Free Product Recovery and Documentation of ‘As Much As Practicable’

Hazardous Waste Program fact sheet
Division of Environmental Quality Acting Director: Steve Feeler


Missouri regulations 10 CSR 26-2.075 and 10 CSR 26-5.020 require tank owners/operators who experience a release of petroleum to remove as much free product as practicable.  The Department of Natural Resources determines whether this requirement has been met and what documentation is required to demonstrate compliance.  This technical bulletin is intended to aid practitioners in complying with this requirement.

“Free product” is defined in 40 CFR 280.12 as “a regulated substance that is present as a non-aqueous phase liquid.”  As knowledge in the field has advanced, practitioners have come to understand that non-aqueous phase liquid may exist in the environment in either a mobile or immobile state.  In this technical bulletin, “light non-aqueous phase liquid” (LNAPL) is used to mean both mobile and immobile non-aqueous phase petroleum, while “free product” refers only to the mobile portion of LNAPL.

LNAPL Conceptual Site Model (LCSM)

Development of an LCSM will aid the consultant in establishing LNAPL remediation objectives and selecting a remedial technology.

Per the Interstate Technology & Regulatory Council’s (ITRC) “Evaluating LNAPL Remedial Technologies for Achieving Project Goals,” the LCSM is similar to a conceptual site model, which identifies the source(s), pathway(s), and receptor(s), but the emphasis in the LCSM is on the contaminant source (i.e., the LNAPL).  Hence, additional information to consider when LNAPL is present includes the following: A well-developed LCSM will usually include some or all of the following scientific and technological information (please see the documents referenced at the end of this technical bulletin): Site setting (historical and current)—including land use, groundwater use, presence and proximity of receptors, etc.;

The LCSM will assist in planning field activities and data collection.  For example, the location and number of monitoring wells needed for dissolved-phase delineation may not suffice for LNAPL body spatial delineation, product testing, or transmissivity testing.

ITRC’s document titled “Evaluating LNAPL Remedial Technologies for Achieving Project Goals” (December 2009) and ASTM E2531-06 (Reapproved 2014) “Standard Guide for Development of Conceptual Site Models and Remediation Strategies for Light Non Aqueous-Phase Liquids Released to the Subsurface” are recommended resources for developing LCSMs, evaluating applicable remedial options, and determining performance metrics for remediation of a petroleum tank release.  Each evaluation will be site-specific and product-specific. 

Evaluation of ‘As Much As Practicable’

Demonstrating that as much free product has been recovered as practicable can be done quantitatively and/or qualitatively.

A quantitative analysis is more typical for a relatively recent release and typically includes documentation to show:

That an active free product recovery method has been or is being employed.

A qualitative analysis is more typical for older releases where various recovery methods have been attempted, such as excavation of soil or other source removal techniques, and sufficient historical data have been collected.  The department will entertain qualitative arguments, which can include (but is not limited to) discussion of the following items. Each site is different and the department will evaluate each site based on its specific merits.  Examples of information that may be used in a qualitative analysis include:


The type and amount of information needed to determine and document that free product has been recovered as much as practicable will vary from site to site and will be based on the type and spatial extent of the LNAPL body and the site conditions. While a detailed LCSM will greatly aid in the analysis, there is no one technique or approach suitable for every site and petroleum release.  Documenting compliance with this requirement is the responsibility of the tank owner/operator and his consultant; the final determination whether this requirement has been met will be made by the department.


ITRC (Interstate Technology & Regulatory Council).  2009.  Evaluating LNAPL Remedial Technologies for Achieving Project Goals.  LNAPL-2.  Washington, D.C.: Interstate Technology & Regulatory Council, LNAPLs Team.

ITRC (Interstate Technology & Regulatory Council). 2009. Evaluating Natural Source Depletion at Sites with LNAPL. LNAPL-1. Washington, D.C.: Interstate Technology & Regulatory Council, LNAPLs Team.

ASTM E2531-06(2014). Standard Guide for Development of Conceptual Site Models and Remediation Strategies for Light Nonaqueous-Phase Liquids Released to the Subsurface,  ASTM International, West Conshohocken, PA, 2014,