Memo to the project file

From: Damon Highsmith

Date: 09/23/2014

Re: Date by which facilities opting to continue operating amalgam separators that achieve less than 

99.0% removal must have installed a separator. 

This proposed rule would establish a pretreatment standard that would require removal of at least 

99.0% of total mercury from amalgam discharges and BMPs. One way affected dental offices would be 

able to meet the standard would be to use, and properly operate and maintain, a dental amalgam 

separator certified to achieve at least 99.0% reduction of total mercury according to the 2008 ISO 11143 

standard, to perform certain BMPs, and to certify to this effect. 

While the proposed rule does not require the use of an amalgam separator to meet the numeric 

standard, EPA expects that most, if not all dentists that place or remove amalgam would use this widely 

available technology to comply with the proposed numeric standard. EPA expects dentists will choose 

to install and operate an amalgam separator because of the nature of dental offices, the variability of 

the flows and resulting waste streams, and the difficulty in obtaining a sample that represents only 

dental amalgam discharges. Moreover, amalgam separators are an easy to use, low cost technology. 

Dental offices that elect to not use an amalgam separator must meet the proposed numeric limit and 

would be subject to the oversight and compliance requirements for indirect discharges subject to 

national pretreatment requirements. 

In selecting an amalgam separator that meets the requirements of today’s proposed pretreatment 

standards, dentists would verify that the amalgam separator is compliant with the 2008 ISO 11143 

standard and meets the design specifications of the proposed regulation for their configuration. Once 

selected and installed, EPA expects dentists will operate and maintain the separator following all 

manufacturer’s instructions and conduct inspections at least monthly to ensure all features are 

functional. 

EPA does not want to penalize existing dental offices or institutional dental facilities that have already 

installed amalgam separators either voluntarily or to comply with state or local requirements. EPA 

recognizes that these offices may currently have amalgam separators in place that are certified to a 

removal rate slightly less than this proposed standard. For example, some states require dental offices 

to employ amalgam separators that are certified to remove 95% total mercury. EPA does not propose a 

rule that would require existing separators that still have a remaining useful life to be retrofitted with 

new separators, both because of the additional costs incurred by dental facilities that moved ahead of 

EPA’s proposed requirements to install a treatment technology and because of the additional solid 

waste that would be generated by disposal of the existing separators. Therefore, EPA is proposing that, 

as long as they continue to properly operate and maintain existing separators, comply with BMPs, and 

comply with recordkeeping requirements, these facilities would be considered in compliance with the 

numeric standard until ten years from the effective date of the final rule. EPA selected ten years 

because it appears to be a conservative estimate of the useful life of the existing equipment. However, 

if prior to that time, the currently installed separator needs to be replaced, these facilities would need to 

install and operate an amalgam separator that meets a removal efficiency of 99.0%. 
EPA decided that facilities that have not installed separators as of the date of publication of the 

proposed rule in the Federal Register and choose to do so to comply, in part, with the proposed rule

would be required to install amalgam separators that achieve at least 99.0% reduction of total mercury 

according to the 2008 ISO 11143 standard. Choosing the date of publication of the proposed rule in the 

Federal Register as the cutoff date takes into account those facilities that have installed amalgam 

separators and prevents them from having to replace their amalgam separators, while avoiding an 

unintended incentive for additional facilities to select amalgam separators that achieve less than the 

99.0% reduction of total mercury that is included in the proposed rule.