What should purge volumes be calculated in accordance with?

Purge volumes should be calculated in accordance with the sampling plan because the sampling plan outlines the specific protocols and procedures to be followed during water sampling activities. The sampling plan takes into account factors such as the purpose of sampling, the specific pollutants of interest, and how to ensure the collected data is representative of the groundwater conditions.

When properly following the sampling plan, purge volume calculations typically consider the well's geometry and the desired volume of water necessary to achieve equilibrium in the well, ensuring that the water sample collected reflects the actual conditions in the aquifer. Adhering to a well-defined sampling plan helps standardize procedures and ensures that the collected samples are reliable and valid for analysis.

In contrast, while the water level in the well, the age of the well, and the type of soil present may influence other aspects of groundwater monitoring, they do not directly guide the calculation of purge volumes in the context of effective sampling practices.