Understanding A CSM – Using On-Site Testing to Strategically Fill Data Gaps

The Triad approach is a set of three strategies, supported by the US EPA, which is widely recognized as the proven modern standard for characterizing and remediating impacted sites. While Canadian regulation does not specifically rely on the Triad approach (although it may introduce similar regulation at some point), Canadian best practices do favour the efficient use of on-site testing and dynamic approaches to site management, as defined in the Triad approach.

When filling the data gaps identified in a conceptual site model (CSM) as part of obtaining a record of site condition (RSC) for a property, the Triad approach gives several distinct advantages in efficiency and accuracy. To learn more about a CSM or data gaps, visit the linked posts.

The foundation of the Triad approach is a CSM which forms the basic understanding and assumptions that the investigative team has regarding the site. The CSM must be accurate in order to reliably direct the team in their investigation. Using the Triad approach in CSM development minimizes uncertainties in site characterization and cleanup that could prove costly to all stakeholders.


The three elements of the Triad approach are:

1. Systematic Project Planning – the planning process, completed at the initiation of an environmental site assessment, lays a foundation that is scientifically defensible and is supported by fact and regulation. This is important for uniting and developing trust between all stakeholders. It is also the stage at which project goals are identified, a CSM can be developed, and uncertainties are evaluated.

2. Dynamic Work Plans – this part of the Triad approach emphasizes the development of documents or strategies that are based on the CSM, but allow the project to be guided by real-time results as new information becomes available. This involves creating a set of criteria and then relying on personnel in the field to make decisions responsibly, based on the information they gather during the investigation.


3. Real-time Measurement Technologies – Work in the field involves the use of on-site testing, providing results within minutes. This allows the investigative team to gain a high quantity of data points from locations of their choice in a short amount of time, promoting efficiency and accuracy. On-site testing allows high accuracy in development of a detailed CSM, which forms the basis for decision making in the field.

An important foundation of the Triad approach is proactively investing in new site characterization and treatment tools. Innovative technologies that can be used in situ to characterize a site can save time and money. Cheaper analytical methods performed in the field, such as XRF analysis, can be used to greatly increase the number of samples that can be tested at a site, thus increasing the volume or area of a site that would otherwise not be tested. Increased volumes of sample results help close data gaps in the CSM, reducing uncertainties. This field data can help identify those samples that will require submission to an accredited lab facility, which will provide analyte-specific results with lower detection limits that will meet the rigorous standards of Ontario regulations (O. Reg. 153).

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