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Product ID: 389127EAU
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Benefits of Using the Unified Guidance for Groundwater Evaluation

OnDemand Webinar (86 minutes)

EPA's Unified Guidance (UG) offers major new recommendations for handling and analyzing groundwater monitoring data. Incorporating these recommendations into your groundwater monitoring program is not only consistent with current EPA guidelines - aiding in complying with regulatory expectations - but it also allows for better and scientifically accurate evaluation of groundwater conditions at your site.

The new recommendations include: an emphasis upon statistical design. How should statistical testing be developed to simultaneously identify "dirty" groundwater with sufficiently high probability while minimizing the chance of labeling "clean" groundwater as "dirty"?; the importance of developing and maintaining background data. How much background data is needed? Are "moving windows" ever appropriate? How should background be updated for intrawell testing? What if background levels are higher than compliance standards?; the necessity of resampling and retesting. What benefits does formal retesting provide? How can it be done right?; and the flexibility of intrawell testing. Why is spatial variation important to check for? How can it be "fixed"? This OnDemand Webinar will highlight each of these important areas.

Learning Objectives

  • You will be able to describe the importance of statistical design.
  • You will be able to discuss developing and maintaining background.
  • You will be able to review recommended retesting plans.
  • You will be able to explain spatial variation and intrawell testing.


Dr. Kirk Cameron, MacStat Consulting, Ltd.


Importance of Statistical Design

• Conceptual Framework: Statistical Decision Errors and Statistical Power

• UG Performance Criteria for Detection Monitoring

• How to Achieve High Power and Low False Positive Rates

• Double Quantification Rule

Developing and Maintaining Background (BG)

• Importance of Sample Size, Especially for Intrawell Tests

• Use of Moving Windows When BG Conditions Are Actively Changing

• Updating Intrawell BG While Using Retesting

• What to Do When BG Is Higher Than Compliance Standards

Philosophy and Importance of Retesting

• Recommended Retesting Plans

• Statistical Benefits of Retesting

• When to Resample

• Retesting Tradeoffs

Spatial Variation and Intrawell Testing

• Impact of Spatial Variation

• Fixing Spatial Variation

• Flexibility of Intrawell Testing