Bookmark and Share
Standardization News Search

Study Shows Positive Impact of
ASTM Risk-Based Corrective Action
(RBCA) Standard

by John A. Connor

In 1998, a study was undertaken to determine if use of the ASTM risk-based corrective action (RBCA) standards by state environmental agencies resulted in more effective management of leaking underground storage tanks. The results of the study are a resounding “yes.”

John Connor, president of the company that conducted the study for ASTM and USEPA, describes the bottom-line value of these ASTM management standards as quantified in the study.

RESULTS of a nationwide study show that the ASTM guidelines for risk-based corrective action (RBCA) have helped state environmental agencies manage environmental cleanups more effectively through faster case processing rates, reduced environmental cleanup costs, and more effective targeting of resources toward higher-risk sites. The ASTM standard E 1739, Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites, provides a risk-based framework for assessment and remediation of soil and groundwater impacted by petroleum. ASTM standard E 2081, Guide for Risk-Based Corrective Action, provides a risk-based framework for assessment and remediation of soil and groundwater impacted by any chemical including, but not limited to, petroleum.

With strong support from the U.S. Environmental Protection Agency (USEPA), the RBCA process has been adopted by many state agencies in an effort to improve the management of environmental cleanup efforts, as needed to address increasing case backlogs and rising costs associated with remediation of leaking underground storage tank (LUST) sites. To evaluate the impact of the ASTM RBCA standards, the Risk-Based Decision-Making (RBDM) Performance Assessment Study, funded by the USEPA Office of Underground Storage Tanks (OUST) under an assistance agreement to ASTM, involved detailed evaluation of five state RBCA regulatory programs. The study was conducted by Groundwater Services, Inc. (GSI), of Houston, Texas, and is documented in two recently released ASTM Technical Bulletins. This article provides background on the RBCA standards and reviews the procedures and results of this study.

Management Challenges Posed by Leaking Underground Storage Tank Facilities

State and federal environmental regulations require owners and operators of underground storage tank facilities to investigate and remediate spills of petroleum products to the underlying soil and groundwater. Such fuel leaks can pose a concern with regard to impacts on drinking water resources, as well as direct exposure to contaminated soils or vapors. USEPA estimates that over 1 million underground storage tanks have been in service in the United States, principally used for fuel storage at gasoline service stations. Of these, over 400,000 leaking underground storage tank (LUST) sites have been identified to date, with new releases reported at rates of 500 to 1000 per week over the past decade. State environmental regulatory agencies have worked hard to oversee the proper investigation and cleanup of LUST sites, completing over 240,000 case closures nationwide. Nevertheless, over 160,000 LUST sites remain to be completed, and new releases continue to be reported at a rate of approximately 20,000 per year, posing a chronic backlog and typical caseloads of 50 to 500 LUST sites per agency staff member.

At a median cost of over $100,000 to investigate and remediate each LUST site, this cleanup effort represents a multi-billion dollar expense on a nationwide basis. To offset the financial burden of LUST cleanups for site owners and operators, 48 states have established assurance funds, providing partial to full reimbursement for corrective action expenditures at eligible sites. However, throughout the past decade, claims have consistently exceeded available fund revenues, posing a chronic financial crisis for many states and, in some cases, leading to fund insolvency. In response, many states are phasing out their assurance funds and/or seeking to reduce LUST expenditures through more stringent cost control measures, reduced reimbursement levels, and more cost-effective cleanup policies. In all cases, however, state environmental agencies are working to achieve such cost controls without compromising protection of public health and the environment.

Development and Use of the ASTM RBCA Standard

To address the challenges posed by remediation of an ever-growing population of LUST sites, in 1993, ASTM Subcommittee E50.01 on Storage Tanks (part of Committee E50 on Environmental Assessment) began work on the development of a streamlined process for assessment and response to subsurface contamination problems. The subcommittee, composed of representatives from USEPA, state regulatory agencies, major oil companies, banking and insurance companies, academia, and environmental consulting firms, identified a risk-based approach as the key to effective LUST site remediation. ASTM E 1739 integrates risk assessment practices with traditional site assessment and remedy selection activities to determine cost-effective measures for protection of public health and the environment. E 2081 is a companion to E 1739 in that it addresses chemicals other than petroleum.

The ASTM RBCA process is a flexible, science-based, decision management framework that may be customized for use by individual regulatory agencies. In simple terms, the RBCA process entails: 1) identification of applicable risk factors on a site-specific basis and 2) implementation of appropriate corrective measures in a timeframe necessary to prevent unsafe conditions. As defined in the ASTM standards, the RBCA process involves three key elements:

• Risk-Based Site Prioritization: Characterize risk drivers at each site and prioritize response actions based on the timing and magnitude of potential impacts to human health and the environment.

• Site-Specific, Risk-Based Remediation Goals: Determine risk-based concentration limits for affected environmental media designed to prevent impacts on human health and the environment. To provide for economical use at both small and large facilities, RBCA employs a tiered approach to the development of risk-based cleanup goals, designed to match the site assessment effort to the relative complexity of each site. Tier 1 remediation goals represent generic concentration limits, based on conservative default assumptions. Under Tiers 2 and 3, the user may derive site-specific concentration limits, based on additional site data and increasingly sophisticated methods of data analysis.

• Remedy Selection: Minimize risk by preventing exposure to unsafe levels of site chemicals. Options for management of contaminated soil and groundwater include removal/ treatment, containment, natural attenuation, institutional controls, or some combination thereof.

In 1996, USEPA OUST, through a cooperative agreement with ASTM and public-private partnership organization known as Partners in RBCA Implementation (PIRI), initiated a nationwide RBCA Training Program designed to familiarize state regulatory agencies with the ASTM RBCA framework and support development of state RBCA regulatory programs customized to local needs. Today, over 43 states have received ASTM RBCA training, 25 states are in the process of developing RBCA regulatory programs, and 16 states have RBCA programs in place.

The RBCA Performance Assessment Study: Objectives and Procedures

States implementing RBCA regulatory programs share the common goal of protecting human health and the environment from impacts associated with releases from LUST sites. Toward this end, the specific program management goals identified by these state agencies include:

Risk Reduction: Reduce risks posed to human health and the environment by releases from LUST sites.

• Expedited Site Evaluation, Remediation, and Closure: Streamline the site assessment process to expedite the remediation of sites posing significant concerns and close cases presenting no significant risks.

• Cost Control/Resource Allocation: Without compromising protection of human health and the environment, reduce the cost of the corrective action program by streamlining the report submittal/review process, targeting resources toward higher-risk sites, and reducing administrative oversight costs.

In order to measure the progress of state RBCA programs toward achieving these management goals, the RBDM Performance Assessment Study was initiated in December 1997 under a cooperative agreement between USEPA OUST and ASTM. Groundwater Services, Inc., was selected to conduct this evaluation with three principal objectives: 1) develop practical, quantitative measures for evaluating the impact of RBCA on achieving state agency management goals, 2) apply these measures to five state RBCA agencies to evaluate program performance, and 3) provide general guidelines for other state or territorial environmental agencies interested in tracking the benefits of their RBCA programs.

Five state environmental regulatory agencies (Illinois, Iowa, North Carolina, Texas, and Utah) that had previously implemented RBCA programs, volunteered to participate as RBCA pilot states for the purpose of this study. These five states provide a broad geographic distribution (e.g., no more than one state per USEPA Region) and represent a variety of state-customized RBCA programs. For this study, each state provided access to their LUST case database and other information used to record the progress of remediation sites through the regulatory process. In addition, the pilot states provided input on the goals of their individual programs, the performance measures currently utilized in their state, and the utility and feasibility of the RBCA performance criteria developed for this study.

In order to evaluate the impact of RBCA, GSI compiled individual state data into a Microsoft Access© database and programmed queries to characterize trends in these performance metrics over the period of 1990 through 1999, encompassing the time period before and after RBCA was implemented in each state. Pre-RBCA and post-RBCA trends were then compared to identify changes in case backlog, processing rates, and other key performance parameters.

Key Findings of the Performance Assessment Study

In addition to the data from the five pilot states, related information was also obtained from the Michigan Department of Environmental Quality (DEQ), Storage Tank Division, which conducted an independent audit of their RBCA program. The results of this study support the following general findings with regard to the common program management goals:

• Expedited Site Evaluation, Remediation, and Closure: Immediately following implementation of their RBCA program, four of the five pilot states observed a dramatic increase in case closures per year and a stabilization or decrease in case backlog. For example, in the first year of the Utah RBCA Tier 1 program (1995), the number of case closures increased by 120%, indicating that a Tier 1 process of generic screening criteria can significantly impact program performance. In Iowa, 77% of RBCA Tier 1 and 28% of Tier 2 site assessments resulted in case closure, indicating that the RBCA process has been effective at identifying sites for closure or remediation. In general, following RBCA implementation, the average age of a LUST case at the time of case closure was observed to increase, which, in combination with the increase in case closure rates, indicates that many older cases that have been in the regulatory process for many years are now being addressed.

• Risk Reduction: Available information regarding risk-based site classification (Texas and North Carolina) indicates that most of the LUST site cases closed by these state RBCA programs are low-risk sites. These data suggest that RBCA programs are effectively meeting the state program objective of closing low-risk cases while retaining higher-risk cases for further evaluation and/or remediation.

• Cost Control/Resource Allocation: Cost data in the LUST site databases provided by the pilot states were not sufficient to measure the cost impacts of RBCA programs at this time. However, the significant reductions in case backlog reported by some states clearly correspond to reduced program cost liabilities. An internal cost survey was conducted by the Texas Natural Resource Conservation Commission to determine the impact of RBCA implementation on the cost of site remediation. Between 1994 and 1998, LUST site remediation/closure costs were reduced by 70% for soil-impact-only sites (median cost reduced to $24,000/site from $80,000/site) and by 58% for low-risk groundwater impact sites (median cost reduced to $107,000 from $250,000/site).

In addition to the five pilot states evaluated for this study, the Michigan Department of Environmental Quality (DEQ) Storage Tank Division, has independently evaluated the performance of their LUST management program following the implementation of RBCA in April 1995. In 1996, Michigan DEQ reported a 61% increase in LUST case closures compared to the average case closure rate for 1990 to 1995. In addition, Michigan DEQ achieved a 30% decrease in case backlog from 1995 to 1998. Implementation of the RBCA program resulted in a 24% average reduction in remediation/closure costs for UST sites, representing a $39,000 cost savings per site (Michigan DEQ, 1996).


The results of the RBDM Performance Assessment Study clearly demonstrate the benefits of the ASTM RBCA standards to state environmental regulatory agencies in terms of more cost-effective management of environmental impacts associated with LUST sites. In the majority of pilot states, implementation of a RBCA program resulted in an immediate increase in LUST case closures and a stabilization or decrease in case backlog. Such backlog reductions represent a decreased administrative burden for the agency as well as a substantial reduction in cost liabilities, allowing staff and funding resources to be focused on remediation of higher-risk sites. In addition, RBCA was found to target low-risk sites for closure, while retaining higher-risk for further action, which is consistent with the objective of streamlining the corrective action process without compromising protection of human health and the environment.

State environmental agencies, with support from USEPA, have made significant progress toward assessing and remediating the over 400,000 LUST cases reported to date nationwide. However, over 160,000 known LUST sites remain to be addressed, and new releases continue to be reported at a rate of approximately 20,000 per year. As state financial assurance programs are phased out in coming years, remediation costs will increasingly shift to tank owners and operators or other insurance mechanisms. Consequently, cost-effective management of LUST sites will remain a critical need for years to come, and regulatory agencies may continue to look to ASTM RBCA as an effective model for addressing this challenge. //


The study was funded by the United States Environmental Protection Agency (USEPA) Office of Underground Storage Tanks (OUST) under Assistance Agreement #X825708-01 to the American Society for Testing and Materials (ASTM). Groundwater Services, Inc. (GSI), of Houston, Texas, conducted the study. Richard Mattick, USEPA OUST project manager, provided oversight and review of this study. In addition, we would like to thank the participating states, USEPA regions, and the Partnership in RBCA Implementation (PIRI) for their support and assistance.

Copyright 2000, ASTM

John A. Connor, P.E., is president of Groundwater Services, Inc. (GSI), Houston, Texas. He is a trainer for the ASTM/ USEPA RBCA Training Initiative and has assisted in regulatory agency training and RBCA program development in numerous states nationwide.