What does a "paste tape wheel" measure?

A "paste tape wheel" is specifically designed to measure the thickness of free product in environments where it has accumulated, such as in groundwater monitoring for underground storage tank (UST) assessments.

When using a paste tape wheel, the tape is coated with a material that changes color or texture when it comes into contact with petroleum products or other free-phase liquids. This allows the user to determine how thick the layer of free product is over the water table, which is essential for calculating the extent of contamination and understanding potential environmental impacts.

The other options pertain to measuring different variables that are not related to the function of a paste tape wheel. pH levels pertain to acidity or alkalinity, soil compaction relates to the density of soil, and temperature measures the thermal state of groundwater, none of which fall within the capabilities of a paste tape wheel. Therefore, when assessing free product in relation to USTs, this tool is crucial for accurate measurements.