ASTM D6235 - 04(2010)

    Standard Practice for Expedited Site Characterization of Vadose Zone and Groundwater Contamination at Hazardous Waste Contaminated Sites

    Active Standard ASTM D6235 | Developed by Subcommittee: D18.01

    Book of Standards Volume: 04.09


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    Significance and Use

    The ESC ProcessThis practice describes a process for characterizing groundwater contamination at sites, that provides cost-effective, timely, high-quality information derived primarily from judgement-based sampling and measurements by an integrated, multidisciplinary project team during a limited number of field mobilizations. (See Appendix X1 for additional background on the ESC process, its distinction from traditional site characterization, and its relationship to other approaches to site characterization and Appendix X6 and Appendix X7 for illustrative examples of the ESC process.)

    Determining Appropriateness of ESCThe ESC process should be initiated when an ESC client, regulatory authority, and stakeholders determine that contaminants at a site present a potential threat to human health or the environment and the ESC process will identify vadose zone, groundwater, and other contaminant migration pathways in a timely and cost-effective manner, especially when decisions concerning remedial or other action must be made as rapidly as possible. Situations where the process may be applicable are as follows:

    CERCLACERCLA remedial investigation/feasibility studies (RI/FS). (See Appendix X2.) This practice should be used in conjunction with U.S. EPA (37)

    RCRARCRA facility investigation/corrective measures studies (RFI/CMS). (See Appendix X2.)

    Note 4—The ESC process can be continued to include CERCLA feasibility studies and RCRA corrective measures studies (see Section 12), but this practice focuses on its use for site characterization. Section X1.4.5 describes the relationship of the ESC process to the DOE SAFER and EPA SACM programs for accelerating the cleanup of contaminated sites.

    ESASites where environmental site assessments (ESAs) conducted by using Practice E1527, Practice E1528, and Guide E1903 identify levels of contamination requiring further, more intensive characterization of the geologic and hydrologic system of contaminant migration pathways. Section X1.5.3 discusses the relationship between ESAs and the ESC process.

    Petroleum Release SitesLarge petroleum release sites, such as refineries. The user should review both this practice and Guide E1912 to evaluate whether the ESC or ASC process is more appropriate for such sites.

    Subsurface RadioactivitySites or facilities with subsurface contamination by radioactivity not regulated by RCRA or CERCLA.

    Defense Department Base Closure Actionswhere vadose zone and groundwater contamination are present.

    Other Subsurface ContaminationOther sites or facilities where contaminant migration in the vadose zone and groundwater is a matter of concern and heterogeneity of the vadose zone and groundwater system or potential complex behavior of contaminants requires use of the ESC process.

    Defining Objectives and Data Quality RequirementsThe ESC process requires project objectives and data quality requirements that will provide the ESC client, regulatory authority, and stakeholders with the necessary information to analyze risk or apply regulatory standards-based cleanup in order to choose a course of action. Once these have been defined, the ESC process relies on the expert judgement of the core technical team, operating within the framework of an approved dynamic work plan, as the primary means for selecting the type and location of measurements and samples throughout the ESC process. An ESC project focuses on collecting only the information required to meet the project objectives and ceases characterization as soon as the objectives are met.

    Note 5—This practice uses the term data quality requirements to refer to the level of data accuracy and precision needed to meet the intended use for the data. The U.S. EPA Data Quality Objectives (DQO) process is one way to accomplish this. The ESC process applies the concept of quality control and data quality requirements to geologic and hydrologic data as well as chemical data, but within a general framework of judgement-based rather than statistical sampling methods. Section X1.4.4 discusses the DQO process in more detail along with the role of judgement-based and statistically based sampling methods in the ESC process. Practice D5792 provides guidance on development of DQOs for generation of environmental data related to waste management.

    Use of ESC Process for Risk Analysis and Remedial Action:

    Characterizing Contaminant Migration PathwaysNormally an ESC project will characterize the contaminant migration pathways (and sources if not already known) before any detailed risk analysis involving exposure to environmental receptors is performed, because environmental receptors are not known until the migration pathways are known. Risk analysis expertise will normally be required as an input into defining project objectives and data quality requirements (see 4.3); such expertise is involved as appropriate during field data collection phases of an ESC project. Identification of contaminant sources and environmental receptors for risk analysis is straightforward at most sites and does not, per se, require the ESC process. The ESC process focuses on characterizing vadose zone and groundwater contaminant migration pathways and determining the distribution, concentration, and fate of contaminants along these migration pathways, because these factors are more difficult to identify than sources and environmental receptors.

    Considering Remedial Action and AlternativesThe ESC process is designed to avoid a presumption that remedial action is required (that is, an engineered solution rather than no further action or ongoing monitoring). In any ESC project, remediation engineering expertise is incorporated into the process at the earliest point at which a need for remedial action is identified. (See 13.3.) Guide D5745 provides guidance for developing and implementing short-term measures or early actions for site remediation.

    Flexibility Within ESCModification of procedures described in this practice may be appropriate if required to satisfy project objectives or regulatory requirements, or for other reasons. The ESC process is flexible enough to accommodate a variety of different technical approaches to obtaining environmental data. However, for an investigation to qualify as an ESC project, as formalized by ASTM, modifications should not eliminate any of the essential features of the ESC process listed in Table 1. Alternative site characterization approaches that use some, but not all, of the essential elements described in Table 1 may be appropriate for a site, but these approaches would not qualify as an ESC project as defined in this practice. ASTM expects that as the ESC process becomes more widely used, modifications, enhancements, and refinements of the process will become evident and will be incorporated into future versions of this practice. ASTM requests that suggestions for revisions to the guide based on field application of the process be addressed to: Committee D18 Staff Manager at ASTM International.

    Note 6—Users may prefer to use or develop alternative terminology for different aspects of the ESC process, depending on the regulatory context in which it is applied. However, precise or approximate equivalencies to steps or functions in the ESC process should be clearly identified. See, for example, RCRA and CERCLA equivalencies in Appendix X2.

    Use of ESC in Conjunction with Other MethodsThis practice can be used in conjunction with Guide D5730 for identification of potentially applicable ASTM standards and major non-ASTM guidance. In karst and fractured rock hydrogeologic settings, this practice can be used in conjunction with Guide D5717.

    1. Scope

    1.1 Applicability of the ECS ProcessThis practice covers a process for expedited site characterization (ESC) of hazardous waste contaminated sites to identify vadose zone, groundwater and other relevant contaminant migration pathways and determine the distribution, concentration, and fate of contaminants for the purpose of providing an ESC client, regulatory authority, and stakeholders with the necessary information to choose a course of action. Generally, the process is applicable to larger-scale projects, such as CERCLA (Superfund) remedial investigations and RCRA facility investigations. When used as part of the Superfund response process, this Practice should be used in conjunction with U.S. EPA's guidance document titled Using Dynamic Field Activities for On-Site Decision Making: A Guide for Project Managers (37). The ESC process is also applicable to other contaminated sites where the ESC process can be reasonably expected to reduce the time and cost of site characterization compared to alternative approaches. The ESC process has been applied successfully at a variety of sites in different states and EPA regions. (See Table X1.1). It typically achieves significant cost and schedule savings compared to traditional site characterization. (See X1.2 and X1.3) .

    1.2 Features of the ESC ProcessThe ESC process operates within the framework of existing regulatory programs. It focuses on collecting only the information required to meet characterization objectives and on ensuring that characterization ceases as soon as the objectives are met. Central to the ESC process is the use of judgement-based sampling and measurement to characterize vadose zone and groundwater contamination in a limited number of field mobilizations by an integrated multidisciplinary team, led by a technical leader and operating within the framework of a dynamic work plan that gives him or her the flexibility of responsibility to select the type and location of measurements needed to optimize data collection activities. Table 1 identifies other essential features of the ESC process, and Fig. 1 presents a flow diagram for the entire ESC process.

    1.3 Investigation MethodsThe process described in this practice is based on good scientific practice but is not tied to any particular regulatory program, site investigation method or technique, chemical analysis method, statistical analysis method, risk analysis method, or computer modeling code. Appropriate investigation techniques in an ESC project are highly site specific and are selected and modified based upon the professional judgement of the core technical team (in particular the technical team leader). Whenever feasible, noninvasive and minimally invasive methods are used, as discussed in Appendix X3. Appropriate chemical analysis methods are equally site specific. Analyses may be conducted in the field or laboratory, depending on data quality requirements, required turnaround time, and costs.

    1.4 Sites Generally Not Appropriate for the ESC ProcessGenerally, the ESC process is not applicable to: small petroleum release sites, real estate property transactions that require no more than a Phase I ESA, sites where contamination is limited to the near surface or there is no basis for suspecting that contaminant movement through the vadose zone and groundwater is a matter of concern, sites where the cost of remedial action is likely to be less than the cost of site characterization, or sites where existing statutes or regulations prohibit the use of essential features of the ESC process.

    1.5 Other Potentially Applicable ASTM Standards for Site CharacterizationGuide E1912 addresses accelerated site characterization (ASC) for petroleum release sites, and Guide E1739 addresses use of the risk-based corrective action (RBCA) process at petroleum release sites. Section X1.5.1 describes the ASC process, and X1.5.2 discusses the relationship between ESC and the RBCA process. Practices E1527 and E1528 and Guide E1903 address real estate property transactions, and X1.5.3 discusses the relationship between the ESC process and investigations for real estate property transactions. Classification D5746 addresses environmental conditions of property area types for Department of Defense installations, and Practice D6008 provides guidance on conducting environmental baseline surveys to determine certain elements of the environmental condition of federal real property.

    1.6 The values stated in both inch-pound and SI units are to be regarded separately as the standard. The values given in parentheses are for information only.

    1.7 This practice offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word Standard in the title of this document means only that the document has been approved through the ASTM consensus process.

    1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

    TABLE 1 Minimum Criteria for a Project Using ASTM Expedited Site Characterization Process

    Note—Other site characterization approaches may include many of the below elements, but all must be present for an investigation using the ASTM ESC process.

    1. A technical team leader oversees the ESC project and leads the ESC core technical team. See Fig. 2, step 1.a in Fig. 3, 6.2 and 7.1.1.
    2. Project objectives, data quality requirements, and performance criteria are defined by some process that includes ESC client, regulatory authority, and stakeholders. See Step 1b in Fig. 3 and 6.3.
    3. The technical team leader and an integrated multidisciplinary core technical team with expertise in geologic, hydrologic, and chemical systems work together, as areas of expertise are needed, in the field and throughout the process. See Fig. 2, Step 2 in Fig. 3, and 7.1.
    4. Intensive compilation, quality evaluation, and independent analysis and interpretation of prior data are used to develop a preliminary site model. See Step 3a in Fig. 3 and 8.1-8.5
    5. Dynamic work plan, approved by ESC client and regulatory authority, provides framework for use of multiple complementary, site-appropriate geologic and hydrologic investigation methods, along with rapid site appropriate methods for containment analysis. See Step 4 in Fig. 3, 8.6, 9.2.4, and Appendix X3.
    6. ESC project is based primarily on judgement-based sampling and measurements to test and improve the concepts and details of the evolving site model. See Steps 5 and 6 in Fig. 3, 3.1.16, 6.3.1, and X1.4.4.1.
    7. Quality control procedures are applied to all aspects of ESC data collection and handling, including field work for geologic and hydrologic characterization. See Steps 5 and 6 in Fig. 3, 9.2.6, 10.1.2, and Appendix X4 and Appendix X5.
    8. Field data collection is initially focused on geologic and hydrologic characterization of vadose zone, groundwater and other relevant contaminant migration pathways (and on identifying contaminants of concern, if they are not already known), followed by delineating the distribution, concentration, and fate of contaminants, based on knowledge of the relevant contaminant migration pathways. This effort typically requires no more than two field mobilizations. See Steps 5a and 6a in Fig. 3 and Sections 10 and 11.
    9. Field data are integrated, analyzed, and interpreted daily to refine the evolving site model and are used to optimize the type and location of subsequent field data collection until project objectives have been met. See Steps 5b and 6b in Fig. 3 and 10.1.3.
    10. Final site model provides ESC client, regulatory authority, and stakeholders with the information required to choose a course of action based on risk analysis of regulatory standards-based cleanup criteria. See Section 12.


    FIG. 1 Overview of the Expedited Site Characterization Process


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D653 Terminology Relating to Soil, Rock, and Contained Fluids

    D5717 Guide for Design of Ground-Water Monitoring Systems in Karst and Fractured-Rock Aquifers

    D5730 Guide for Site Characterization for Environmental Purposes With Emphasis on Soil, Rock, the Vadose Zone and Ground Water

    D5745 Guide for Developing and Implementing Short-Term Measures or Early Actions for Site Remediation

    D5746 Classification of Environmental Condition of Property Area Types for Defense Base Closure and Realignment Facilities

    D5792 Practice for Generation of Environmental Data Related to Waste Management Activities: Development of Data Quality Objectives

    D5979 Guide for Conceptualization and Characterization of Groundwater Systems

    D6008 Practice for Conducting Environmental Baseline Surveys

    D6044 Guide for Representative Sampling for Management of Waste and Contaminated Media

    E1527 Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process

    E1528 Practice for Limited Environmental Due Diligence: Transaction Screen Process

    E1689 Guide for Developing Conceptual Site Models for Contaminated Sites

    E1739 Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites

    E1903 Practice for Environmental Site Assessments: Phase II Environmental Site Assessment Process

    E1912 Guide for Accelerated Site Characterization for Confirmed or Suspected Petroleum Releases


    ICS Code

    ICS Number Code 13.030.99 (Other standards related to wastes)

    UNSPSC Code

    UNSPSC Code


    Referencing This Standard

    DOI: 10.1520/D6235-04R10

    ASTM International is a member of CrossRef.

    Citation Format

    ASTM D6235-04(2010), Standard Practice for Expedited Site Characterization of Vadose Zone and Groundwater Contamination at Hazardous Waste Contaminated Sites, ASTM International, West Conshohocken, PA, 2010, www.astm.org

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