02-30261. Draft Guidance For Evaluating The Vapor Intrusion to Indoor Air Pathway From Groundwater And Soils (Subsurface Vapor Intrusion Guidance)

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Notice.

SUMMARY:

EPA is publishing a draft guidance addressing the evaluation of the “vapor intrusion pathway.” The draft guidance is intended to provide a tool to help the user conduct a screening evaluation as to whether or not the vapor intrusion exposure pathway is complete and, if so, whether it poses an unacceptable risk to human health. It is not intended to provide recommendations for delineating extent of risk or eliminating risk.

DATES:

Send your comments to reach us on or before February 27, 2003.

ADDRESSES:

Comments may be submitted electronically, by mail, by facsimile, or through hand delivery/courier. Send an original and two copies of your comments to: OSWER Docket, Environmental Protection Agency, Mailcode: 5305-G, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, Attention Docket ID No. RCRA-2002-0033. Follow the detailed instructions as provided in section I.B.

FOR FURTHER INFORMATION CONTACT:

For general information, contact the RCRA Hotline at [phone] (toll free) or call [phone]; or, for hearing impaired, call TDD [phone] or TDD [phone]. For more information on specific aspects of this guidance, contact Henry Schuver, Office of Solid Waste (5303W), U. S. Environmental Protection Agency, Ariel Rios Building, 1200 Pennsylvania Avenue, NW, Washington, DC 20460-0002, [phone], e-mail address: [e-mail].

SUPPLEMENTARY INFORMATION:

I. General Information

A. How Can I Get Copies Of This Document And Other Related Information?

1. Docket

EPA has established an official public docket for this action under Docket ID No. RCRA-2002-0033. The official public docket consists of the documents specifically referenced in this action, any public comments received, and other information related to this action. Although a part of the official docket, the public docket does not include Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. The official public docket is the collection of materials that is available for public viewing at the OSWER Docket in the EPA Docket Center, (EPA/DC) EPA West, Room B102, 1301 Constitution Ave., NW, Washington, DC. The EPA Docket Center Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is [phone] and the telephone number for OSWER Docket is 202-566-0207. To view docket materials, you should call in advance and make an appointment. You may copy a maximum of 100 pages from any regulatory docket at no charge (unless the documents require copyright permission). Additional copies cost $0.15 per page.

2. Electronic Access

You may access this Federal Register document electronically through the EPA Internet under the “Federal Register” listings at http://www.epa.gov/​fedrgstr/​.

An electronic version of the public docket is available through EPA's electronic public docket and comment system, EPA Dockets. You may use EPA Dockets at http://www.epa.gov/​edocket/​ to submit or view public comments, access the index listing of the contents of the official public docket, and to access those documents in the public docket that are available electronically. Once in the system, select “search,” then key in the appropriate docket identification number.

Certain types of information will not be placed in the EPA Dockets. Information claimed as CBI and other information whose disclosure is restricted by statute, which is not included in the official public docket, will not be available for public viewing in EPA's electronic public docket. EPA's policy is that copyrighted material will not be placed in EPA's electronic public docket but will be available only in printed, paper form in the official public docket. When a document is selected from the index list in EPA Dockets, the system will identify whether the document is available for viewing in EPA's electronic public docket. Although not all docket materials may be available electronically, you may still access any of the publicly available docket materials through the docket facility identified in Unit I.B.

For public commenters, it is important to note that EPA's policy is that public comments, whether submitted electronically or in paper, will be made available for public viewing in EPA's electronic public docket as EPA receives them and without change, unless the comment contains copyrighted material, CBI, or other information whose disclosure is restricted by statute. When EPA identifies a comment containing copyrighted material, EPA will provide a reference to that material in the version of the comment that is placed in EPA's electronic public docket. The entire printed comment, including the copyrighted material, will be available in the public docket.

Public comments submitted on computer disks that are mailed or delivered to the docket will be transferred to EPA's electronic public docket. Public comments that are mailed or delivered to the Docket will be scanned and placed in EPA's electronic public docket. Where practical, physical objects will be photographed, and the photograph will be placed in EPA's electronic public docket along with a brief description written by the docket staff.

B. How and To Whom Do I Submit Comments?

You may submit comments electronically, by mail, by facsimile, or through hand delivery/courier. To ensure proper receipt by EPA, identify the appropriate docket identification number in the subject line on the first page of your comment. Please ensure that your comments are submitted within the specified comment period. Comments received after the close of the comment period will be marked “late.” EPA is not required to consider these late comments, but will make every effort to do so if time and resources permit. If you wish to submit CBI or information that is otherwise protected by statute, please follow the instructions in section I.C. Do not use EPA Dockets or e-mail to submit CBI or information protected by statute.

1. Electronically

If you submit an electronic comment as prescribed below, EPA recommends that you include your name, mailing address, and an e-mail address or other contact information in the body of your comment. Also include this contact information on the outside of any disk or CD ROM you submit, and in any cover letter accompanying the disk or CD ROM. This ensures that you can be identified as the submitter of the comment and allows EPA to contact you in case EPA cannot read your comment due to technical difficulties or needs further information on the substance of your comment. EPA's policy is that EPA will not edit your comment, and any identifying or contact information provided in the body of a comment will be included as part of the comment that is placed in the official public docket, and made available in EPA's electronic public docket. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment.

i. EPA Dockets

Your use of EPA's electronic public docket to submit comments to EPA electronically is EPA's preferred method for receiving comments. Go directly to EPA Dockets at http://www.epa.gov/​edocket,, and follow the online instructions for submitting comments. To access EPA's electronic public docket from the EPA Internet Home Page, select “Information Sources,” “Dockets,” and “EPA Dockets.” Once in the system, select “search,” and then key in Docket ID No. RCRA-2002-0033. The system is an “anonymous access” system, which means EPA will not know your identity, e-mail address, or other contact information unless you provide it in the body of your comment.

ii. E-mail

Comments may be sent by electronic mail (e-mail) to [e-mail], Attention Docket ID No. RCRA-2002-0033. In contrast to EPA's electronic public docket, EPA's e-mail system is not an “anonymous access” system. If you send an e-mail comment directly to the Docket without going through EPA's electronic public docket, EPA's e-mail system automatically captures your e-mail address. E-mail addresses that are automatically captured by EPA's e-mail system are included as part of the comment that is placed in the official public docket, and made available in EPA's electronic public docket.

iii. Disk or CD ROM

You may submit comments on a disk or CD ROM that you mail to the mailing address identified in Unit I.B.2, below. These electronic submissions will be accepted in WordPerfect or ASCII file format. Avoid the use of special characters and any form of encryption.

2. By Mail

Send an original and two copies of your comments to: OSWER Docket, Environmental Protection Agency, Mailcode: 5305-G, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, Attention Docket ID No. RCRA-2002-0033.

3. By Hand Delivery or Courier

Deliver your comments to: OSWER Docket, EPA West Building, Room B102, 1301 Constitution Avenue, NW, Washington DC, 20004, Attention Docket ID No. RCRA-2002-0033. Such deliveries are only accepted during the Docket's normal hours of operation as identified in section I.A.1.

4. By Facsimile

Fax your comments to [phone], Attention Docket ID No. RCRA-2002-0033.

C. How Should I Submit CBI To the Agency?

Do not submit information that you consider to be CBI electronically through EPA's electronic public docket or by e-mail. Send or deliver information identified as CBI only to the following address: RCRA CBI Document Control Officer, Office of Solid Waste, Environmental Protection Agency, Mailcode 5305-W, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, Attention Docket ID No. RCRA-2002-0033. You may claim information that you submit to EPA as CBI by marking any part or all of that information as CBI (if you submit CBI on disk or CD ROM, mark the outside of the disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is CBI). Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2.

In addition to one complete version of the comment that includes any information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket and EPA's electronic public docket. If you submit the copy that does not contain CBI on disk or CD ROM, mark the outside of the disk or CD ROM clearly that it does not contain CBI. Information not marked as CBI will be included in the public docket and EPA's electronic public docket without prior notice. If you have any questions about CBI or the procedures for claiming CBI, please consult the person identified in the FOR FURTHER INFORMATION CONTACT section.

D. What Should I Consider as I Prepare My Comments for EPA?

You may find the following suggestions helpful for preparing your comments:

1. Explain your views as clearly as possible.

2. Describe any assumptions that you used.

3. Provide any technical information and/or data you used that support your views.

4. If you estimate potential burden or costs, explain how you arrived at your estimate.

5. Provide specific examples to illustrate your concerns.

6. Offer alternatives.

7. Make sure to submit your comments by the comment period deadline identified.

8. To ensure proper receipt by EPA, identify the appropriate docket identification number in the subject line on the first page of your response. It would also be helpful if you provided the name, date, and Federal Register citation related to your comments.

II. Summary

The draft guidance (Evaluating the Vapor Intrusion to Indoor Air Pathway From Groundwater and Soils) examines a single exposure pathway—the “vapor intrusion pathway.” It is intended to be a screening tool to aid users in determining whether a vapor intrusion pathway is complete and, if so, whether the completed pathway poses an unacceptable risk to human health. A complete pathway means that humans are exposed to vapors originating from site contamination. The draft guidance begins with simple and generally reasonable conservative screening approaches and gradually progresses toward a more complex assessment involving increasingly greater use of site-specific data. For those sites determined to have an incomplete vapor intrusion pathway, further consideration of the current site situation generally should not be needed. For those sites determined to have a complete pathway, guidance is provided to evaluate whether the pathway does or does not pose a potential significant risk to human health.

This draft guidance is not intended to provide recommendations to delineate the extent of risk or eliminate the risk. Its sole purpose is to determine if there is a potential for an unacceptable risk. EPA generally recommends reevaluation of those sites that are screened-out if site conditions or land use changes in a way that might alter a decision to screen-out, or other new information suggests greater conservatism is appropriate in assessing the vapor intrusion pathway.

Because this is a draft guidance document, not a regulation, it is not subject to the notice and comment requirements of the Administrative Procedure Act. Nonetheless, EPA is choosing, in its discretion, to solicit comments on the document in the interest of developing the most accurate, useful guidance document.

III. At What Sites Are We Currently Suggesting You Use This Guidance?

EPA suggests that you use this draft guidance at RCRA Corrective Action, CERCLA (National Priorities List and Superfund Alternative Sites), and Brownfields sites, but, at this time, we do not recommended it for use at Subtitle I Underground Storage Tank (UST) sites.

We recommend that State and Regional UST corrective action programs continue to use a risk-based decision making approach as described in OSWER Directive 9610.17: Use of Risk-Based Decision Making in UST Corrective Action Program to address this pathway at UST sites.

IV. Data Evaluation

Vapor intrusion is a rapidly developing field of science and policy and this draft guidance is intended to aid in evaluating the potential for human exposure from this pathway given the state-of-the-science at this time. EPA will continue to explore this area in efforts to improve the state-of-the-science of this complex exposure pathway. A workgroup of EPA and State representatives is currently being organized to evaluate this pathway over the next several years. As the state-of-the-science improves, this guidance will be revised as appropriate. EPA and State site managers are encouraged to contact EPA's Office of Solid Waste (OSW) to join the workgroup and/or provide the workgroup with relevant site information that can be added to the Office of Solid Waste and Emergency Response (OSWER) database to facilitate these efforts.

V. Will This Draft Guidance Supersede Existing Guidance?

This draft guidance supersedes the draft RCRA EI Supplemental Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway (December 2001). It does not supersede State guidance. However, EPA believes that States will find this guidance useful and anticipates that States will consider this draft guidance when evaluating the vapor intrusion pathway. Additionally, the lead regulatory authority for a site may determine that criteria other than those recommended in this draft guidance are more appropriate for the specific site or area. For example, site-specific indoor air criteria may differ from the generic indoor air criteria generally recommended in this guidance and, consequently, the corresponding soil gas or groundwater screening levels may differ. Also, the site-specific relationship between indoor air concentrations and subsurface soil gas or groundwater concentrations may differ from that assumed in developing this guidance. Therefore, we suggest that the first step generally should be to consult with the lead regulatory authority to identify the most appropriate approach for evaluation of any potential vapor intrusion to indoor air pathway.

VI. When Do We Recommend You Start Using This Draft Guidance?

EPA recommends that you consider the use of this draft guidance now.

Although the document is still in draft and EPA is requesting comment on it, it has gone through extensive internal and inter-agency review, and we believe it is a technically sound product. While we hope to receive useful comments that will result in improvements when the draft is finalized, we believe the document in its current state provides the best guidance and information currently available on these issues.

Please recognize that this is a guidance document, not a regulation. This document presents current technical and policy recommendations of the Office of Solid Waste and Emergency Response, based EPA's current understanding of the subsurface vapor intrusion. EPA personnel (and of course, states) are free to use and accept other technically sound approaches, either on their own initiative, or at the suggestion of responsible parties or other interested parties. In addition, personnel who use this guidance document are free to modify the approach recommended in this guidance. This guidance document does not impose any requirements or obligations on EPA, states, or the regulated community. Rather, the sources of authority and requirements for addressing subsurface vapor intrusion are the relevant statutes and regulations (e.g., RCRA, CERCLA and the NCP).

Dated: November 22, 2002.

Marianne Lamont Horinko,

Assistant Administrator, Office of Solid Waste and Emergency Response.