spring.
Could the contaminant reach groundwater or a water abstraction point within a relevant timeframe?
To answer this, the assessment integrates site conditions, aquifer characteristics, and contaminant properties. It considers more than infiltration: the subsurface may delay, attenuate, or facilitate contaminant transport.
The analysis may consider two stages: migration through the unsaturated zone and movement within the saturated zone, where the contaminant may move toward a receptor along the groundwater flow path.
Travel time from the source to the water table
The unsaturated zone is the first medium a contaminant must pass through before reaching the aquifer. Its thickness and characteristics strongly influence the arrival time.
Arrival time depends on the site's natural protection
This stage examines how quickly or slowly the substance could move through soil and the unsaturated subsurface before reaching groundwater.
- Thickness of the unsaturated zone.
- Lithology and subsurface materials.
- Porosity and hydraulic conductivity.
- Depth to groundwater.
- Conditions that facilitate or hinder infiltration.
Depending on the case, the analysis may use existing records, field observations, lithological logs, piezometers, geophysics, or other supplementary investigations.
Contaminant migration through the aquifer toward a receptor
Once a contaminant reaches the saturated zone, the analysis focuses on how it may move through the aquifer and whether it could reach a well, spring, or other sensitive location.
Reaching the aquifer is not enough: the direction of movement matters
The assessment may estimate transport through the aquifer based on groundwater flow direction, distance to the receptor, and the substance's behavior in the saturated medium.
The report integrates the source, hydrogeological setting, and receptor
The goal is not merely to obtain a number, but to develop a technical interpretation of potential contaminant transport and its significance for the project or activity under assessment.
Main assessment variables
- Potential contamination source or scenario assessed.
- Characteristics of the unsaturated zone.
- Hydraulic characteristics of the aquifer.
- Potential pathway toward a receptor.
- General behavior of the contaminant.
Technical input for evaluation and decision-making
- Estimated travel time through the unsaturated zone.
- Estimated potential transport through the saturated zone.
- Relationship between source, aquifer, and receptor.
- Technical interpretation of the scenario assessed.
- Recommendations where applicable.
Water transports; the medium may retard; contaminants may degrade
The assessment integrates these processes to evaluate whether a substance might reach groundwater or a receptor before being attenuated, degraded, or losing technical significance.
When is a Contaminant Transport Assessment useful?
This report can be particularly useful when an activity, infrastructure, or site condition requires evaluation of its potential interaction with groundwater.
Treatment or disposal systems
When it is necessary to assess whether a contaminant load from wastewater-related works or activities could reach the aquifer.
Tanks, fuels, or potential spills
When evaluating the potential pathway of substances associated with fuel storage, handling, or accidental release.
Agricultural activities or sensitive land uses
It can help evaluate potential contaminant mobility in areas where surface activities require special attention.
Wells, springs, or aquifers of concern
When the primary concern is whether a source could affect a water abstraction point or part of an aquifer within a relevant timeframe.
Contaminant transport assessments can be complemented by other hydrogeological studies
Common questions about contaminant transport
Can this assessment determine whether a contaminant may reach an aquifer?
Yes. The assessment can estimate the potential pathway and travel time from the source to groundwater and, where relevant, a specific receptor.
Is this the same as an infiltration test?
No. Infiltration data may be useful, but contaminant transport also considers aquifer characteristics, groundwater flow direction, distance to the receptor, and contaminant behavior.
Does there always need to be a well or spring for this assessment?
Not necessarily. In some cases, the main concern is arrival at the aquifer; in others, the relationship to a water abstraction point or another sensitive receptor is central to the analysis.
Is the result an exact, unchanging travel time?
No. The assessment uses technical parameters and assumptions to estimate transport scenarios. Interpreting the result is therefore as important as the calculation itself.
Request Your Contaminant Transport Assessment
Geo Costa Rica conducts studies of potential contaminant movement toward groundwater, integrating the source, hydrogeological medium, receptor, and technical interpretation criteria.