What is an acceptable composite sample?
Composite sampling must be designed to ensure that it fulfills the specific sampling objective, site characteristics, and statistical assumptions. For example, the design to derive exposure point concentrations for an ecological receptor may be substantially different from that to determine the success of a soil removal action in the same area. The number of discrete samples forming the composite must consider the expected ability to detect exceedances of the benchmark (see Carson 2001), while minimizing the error rates (see Correll 2001). The composite must be limited to discrete samples from areas where contaminants are expected to be randomly distributed and variability is expected to be low. Areas with known or expected biased distribution of contaminants (e.g., waste trenches, discharge pipes) must be sampled separately with either discrete samples or composite sampling restricted to within the biased area. Habitat type and receptor home range would still dictate whether and how d
