4 The record articles

6 Months Left to Comply with the Subpart MM Amendments

Posted: April 19th, 2019

Authors: Lindsey K. 

Six months ago I wrote about what you should be doing to begin preparing for the October 11, 2019 compliance date for amendments to 40 CFR Part 63, Subpart MM (National Emission Standards for Hazardous Air Pollutants for Chemical Recovery Combustion Sources at Kraft, Soda, Sulfite, and Stand-Alone Semichemical Pulp Mills).  How did you do?  In this blogpost I’ll share some of the ways we’ve been supporting mills with the rule.

Compliance Strategy Guidance

Understanding how all of the changes to the rule will impact your mill can be overwhelming.  That’s why we’ve helped some mills with the development of a compliance strategy guidance document; a “blueprint” that describes each change to the rule, how it impacts your mill, and what needs to be done to address it.  We’ve found this to be a great way to systematically and comprehensively identify each change and potential hurdles you may encounter to comply.

Permit Modifications

In my last blogpost I suggested reviewing the Subpart MM requirements in your operating permit and identifying the permit expiration date.  If it expires after October 11, 2020, you have an obligation to open the permit to incorporate the amended requirements.  Even if it expires before October 11, 2020, it’s advisable to submit a permit modification (or the renewal application) in advance of the October 11, 2019 compliance date.  This acknowledges your intent to comply with the amended requirements even though your permit may specify conflicting requirements after the compliance date.  For example, your permit may require quarterly reporting whereas the amendments now require semiannual reporting.  Ideally, you would obtain a revised permit in advance of the compliance date to avoid conflicting requirements (which would complicate the annual compliance certification).

Continuous Monitoring System Considerations

The amendments to Subpart MM clarify that mills must maintain data quality procedures for continuous monitoring systems (CMS), which include Continuous Opacity Monitoring Systems (COMS), Continuous Emissions Monitoring Systems (CEMS), and Continuous Parametric Monitoring Systems (CPMS) (e.g., scrubber flow rate and pressure drop).  Prior to the amendments, this requirement existed through a reference to the Part 63 General Provisions [i.e., 40 CFR §63.8(d)].  Now, 40 CFR §63.864(f) presents this requirement directly in addition to referencing the Part 63 General Provisions.  While not necessarily new, having the language directly in the rule draws attention to the requirement.  We can support mills with the documentation of these CMS data quality procedures, which must include activities like calibrations, preventative maintenance, corrective maintenance, and data handling. 

Testing Considerations

The first periodic performance test to demonstrate compliance with the amended rule is not due until October 2020, but there is plenty to think about in advance of that date.


I hope you’ve found these suggestions helpful and will consider reaching out to us to help you navigate your way to the October 11, 2019 compliance date.  Should you have any questions about the amendments, feel free to reach out to me at lkroos@all4inc.com or 610.933.5246 x122.


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