ASTM E2531-06

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

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 , guide terminology is in Section , and technical glossaries are in . 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 answered with existing information.
1.6 This guide does not develop new risk assessment protocols. It is intended to be used in conjunction with existing risk-based corrective action guidance (for example, Guides E 1739 and E 2081) and regulatory agency requirements (for example, USEPA 1989, 1991, 1992, 1996, 1997).
1.7 This guide assists the user in developing an LCSM upon which a decision framework is applied to assist the user in selecting remedial action options.
1.8 The goal of this guide is to provide sound technical underpinning to LNAPL corrective action using appropriately scaled, site-specific knowledge of the physical and chemical processes controlling LNAPL and the associated plumes in ground water and soil vapor.
1.9 This guide provides flexibility and assists the user in developing general LNAPL site objectives based on the LCSM. This guide recognizes LNAPL site objectives are determined by regulatory, business, regional, social, and other site-specific factors. Within the context of the Guide E 2081 RBCA process, these factors are called the technical policy decisions.
1.10 Remediation metrics are defined based on the site objectives and are measurable attributes of a remedial action. Remediation metrics may include environmental benefits, such as flux control, risk reduction, or chemical longevity reduction. Remediation metrics may also include costs, such as installation costs, energy use, business impairments, waste generation, water disposal, and others. Remediation metrics are used in the decision analysis for remedial options and in tracking the performance of implemented remedial action alternatives.
1.11 This guide does not provide procedures for selecting one type of remedial technology over another. Rather, it recommends that technology selection decisions be based on the LCSM, sound professional judgment, and the LNAPL site objectives. These facets are complex and interdisciplinary. Appropriate user knowledge, skills, and judgment are required.
1.12 This guide is not a detailed procedure for engineeri...

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
Designation: E 2531 – 06
Standard Guide for
Development of Conceptual Site Models and Remediation
Strategies for Light Nonaqueous-Phase Liquids Released to
1
the Subsurface
This standard is issued under the fixed designation E 2531; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
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 E 1739 and E 2081), 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 RBCA process, 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 E 1689) by considering LNAPL conditions in sufficient detail
to evaluate risks and remedial action options.
1.1 This guide applies to sites with LNAPL present as
1.3 Federal, state, and local regulatory policies and statutes
residual, free, or mobile phases, and anywhere that LNAPL is
should be followed and form the basis of determining the
a source for impacts in soil, ground water, and soil vapor. Use
remedial objectives, whether risk-based or otherwise. Fig. 1
of this guide may show LNAPL to be present where it was
illustrates the interaction between this guide and other related
previously unrecognized. Information about LNAPL phases
guidance and references.
and methods for evaluating its potential presence are included
1.4 Petroleum and other chemical LNAPLs are the primary
in 4.3, guide terminology is in Section 3, and technical
focus of this guide. Certain technical aspects apply to dense
glossaries are in Appendix X7 and Appendix X8. Fig. 1 is a
NAPL(DNAPL),butthisguidedoesnotaddresstheadditional
flowchart that summarizes the procedures of this guide.
complexities of DNAPLs.
1.2 This guide is intended to supplement the conceptual site
1.5 The composite chemical and physical properties of an
model developed in the RBCA process (Guides E 1739 and
LNAPL are a function of the individual chemicals that
E 2081) and in the conceptual site model standard (Guide
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
1
ThisguideisunderthejurisdictionofASTMCommitteeE50onEnvironmental
the LCSM varies depending on the exposure pathways and
Assessment, Risk Management and CorrectiveAction and is the direct responsibil-
risks and the scope and extent of the remedial actions that are
ity of Subcommittee E50.04 on Corrective Action.
Current edition approved Nov. 1, 2006. Published February 2007. needed. The LCSM follows a tiered development of sufficient
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E2531–06
detail for risk assessment and remedial action decisions to be 1.14.2 Remedial actions taken should be protective of
made. Additional data collection or technical analysis is human health and the environment now and in the future.
typically needed when fundamental questions about the
1.14.3 Remedial actions should have a reasonable probabil-
LNAPL cannot be answered with existing information. ity of meeting the LNAPL site
...