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Introduction to Risk-Based Corrective Action (RBCA)

Contact: Chris Christensen, Geology Specialist Grand Rapids (616) 356-0225
Agency: Environmental Quality

WHAT IS RBCA?

Risk-based corrective action (RBCA) is a generic term for corrective action strategies that categorize sites according to risk and move all sites toward completion using appropriate levels of action and oversight.  The ASTM standard is a good example of a framework for implementing a RBCA strategy.  With this process, regulators can make sound, quick, consistent management decisions for a variety of sites using a three-tiered approach to data collection and site review contained in ASTM's E1739 standard guide for "Risk-Based Corrective Action applied at Petroleum Release Sites."
HOW CAN RBCA HELP YOU?
RBCA helps you to:
  • Categorize sites according to risk
  • Allocate resources for maximum protection of human health and the environment
  • Provide appropriate level of oversight
  • Move all sites forward quickly
You can use RBCA to:
  • Identify exposure pathways and receptors at a site
  • Determine the level and urgency of response required at a site
  • Determine the level of oversight appropriate for a site
  • Incorporate risk analysis into all phases of the corrective action process
  • Select appropriate and cost-effective corrective action measures
RBCA is not a substitute for corrective action, but a tool for determining the amount and urgency of action necessary.  RBCA should never be used solely to justify inaction at a site or to save money.
How does RBCA Work?
The ASTM standard (E1739) is based on a "tiered" approach to risk and exposure assessment, where each tier refers to a different level of complexity.  For example, in the three-tiered approach:
  • Tier 1

Tier 1 consists of a qualitative risk-assessment based on general site assessment information.  This data would need to identify obvious environmental impacts (if any), potentially affected sensitive receptors (schools, homes, water bodies, etc.), and significant exposure pathways (drinking water wells, recreational use of streams, vapor transport, etc.).  When gathered for a number of sites, this information is typically sufficient to help categorize sites and determine acceptable time frames for corrective action (immediacy of response), if necessary.

  • Tier 2

Tier 2, more site-specific data is utilized to determine the appropriate risk-based actions.  Here, the reasonable maximum site-specific impact is evaluated through the use of site-specific characterization and monitoring data, conservative projections of expected levels of contaminates after treatment and potential plume migration, and reasonable maximum exposure scenarios.  This information is used to set conservative corrective action objectives that are protective of human health and the environment.

  • Tier 3

Tier 3 focuses completely on the site-specific conditions.  More sophisticated mathematical descriptions of fate and transport phenomena are used and descriptions of the range of possible exposures/risks are generated.  At this level of complexity, site specific risk assessment models may be developed.  Due to the costs involved, this analysis is suited to only large sites.

It is important to note that the goal of all tiers is to achieve similar levels of protection.  The difference is that, in moving to higher tiers, more efficient and cost-effective corrective action results because the conservative assumptions of earlier tiers are replaced with more realistic site-specific assumptions.  Additional site assessment data may be required as sites move to higher tiers.  
Want to Know More?
EPA:  Use of Risk-Based Decision Making in UST Corrective Action Programs
Operational Memo 4
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