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From: Putney, David

Sent: Thursday, December 18, 2014 10:51 AM

To: 'Van Der Meyden, Henk'

Cc: Matthew Hakos (mhakos@rti.org); David Green

Subject: RE: Primary Aluminum MACT question

Mr. van der Meyden,

Thank you very much for your interest in the supple mental proposal for RTR amendments to the primary aluminum NESHAP that was published in the FR on 12/08/14 and for bringing these issues to my attention. I will attempt to address your concerns briefly in th is email, but I want to mention that it would be very helpful if yo u would include your questions (i.e., from your email below), along with any other comments you might have on the supplemental proposa l, in a comment to the docket (Docket ID No. EPA-HQ-OAR-2011-0797) dur ing the public comment period. That way these issues (and the EPA responses) will be in the response to comments document.

In your first question you asked what limitation th e bag leak detection systems (BLDS) are to be used to demonstr ate compliance with. As proposed, the RTR amendments would require the use of either a BLDS or a particulate matter (PM) continuous emis sions monitoring system (CEMS) to demonstrate continuous compliance with the newly proposed PM standards.

In your second question you ask for clarification o f paragraph §63.848(o). Specifically, there is confusion as to whether a BLDS is required in order to demonstrate continuous complia nce with the newly proposed PM standards or if a BLDS is simply one of the options for demonstrating continuous compliance. The cited para graph reads, in part, “[f]or each baghouse used to control PM emiss ions, you must install, operate and maintain a bag leak detection system according to paragraphs (o)(1) through (3) of this section, unle ss a system meeting the requirements of paragraph (p) of this section, for a CEMS and continuous emissions rate monitoring system, is ins talled for monitoring the concentration of particulate matter. ” (emphasis added). So, we intended to give 2 options for demonstrating continuous compliance with the newly proposed PM standards – e ither a BLDS or a
PM CEMS.

In your third question you ask for the basis for re quiring BLDS (or, presumably, PM CEMS). I’m not completely clear what you are asking for but I think you are asking for the regulatory basis for this requirement. That is, the regulatory authority unde rlying this requirement. At the beginning of the regulatory tex t in the FR notice we cite 42 U.S.C. 7401, et seq. as the authority fo r these requirements. If I misunderstand your question, or if you want a more specific regulatory citation, please let me know.page 2 of 3

Thanks again for bringing these issues to my attent ion.

David Putney, Environmental Engineer U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Sector Policies and Programs Division 109 T.W. Alexander Drive, RTP, NC 27711 Mail Drop D243-02 Ph: (919) 541-2016 Fax: (919) 541-3207 Email: putney.david@epa.gov

From: Van Der Meyden, Henk [mailto:Henk.VanDerMeyde n@alcoa.com]

Sent: Wednesday, November 26, 2014 9:18 AM

To: Putney, David

Subject: Primary Aluminum MACT question

Mr. Putney,
I am following up on my call from 11/25/2014 regard ing the supplemental proposed rulemaking for the NESHAP for Primary Aluminum Reduction Plants which was signed on 11/13/2014. I have a couple of questions regarding the use of bag leak detection s ystems as proposed under 63.848(f)(6) and (o).

The proposed rule amends Section 63.848 by adding a new paragraph (f)(6) which states:

“(6) For emission sources with fabric filters that choose to demonstrate continuous compliance through bag leak detection systems you must install a bag leak detection system accord ing to the requirements in paragraph (o) of this section, and you must set your operating limit such that the sum of the durations of bag leak detection system alarms does not exceed 5 percent o f the process operating time during a 6-month period.”

First, can you clarify what the limitation is that the bag leak detection systems are to be used for to demonstrate continuous compliance with? Is this to be an option in lieu o f doing a daily visible emissions check as is currently required un der 648(g), or is this a new separate requirement? Second, the wordi ng of the paragraph indicates that a bag leak detection system is one o ption (“choose”). Yet, paragraph 648 (o) indicates that a bag leak de tection system is required (“For each baghouse used to control PM emi ssions, you mustpage 3 of 3

install, operate and maintain a bag leak detection system...”). Can you clarify the option/requirement for bag leak detecti on systems? Third, there is no mention in the preamble of the proposed rule regarding the basis for requiring bag leak detection systems. Ca n you clarify the basis for the proposed requirements regarding bag l eak detection system? Is there a document in the docket?

Thanks for your consideration,

Henk van der Meyden, PG

Sr. Environmental Consultant

Alcoa Inc.

Cell: (843) 296-3359

henk.vandermeyden@alcoa.com