In environmental monitoring, wells are installed downgradient of a landfill to determine what?

• A. Yes, to determine groundwater contamination
• B. No, for other purposes
• C. Only to measure groundwater depth
• D. Only to assess surface water quality

Answer: (A)

Wells placed downgradient of a landfill exist to detect and characterize contamination in groundwater caused by leachate. Groundwater moves with the natural hydraulic gradient, so contaminants released from the landfill are most likely to reach wells placed in the downgradient direction. By sampling these wells, you determine whether contamination has occurred, how concentrated the contaminants are, and how far the plume has spread. This information is essential for assessing risk to receptors like drinking water wells and for designing any needed remedy.

While measuring groundwater depth can be done with monitoring wells, that is not the primary purpose here; the focus is on detecting and evaluating groundwater contamination. Monitoring surface water quality involves different systems and sampling, not downgradient groundwater wells.