With proper identification of sampling goals and use of the systematic planning process, an ISM sampling design can be created to identify specific areas of high contaminant concentration within an area of interest (DU) (see Figure 8-7). However, a significant percentage of survey respondents either felt that ISM cannot accomplish this goal or were undecided. This opinion was particularly pronounced in responses by regulators relative to nonregulators respondents.
Figure 8-7. Survey responses for the statement "ISM is ineffective because it cannot identify specific areas of high concentration."
As described in Section 4.3, an ISM sampling plan can be designed to collect information about contaminant distribution variability and provide input for conventional risk assessment calculations. About 30% of regulators and 46% of nonregulators are undecided whether this is the case (Figure 8-8).
Figure 8-8. Survey responses for the statement "incremental sampling cannot be used for risk assessment because it does not address variability."
As stated in Section 2, the contaminant concentration reported by the lab is a ratio of the mass of contaminant measured to the total mass of the analytical subsample. Approximately 47% of respondents disagree that contaminant concentrations are related to the amount of the soil sample (see Figure 8-9).
Figure 8-9. Survey responses for the statement "contaminant concentration depends on the amount of soil sample."
Figure 8-10. Survey responses for the statement "ISM is generally more expensive than conventional discrete sampling."
Although an important element of ISM is sample processing procedures that are typically employed prior to sample analysis, there appears to be a significant level of misunderstanding regarding this issue. Over half of regulator survey respondents were either undecided or disagreed that these additional measures are commonly needed (see Figure 8-11).
Figure 8-11. Survey responses for the statement "Incremental samples commonly require additional laboratory sample preparation."