Risk-based site evaluation guidance

The Minnesota Pollution Control Agency has developed guidance outlining a risk-based approach to decision making during site investigation and remedy selection under the state's Superfund and Brownfields Programs. The Risk-Based Site Evaluation (RBSE) Manual provides a tiered process for making decisions based on an evaluation of risks to human health and the environment. MPCA staff with expertise in risk assessment, soil physics, hydrogeology, and remediation technologies have developed the following risk guidance.

The RBSE manual includes individual documents describing the process of site characterization, community involvement, evaluating the risk to human health and the environment posed at a site, and how to address that risk. Working drafts of the manual documents are maintained here.

What's new

October 2016: Draft SRV related documents

The MPCA’s VIC, RCRA and Superfund programs are seeking stakeholder input regarding the October 2016 draft SRV related documents listed above. Please submit your comments to SRVcomments.pca@state.mn.us by December 2, 2016.

Note: Some of the SRVs did change due to a change in the definition of a VOC based on EPA’s recommendation. This revision was completed to ensure we were both consistent with EPA and with our intrusion screening values (ISVs) used to investigate vapor intrusion sites. Background threshold values (BTVs) for arsenic and BaP have not changed. All changes are shown on the “Comparisons” tab in the SRV Spreadsheet.

The MPCA will be hosting a stakeholder meeting on October 31, 2016. Details regarding this meeting will be announced later in October.

Timeline for SRV revisions

June 2015 SRV stakeholder meeting presentations

September 2015 community stakeholder information session

October 2016 SRV related document stakeholder meeting presentations

Background

The Minnesota Department of Health’s (MDH) “Guidance for Evaluating the Cancer Potency of Polycyclic Aromatic Hydrocarbon (PAH) Mixtures in Environmental Samples” is available at the link below.

This guidance recommends a revised method to evaluate carcinogenic PAHs (cPAHs) using relative potency factors (RPF) instead of potency equivalence factors (PEF) and an alternative surrogate mixture method using 7X the concentration of benzo[a]pyrene (BaP). Six new cPAHs have been added to the list to analyze and ten have been removed.   

MPCA Interim Policy

Although it is MPCA's practice to adopt MDH's guidance, since laboratory analytical methods are not available to analyze the six additional cPAH compounds added to the RPF list, it is not feasible at this time. MPCA and MDH are working together to develop analytical methods for the new cPAH compounds. Once analytical methods have been established MPCA will re-evaluate the feasibility of implementing this guidance. Until then, MPCA will continue to use the PEF method to evaluate human health risks from cPAHs. 

Current RBSE manual documents