The Incremental Sampling Methodology (ISM) document describes the principles and the approaches needed to ensure representative, reproducible, and defensible data during soil sampling. ISM involves planning, sample collection, and laboratory processing and analysis to provide a representative sample with results that more accurately reflect the mean concentration of the area of interest than discrete samples. The ISM document provides you the key principles regarding sampling and sampling error and how ISM reduces those errors so that you can have more confidence in your sampling results.
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This updated Incremental Sampling Methodology (ISM-2) web-based document builds upon the 2012 version (ISM-1) and reflects advancements in technology in the ensuing eight years. ISM-type investigation methods have evolved, and regulators have gained more experience in the application of ISM in the field and in the laboratory. The original 2009 survey of regulators and industry environmental experts was updated with current information on ISM practices to measure progress and understand what obstacles are still being encountered.
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The updated document includes multiple examples of site scenarios for DU designation and the collection of ISM samples under different field conditions. A separate section on the use of ISM investigation methods to support human health and ecological risk assessments has been added and the simulations in the original appendices have been updated and include a recent study on Student t and Chebyshev discussion of UCL. Current case studies are summarized to provide insight into the potential applications, benefits, and challenges of the approach from recent sites.
An updated ITRC guidance (ISM-2) was developed and posted in the fall of 2020. The ISM-2 Update Team clarified inappropriate or inconsistent information in ISM-1 is as seen in the attached statement. Please review this document before downloading the ISM-1 PDF.
ISM is increasingly being used in the environmental field for sampling contaminants in soil. Proponents have found that the sampling density afforded by collecting many increments, together with the disciplined processing and subsampling of the combined increments, in most cases yields more consistent and reproducible results than those obtained by more traditional (i.e., discrete) sampling approaches.
In 2009, ITRC established a technical team to evaluate ISM for sampling soils at hazardous waste sites and potentially contaminated properties. The ISM Team convened national experts in fields such as toxicology, risk assessment, statistics, and soil sampling. This 2012 guidance analyzes ISM performance, identifies considerations for unique laboratory processes and procedures, evaluates the suitability of ISM to various contamination scenarios and contaminant categories, and identifies the strengths and weaknesses of ISM.