Groundwater monitoring can be used only if the stored product does what relative to water?

• A. Dissolves in water
• B. Sinks to bottom
• C. Does not mix easily with water and floats on the surface
• D. Reacts with water

Answer: (C)

Groundwater monitoring relies on detecting a distinct contaminant phase rather than a dissolved or reacting substance. When the stored product does not mix with water and floats on the surface, a leak will create a separate liquid layer at the water table that can be found by monitoring wells and surface indicators. This makes leaks detectable and trackable. If the product dissolves in water, sinks, or reacts with water, it won’t form that easy-to-see, recoverable layer, making leaks harder to identify with standard groundwater monitoring.