Which option is NOT a geophysical method typically used to sense hazardous waste underground?

Which option is NOT a geophysical method typically used to sense hazardous waste underground?

• A. Metal detection
• B. Ground-penetrating radar
• C. Resistivity
• D. Paint filter test

Answer: (D)

Sensing hazardous waste underground relies on measuring physical properties of the subsurface so we can see anomalies without disturbing the ground. The paint filter test doesn’t do that—it’s a simple lab screening used to decide if a waste sample contains free liquids for regulatory purposes. It tells you about the liquid content of a material, not about conditions beneath the soil or rock. In contrast, metal detection, ground-penetrating radar, and resistivity all probe subsurface properties: metal detection uses electromagnetic fields to locate buried metal objects, ground-penetrating radar sends radar waves and analyzes reflections to image buried features, and resistivity measures how easily electric current flows through the ground to infer moisture or contaminant-filled zones. So the paint filter test is not a geophysical method for sensing underground waste, which is why it’s the correct choice.

Sensing hazardous waste underground relies on measuring physical properties of the subsurface so we can see anomalies without disturbing the ground. The paint filter test doesn’t do that—it’s a simple lab screening used to decide if a waste sample contains free liquids for regulatory purposes. It tells you about the liquid content of a material, not about conditions beneath the soil or rock. In contrast, metal detection, ground-penetrating radar, and resistivity all probe subsurface properties: metal detection uses electromagnetic fields to locate buried metal objects, ground-penetrating radar sends radar waves and analyzes reflections to image buried features, and resistivity measures how easily electric current flows through the ground to infer moisture or contaminant-filled zones. So the paint filter test is not a geophysical method for sensing underground waste, which is why it’s the correct choice.