II Application of geophysical methods for waste landfill characterisation and contamination monitoring Flashcards
Why is groundwater contamination a critical issue in waste landfills?
Groundwater contamination occurs when harmful chemicals and pollutants from landfill leachate seep into the water table. Leachate, a mix of organic matter, heavy metals, and xenobiotic organic compounds, poses significant environmental and public health risks by potentially spreading toxic substances into drinking water sources
How does geophysics help in waste landfill characterisation compared to traditional methods like drilling?
Geophysics offersnon-invasivetechniques that provide large-scale coverage of the subsurface without the need for extensive drilling. This reduces the risk of cross-contamination, minimizes damage to the environment, and is generally more cost-effective than drilling, which can be expensive and only provides localized information
What are the key advantages and limitations of using geophysical methods for landfill monitoring?
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Advantages:
- Non-invasive, minimizing environmental disruption.
- Cost-effective, especially for large areas.
- Provides a broader spatial view of subsurface conditions.
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Limitations:
- Resolution decreases with depth.
- Interpretation can be prone to errors (artifacts).
- Requires combination with traditional data for better accuracy
What geophysical techniques are commonly used for landfill site investigations, and how do they complement each other?
Electrical Resistivity Tomography (ERT)andInduced Polarization (IP)are commonly used. ERT measures subsurface resistivity to detect material contrasts, while IP helps identify electrochemical properties, such as the presence of contaminants. When combined, these methods provide a more comprehensive understanding of the landfill’s composition
Describe the steps in the geophysical workflow for landfill assessment.
- Step 1: Archives & Inventory: Gathering historical data and building a conceptual model.
- Step 2: Geophysical Characterization: Using methods like ERT and EMI to gather subsurface data.
- Step 3: Targeted Sampling: Conducting sampling based on geophysical results, reducing risks and costs.
- Step 4: Resource Model Construction: Building a detailed model of the landfill to understand waste distribution and contamination
How does electrical resistivity tomography (ERT) differ from induced polarization (IP), and why are they often used together?
ERTmeasures the resistivity of subsurface materials, identifying contrasts between waste, soil, and bedrock.IPdetects electrochemical properties that can highlight the presence of clays, ore bodies, or contaminants. Using them together provides a more complete picture, as ERT identifies material composition while IP gives insights into chemical properties
In what ways do geophysical methods reduce risks in landfill investigations?
Geophysical methods reduce the need for extensive drilling, minimizing the potential for cross-contamination or damaging underlying structures. They also allow for more targeted sampling, which reduces exposure to hazardous materials
What was the main goal of the geophysical investigation at the Onoz landfill?
The main goals were to estimate the extent and boundaries of the waste, identify the layers of ash and lime deposits, and assess the presence of leachate. The investigation aimed to map the site’s contamination risks and provide data for targeted remediation efforts
What are the main environmental hazards associated with old landfills, as highlighted in the presentation?
Old landfills often leach harmful pollutants into groundwater, contributing to contamination. Hazardous elements like heavy metals and organic compounds in leachate pose long-term risks to human health and the environment, and many old landfills were not designed with proper containment systems
