MCP Regulatory Reform Proposal

MassDEP is proposing significant amendments to the Massachusetts Contingency Plan (MCP), 310 CMR 40.0000, as part of the agency’s regulatory reform efforts. The MCP sets forth the procedures and standards for notification, assessment, and remediation of disposal sites resulting from the release of oil and/or hazardous materials to the environment.  These regulations govern the response to sudden oil and hazardous material spills, as well as the assessment and cleanup of Brownfields, properties contaminated by past use as industrial or commercial facilities, prior to their redevelopment and productive reuse. Consistent with regulatory reform goals, the proposed MCP amendments enhance regulatory efficiency in a manner that benefits both parties conducting response actions and MassDEP, while maintaining a high standard of environmental protection.

The proposal include several issues specific to vapor intrusion, including the closure of sites with an active sub-slab system and  consideration of future buildings (and possible vapor intrusion) on currently vacant land.

The MassDEP website (http://www.mass.gov/dep/service/regulations/newregs.htm#proposed and then scroll down to the MCP revisions) offers the proposed revisions as both a redline/strikeout document and a “clean” (just the new text) version. The spreadsheets documenting changes to the MCP numerical standards are also available to download, as is a 4-page summery of the proposals.

An extended (until May 17, 2013) Public Comment Period will allow reviewers time to develop comments on this substantial package. MassDEP also expects to hold discussion sessions over the next few months to address specific issues in the proposal.

Updates on TCE & Vapor Intrusion

MassDEP is following other state and federal agencies as they develop approaches to addressing exposure to trichloroethylene, particularly through the vapor intrusion pathway.  Please feel free to send along any additional links you are aware of through the Comments link below.

TCE Updates

MassDEP has recently published several item related to indoor air/vapor intrusion sites.

TCE Status Update
TCE Status Update REVISED 4/18/2013 (PDF): Revised TCE Fact Sheet – 04-18-2013
TCE Status Update REVISED 4/18/2013 (MS Word): Revised TCE Fact Sheet – 04-18-2013
This update provides a summary of the available toxicity information for TCE, the status of the MassDEP review of this information, and an appropriate approach to assessing disposal sites during this review period.

An Example Fact Sheet for an Indoor Air Contamination Site
EXAMPLE-Fact_Sheet_TCE-PCE-DCE_Site.pdf (PDF file)
EXAMPLE-Fact_Sheet_TCE-PCE-DCE_Site.doc (MS Word file)

An Example Notice of Immediate Response Action for an Indoor Air Contamination Site
EXAMPLE_Notice-of-IRA_TCE-PCE-DCE-Site.pdf (PDFfile)
EXAMPLE_Notice-of-IRA_TCE-PCE-DCE-Site.doc (MS Word file)

The Department has also updated the Risk Assessment ShortForms, including those for evaluating indoor air contamination. They can be downloaded from the MassDEP website by clicking on this link:  http://www.mass.gov/dep/cleanup/compliance/shortforms.zip.

(The download is a ZIP file containing the ShortForm Excel files, an index and a User’s Guide.)

PCE Toxicity Value Review

On February 10, 2012, U.S. EPA published a final Health Assessment for Tetrachloroethylene (Perchloroethylene, or “Perc” or PCE) on the IRIS database (http://cfpub.epa.gov/ncea/iris/index.cfm?fuseaction=iris.showQuickView&substance_nmbr=0106). In the new Health Assessment, EPA provides revised toxicity values for oral exposures (a reference dose [RfD] for non-cancer and a cancer slope factor [CSF] for cancer risk) and for inhalation exposures (a reference concentration [RfC]for non-cancer and an inhalation unit risk factor [URF] for cancer).

Several years ago, while EPA’s Health Assessment was still in progress, assessment of tetracholorethylene in indoor air arose as a critical issue for a number of MCP sites.  The Bureau of Waste Site Cleanup (BWSC) requested that the Office of Research and Standards (ORS) review the inhalation unit risk factor (URF, for evaluating cancer risk from exposure to air contaminants) in use at the time.  ORS toxicologists conducted the review of the scientific literature available at the time, obtained a peer-review of the ORS assessment, and published a revised inhalation unit risk value in 2008 (http://www.mass.gov/dep/toxics/chemrs.htm).

In addition to the URF published in 2008, ORS has recently reviewed and updated the RfC used to calculate MassDEP’s Threshold Effects Limits (non-cancer) for tetrachloroethylene (http://www.mass.gov/dep/toxics/stypes/telaal.htm).  This review considered all of the toxicological data currently available.

Some of the toxicity values published in EPA’s Health Assessment differ significantly from those developed by MassDEP.  ORS plans to review the basis for the values provided by EPA before adopting final values.  MassDEP expects to complete the review by the end of March. Until then, MassDEP recommends the continued use of the MassDEP cancer slope factor of 5 x 10-2 (mg/kg/day)-1 and the inhalation unit risk of 1 x 10-5 (µg/m3)-1 for site-specific risk assessments conducted under the Massachusetts Contingency Plan (310 CMR 40.0000).

Any questions may be directed to BWSC.Information@state.ma.us.

Vapor Intrusion Discussion Summary

A summary of the February 9, 2012 discussion about revisions related to the Vapor Intrusion pathway is now available. These are notes from the discussion and not MassDEP’s interpretation. For those who participated in the conversation, please read the notes and comment on anything we may have missed or misinterpreted. For those who missed the meeting, this is a great chance to add your voice to the discussion! Either way, please use the comment block below so that the wider community can benefit from your thoughts & observations.

MS Word version: VI-Discussion-2012-02-09-notes (63 KB)

Adobe PDF version: VI-Discussion-2012-02-09-notes (373 KB)

Questions to Ponder for Workgroup Meeting

A list of topics and discussion items for the February 9, 2012 workgroup meeting has been posted on the MCP Reg Reform Blog.

Workgroup Meeting

During the development of the Vapor Intrusion Guidance, MassDEP staff and Workgroup members identified several potential changes to the MCP that could strengthen and streamline the notification, assessment, cleanup & closure of vapor intrusion sites.  A Workgroup meeting has been scheduled to discuss such potential regulation revisions:

  • Thursday, February 9th, 1:00 – 3:00 pm @ MassDEP, One Winter Street, Boston, MA 02108

In addition, this and other reg reform initiatives will be on the agenda for the January 26, 2012 Waste Site Cleanup Advisory Committee meeting (9:30 AM – 12:00 PM, MassDEP Boston).