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APPENDIX A - THE ACCELERATED SITE CHARACTERIZATION PROCESS

Appendix A has been derived from the following:

American Society for Testing and Materials (ASTM). (January, 1996). Provisional Standard Guide for Accelerated Site Characterization for Confirmed or Suspected Petroleum Releases. ASTM Designation: PS 3 - 95

Introduction

The purpose of this appendix is two-fold. First, to describe an accelerated site characterization process that can be used to generate near-real-time information about the nature and extent of contamination at a site. Secondly, it identifies where and when to use the field analytical and sampling technologies described in this Reference Guide. There are really two goals to be achieved in implementing the accelerated site characterization process. The first is to generate enough data of the right kind and quality to allow decisions to be made concerning the appropriate level of clean up. The second is to gather the data and information in a single mobilization1. This appendix describes the six steps in the accelerated site characterization process and the points in the process where field analytical technologies and sampling methods can be used.

The typical approach to site characterization is to visit the site two or more times to collect information necessary to make remediation decisions. This iterative characterization process is necessary because analysis results are often provided to the decision-makers weeks or months after sample collection. Data generated by field analytical technologies are not relied on as much as data generated by off-site, fixed laboratories. If any information needs are not met, then an additional visit or visits to the site are necessary. For each site visit a work plan needs to be prepared and approved, contractors must be identified and contracts negotiated and awarded. Obviously, making multiple visits to a site can delay a final decision or action for months or even years.

The accelerated site characterization approach is not a panacea nor are field analytical methods intended to replace fixed analytical laboratories. An expedited process for delineating, to the fullest extent possible, the source(s), extent, and concentration of contaminants at a site has been shown to be a cost effective and efficient process. Field analytical techniques produce near-real-time results, allowing decision-makers to identify additional sampling locations during the mobilization. The overall characterization effort can be precise and efficient by combining on-site analytical results with those generated by fixed laboratories.

Effective implementation of this process requires an on-site field manager who can interpret results, communicate with the stakeholders2 , and who is empowered to make decisions in the field. Involvement of the stakeholders early and continuously in the process is critical to the success of the process. In addition, generating the proper documentation is also necessary so that decisions made in the field can be defended at a later date.

The Accelerated Site Characterization Process

The Accelerated Site Characterization process has six major steps as summarized in Figure 1.

Figure 1

Step 1 - Develop the Conceptual Model

The conceptual model is the starting and ending point for any investigation. It is the basis for selecting sample collection and analysis tools and is used to determine when the investigation is complete. The conceptual model is an initial hypothesis about the nature and extent of contamination. It is based upon the compilation and interpretation of existing site information, which can include:

This information should be summarized on large-scale topographic maps, ground water elevation contour maps, isoconcentration contour maps, or geologic/hydrogeologic cross sections. This type of information should be used on-site during the investigation and should be updated as the characterization progresses.

Step 2 - Define the Investigation Purpose and Develop Decision Criteria

Defining a purpose limits many investigation parameters such as detection limits and sample collection densities. The investigation purpose will drive the types of sample collection and analytical techniques chosen in Step 3.

Common investigation purposes include:

  1. Finding the source of contamination.
  2. Determining the extent of contamination.
  3. Confirming the level of risk (human health and the environment) posed by the contamination.
  4. Determining the type of clean-up action(s) required.
  5. Gaining a No Further Action or site close-out approval.
  6. Tracking the long term effectiveness of remediation systems.

With the purpose defined, decision criteria, such as size of the contaminated area of concern and acceptable contaminant concentrations, can be developed with input from stakeholders.

For example, to gain a No Further Action approval in California, the site owner is required to demonstrate that the contaminants do not pose a risk under residential property use scenarios. This risk scenario assumes that families will be living on the site with young children being the potential receptors, and is applicable at all locations regardless of actual conditions. This scenario imposes analytical detection limits (parts per billion for soil and parts per trillion for water) and the size of the contaminated area (i.e., hot spot) that might be of concern.

Step 3 - Develop the Data Collection and Analysis Program

The data collection and analysis program needs to be a formal document. However, only a few initial sample point locations are specified, additional points will be located based upon initial sample analysis results. The program documentation should focus on methods and procedures used to collect and analyze samples. The data collection and analysis program should include:

  1. Existing information (obtained from Steps 1 and 2)

    a. Purpose - state the consensus investigation purpose.
    b. Decision Criteria - state the required detection limit and acceptable size of contamination.
    c. Conceptual Model - including all graphics.
    d. Subsurface clearance requirements.
    e. Qualifications of the on-site field manager.
    f. Stakeholders - names, telephone, and fax numbers.
    g. Stakeholder communication requirements.
    h. Schedule (including preliminary, on-site, off-site, and reporting activities.

  2. Sample collection

    a. Location of first round of samples and ultimate sample density3.
    b. Description of collection tools - capabilities, limitations.
    c. Sample collection procedure(s).
    d. Decontamination procedure(s).
    e. Decontamination verification procedures.

  3. Sample analysis

    a. Description of analytical equipment - capabilities, limitations.
    b. Calibration requirements4.
    c. Analysis procedure(s) (including any sample preparation methods).
    d. Method quality control check requirements4.

  4. Validation procedures - In-field validation4, Off-site validation4
TABLE 1
Data Quality Classification
Modified from NJDEP Field Analysis Manual, July 1994
Data Quality Level Potential Applications Example Methods or Instruments
1 - Screening:
1A - Qualitative
1B - Semiquantitative		 Finding the nature and source of contamination (1A/1B)
Tracking the long term effectiveness of remediation systems (1B)		 portable PID, portable FID,PID/FID, colorimetric analysis,headspace analysis
2 - Delineate: Quantitative Determining the extent of contamination
Determining the type of clean-up action(s) required		 portable GC, portable IR, immunoassay, USEPA SW-846 field methods, mobile laboratories
3 - Clean Zone: Quantitative Confirming the level of risk (human health and the environment) posed by the contamination
Gaining a No Further Action or site close-out approval		 standard laboratory analyses with SW-846 QA/QC mobile laboratories using standard methods
4 - Nonstandard: Quantitative specialty analysis Constituent surveys of unknown contamination survey instrumentation, modified laboratory methods with full QA/QC

Figure 2 provides guidance on choosing characterization tools.

Figure 2

Step 4 - Implement the Data Collection and Analysis Program

Figure 3 is an illustration of the actions recommended during implementation of the data collection and analysis program. The actions recommended to implement the data collection and analysis program include:

  1. Collect and Analyze an Initial Set of Samples
  2. Field Validate Data

    Field analytical results must be validated to ensure proper operation of equipment and procedure.

  3. Compare Data to the Conceptual Model

    a) Flag data results that are significantly different from the conceptual model
    b) Update conceptual model as required

  4. Determine if Characterization is Complete

    The following criteria should be confirmed to support the conclusion that site characterization is complete:

    • The conceptual model of the site geology /hydrology, the nature and extent of the chemicals of concern, and the indicator compounds fit the regional geologic/hydrogeologic setting;
      and
    • The conceptual model of the site generally incorporates/fits all of the site data;
      and
    • The conceptual model can be used to make accurate predictions;
      and
    • Sufficient detail and delineation of the chemicals of concern have been achieved to fulfill the requirements of the stakeholders;
      or
    • Constraints prevent collection of any additional data.

    If characterization is not complete, then:

    • develop plan for additional sampling and analysis
    • update stakeholders
    • go back to step 1


    If characterization is complete, go to Step 5.

Figure 3

Step 5 - Issue Field Report

Upon completion of the fieldwork, a report of findings is provided to the appropriate stakeholders. The report should contain at a minimum:

The field report allows the decision process to immediately move forward based on available field analytical information. Confirmation of the field analysis (with laboratory analytical results) will be in the final report.

Step 6 - Issue Final Report

The final report will contain the following information:

Summary

The accelerated site characterization process described in the previous six steps can be summarized as the flowchart depicted in Figure 4.

Figure 4

*Characterization is complete when:
  • The conceptual model of the site geology/hydrology, the nature and extent of chemicals of concern, and indicator compounds fit the regional geologic/hydrogeologic setting; and
  • The conceptual model of the site generally incorporated/fits all of the site data; and
  • The conceptual model can be used to make accurate predictions; and
  • Sufficient detail and delineation of the chemicals of concern have been achieved to fulfill the requirements of the stakeholders; or
  • Constraints prevent collection of any additional data.

1A mobilization is the movement of equipment and personnel to a site, during a continuous time frame, to prepare for, collect, and evaluate site characterization data. These activities, when conducted as one continuous event (lasting from one day to several weeks), are referred to as a single mobilization.

2Stakeholders are all people who have a legitimate interest in the outcome of the investigation process. They typically include Federal and state, and local regulatory agencies and local citizens.

3Determined from the decision criteria.

4The requirements will depend on the degree of data quality required to meet the investigation purpose. The New Jersey Department of Environmental Protection (NJDEP) has developed a useful field analysis manual (FIELD ANALYSIS MANUAL, New Jersey Dept. of Environmental Protection, Site Remediation Program, July 1994. Available at http://www.state.nj.us/dep/srp/regs/ guidance.htm#fam) which provides required deliverables to meet data quality levels indicated in Table 1.

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