Light Non Aqueous Phase Liquids (Free Product)

LNAPL (light non-aqueous phase liquid) is an immiscible organic liquid that is less dense than water. Initially, all petroleum releases originate as LNAPL in the form of gasoline, diesel fuel, lube oils or other petroleum products.

LNAPL may represent the greatest mass of contamination in the subsurface from a petroleum release and may also be a source of petroleum vapors to intrude into structures, and an ongoing source of dissolved phase groundwater contaminant plumes. Therefore, it is critical to accurately characterize the spatial distribution of LNAPL to enable LNAPL abatement, remediation, and risk management to protect human health and the environment.

The complex distribution of LNAPL in the subsurface makes assessment and remediation challenging. Recent advances in LNAPL science have improved the understanding of LNAPL behavior in the subsurface. The purpose of this guidance is to apply this improved understanding of LNAPL behavior to adequately characterize LNAPL distribution and identify site-specific LNAPL concerns.

 Additional Resources

ASTM Standard Guide for Development of Conceptual Site Models and Remediation Strategies for LNAPL Subsurface Releases

Evaluating LNAPL Remedial Technologies

Evaluating Natural Source Zone Depletion at Sites with LNAPL

API LNAPL Distribution and Recovery Model

API Interactive LNAPL Guide Version 2.0.4

API LNAPL Transmissivity Workbook: A Tool for Baildown Test Analysis

ASTM Standard Guide for Estimation of LNAPL Transmissivity

Colorado Division of Oil and Public Safety

633 17th Street, Suite 500, Denver, CO 80202

Phone: 303-318-8525

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