ASTM E3361

ASTM E3361 is a technical standard guide for estimating natural attenuation rates for non-aqueous phase liquids in the subsurface. It provides a structured way to evaluate how these liquids may degrade, dissipate, or otherwise reduce over time in underground environments. For environmental assessment and remediation planning, this guidance matters because it can help support more consistent interpretation of site conditions, improve decision-making, and reduce uncertainty when reviewing attenuation behavior.

What is ASTM E3361?

ASTM E3361 is a guide, not a prescriptive treatment method, and its focus is on estimating natural attenuation rates for non-aqueous phase liquids in the subsurface. The standard is intended to support technical evaluation of how such liquids behave underground over time. In practice, it may be used to organize information, frame analysis, and promote consistent estimation approaches. As an ASTM standard, it is most useful when a documented, repeatable basis is needed for environmental assessment.

Where is ASTM E3361 used?

This guide is commonly used in subsurface environmental work where non-aqueous phase liquids are present or suspected. It is relevant to site investigations, monitoring programs, and remediation-related evaluations that need a practical estimate of natural attenuation rates. The standard may support work performed by environmental consultants, site owners, regulators, and technical teams responsible for assessing underground contamination behavior. ASTM E3361 is especially useful when comparing conditions across locations or tracking changes over time.

Why is ASTM E3361 important?

ASTM E3361 helps bring consistency to the estimation of natural attenuation rates, which can be important for compliance, reporting, and technical review. By using a recognized ASTM standard, organizations can improve the credibility of their methods and reduce ambiguity in site evaluations. It may also support better risk management by helping teams interpret whether attenuation is occurring at a meaningful rate. For procurement and project documentation, the standard provides a clear technical reference point.

• Natural attenuation rate estimation
• Non-aqueous phase liquids in the subsurface
• Environmental site assessment support
• Technical guidance for repeatable analysis
• Documentation for review and compliance