Soil contamination is often distributed unevenly across a site, making it challenging to obtain representative results using traditional discrete sampling methods. Incremental sampling methodology (ISM) addresses this issue by collecting multiple soil increments from a defined area and combining them into a single sample that is processed using standardized procedures. By increasing sample representativeness and reducing data variability, incremental sampling methodology provides a more reliable estimate of average contaminant concentrations and supports stronger environmental decision-making.
To help practitioners understand and apply this approach, ITRC published the Incremental Sampling Methodology (ISM-1, 2012) guidance. Developed by a team of national experts, the guidance evaluates the performance, explains sampling design and laboratory considerations, and discusses its applicability to different contaminants and site conditions. The document outlines the strengths and limitations of incremental sampling methodology and provides recommendations for using the methodology to support more consistent, defensible environmental investigations. The Clarifications to ITRC 2012 ISM-1 Guidance (2020) was later issued to address information that was updated or refined in the more recent Incremental Sampling Methodology Update (ISM-2, 2020) guidance.
Topic(s): Incremental Sampling Methodology, Remediation Technologies, Sediments, Soil Background, Soils
