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Frequently Asked Questions



What is data verification?

What is data validation?

What are the U.S. Environmental Protection Agency regulations and standards for definitive data?

What is the nature of the Resource Conservation and Recovery Act (RCRA)?

Who must be regulated under RCRA?

What is a RCRA Facility Investigation (RFI)?

What is the nature of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)?

What is a remedial investigation?

What is the process for conducting a RCRA Facility Investigation/Remedial Investigation (RFI/RI)?

What are the follow-up investigative stages of Phase I environmental assessments?

What is a multiphase investigation?



What is data verification?
Data verification is a systematic evaluation of data to ensure that sample identification, analytical methods, and detection limits meet contractual requirements. We assess the data for the following features:
    • completeness
    • consistency
    • data-field syntax
    • data entry
    • format


What is data validation?
Data validation is a technical function involving judgments about the precision, accuracy, and defensibility of analytical results. Data validation activities include a combination of statistical tests and an examination of specific quality assurance issues, which determine whether or not analytical results can be classified as definitive data.

The data validation process includes the following steps:
    • Analytical aboratories send groundwater and soil analysis results on diskette as electronic data deliverables (EDDs), accompanied by analytical case narratives and chain-of-custody forms.
    • This delivery, combined with a laboratory data records review, which investigates technical validation issues that are not adequately addressed by computer review of the EDDs and case narratives, provides a comprehensive set of analytical and quality control data for a sampling event or project.
    • If there are historical results for a sampling site, such as groundwater monitoring wells, current results are compared with the historical results to determine if the value approximates an expected value for that site.


What are the U.S. Environmental Protection Agency regulations and standards for definitive data?
The EPA's data quality objectives process for Superfund identifies the quality assurance issues to be addressed for achieving definitive data for use in investigations under the Comprehensive Environmental Response, Compensations, and Liability Act (CERCLA).

Quality Assurance Objective 3, as defined in Quality Assurance/Quality Control Guidance for Removal Activities, provides specific data validation guidelines. Data meeting these objectives enable the scientist to make confident decisions regarding
    • pollutant source identification
    • delineation of contaminants
    • site remediation
    • removal of pollutants
    • health risk impact
    • environmental impact

These guidelines are used in the evaluation of data for groundwater monitoring, environmental screening, and data used in baseline risk assessments of individual Resource Conservation and Recovery Act (RCRA)/CERCLA sites.


What is the nature of the Resource Conservation and Recovery Act (RCRA)?
Facilities that generate, handle, store, treat, or dispose of hazardous materials or hazardous constituents are regulated under RCRA and must undergo a RCRA Facility Investigation.


Who must be regulated under RCRA?
    • Facility-specific areas where solid and/or hazardous wastes are managed are termed solid waste management units and include, but are not limited to, landfill, surface impoundment, waste pile, land treatment unit, and incinerator.
    • RCRA applies to a majority of manufacturing facilities because most manufacturing processes include the use of hazardous materials and wastes as defined by RCRA.
    • The RCRA Corrective Action Program applies to all operating, inactive, and closed facilities.


What is a RCRA Facility Investigation (RFI)?
RFIs address the nature and extent of contamination at a solid waste management unit.


What is the nature of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)?
Sites where uncontrolled releases of hazardous substances are suspected or documented are often regulated under CERCLA. The Environmental Protection Agency established the National Priorities List, which consists of a risk-prioritized list of sites in the United States that pose a potential threat to human health and the environment. Sites that fall under CERCLA must undergo a remedial investigation.


What is a remedial investigation?
Remedial investigations, which address the nature and extent of contamination at these waste sites, focus on the collection of data to support a remedial decision.


What is the process for conducting a RCRA Facility Investigation/Remedial Investigation (RFI/RI)?
    • Prior to conducting an RFI/RI, a preliminary assessment is performed that focuses on identifying the disposal history, developing a preliminary list of contaminants of concern, and determining the physical characteristics of the local area.
    • Based on these data, an RFI/RI work plan is developed that describes investigation rationale, types and quantities of data to be collected, and methods to be used to reduce the uncertainties associated with the site.
    • Preparation of the work plan is developed using the Data Quality Objectives process to insure the collection of adequate and defensible data, and to avoid the collection of unnecessary data. ExR provides turnkey scoping, design, and preparation of RFI/RI work plans that ensure the collection of adequate and defensible data that are necessary for the complete characterization of RCRA and CERCLA waste units and sites.
    • Mobilization and implementation of the RFI/RI are initiated upon regulatory approval of the work plan. These efforts require extensive planning and scheduling among facility management, oversight, subcontract, and regulatory personnel. A third party oversight contractor typically coordinates the investigation and subcontracts drilling, surveying, and analytical services, ensures adherence to the approved work plan, and provides overall data management and reporting. The investigation typically consists of, but is not limited to, the collection of the following types of data to adequately define the nature and extent of contamination and to support a remedial decision:
      • soil lithology and geochemical data
      • hydrogeologic and hydrochemical data
      • geotechnical data
      • ecological data
      • radiation survey data
    • These data are used to support a risk assessment and feasibility study, if necessary, to provide for corrective measures or remedial action selection.


What are the follow-up investigative stages of Phase I environmental assessments?
Phase I environmental assessments often identify environmental conditions at a site that merit additional investigation to determine actual impacts to environmental media (e.g., site soils, surface water, and groundwater). These follow-up phases of investigation typically consist of sampling and analysis of environmental media to determine the presence and extent of hazardous substances. Sampling activities are initially focused on suspect areas to determine the magnitude of impact. In the event that significant environmental impact is identified, a comprehensive investigation may be appropriate. These comprehensive investigations often require notification of local regulatory agencies, preparation of comprehensive work plans that describe sampling rationale, locations, and methods, and preparation of summary reports for regulatory submittal. Comprehensive investigations may be followed by multiphase investigations.


What is a multiphase investigation?
Multiphase investigations are focused on determining the appropriate corrective action following a finding of need resulting from a Phase I environmental assessment. Depending on summary reports, the impact, facility location, and applicable regulations, a risk assessment may be appropriate to determine the actual risk. Once the risk has been determined, a feasibility study may determine the appropriate corrective action. Corrective actions can consist of no further action, a simple removal action, or full-blown corrective action under Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) or the Resource Conservation and Recovery Act (RCRA).