Where, When, and Why is composite sampling used?
Composite sampling can improve spatial or temporal coverage of an area without increasing sample number. As the resulting information on contaminant extremes and variability is substantially reduced compared to discrete sampling, the appropriateness of composite sampling is dependent upon the sampling objectives and the site characteristics. Project managers and risk assessors should consult with the BTAG, a statistician, and possibly other technical specialists when developing a sampling plan that includes composite sampling for the following purposes: • to obtain data for ecological risk assessments, • to determine the extent of receptor exposure, • to develop ecological PRGs, • to determine the areal extent to which an ecological PRG will be applied, or • to demonstrate compliance with ecological remedial objectives. Composites are appropriate for inorganic contaminants and persistent, nonvolatile organic compounds such as PCBs (EPA 1991) in all media and biota under the following c
