A critical aspect of characterization of the amount and species of contamination of a hazardous waste site is the sampling plan developed for that site. If the sampling plan is not thoroughly conceptualized before sampling takes place, then certain critical aspects of the limits of the contamination may be ignored. If a contaminant has both a petroleum and a heavy metal component there may be a separation of components in the subsurface because of interaction with the mineral matter contained in the subsurface environment. The paper presents a discussion of some strategic sampling questions that should be addressed before going into the field to collect data.