Special Topics in Environmental Management

10 Things to Know about the Proposed Dental Amalgam Rule—Part 2

10 Things to Know about the Proposed Dental Amalgam Rule—Part 2

6. New Category—Dental Industrial Users. When the EPA promulgates categorical industrial pretreatment standards, the affected dischargers are called, in general, “Categorical Industrial Users (CIUs).” For the proposed new rule, the EPA is establishing a new CIU tailored to the dental offices covered, which is the “Dental Industrial User (DIU).” DIUs will not be subject to the more stringent Significant Industrial User (SIU) requirements but, instead, will allow Control Authorities (e.g., EPA, states, or POTWs) to focus on facilities zthat do not meet the compliance requirements of the DIU. Control Authorities will also have the authority to implement the Non-Significant Categorical Industrial User (NSCIU) category if they meet the conditions in 40 CFR 403.3(v)(2).

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7. General Pretreatment Standards. Unlike direct dischargers that must comply with National Pollutant Discharge Elimination System (NPDES) permit effluent limitations, indirect dischargers must comply with pretreatment standards. Due to the approximately 100,000 covered facilities, the EPA is proposing amendments to the General Pretreatment Standards regulations at 40 CFR Part 403 for indirect discharges to POTWs for DIUs that are based on performance and control and treatment technologies, which, in this case are:

  • Best Available Technology Economically Feasible (BAT),
  • Best management practices (BMPs),
  • New Source Performance Standards (NSPS),
  • Pretreatment standards for existing sources (PSES), and
  • Pretreatment standards for new sources (PSNS).

Regarding the above performance standards (NSPS/PSES/PSNS), the EPA did not propose more stringent requirements for new sources as opposed to existing sources. Both existing and new sources will be subject to the BAT and BMPs proposed, because, according to the EPA, there are no newer technologies available that are demonstrated to be more effective, and the proposed standards do not present a barrier to entry. In addition, PSES facilities that already operate amalgam separators with certified removal efficiency of 95 percent will not be required to meet the 99 percent efficiency requirements until 10 years from the effective date of the final rule (or if the equipment is replaced before then), as long as they are in compliance with BMPs and other requirements.

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8. Best Available Technology. The EPA assessed different technologies for capturing mercury and found amalgam separators to be “practical, affordable, and readily available.” The EPA estimates that about 40 percent of dentist offices nationally have already installed amalgam separators with removal efficiencies of from 95 percent to 99 percent. The proposed rule would require dental offices to use amalgam separators “certified to achieve at least 99.0% reduction of total mercury according to the 2008 ISO 11143 standard …” and to properly operate and maintain them.  Existing sources will have 3 years from the date of the final rule to meet the numeric standards while new sources must be in compliance when they began discharging.

9. Best Management Practices. In addition to the amalgam separator requirements, the EPA identified two additional BMPs to further protect against mercury discharges, which prohibit:

  • Use of vacuum line cleaners that contain bleach or are corrosive and that can solubilize bound mercury, potentially increasing mercury discharges. The EPA proposes to require use of cleaners that are pH neutral.
  • The flushing of scrap amalgam (contact and noncontact) into drains that do not lead to an amalgam separator (e.g., a cuspidor not attached to the vacuum line), and into general use sinks.

10. Reporting Requirements. Offices and facilities that are subject to the proposed rule would be required to submit an annual certification to the Control Authority as well as two onetime reports:

  • A 90-day compliance report, and
  • A baseline monitoring report, which must be submitted within 180 days of the effective date of any final rule.

Those facilities that do not “place or remove” amalgam, except in limited emergency circumstances, would also need to certify that to the Control Authority.


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