5.1 Introduction

Section 2 discussed some of the common sources of sampling error. To obtain representative field samples, sampling error must be limited or managed (Ramsey and Hewitt 2005). In the absence of error, a sample result by definition would be accurate. However, it is impossible to completely eliminate error and produce an accurate result unless the soil in the entire DU is included in the analytical determination, which is obviously impractical. Thus, limiting sampling error is a critical function of any sampling design and implementation. This section addresses those field practices that limit or manage sampling error and provides guidance for obtaining representative samples. It should be noted that for many types of contaminants (e.g., metals, VOCs, semivolatile organic compounds [SVOCs]) specific studies have not been conducted to evaluate the applicability of all of the approaches discussed in this section and in Section 6.

To help ensure data quality, all field sampling and field processing activities should be performed and supervised by personnel trained in ISM. Figure 5-1 is a flowchart for ISM field implementation.

Figure 5-1. Field sampling implementation flowchart.