**Summary of Major Changes From March 2011 Boiler Final Rules**

**Boiler MACT (Major Source)** 1. Dioxin work practices a. W ork practice standards, in lieu of numeric emission limits, for dioxin/furan emissions for all subcategories 2. PM now considered a combustion - based pollutant for biomass a. S eparate PM emission limits for each design - based biomass subcategory instead of single limit for all units firing biomass l 3. Total selected metals a. A lternate TSM emission limits (to PM emission limits) for subcategories 4. CO CEMS a. A lternate CO CEMS - based emission limits (to stack test

– based limits) for subcategories with CEMS data, couple with CEMS - based monitoring 5. Emission limit changes, based on the following: a. New data b. Changes to old data based on data QA efforts c. Shifting of units between subcategories d. 99% UPLfor CO instead of 99.9% e. Changes to e xisting source emission limits: i. 13 limits are more stringent, 20 are less stringent, and 2 are the same f. Changes to new source emission limits: i. 7 limits are more stringent, 24 are less stringent, and 4 are the same 6. Subcategory

changes a. S eparate subcategories for units designed to combust l ight or heavy liquids instead of single liquid fuel subcategory b. S eparate subcategories for kiln - dried biomass stokers and wet biomass stokers instead of a single biomass stoker subcategory c. A new coal fluidized bed with fluidized bed heat exchanger subcategory 7. Monitoring changes a. Proposing the use of O 2 trim systems instead of O 2 CEMS b. 30 - day

rolling averages for most parameter monitoring instead of 12 - hour bloch averages c. PM CEMS requirement removed for biomass units d. PM CEM requirement for other large units changed to a parameter monitoring sy stem . 8. Control Costs (2008$) a. March 2011 rule: $1.4 billion per year b. Reconsideration final: $1.4 billion per ye ar 9. Benefits (2008$) a. March 2011 rule: $20 billion to $49 billion per year (7% discount rate) b. Reconsideration final: $25 billion to $61 billion per year (7% discount rate)**Boiler Area Source Rule**

 Created a new subcategory for seasonall y operated boilers o Required to complete a tune - up every five ye ars, instead of on a biennial basis as is required for non - seasonal boilers  Added temporary

boilers to the list of boilers not subject to subpart JJJJJJ. o To be consistent with the Boiler MACT  Amending r

ule to specify that all existing boilers subject to the tune - up requirement would have three years (by March 21, 2014) in which to demonstrate initial compliance, instead of one ye ar to demonstrate initial compliance.  Amending the monitoring requirements to allow sources subject to a carbon monoxide emission limit the option to install, operate and maintain a carbon monoxide and oxygen continuous emission monitoring s ys tem.  Changing the requirement for subsequent tune - ups only for oil - fired boilers equal to or less than 5 MMBtu/hr to a tune - up once every 5 years.  A dding residential boilers and electric boilers to the list of boiler s not subject to subpart JJJJJJ to clarify

that boiler used in residences located at commercial (farms) and institutional (universities) facilities are not subject to the rule.  Revising the definition for “Hot water heater” to include small not water boilers.  Amending the mercury and CO emission limits for coal fired boilers. o Mercury

limit changing from 4.8 lb/TBtu to 22 lb/TB tu o CO limit changing from 400 ppm to 420 ppm  Control costs and benefits (2008$) o March 2011 final rule  Costs: $535 million per year  Benefits: $190 million to $470 million per year (7% discount rate) o Reconsideration final  Costs: $490 million per year  Benefits: unchanged

06/07/12