Voluntary Remediation Program
Risk Assessment Guidance
Welcome to the Virginia Voluntary Remediation Program (VRP) Risk Assessment Guidance Web site. This online resource offers information that will help interested parties conduct risk assessments required as a component of their participation in the VRP.
The regulatory basis for performing risk assessments under the Virginia VRP is found in the Voluntary Remediation Regulations section 9 VAC 20-160-70(A)(1)(a). The risk assessment is included in the site characterization report and should include an evaluation of the risks to human health and the environment posed by the release. If the risk assessment shows that a remedial action is necessary, a proposed set of remediation levels as described in 9 VAC 20-160-90 should also be included.
Risk assessments under the VRP generally follow the methodology described in Risk Assessment Guidance for Superfund (RAGS). The risk assessment process consists of four major steps. These steps are data collection and evaluation, exposure assessment, toxicity assessment, and risk characterization. These steps, as applied to the VRP, are described in the guidance.
How to use this guidance
This guidance is designed to be used as a web-based document. Follow the links above to read the guidance online and download tables on an individual basis.
Also see Instructions for Using VRP Calculation Spreadsheets for help in using the tables.
Periodic Updates
Please note that the guidance includes screening levels and toxicity values that are updated periodically by EPA. VRP staff will make every attempt to update the information in the guidance accordingly. The guidance is updated at least twice a year to incorporate new toxicity information and new guidance from EPA. We are currently compiling a mailing list to notify our users by email when the guidance is updated. The email notifications will be provided as a convenience to our participants. However, please note that it is the participant's responsibility to ensure that the most current toxicity information is used in VRP risk assessments regardless of whether the VRP guidance has been updated and regardless of whether they have received notification. If you would like to be included on the mailing list please send an email to pamcmurray@deq.virginia.gov.
The July 2008 updates include:
The primary source for the VRP screening levels is now the EPA Regional Screening Level (RSL) Table located at http://epa-prgs.ornl.gov/chemicals/download.shtml. The RSL Table replaces the EPA Region 3 Risk-based Concentration (RBC) Table. The RSLs are similar to the RBCs but there are some differences. See http://www.epa.gov/reg3hwmd/risk/human/covmay08.pdf for an explanation of the differences between the RBCs and the RSLs. The RSLs for soil incorporate dermal and inhalation exposure as well as ingestion. Since the RBCs only included ingestion, many of the RSLs are lower than the RBCs. On the VRP screening tables we have eliminated the Soil Screening Levels (SSL) for migration from soil to air since this pathway is already incorporated into the RSLs. For inhalation exposure, the toxicity values on the RSL Table are inhalation unit risks (IUR) and reference concentrations (RfC) rather than inhalation slope factors and RfDs. We have incorporated these toxicity values into our VRP calculation tables as well.
In addition, VDEQ has developed a fact sheet to provide project managers with guidance on screening sites that have the potential for risk from vapor intrusion of volatile contaminants to indoor air. The fact sheet provides the minimum characterization that is required for a site with volatile contaminants. We have also developed new Tier III vapor intrusion screening tables (2.10, 2.11, and 2.12) to accompany the fact sheet. The new screening levels are based on attenuation factors from the U. S. EPA's Vapor Intrusion Database. The fact sheet also describes the basis and how to use the new screening levels. Please see the VRP Vapor Intrusion Fact Sheet for details. Also note that our Tier III table numbering system has changed.
The May 2007 updates included:
Revisions to the surface water screening tables (2.7a, 2.7b, and 2.7c) based on the 2006 revisions to the Virginia Water Quality Standards.
The October 2006 EPA Region 3 RBC Table updates (1,2-dibromo-3-chloropropane, cis-1,2-dichloroethene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene.)
The April 2007 EPA Region 3 RBC Table updates (aluminum, iron, trans-1,2-dichloroethene, 1,1,2,2-tetrachloroethane, and dibenzofuran.)
We have also made some changes to our calculation and screening tables. We have eliminated the "other" worksheets and incorporated those chemicals into the main worksheet. We have also eliminated the separate exposure factor worksheets in the calculation tables. They have also been incorporated into the main worksheet.
In addition, note that for carcinogens that act via a mutagenic mode of action, special adjustments are needed to account for susceptability during early life. Therefore exposure to these chemicals is assessed separately for ages 0-2, 2-6, 6-16, and 16-30 years. The following age-dependent adjustment factors (ADAFs) are applied to the risk calculations for each age group:
Age ADAF
0-2 10
2-4 3
4-16 3
16 and up 1
The separate calculations have been incorporated into the VRP calculation spreadsheets so you will not need to make any additional adjustments. For additional information please see Guidelines for Carcinogen Risk Assessment and Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens.
Please see Instructions for Using VRP Calculation Spreadsheets for help in using the revised spreadsheets.
We hope that these changes streamline your risk assessment preparation and VDEQ's review. Please contact us if you have any questions or comments.