ISO 18400-202:2018

Overview

ISO 18400-202:2018 - "Soil quality - Sampling - Part 202: Preliminary investigations" provides guidance for designing and executing preliminary investigations whenever soil sampling or site investigations are required to determine soil quality. Published by ISO in 2018, this standard focuses on non-intrusive preparatory work: desk studies, site reconnaissance (walk-over surveys), and where relevant, preliminary risk assessment. The outcome is a first-stage conceptual site model that informs whether and how intrusive sampling or remedial work is needed.

Key topics and requirements

• Mandatory preliminary investigation: A Phase I investigation is required before any intrusive sampling.
• Two-step data collection: Desk study (including consultations and archive/database searches) followed by site reconnaissance.
• Conceptual site model (CSM): Synthesize all known information about the site - geology, pedology, hydrogeology, past and present land use, potential contaminant sources, pathways and receptors - and explicitly record uncertainties.
• Phased, iterative approach: Use preliminary findings to decide on exploratory and detailed investigations; revisit the CSM as new data arrive.
• Data quality objectives (DQOs): Define the type, quantity and quality of information needed up front to ensure investigation outputs support intended decisions.
• Preliminary risk assessment: Where contamination is suspected, formulate hypotheses on contaminant nature, location and distribution to guide further work.
• Reporting: Document desk study results, site reconnaissance observations and the preliminary CSM to support planning and regulatory dialogue.

Practical applications and users

ISO 18400-202 is practical for professionals and organizations involved in land assessment, redevelopment and environmental due diligence:

• Environmental consultants and site investigation teams use it to plan effective field programs.
• Developers, brownfield project managers and landowners rely on the standard to scope risk-based site assessments and avoid unnecessary intrusive work.
• Regulators and remediation contractors use the preliminary CSM and desk study outputs to evaluate compliance, permit needs and remediation options.
• Geotechnical engineers and urban planners benefit from early identification of subsurface constraints affecting design and construction.

Typical uses include Phase I site assessments, pre-purchase environmental due diligence, planning for remediation, and informing geotechnical sampling strategies.

Related standards

• ISO 18400 series (other parts such as ISO 18400-104 referenced for phased investigation guidance)
• ISO 11074 (Soil quality - Vocabulary)
• National geotechnical and contaminated land guidance documents (often referenced for local information sources and implementation)

Keywords: ISO 18400-202, soil quality, preliminary investigations, sampling, desk study, site reconnaissance, conceptual site model, preliminary risk assessment, contaminated sites.