2012-16692. Availability of Addendum to Documentation Supporting the Proposal of the Leeds Metal Site to the National Priorities List

AGENCY:

Environmental Protection Agency.

ACTION:

Proposed rule; notice of data availability.

SUMMARY:

This Notice provides an opportunity to comment on the EPA's revised Hazard Ranking System (HRS) scoring for the Leeds Metal site in Leeds, Maine. The site was proposed to the National Priorities List (NPL) on September 16, 2011.

DATES:

Comments must be submitted (postmarked) on or before August 8, 2012.

ADDRESSES:

Submit your comments, identified by Docket number EPA-HQ-SFUND-2011-0647, by one of the following methods:

• www.regulations.gov: Follow the online instructions for submitting comments.
• Email: [e-mail].
• Mail: Mail comments (no facsimiles or tapes) to Docket Coordinator, Headquarters; U.S. Environmental Protection Agency; CERCLA Docket Office; (Mail Code 5305T); 1200 Pennsylvania Avenue NW.; Washington, DC 20460.
• Hand Delivery or Express Mail: Send comments (no facsimiles or tapes) to Docket Coordinator, Headquarters; U.S. Environmental Protection Agency; CERCLA Docket Office; 1301 Constitution Avenue NW.; EPA West, Room 3334, Washington, DC 20004. Such deliveries are accepted only during the Docket's normal hours of operation (8:30 a.m. to 4:30 p.m., Monday through Friday, excluding Federal holidays).

Instructions: Direct your comments to Docket number EPA-HQ-SFUND-2011-0647. The EPA's policy is that all comments received will be included in the public Docket without change and may be made available online at www.regulations.gov,, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through www.regulations.gov or email. The www.regulations.gov Web site is an “anonymous access” system; that means the EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an email comment directly to the EPA without going through www.regulations.gov,, your email address will be automatically captured and included as part of the comment that is placed in the public Docket and made available on the Internet. If you submit an electronic comment, the EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If the EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, the EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses.

Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in www.regulations.gov or in hard copy at the EPA Headquarters CERCLA Docket Office, 1301 Constitution Avenue NW.; EPA West, Room 3334, Washington, DC 20004. The 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 the EPA Headquarters CERCLA Docket Office is [phone]. Comments must be submitted to the EPA Headquarters as detailed at the beginning of this preamble in the “Addresses” section. Please note that the mailing addresses differ according to method of delivery. There are two different addresses that depend on whether comments are sent by express mail or by postal mail.

FOR FURTHER INFORMATION CONTACT:

Terry Jeng, phone: [phone], email: [e-mail], Site Assessment and Remedy Decisions Branch, Assessment and Remediation Division, Office of Superfund Remediation and Technology Innovation (Mail Code 5204P), U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue NW., Washington, DC 20460.

SUPPLEMENTARY INFORMATION:

Site Scoring Information

The Leeds Metal HRS site score at the time of proposal to the National Priorities List was based on an observed release to ground water of tetrachloroethylene (PCE) and trichloroethylene (TCE) attributable to waste piles and contaminated soil at the Leeds Metal facility resulting in a likelihood of release factor category value of 550. The waste characteristics factor category value of 56 at proposal was based on a hazardous waste quantity for TCE of 10,000, a toxicity value for TCE of 10,000 and a mobility factor for TCE of 1. The TCE toxicity value was based on the most recent health effects data review by the EPA at the time of proposal (76 FR 57702, September 16, 2011).

The targets factor category value was 176.4 at proposal based on populations relying on contaminated drinking water supplies with either PCE or TCE levels above HRS health-based benchmarks (i.e., Level I concentrations). Seven residential wells were documented to contain Level I concentrations of TCE based on the lowest benchmark value for TCE for ground water. One of these seven wells was also documented to contain Level I concentrations of PCE based on the lowest benchmark value for TCE for ground water. The lowest benchmark for TCE was the cancer slope screening concentration (0.21 μg/L) and the lowest benchmark for PCE was also the cancer slope screening concentration (1.6 μg/L) based on the most recent health effects data review by the EPA at the time of proposal. Seventeen residents were documented to drink the water from the seven wells with Level I concentrations. The likelihood of release, waste characteristics and targets factor category values resulted in a ground water migration pathway score of 100.00 and an HRS site score of 50.00 at proposal (see 76 FR 57702, September 16, 2011).

Background on TCE and PCE Benchmarks and Toxicity Values

Following the September 16, 2011, proposal of the Leeds Metal site to the National Priorities List, the toxicity and benchmark values for PCE and TCE used in HRS scoring were updated to reflect the EPA's most recent health effects evaluations on these two substances. The revisions for these two substances were made available to the public on March 31, 2012 (see http://www.epa.gov/​superfund/​sites/​npl/​hrsres/​tools/​scdm.htm). Among the factors that changed, which affect the toxicity and drinking water benchmarks, are the oral reference dose (RfD) and the oral cancer slope factors. Using the HRS methods for determining toxicity and benchmarks (see HRS Sections 2.4.1.1 and 2.5.2), the toxicity for TCE has changed from 10,000 to 1,000, however the toxicity for PCE remains the same at 100. When recalculating the drinking water benchmarks for TCE, the lowest TCE benchmark value for drinking water remains based on the cancer slope screening concentrations; the recalculated TCE benchmark value changes from 0.21 μg/L to 1.0 μg/L. The lowest drinking water benchmark for PCE changes from 1.6 μg/L to 5.0 μg/L.

Background on Targets Factor Category Value

Based on the changes to the TCE and PCE benchmarks, two drinking water wells within the 4-mile target distance limit have TCE concentrations above its lowest benchmark and no well had PCE concentrations above its lowest benchmark. Thus, now only two wells and the population using these wells are considered Level I.

The Leeds Metal site's potential population factor value has been updated to reflect those people utilizing drinking water not currently found to be contaminated due to this site, but that for HRS purposes are considered potentially threatened. The basic information supporting the calculation of this value was presented in Reference 11 which was available to the public at the time of NPL proposal; however, the factor value was not included in the HRS documentation record at that time. Populations utilizing either public or private water supplies have been incorporated into the HRS evaluation based on the information in Reference 11 to the HRS documentation record at proposal, which relied on 1990 and 2000 census data and 2009 population data from the State of Maine. The impact on eligibility of the site to qualify for the NPL has been confirmed based on the most current information, including updated census data (2010) and 2012 well use information.

New Benchmarks, Toxicities, Targets and Site Score

Due to the revised toxicity values and the update to the evaluation of the potential targets, the likelihood of release factor category value remains 550, the same as at proposal; the waste characteristics factor category value, which was 100 at proposal, drops to 56 due to the changes in the Level I wells; the potential population factor value, the applicable targets factor category value, changes from 220 to 176.4. As a result of these updates, the HRS ground water migration pathway score changes from 100.00 to 65.85; and the HRS site score changes from 50.00 to 32.92. The NPL listing decision is not changed by this updated information and scoring.

The updated HRS scoring documentation is available in www.regulations.gov under docket number EPA-HQ-SFUND-2011-0647.

List of Subjects in 40 CFR 300

• Environmental protection
• Air pollution control
• Chemicals
• Hazardous substances
• Hazardous waste
• Intergovernmental relations
• Natural resources
• Oil pollution
• Penalties
• Reporting and recordkeeping requirements
• Superfund
• Water pollution control
• Water supply

Dated: June 29, 2012.

James E. Woolford,

Director, Office of Superfund Remediation and Technology Innovation.