ASTM E2531-06e1

Standard Guide for Development of Conceptual Site Models and Remediation Strategies for Light Nonaqueous-Phase Liquids Released to the Subsurface

SIGNIFICANCE AND USE
This guide will help users answer simple and fundamental questions about the LNAPL occurrence and behavior in the subsurface. It will help users to identify specific risk-based drivers and non-risk factors for action at a site and prioritize resources consistent with these drivers and factors.
The site management decision process described in this guide includes several features that are only examples of standardized approaches to addressing the objectives of the particular activity. For example, Table 1 provides example indicators of the presence of LNAPL. Table 1 should be customized by the user with a modified list of LNAPL indicators as technically appropriate for the site or group of sites being addressed.
This guide advocates use of simple analyses and available data for the LCSM in Tier 1 to make use of existing data and to interpret existing data potentially in new ways. The Tier 1 LCSM is designed to identify where additional data may be needed and where decisions can be made using existing data and bounding estimates.
This guide expands the LCSM in Tier 2 and Tier 3 to a detailed, dynamic description that considers three-dimensional plume geometry, chemistry, and fluxes associated with the LNAPL that are both chemical- and location-specific.
This guide fosters effective use of existing site data, while recognizing that information may be only indirectly related to the LNAPL body conditions. This guide also provides a framework for collecting additional data and defining the value of improving the LCSM for remedial decisions.
By defining the key components of the LCSM, this guide helps identify the framework for understanding LNAPL occurrence and behavior at a site. This guide recommends that specific LNAPL site objectives be identified by the user and stakeholders and remediation metrics be based on the LNAPL site objectives. The LNAPL site objectives should be based on a variety of issues, including:
Potential human health risks and risks to r...
SCOPE
1.1 This guide applies to sites with LNAPL present as residual, free, or mobile phases, and anywhere that LNAPL is a source for impacts in soil, ground water, and soil vapor. Use of this guide may show LNAPL to be present where it was previously unrecognized. Information about LNAPL phases and methods for evaluating its potential presence are included in 4.3, guide terminology is in Section 3, and technical glossaries are in Appendix X7 and Appendix X8. Fig. 1 is a flowchart that summarizes the procedures of this guide.
1.2 This guide is intended to supplement the conceptual site model developed in the RBCA process (Guides E 1739 and E 2081) and in the conceptual site model standard (Guide E 1689) by considering LNAPL conditions in sufficient detail to evaluate risks and remedial action options.
1.3 Federal, state, and local regulatory policies and statutes should be followed and form the basis of determining the remedial objectives, whether risk-based or otherwise. Fig. 1 illustrates the interaction between this guide and other related guidance and references.
1.4 Petroleum and other chemical LNAPLs are the primary focus of this guide. Certain technical aspects apply to dense NAPL (DNAPL), but this guide does not address the additional complexities of DNAPLs.
1.5 The composite chemical and physical properties of an LNAPL are a function of the individual chemicals that make-up an LNAPL. The properties of the LNAPL and the subsurface conditions in which it may be present vary widely from site to site. The complexity and level of detail needed in the LCSM varies depending on the exposure pathways and risks and the scope and extent of the remedial actions that are needed. The LCSM follows a tiered development of sufficient detail for risk assessment and remedial action decisions to be made. Additional data collection or technical analysis is typically needed when fundamental questions about the LNAPL cannot be answe...

General Information

• Status: Historical
• Publication Date: 31-Oct-2006
• ICS: 13.080.05 - Examination of soils in general
• Technical Committee: E50 - Environmental Assessment, Risk Management and Corrective Action
• Drafting Committee: E50.04 - Corrective Action

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
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Designation: E2531 − 06
StandardGuide for
Development of Conceptual Site Models and Remediation
Strategies for Light Nonaqueous-Phase Liquids Released to
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the Subsurface
This standard is issued under the fixed designation E2531; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
´ NOTE—The LNAPL transmissivity metric in TableX5.1 was editorially corrected in July 2009.
INTRODUCTION
This guide provides a framework for developing a light nonaqueous phase liquid (LNAPL)
conceptual site model (LCSM) and for using that LCSM in a corrective action decision framework.
LNAPLs are most commonly petroleum or petroleum products liquids. Historically, subsurface
LNAPL distribution has been conceptualized based on the thickness observed in monitoring wells.
However, these conceptualizations often result in an insufficient risk analysis and frequently lead to
poor remedial strategies. By using this guide, the user will be able to perform a more appropriate
assessment and develop an LCSM from which better remedial decisions can be made.
The design of this guide is a “tiered” approach, similar to the risk-based corrective action (RBCA)
process (Guides E1739 and E2081), where an increase in tiers results from an increase in the site
complexity and site-specific information required for the decision-making process.The RBCAguides
apply to LNAPL and to dissolved and vapor phases. This guide supplements the RBCA guides by
providing more information about identifying LNAPL, linking the LCSM to the RBCAprocess, and
describing how the presence of LNAPL impacts corrective action at sites.
In addition to developing the LCSM, the components of this guide will support the user in
identifying site objectives, determining risk-based drivers and non-risk factors, defining remediation
metrics, evaluating remedial strategies, and preparing a site for closure. If the processes in this guide
are adequately followed for sites with LNAPL, it is expected that more efficient, consistent,
economical, and environmentally protective decisions will be made.
1. Scope E2081) and in the conceptual site model standard (Guide
E1689)byconsideringLNAPLconditionsinsufficientdetailto
1.1 This guide applies to sites with LNAPL present as
evaluate risks and remedial action options.
residual, free, or mobile phases, and anywhere that LNAPL is
a source for impacts in soil, ground water, and soil vapor. Use 1.3 Federal, state, and local regulatory policies and statutes
of this guide may show LNAPL to be present where it was should be followed and form the basis of determining the
previously unrecognized. Information about LNAPL phases remedial objectives, whether risk-based or otherwise. Fig.1
and methods for evaluating its potential presence are included illustrates the interaction between this guide and other related
in 4.3, guide terminology is in Section 3, and technical
guidance and references.
glossaries are in Appendix X7 and Appendix X8. Fig.1 is a
1.4 Petroleum and other chemical LNAPLs are the primary
flowchart that summarizes the procedures of this guide.
focus of this guide. Certain technical aspects apply to dense
1.2 Thisguideisintendedtosupplementtheconceptualsite NAPL(DNAPL),butthisguidedoesnotaddresstheadditional
model developed in the RBCA process (Guides E1739 and
complexities of DNAPLs.
1.5 The composite chemical and physical properties of an
LNAPL are a function of the individual chemicals that
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ThisguideisunderthejurisdictionofASTMCommitteeE50onEnvironmental
make-up an LNAPL. The properties of the LNAPL and the
Assessment, Risk Management and CorrectiveAction and is the direct responsibil-
subsurface conditions in which it may be present vary widely
ity of Subcommittee E50.04 on Corrective Action.
from site to site. The complexity and level of detail needed in
CurrenteditionapprovedNov.1,2006.PublishedFebruary2007.DOI:10.1520/
E2531-06E01. the LCSM varies depending on the exposure pathways and
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E2531 − 06
risks and the scope and extent of the remedial actions that are 1.14.1 Data and information collected should be relevant to
needed. The LCSM follows a tiered development of sufficient and of sufficient quantity and quality to develop a technically-
detail for risk assessment and remedial action decisions to be sound LCSM.
made. Additional data collection or technical analysis is 1.14.2 Remedial actions taken should be protective of
typically needed when funda
...